Changeset 2032

Timestamp:

Jun 19, 2008 2:10:28 PM (16 years ago)

Author:

bennylp

Message:

Ticket #549: major modification in media transport API to support more offer/answer scenarios

Location:

pjproject/trunk

Files:

• pjmedia/include/pjmedia/sdp.h (modified) (1 diff)
• pjmedia/include/pjmedia/transport.h (modified) (7 diffs)
• pjmedia/src/pjmedia/endpoint.c (modified) (1 diff)
• pjmedia/src/pjmedia/sdp.c (modified) (1 diff)
• pjmedia/src/pjmedia/transport_ice.c (modified) (10 diffs)
• pjmedia/src/pjmedia/transport_srtp.c (modified) (30 diffs)
• pjmedia/src/pjmedia/transport_udp.c (modified) (6 diffs)
• pjsip/include/pjsua-lib/pjsua_internal.h (modified) (4 diffs)
• pjsip/src/pjsua-lib/pjsua_call.c (modified) (17 diffs)
• pjsip/src/pjsua-lib/pjsua_media.c (modified) (15 diffs)

pjproject/trunk/pjmedia/include/pjmedia/sdp.h

@@ -318 +318 @@
                                                pjmedia_sdp_rtcp_attr *rtcp);
 
+
+/**
+ * Create a=rtcp attribute.
+ *
+ * @param pool          Pool to create the attribute.
+ * @param a             Socket address.
+ *
+ * @return              SDP RTCP attribute.
+ */
+PJ_DECL(pjmedia_sdp_attr*) pjmedia_sdp_attr_create_rtcp(pj_pool_t *pool,
+                                                        const pj_sockaddr *a);
 
 

pjproject/trunk/pjmedia/include/pjmedia/transport.h

@@ -321 +321 @@
 
     /**
+     * Prepare the transport for a new media session.
+     *
+     * Application should call #pjmedia_transport_media_create() instead of 
+     * calling this function directly.
+     */
+    pj_status_t (*media_create)(pjmedia_transport *tp,
+                                pj_pool_t *sdp_pool,
+                                unsigned options,
+                                const pjmedia_sdp_session *remote_sdp,
+                                unsigned media_index);
+
+    /**
      * This function is called by application to generate the SDP parts
      * related to transport type, e.g: ICE, SRTP.
      *
-     * Application should call #pjmedia_transport_media_create() instead of 
-     * calling this function directly.
-     */
-    pj_status_t (*media_create)(pjmedia_transport *tp,
-                                pj_pool_t *pool,
-                                unsigned options,
-                                pjmedia_sdp_session *sdp_local,
-                                const pjmedia_sdp_session *sdp_remote,
-                                unsigned media_index);
+     * Application should call #pjmedia_transport_encode_sdp() instead of
+     * calling this function directly.
+     */
+    pj_status_t (*encode_sdp)(pjmedia_transport *tp,
+                              pj_pool_t *sdp_pool,
+                              pjmedia_sdp_session *sdp_local,
+                              const pjmedia_sdp_session *rem_sdp,
+                              unsigned media_index);
 
     /**
@@ -342 +353 @@
      */
     pj_status_t (*media_start) (pjmedia_transport *tp,
-                                pj_pool_t *pool,
-                                pjmedia_sdp_session *sdp_local,
+                                pj_pool_t *tmp_pool,
+                                const pjmedia_sdp_session *sdp_local,
                                 const pjmedia_sdp_session *sdp_remote,
                                 unsigned media_index);
@@ -627 +638 @@
 
 /**
- * Generate local SDP parts that are related to the specified media transport.
- * Remote SDP might be needed as reference when application is in deciding
- * side of negotiation (callee side), otherwise it should be NULL.
- *
- * This API is provided to allow the media transport to add more information
- * in the SDP offer, before the offer is sent to remote. Additionally, for 
- * answerer side, this callback allows the media transport to reject the 
- * offer before this offer is processed by the SDP negotiator. 
+ * Prepare the media transport for a new media session, and optionally
+ * encode the relevant information in the \a sdp_local. Application must
+ * call this function before starting a new media session using this
+ * transport.
  *
  * This is just a simple wrapper which calls <tt>media_create()</tt> member 
@@ -640 +647 @@
  *
  * @param tp            The media transport.
- * @param pool          The memory pool.
+ * @param sdp_pool      Pool object to allocate memory related to SDP
+ *                      messaging components.
  * @param option        Option flags, from #pjmedia_tranport_media_option
- * @param sdp_local     Local SDP.
- * @param sdp_remote    Remote SDP.
+ * @param rem_sdp       Remote SDP if it's available.
  * @param media_index   Media index in SDP.
  *
@@ -649 +656 @@
  */
 PJ_INLINE(pj_status_t) pjmedia_transport_media_create(pjmedia_transport *tp,
-                                    pj_pool_t *pool,
+                                    pj_pool_t *sdp_pool,
                                     unsigned options,
-                                    pjmedia_sdp_session *sdp_local,
-                                    const pjmedia_sdp_session *sdp_remote,
+                                    const pjmedia_sdp_session *rem_sdp,
                                     unsigned media_index)
 {
-    return (*tp->op->media_create)(tp, pool, options, sdp_local, sdp_remote, 
+    return (*tp->op->media_create)(tp, sdp_pool, options, rem_sdp, 
                                    media_index);
 }
+
+
+/**
+ * Put transport specific information into the SDP. This function can be
+ * called to create SDP offer or answer, depending whether \a rem_sdp
+ * parameter is present.
+ *
+ * This is just a simple wrapper which calls <tt>encode_sdp()</tt> member 
+ * of the transport.
+ *
+ * @param tp            The media transport.
+ * @param sdp_pool      Pool object to allocate memory related to SDP
+ *                      messaging components.
+ * @param sdp           The local SDP to be filled in information from the
+ *                      media transport.
+ * @param rem_sdp       Remote SDP if it's available.
+ * @param media_index   Media index in SDP.
+ *
+ * @return              PJ_SUCCESS on success, or the appropriate error code.
+ */
+PJ_INLINE(pj_status_t) pjmedia_transport_encode_sdp(pjmedia_transport *tp,
+                                            pj_pool_t *sdp_pool,
+                                            pjmedia_sdp_session *sdp,
+                                            const pjmedia_sdp_session *rem_sdp,
+                                            unsigned media_index)
+{
+    return (*tp->op->encode_sdp)(tp, sdp_pool, sdp, rem_sdp, media_index);
+}
+
 
 /**
@@ -674 +709 @@
  *
  * @param tp            The media transport.
- * @param pool          The memory pool.
+ * @param tmp_pool      The memory pool for allocating temporary objects.
  * @param option        The media transport option.
  * @param sdp_local     Local SDP.
@@ -683 +718 @@
  */
 PJ_INLINE(pj_status_t) pjmedia_transport_media_start(pjmedia_transport *tp,
-                                    pj_pool_t *pool,
-                                    pjmedia_sdp_session *sdp_local,
+                                    pj_pool_t *tmp_pool,
+                                    const pjmedia_sdp_session *sdp_local,
                                     const pjmedia_sdp_session *sdp_remote,
                                     unsigned media_index)
 {
-    return (*tp->op->media_start)(tp, pool, sdp_local, sdp_remote, media_index);
+    return (*tp->op->media_start)(tp, tmp_pool, sdp_local, sdp_remote, 
+                                  media_index);
 }
 

pjproject/trunk/pjmedia/src/pjmedia/endpoint.c

@@ -363 +363 @@
 #if defined(PJMEDIA_HAS_RTCP_IN_SDP) && PJMEDIA_HAS_RTCP_IN_SDP!=0
     if (sock_info->rtcp_addr_name.addr.sa_family != 0) {
-        const pj_sockaddr *rtcp_addr = &sock_info->rtcp_addr_name;
-
-        attr = PJ_POOL_ALLOC_T(pool, pjmedia_sdp_attr);
-        attr->name = pj_str("rtcp");
-        attr->value.ptr = (char*) pj_pool_alloc(pool, 80);
-        if (rtcp_addr->addr.sa_family == pj_AF_INET()) {
-            attr->value.slen = 
-                pj_ansi_snprintf(attr->value.ptr, 80,
-                                "%u IN IP4 %s",
-                                pj_ntohs(rtcp_addr->ipv4.sin_port),
-                                pj_inet_ntoa(rtcp_addr->ipv4.sin_addr));
-        } else if (rtcp_addr->addr.sa_family == pj_AF_INET6()) {
-            char tmp_addr[PJ_INET6_ADDRSTRLEN];
-            attr->value.slen = 
-                pj_ansi_snprintf(attr->value.ptr, 80,
-                                "%u IN IP6 %s",
-                                pj_sockaddr_get_port(rtcp_addr),
-                                pj_sockaddr_print(rtcp_addr, tmp_addr, 
-                                                  sizeof(tmp_addr), 0));
-
-        } else {
-            pj_assert(!"Unsupported address family");
-            return PJ_EAFNOTSUP;
-        }
-        pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+        attr = pjmedia_sdp_attr_create_rtcp(pool, &sock_info->rtcp_addr_name);
+        if (attr)
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
     }
 #endif

pjproject/trunk/pjmedia/src/pjmedia/sdp.c

@@ -414 +414 @@
 }
 
+
+PJ_DEF(pjmedia_sdp_attr*) pjmedia_sdp_attr_create_rtcp(pj_pool_t *pool,
+                                                       const pj_sockaddr *a)
+{
+    enum {
+        ATTR_LEN = PJ_INET6_ADDRSTRLEN+16
+    };
+    pjmedia_sdp_attr *attr;
+
+    attr = PJ_POOL_ALLOC_T(pool, pjmedia_sdp_attr);
+    attr->name = pj_str("rtcp");
+    attr->value.ptr = (char*) pj_pool_alloc(pool, ATTR_LEN);
+    if (a->addr.sa_family == pj_AF_INET()) {
+        attr->value.slen = 
+            pj_ansi_snprintf(attr->value.ptr, ATTR_LEN,
+                            "%u IN IP4 %s",
+                            pj_ntohs(a->ipv4.sin_port),
+                            pj_inet_ntoa(a->ipv4.sin_addr));
+    } else if (a->addr.sa_family == pj_AF_INET6()) {
+        char tmp_addr[PJ_INET6_ADDRSTRLEN];
+        attr->value.slen = 
+            pj_ansi_snprintf(attr->value.ptr, ATTR_LEN,
+                            "%u IN IP6 %s",
+                            pj_sockaddr_get_port(a),
+                            pj_sockaddr_print(a, tmp_addr, 
+                                              sizeof(tmp_addr), 0));
+
+    } else {
+        pj_assert(!"Unsupported address family");
+        return NULL;
+    }
+
+    return attr;
+}
 
 

pjproject/trunk/pjmedia/src/pjmedia/transport_ice.c

@@ -24 +24 @@
 
 #define THIS_FILE   "transport_ice.c"
-
-static const pj_str_t ID_RTP_AVP  = { "RTP/AVP", 7 };
+#if 0
+#   define TRACE__(expr)    PJ_LOG(5,expr)
+#else
+#   define TRACE__(expr)
+#endif
+
+enum oa_role
+{
+    ROLE_NONE,
+    ROLE_OFFERER,
+    ROLE_ANSWERER
+};
+
+struct sdp_state
+{
+    unsigned            match_comp_cnt; /* Matching number of components    */
+    pj_bool_t           ice_mismatch;   /* Address doesn't match candidates */
+    pj_bool_t           ice_restart;    /* Offer to restart ICE             */
+    pj_ice_sess_role    local_role;     /* Our role                         */
+};
 
 struct transport_ice
@@ -32 +50 @@
     pj_pool_t           *pool;
     int                  af;
+
     unsigned             comp_cnt;
     pj_ice_strans       *ice_st;
+
     pjmedia_ice_cb       cb;
     unsigned             media_option;
+
+    pj_bool_t            initial_sdp;
+    enum oa_role         oa_role;       /**< Last role in SDP offer/answer  */
+    struct sdp_state     rem_offer_state;/**< Describes the remote offer            */
 
     void                *stream;
@@ -85 +109 @@
                                        pj_pool_t *pool,
                                        unsigned options,
-                                       pjmedia_sdp_session *sdp_local,
                                        const pjmedia_sdp_session *rem_sdp,
                                        unsigned media_index);
-static pj_status_t transport_media_start (pjmedia_transport *tp,
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+                                        pj_pool_t *tmp_pool,
+                                        pjmedia_sdp_session *sdp_local,
+                                        const pjmedia_sdp_session *rem_sdp,
+                                        unsigned media_index);
+static pj_status_t transport_media_start(pjmedia_transport *tp,
                                        pj_pool_t *pool,
-                                       pjmedia_sdp_session *sdp_local,
+                                       const pjmedia_sdp_session *sdp_local,
                                        const pjmedia_sdp_session *rem_sdp,
                                        unsigned media_index);
@@ -121 +149 @@
     &transport_send_rtcp2,
     &transport_media_create,
+    &transport_encode_sdp,
     &transport_media_start,
     &transport_media_stop,
@@ -127 +156 @@
 };
 
-static const pj_str_t STR_CANDIDATE = {"candidate", 9};
-static const pj_str_t STR_ICE_LITE = {"ice-lite", 8};
-static const pj_str_t STR_ICE_MISMATCH = {"ice-mismatch", 12};
-
+static const pj_str_t STR_RTP_AVP       = { "RTP/AVP", 7 };
+static const pj_str_t STR_CANDIDATE     = { "candidate", 9};
+static const pj_str_t STR_REM_CAND      = { "remote-candidates", 17 };
+static const pj_str_t STR_ICE_LITE      = { "ice-lite", 8};
+static const pj_str_t STR_ICE_MISMATCH  = { "ice-mismatch", 12};
+static const pj_str_t STR_ICE_UFRAG     = { "ice-ufrag", 9 };
+static const pj_str_t STR_ICE_PWD       = { "ice-pwd", 7 };
+static const pj_str_t STR_IP4           = { "IP4", 3 };
+static const pj_str_t STR_IP6           = { "IP6", 3 };
+static const pj_str_t STR_RTCP          = { "rtcp", 4 };
+
+enum {
+    COMP_RTP = 1,
+    COMP_RTCP = 2
+};
 
 /*
@@ -158 +198 @@
     tp_ice->base.op = &transport_ice_op;
     tp_ice->base.type = PJMEDIA_TRANSPORT_TYPE_ICE;
+    tp_ice->initial_sdp = PJ_TRUE;
+    tp_ice->oa_role = ROLE_NONE;
 
     if (cb)
@@ -184 +226 @@
     return PJ_SUCCESS;
 }
+
+/* Disable ICE when SDP from remote doesn't contain a=candidate line */
+static void set_no_ice(struct transport_ice *tp_ice, const char *reason,
+                       pj_status_t err)
+{
+    if (err != PJ_SUCCESS) {
+        char errmsg[PJ_ERR_MSG_SIZE];
+        pj_strerror(err, errmsg, sizeof(errmsg));
+        PJ_LOG(4,(tp_ice->base.name, 
+                  "Stopping ICE, reason=%s:%s", reason, errmsg));
+    } else {
+        PJ_LOG(4,(tp_ice->base.name, 
+                  "Stopping ICE, reason=%s", reason));
+    }
+
+    pj_ice_strans_stop_ice(tp_ice->ice_st);
+}
+
 
 /* Create SDP candidate attribute */
@@ -228 +288 @@
 }
 
+
+/* Get ice-ufrag and ice-pwd attribute */
+static void get_ice_attr(const pjmedia_sdp_session *rem_sdp,
+                         const pjmedia_sdp_media *rem_m,
+                         const pjmedia_sdp_attr **p_ice_ufrag,
+                         const pjmedia_sdp_attr **p_ice_pwd)
+{
+    pjmedia_sdp_attr *attr;
+
+    /* Find ice-ufrag attribute in media descriptor */
+    attr = pjmedia_sdp_attr_find(rem_m->attr_count, rem_m->attr,
+                                 &STR_ICE_UFRAG, NULL);
+    if (attr == NULL) {
+        /* Find ice-ufrag attribute in session descriptor */
+        attr = pjmedia_sdp_attr_find(rem_sdp->attr_count, rem_sdp->attr,
+                                     &STR_ICE_UFRAG, NULL);
+    }
+    *p_ice_ufrag = attr;
+
+    /* Find ice-pwd attribute in media descriptor */
+    attr = pjmedia_sdp_attr_find(rem_m->attr_count, rem_m->attr,
+                                 &STR_ICE_PWD, NULL);
+    if (attr == NULL) {
+        /* Find ice-pwd attribute in session descriptor */
+        attr = pjmedia_sdp_attr_find(rem_sdp->attr_count, rem_sdp->attr,
+                                     &STR_ICE_PWD, NULL);
+    }
+    *p_ice_pwd = attr;
+}
+
+
+/* Encode and add "a=ice-mismatch" attribute in the SDP */
+static void encode_ice_mismatch(pj_pool_t *sdp_pool,
+                                pjmedia_sdp_session *sdp_local,
+                                unsigned media_index)
+{
+    pjmedia_sdp_attr *attr;
+    pjmedia_sdp_media *m = sdp_local->media[media_index];
+
+    attr = PJ_POOL_ALLOC_T(sdp_pool, pjmedia_sdp_attr);
+    attr->name = STR_ICE_MISMATCH;
+    attr->value.slen = 0;
+    pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+}
+
+
+/* Encode ICE information in SDP */
+static pj_status_t encode_session_in_sdp(struct transport_ice *tp_ice,
+                                         pj_pool_t *sdp_pool,
+                                         pjmedia_sdp_session *sdp_local,
+                                         unsigned media_index,
+                                         unsigned comp_cnt,
+                                         pj_bool_t restart_session)
+{
+    enum { 
+        ATTR_BUF_LEN = 160,     /* Max len of a=candidate attr */
+        RATTR_BUF_LEN= 160      /* Max len of a=remote-candidates attr */
+    };
+    pjmedia_sdp_media *m = sdp_local->media[media_index];
+    pj_str_t local_ufrag, local_pwd;
+    pjmedia_sdp_attr *attr;
+    pj_status_t status;
+
+    /* Must have a session */
+    PJ_ASSERT_RETURN(pj_ice_strans_has_sess(tp_ice->ice_st), PJ_EBUG);
+
+    /* Get ufrag and pwd from current session */
+    pj_ice_strans_get_ufrag_pwd(tp_ice->ice_st, &local_ufrag, &local_pwd,
+                                NULL, NULL);
+
+    /* The listing of candidates depends on whether ICE has completed
+     * or not. When ICE has completed:
+     *
+     * 9.1.2.2: Existing Media Streams with ICE Completed
+     *   The agent MUST include a candidate attributes for candidates
+     *   matching the default destination for each component of the 
+     *   media stream, and MUST NOT include any other candidates.
+     *
+     * When ICE has not completed, we shall include all candidates.
+     *
+     * Except when we have detected that remote is offering to restart
+     * the session, in this case we will answer with full ICE SDP and
+     * new ufrag/pwd pair.
+     */
+    if (!restart_session && pj_ice_strans_sess_is_complete(tp_ice->ice_st)) {
+        const pj_ice_sess_check *check;
+        char *attr_buf;
+        pjmedia_sdp_conn *conn;
+        pjmedia_sdp_attr *a_rtcp;
+        pj_str_t rem_cand;
+        unsigned comp;
+
+        /* Encode ice-ufrag attribute */
+        attr = pjmedia_sdp_attr_create(sdp_pool, STR_ICE_UFRAG.ptr,
+                                       &local_ufrag);
+        pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+
+        /* Encode ice-pwd attribute */
+        attr = pjmedia_sdp_attr_create(sdp_pool, STR_ICE_PWD.ptr, 
+                                       &local_pwd);
+        pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+
+        /* Prepare buffer */
+        attr_buf = (char*) pj_pool_alloc(sdp_pool, ATTR_BUF_LEN);
+        rem_cand.ptr = (char*) pj_pool_alloc(sdp_pool, RATTR_BUF_LEN);
+        rem_cand.slen = 0;
+
+        /* 9.1.2.2: Existing Media Streams with ICE Completed
+         *   The default destination for media (i.e., the values of 
+         *   the IP addresses and ports in the m and c line used for
+         *   that media stream) MUST be the local candidate from the
+         *   highest priority nominated pair in the valid list for each
+         *   component.
+         */
+        check = pj_ice_strans_get_valid_pair(tp_ice->ice_st, 1);
+        if (check == NULL) {
+            pj_assert(!"Shouldn't happen");
+            return PJ_EBUG;
+        }
+
+        /* Override connection line address and media port number */
+        conn = m->conn;
+        if (conn == NULL)
+            conn = sdp_local->conn;
+
+        conn->addr.ptr = (char*) pj_pool_alloc(sdp_pool, 
+                                               PJ_INET6_ADDRSTRLEN);
+        pj_sockaddr_print(&check->lcand->addr, conn->addr.ptr, 
+                          PJ_INET6_ADDRSTRLEN, 0);
+        conn->addr.slen = pj_ansi_strlen(conn->addr.ptr);
+        m->desc.port = pj_sockaddr_get_port(&check->lcand->addr);
+
+        /* Override address RTCP attribute if it's present */
+        if (comp_cnt == 2 &&
+            (check = pj_ice_strans_get_valid_pair(tp_ice->ice_st, 
+                                                  COMP_RTCP)) != NULL &&
+            (a_rtcp = pjmedia_sdp_attr_find(m->attr_count, m->attr, 
+                                            &STR_RTCP, 0)) != NULL) 
+        {
+            pjmedia_sdp_attr_remove(&m->attr_count, m->attr, a_rtcp);
+
+            a_rtcp = pjmedia_sdp_attr_create_rtcp(sdp_pool, 
+                                                  &check->lcand->addr);
+            if (a_rtcp)
+                pjmedia_sdp_attr_add(&m->attr_count, m->attr, a_rtcp);
+        }
+
+        /* Encode only candidates matching the default destination 
+         * for each component 
+         */
+        for (comp=0; comp < comp_cnt; ++comp) {
+            int len;
+            pj_str_t value;
+
+            /* Get valid pair for this component */
+            check = pj_ice_strans_get_valid_pair(tp_ice->ice_st, comp+1);
+            if (check == NULL)
+                continue;
+
+            /* Print and add local candidate in the pair */
+            value.ptr = attr_buf;
+            value.slen = print_sdp_cand_attr(attr_buf, ATTR_BUF_LEN, 
+                                             check->lcand);
+            if (value.slen < 0) {
+                pj_assert(!"Not enough attr_buf to print candidate");
+                return PJ_EBUG;
+            }
+
+            attr = pjmedia_sdp_attr_create(sdp_pool, STR_CANDIDATE.ptr,
+                                           &value);
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+
+            /* Append to a=remote-candidates attribute */
+            if (pj_ice_strans_get_role(tp_ice->ice_st) == 
+                                    PJ_ICE_SESS_ROLE_CONTROLLING) 
+            {
+                char rem_addr[PJ_INET6_ADDRSTRLEN];
+
+                pj_sockaddr_print(&check->rcand->addr, rem_addr, 
+                                  sizeof(rem_addr), 0);
+                len = pj_ansi_snprintf(
+                           rem_cand.ptr + rem_cand.slen,
+                           RATTR_BUF_LEN - rem_cand.slen,
+                           "%s%u %s %u", 
+                           (rem_cand.slen==0? "" : " "),
+                           comp+1, rem_addr,
+                           pj_sockaddr_get_port(&check->rcand->addr)
+                           );
+                if (len < 1 || len >= RATTR_BUF_LEN) {
+                    pj_assert(!"Not enough buffer to print "
+                               "remote-candidates");
+                    return PJ_EBUG;
+                }
+
+                rem_cand.slen += len;
+            }
+        }
+
+        /* 9.1.2.2: Existing Media Streams with ICE Completed
+         *   In addition, if the agent is controlling, it MUST include
+         *   the a=remote-candidates attribute for each media stream 
+         *   whose check list is in the Completed state.  The attribute
+         *   contains the remote candidates from the highest priority 
+         *   nominated pair in the valid list for each component of that
+         *   media stream.
+         */
+        if (pj_ice_strans_get_role(tp_ice->ice_st) == 
+                                    PJ_ICE_SESS_ROLE_CONTROLLING) 
+        {
+            attr = pjmedia_sdp_attr_create(sdp_pool, STR_REM_CAND.ptr, 
+                                           &rem_cand);
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+        }
+
+    } else if (pj_ice_strans_has_sess(tp_ice->ice_st)) {
+        /* Encode all candidates to SDP media */
+        char *attr_buf;
+        unsigned comp;
+
+        /* If ICE is not restarted, encode current ICE ufrag/pwd.
+         * Otherwise generate new one.
+         */
+        if (!restart_session) {
+            attr = pjmedia_sdp_attr_create(sdp_pool, STR_ICE_UFRAG.ptr,
+                                           &local_ufrag);
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+
+            attr = pjmedia_sdp_attr_create(sdp_pool, STR_ICE_PWD.ptr, 
+                                           &local_pwd);
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+
+        } else {
+            pj_str_t str;
+
+            str.slen = PJ_ICE_UFRAG_LEN;
+            str.ptr = (char*) pj_pool_alloc(sdp_pool, str.slen);
+            pj_create_random_string(str.ptr, str.slen);
+            attr = pjmedia_sdp_attr_create(sdp_pool, STR_ICE_UFRAG.ptr, &str);
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+
+            str.ptr = (char*) pj_pool_alloc(sdp_pool, str.slen);
+            pj_create_random_string(str.ptr, str.slen);
+            attr = pjmedia_sdp_attr_create(sdp_pool, STR_ICE_PWD.ptr, &str);
+            pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+        }
+
+        /* Create buffer to encode candidates as SDP attribute */
+        attr_buf = (char*) pj_pool_alloc(sdp_pool, ATTR_BUF_LEN);
+
+        for (comp=0; comp < comp_cnt; ++comp) {
+            unsigned cand_cnt;
+            pj_ice_sess_cand cand[PJ_ICE_ST_MAX_CAND];
+            unsigned i;
+
+            cand_cnt = PJ_ARRAY_SIZE(cand);
+            status = pj_ice_strans_enum_cands(tp_ice->ice_st, comp+1,
+                                              &cand_cnt, cand);
+            if (status != PJ_SUCCESS)
+                return status;
+
+            for (i=0; i<cand_cnt; ++i) {
+                pj_str_t value;
+
+                value.slen = print_sdp_cand_attr(attr_buf, ATTR_BUF_LEN, 
+                                                 &cand[i]);
+                if (value.slen < 0) {
+                    pj_assert(!"Not enough attr_buf to print candidate");
+                    return PJ_EBUG;
+                }
+
+                value.ptr = attr_buf;
+                attr = pjmedia_sdp_attr_create(sdp_pool, 
+                                               STR_CANDIDATE.ptr,
+                                               &value);
+                pjmedia_sdp_attr_add(&m->attr_count, m->attr, attr);
+            }
+        }
+    } else {
+        /* ICE has failed, application should have terminated this call */
+    }
+
+    return PJ_SUCCESS;
+}
+
+
+/* Parse a=candidate line */
+static pj_status_t parse_cand(const char *obj_name,
+                              pj_pool_t *pool,
+                              const pj_str_t *orig_input,
+                              pj_ice_sess_cand *cand)
+{
+    pj_str_t input;
+    char *token, *host;
+    int af;
+    pj_str_t s;
+    pj_status_t status = PJNATH_EICEINCANDSDP;
+
+    pj_bzero(cand, sizeof(*cand));
+    pj_strdup_with_null(pool, &input, orig_input);
+
+    PJ_UNUSED_ARG(obj_name);
+
+    /* Foundation */
+    token = strtok(input.ptr, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE foundation in candidate"));
+        goto on_return;
+    }
+    pj_strdup2(pool, &cand->foundation, token);
+
+    /* Component ID */
+    token = strtok(NULL, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE component ID in candidate"));
+        goto on_return;
+    }
+    cand->comp_id = (pj_uint8_t) atoi(token);
+
+    /* Transport */
+    token = strtok(NULL, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE transport in candidate"));
+        goto on_return;
+    }
+    if (pj_ansi_stricmp(token, "UDP") != 0) {
+        TRACE__((obj_name, 
+                 "Expecting ICE UDP transport only in candidate"));
+        goto on_return;
+    }
+
+    /* Priority */
+    token = strtok(NULL, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE priority in candidate"));
+        goto on_return;
+    }
+    cand->prio = atoi(token);
+
+    /* Host */
+    host = strtok(NULL, " ");
+    if (!host) {
+        TRACE__((obj_name, "Expecting ICE host in candidate"));
+        goto on_return;
+    }
+    /* Detect address family */
+    if (pj_ansi_strchr(host, ':'))
+        af = pj_AF_INET6();
+    else
+        af = pj_AF_INET();
+    /* Assign address */
+    if (pj_sockaddr_init(af, &cand->addr, pj_cstr(&s, host), 0)) {
+        TRACE__((obj_name, "Invalid ICE candidate address"));
+        goto on_return;
+    }
+
+    /* Port */
+    token = strtok(NULL, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE port number in candidate"));
+        goto on_return;
+    }
+    pj_sockaddr_set_port(&cand->addr, (pj_uint16_t)atoi(token));
+
+    /* typ */
+    token = strtok(NULL, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE \"typ\" in candidate"));
+        goto on_return;
+    }
+    if (pj_ansi_stricmp(token, "typ") != 0) {
+        TRACE__((obj_name, "Expecting ICE \"typ\" in candidate"));
+        goto on_return;
+    }
+
+    /* candidate type */
+    token = strtok(NULL, " ");
+    if (!token) {
+        TRACE__((obj_name, "Expecting ICE candidate type in candidate"));
+        goto on_return;
+    }
+
+    if (pj_ansi_stricmp(token, "host") == 0) {
+        cand->type = PJ_ICE_CAND_TYPE_HOST;
+
+    } else if (pj_ansi_stricmp(token, "srflx") == 0) {
+        cand->type = PJ_ICE_CAND_TYPE_SRFLX;
+
+    } else if (pj_ansi_stricmp(token, "relay") == 0) {
+        cand->type = PJ_ICE_CAND_TYPE_RELAYED;
+
+    } else if (pj_ansi_stricmp(token, "prflx") == 0) {
+        cand->type = PJ_ICE_CAND_TYPE_PRFLX;
+
+    } else {
+        PJ_LOG(5,(obj_name, "Invalid ICE candidate type %s in candidate", 
+                  token));
+        goto on_return;
+    }
+
+    status = PJ_SUCCESS;
+
+on_return:
+    return status;
+}
+
+
+/* Create initial SDP offer */
+static pj_status_t create_initial_offer(struct transport_ice *tp_ice,
+                                        pj_pool_t *sdp_pool,
+                                        pjmedia_sdp_session *loc_sdp,
+                                        unsigned media_index)
+{
+    pj_status_t status;
+
+    /* Encode ICE in SDP */
+    status = encode_session_in_sdp(tp_ice, sdp_pool, loc_sdp, media_index, 
+                                   tp_ice->comp_cnt, PJ_FALSE);
+    if (status != PJ_SUCCESS) {
+        set_no_ice(tp_ice, "Error encoding SDP answer", status);
+        return status;
+    }
+
+    return PJ_SUCCESS;
+}
+
+
+/* Verify incoming offer */
+static pj_status_t verify_ice_sdp(struct transport_ice *tp_ice,
+                                  pj_pool_t *tmp_pool,
+                                  const pjmedia_sdp_session *rem_sdp,
+                                  unsigned media_index,
+                                  pj_ice_sess_role current_ice_role,
+                                  struct sdp_state *sdp_state)
+{
+    const pjmedia_sdp_media *rem_m;
+    const pjmedia_sdp_attr *attr, *ufrag_attr, *pwd_attr;
+    const pjmedia_sdp_conn *rem_conn;
+    pj_bool_t comp1_found=PJ_FALSE, comp2_found=PJ_FALSE;
+    pj_sockaddr rem_conn_addr, rtcp_addr;
+    unsigned i;
+    pj_status_t status;
+
+    rem_m = rem_sdp->media[media_index];
+
+    /* Get the "ice-ufrag" and "ice-pwd" attributes */
+    get_ice_attr(rem_sdp, rem_m, &ufrag_attr, &pwd_attr);
+
+    /* If "ice-ufrag" or "ice-pwd" are not found, disable ICE */
+    if (ufrag_attr==NULL || pwd_attr==NULL) {
+        sdp_state->match_comp_cnt = 0;
+        return PJ_SUCCESS;
+    }
+
+    /* Verify that default target for each component matches one of the 
+     * candidatefor the component. Otherwise stop ICE with ICE ice_mismatch 
+     * error.
+     */
+
+    /* Component 1 is the c= line */
+    rem_conn = rem_m->conn;
+    if (rem_conn == NULL)
+        rem_conn = rem_sdp->conn;
+    if (!rem_conn)
+        return PJMEDIA_SDP_EMISSINGCONN;
+
+    /* Verify address family matches */
+    if ((tp_ice->af==pj_AF_INET() && 
+         pj_strcmp(&rem_conn->addr_type, &STR_IP4)!=0) ||
+        (tp_ice->af==pj_AF_INET6() && 
+         pj_strcmp(&rem_conn->addr_type, &STR_IP6)!=0))
+    {
+        return PJMEDIA_SDP_ETPORTNOTEQUAL;
+    }
+
+    /* Assign remote connection address */
+    status = pj_sockaddr_init(tp_ice->af, &rem_conn_addr, &rem_conn->addr,
+                              (pj_uint16_t)rem_m->desc.port);
+    if (status != PJ_SUCCESS)
+        return status;
+
+    /* Component 2 is a=rtcp line, if present. */
+    attr = pjmedia_sdp_attr_find(rem_m->attr_count, rem_m->attr, 
+                                 &STR_RTCP, NULL);
+    if (attr && tp_ice->comp_cnt > 1) {
+        pjmedia_sdp_rtcp_attr rtcp_attr;
+
+        status = pjmedia_sdp_attr_get_rtcp(attr, &rtcp_attr);
+        if (status != PJ_SUCCESS) {
+            /* Error parsing a=rtcp attribute */
+            return status;
+        }
+        
+        /* Verify address family matches */
+        if ((tp_ice->af==pj_AF_INET() && 
+             pj_strcmp(&rtcp_attr.addr_type, &STR_IP4)!=0) ||
+            (tp_ice->af==pj_AF_INET6() && 
+             pj_strcmp(&rtcp_attr.addr_type, &STR_IP6)!=0))
+        {
+            return PJMEDIA_SDP_ETPORTNOTEQUAL;
+        }
+
+        /* Assign RTCP address */
+        status = pj_sockaddr_init(tp_ice->af, &rtcp_addr,
+                                  &rtcp_attr.addr,
+                                  (pj_uint16_t)rtcp_attr.port);
+        if (status != PJ_SUCCESS) {
+            return PJMEDIA_SDP_EINRTCP;
+        }
+
+        sdp_state->match_comp_cnt = 2;
+
+    } else {
+        /* Don't have RTCP component */
+        comp2_found = PJ_TRUE;
+        sdp_state->match_comp_cnt = 1;
+    }
+
+    /* Find the default address in a=candidate attributes. 
+     */
+    for (i=0; i<rem_m->attr_count; ++i) {
+        pj_ice_sess_cand cand;
+
+        if (pj_strcmp(&rem_m->attr[i]->name, &STR_CANDIDATE)!=0)
+            continue;
+
+        status = parse_cand(tp_ice->base.name, tmp_pool, 
+                            &rem_m->attr[i]->value, &cand);
+        if (status != PJ_SUCCESS) {
+            PJ_LOG(4,(tp_ice->base.name, 
+                      "Error in parsing SDP candidate attribute '%.*s', "
+                      "candidate is ignored",
+                      (int)rem_m->attr[i]->value.slen, 
+                      rem_m->attr[i]->value.ptr));
+            continue;
+        }
+
+        if (!comp1_found && cand.comp_id==COMP_RTP &&
+            pj_sockaddr_cmp(&rem_conn_addr, &cand.addr)==0) 
+        {
+            /* Found */
+            comp1_found = PJ_TRUE;
+            if (comp1_found && comp2_found)
+                break;
+        } else if (!comp2_found && cand.comp_id==COMP_RTCP &&
+                    pj_sockaddr_cmp(&rtcp_addr, &cand.addr)==0) 
+        {
+            /* Found */
+            comp2_found = PJ_TRUE;
+            if (comp1_found && comp2_found)
+                break;
+        }
+
+    }
+
+    if (!comp1_found || !comp2_found) {
+        /* ICE ice_mismatch */
+        sdp_state->ice_mismatch = PJ_TRUE;
+    } else {
+        sdp_state->ice_mismatch = PJ_FALSE;
+    }
+
+    /* Detect remote restarting session */
+    if (pj_ice_strans_has_sess(tp_ice->ice_st) &&
+        (pj_ice_strans_sess_is_running(tp_ice->ice_st) ||
+         pj_ice_strans_sess_is_complete(tp_ice->ice_st))) 
+    {
+        pj_str_t rem_run_ufrag, rem_run_pwd;
+        pj_ice_strans_get_ufrag_pwd(tp_ice->ice_st, NULL, NULL,
+                                    &rem_run_ufrag, &rem_run_pwd);
+        if (pj_strcmp(&ufrag_attr->value, &rem_run_ufrag) ||
+            pj_strcmp(&pwd_attr->value, &rem_run_pwd))
+        {
+            /* Remote offers to restart ICE */
+            sdp_state->ice_restart = PJ_TRUE;
+        } else {
+            sdp_state->ice_restart = PJ_FALSE;
+        }
+    } else {
+        sdp_state->ice_restart = PJ_FALSE;
+    }
+
+    /* Detect our role */
+    if (current_ice_role==PJ_ICE_SESS_ROLE_CONTROLLING) {
+        sdp_state->local_role = PJ_ICE_SESS_ROLE_CONTROLLING;
+    } else {
+        if (pjmedia_sdp_attr_find(rem_sdp->attr_count, rem_sdp->attr,
+                                  &STR_ICE_LITE, NULL) != NULL)
+        {
+            /* Remote is ICE Lite */
+            sdp_state->local_role = PJ_ICE_SESS_ROLE_CONTROLLING;
+        } else {
+            sdp_state->local_role = PJ_ICE_SESS_ROLE_CONTROLLED;
+        }
+    }
+
+    PJ_LOG(4,(tp_ice->base.name, 
+              "Processing SDP: support ICE=%u, common comp_cnt=%u, "
+              "ice_mismatch=%u, ice_restart=%u, local_role=%s",
+              (sdp_state->match_comp_cnt != 0), 
+              sdp_state->match_comp_cnt, 
+              sdp_state->ice_mismatch, 
+              sdp_state->ice_restart,
+              pj_ice_sess_role_name(sdp_state->local_role)));
+
+    return PJ_SUCCESS;
+
+}
+
+
+/* Verify incoming offer and create initial answer */
+static pj_status_t create_initial_answer(struct transport_ice *tp_ice,
+                                         pj_pool_t *sdp_pool,
+                                         pjmedia_sdp_session *loc_sdp,
+                                         const pjmedia_sdp_session *rem_sdp,
+                                         unsigned media_index)
+{
+    const pjmedia_sdp_media *rem_m = rem_sdp->media[media_index];
+    pj_status_t status;
+
+    /* Check if media is removed (just in case) */
+    if (rem_m->desc.port == 0) {
+        return PJ_SUCCESS;
+    }
+
+    /* Verify the offer */
+    status = verify_ice_sdp(tp_ice, sdp_pool, rem_sdp, media_index, 
+                            PJ_ICE_SESS_ROLE_CONTROLLED, 
+                            &tp_ice->rem_offer_state);
+    if (status != PJ_SUCCESS) {
+        set_no_ice(tp_ice, "Invalid SDP offer", status);
+        return status;
+    }
+
+    /* Does remote support ICE? */
+    if (tp_ice->rem_offer_state.match_comp_cnt==0) {
+        set_no_ice(tp_ice, "No ICE found in SDP offer", PJ_SUCCESS);
+        return PJ_SUCCESS;
+    }
+
+    /* ICE ice_mismatch? */
+    if (tp_ice->rem_offer_state.ice_mismatch) {
+        set_no_ice(tp_ice, "ICE ice_mismatch in remote offer", PJ_SUCCESS);
+        encode_ice_mismatch(sdp_pool, loc_sdp, media_index);
+        return PJ_SUCCESS;
+    }
+
+    /* Encode ICE in SDP */
+    status = encode_session_in_sdp(tp_ice, sdp_pool, loc_sdp, media_index, 
+                                   tp_ice->rem_offer_state.match_comp_cnt,
+                                   PJ_FALSE);
+    if (status != PJ_SUCCESS) {
+        set_no_ice(tp_ice, "Error encoding SDP answer", status);
+        return status;
+    }
+
+    return PJ_SUCCESS;
+}
+
+
+/* Create subsequent SDP offer */
+static pj_status_t create_subsequent_offer(struct transport_ice *tp_ice,
+                                           pj_pool_t *sdp_pool,
+                                           pjmedia_sdp_session *loc_sdp,
+                                           unsigned media_index)
+{
+    unsigned comp_cnt;
+
+    if (pj_ice_strans_has_sess(tp_ice->ice_st) == PJ_FALSE) {
+        /* We don't have ICE */
+        return PJ_SUCCESS;
+    }
+
+    comp_cnt = pj_ice_strans_get_running_comp_cnt(tp_ice->ice_st);
+    return encode_session_in_sdp(tp_ice, sdp_pool, loc_sdp, media_index,
+                                 comp_cnt, PJ_FALSE);
+}
+
+
+/* Create subsequent SDP answer */
+static pj_status_t create_subsequent_answer(struct transport_ice *tp_ice,
+                                            pj_pool_t *sdp_pool,
+                                            pjmedia_sdp_session *loc_sdp,
+                                            const pjmedia_sdp_session *rem_sdp,
+                                            unsigned media_index)
+{
+    pj_status_t status;
+
+    /* We have a session */
+    status = verify_ice_sdp(tp_ice, sdp_pool, rem_sdp, media_index, 
+                            PJ_ICE_SESS_ROLE_CONTROLLED, 
+                            &tp_ice->rem_offer_state);
+    if (status != PJ_SUCCESS) {
+        /* Something wrong with the offer */
+        return status;
+    }
+
+    if (pj_ice_strans_has_sess(tp_ice->ice_st)) {
+        /*
+         * Received subsequent offer while we have ICE active.
+         */
+
+        if (tp_ice->rem_offer_state.match_comp_cnt == 0) {
+            /* Remote no longer offers ICE */
+            return PJ_SUCCESS;
+        }
+
+        if (tp_ice->rem_offer_state.ice_mismatch) {
+            encode_ice_mismatch(sdp_pool, loc_sdp, media_index);
+            return PJ_SUCCESS;
+        }
+
+        status = encode_session_in_sdp(tp_ice, sdp_pool, loc_sdp, media_index,
+                                       tp_ice->rem_offer_state.match_comp_cnt,
+                                       tp_ice->rem_offer_state.ice_restart);
+        if (status != PJ_SUCCESS)
+            return status;
+
+        /* Done */
+
+    } else {
+        /*
+         * Received subsequent offer while we DON'T have ICE active.
+         */
+
+        if (tp_ice->rem_offer_state.match_comp_cnt == 0) {
+            /* Remote does not support ICE */
+            return PJ_SUCCESS;
+        }
+
+        if (tp_ice->rem_offer_state.ice_mismatch) {
+            encode_ice_mismatch(sdp_pool, loc_sdp, media_index);
+            return PJ_SUCCESS;
+        }
+
+        /* Looks like now remote is offering ICE, so we need to create
+         * ICE session now.
+         */
+        status = pj_ice_strans_init_ice(tp_ice->ice_st, 
+                                        PJ_ICE_SESS_ROLE_CONTROLLED,
+                                        NULL, NULL);
+        if (status != PJ_SUCCESS) {
+            /* Fail to create new ICE session */
+            return status;
+        }
+
+        status = encode_session_in_sdp(tp_ice, sdp_pool, loc_sdp, media_index,
+                                       tp_ice->rem_offer_state.match_comp_cnt,
+                                       tp_ice->rem_offer_state.ice_restart);
+        if (status != PJ_SUCCESS)
+            return status;
+
+        /* Done */
+    }
+
+    return PJ_SUCCESS;
+}
+
+
 /*
  * For both UAC and UAS, pass in the SDP before sending it to remote.
@@ -233 +1051 @@
  */
 static pj_status_t transport_media_create(pjmedia_transport *tp,
-                                          pj_pool_t *pool,
+                                          pj_pool_t *sdp_pool,
                                           unsigned options,
-                                          pjmedia_sdp_session *sdp_local,
                                           const pjmedia_sdp_session *rem_sdp,
                                           unsigned media_index)
 {
     struct transport_ice *tp_ice = (struct transport_ice*)tp;
-    pj_bool_t init_ice;
-    unsigned i;
+    pj_ice_sess_role ice_role;
     pj_status_t status;
 
+    PJ_UNUSED_ARG(media_index);
+    PJ_UNUSED_ARG(sdp_pool);
+
     tp_ice->media_option = options;
+    tp_ice->oa_role = ROLE_NONE;
+    tp_ice->initial_sdp = PJ_TRUE;
+
+    /* Init ICE, the initial role is set now based on availability of
+     * rem_sdp, but it will be checked again later.
+     */
+    ice_role = (rem_sdp==NULL ? PJ_ICE_SESS_ROLE_CONTROLLING : 
+                                PJ_ICE_SESS_ROLE_CONTROLLED);
+    status = pj_ice_strans_init_ice(tp_ice->ice_st, ice_role, NULL, NULL);
+
+    /* Done */
+    return status;
+}
+
+
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+                                        pj_pool_t *sdp_pool,
+                                        pjmedia_sdp_session *sdp_local,
+                                        const pjmedia_sdp_session *rem_sdp,
+                                        unsigned media_index)
+{
+    struct transport_ice *tp_ice = (struct transport_ice*)tp;
+    pj_status_t status;
 
     /* Validate media transport */
     /* For now, this transport only support RTP/AVP transport */
     if ((tp_ice->media_option & PJMEDIA_TPMED_NO_TRANSPORT_CHECKING) == 0) {
-        pjmedia_sdp_media *m_rem, *m_loc;
-
-        m_rem = rem_sdp? rem_sdp->media[media_index] : NULL;
-        m_loc = sdp_local->media[media_index];
-
-        if (pj_stricmp(&m_loc->desc.transport, &ID_RTP_AVP) ||
-           (m_rem && pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP)))
+        pjmedia_sdp_media *loc_m, *rem_m;
+
+        rem_m = rem_sdp? rem_sdp->media[media_index] : NULL;
+        loc_m = sdp_local->media[media_index];
+
+        if (pj_stricmp(&loc_m->desc.transport, &STR_RTP_AVP) ||
+           (rem_m && pj_stricmp(&rem_m->desc.transport, &STR_RTP_AVP)))
         {
-            pjmedia_sdp_media_deactivate(pool, m_loc);
+            pjmedia_sdp_media_deactivate(sdp_pool, loc_m);
             return PJMEDIA_SDP_EINPROTO;
         }
     }
 
-    /* If we are UAS, check that the incoming SDP contains support for ICE. */
-    if (rem_sdp) {
-        const pjmedia_sdp_media *rem_m;
-
-        rem_m = rem_sdp->media[media_index];
-
-        init_ice = pjmedia_sdp_attr_find2(rem_m->attr_count, rem_m->attr,
-                                          "ice-ufrag", NULL) != NULL;
-        if (init_ice == PJ_FALSE) {
-            init_ice = pjmedia_sdp_attr_find2(rem_sdp->attr_count, 
-                                              rem_sdp->attr,
-                                              "ice-ufrag", NULL) != NULL;
-        }
-
-        if (init_ice) {
-            init_ice = pjmedia_sdp_attr_find2(rem_m->attr_count, rem_m->attr,
-                                              "candidate", NULL) != NULL;
+    if (tp_ice->initial_sdp) {
+        if (rem_sdp) {
+            status = create_initial_answer(tp_ice, sdp_pool, sdp_local, 
+                                           rem_sdp, media_index);
+        } else {
+            status = create_initial_offer(tp_ice, sdp_pool, sdp_local,
+                                          media_index);
         }
     } else {
-        init_ice = PJ_TRUE;
-    }
-
-    /* Init ICE */
-    if (init_ice) {
-        pj_ice_sess_role ice_role;
-        enum { MAXLEN = 256 };
-        pj_str_t ufrag, pass;
-        char *buffer;
+        if (rem_sdp) {
+            status = create_subsequent_answer(tp_ice, sdp_pool, sdp_local,
+                                              rem_sdp, media_index);
+        } else {
+            status = create_subsequent_offer(tp_ice, sdp_pool, sdp_local,
+                                             media_index);
+        }
+    }
+
+    if (status==PJ_SUCCESS) {
+        if (rem_sdp)
+            tp_ice->oa_role = ROLE_ANSWERER;
+        else
+            tp_ice->oa_role = ROLE_OFFERER;
+    }
+
+    return status;
+}
+
+
+/* Start ICE session with the specified remote SDP */
+static pj_status_t start_ice(struct transport_ice *tp_ice,
+                             pj_pool_t *tmp_pool,
+                             const pjmedia_sdp_session *rem_sdp,
+                             unsigned media_index)
+{
+    pjmedia_sdp_media *rem_m = rem_sdp->media[media_index];
+    pjmedia_sdp_attr *ufrag_attr, *pwd_attr;
+    pj_ice_sess_cand *cand;
+    unsigned i, cand_cnt;
+    pj_status_t status;
+
+    get_ice_attr(rem_sdp, rem_m, &ufrag_attr, &pwd_attr);
+
+    /* Allocate candidate array */
+    cand = (pj_ice_sess_cand*)
+           pj_pool_calloc(tmp_pool, PJ_ICE_MAX_CAND, 
+                          sizeof(pj_ice_sess_cand));
+
+    /* Get all candidates in the media */
+    cand_cnt = 0;
+    for (i=0; i<rem_m->attr_count && cand_cnt < PJ_ICE_MAX_CAND; ++i) {
         pjmedia_sdp_attr *attr;
-        unsigned comp;
-
-        ice_role = (rem_sdp==NULL ? PJ_ICE_SESS_ROLE_CONTROLLING : 
-                                    PJ_ICE_SESS_ROLE_CONTROLLED);
-
-        ufrag.ptr = (char*) pj_pool_alloc(pool, PJ_ICE_UFRAG_LEN);
-        pj_create_random_string(ufrag.ptr, PJ_ICE_UFRAG_LEN);
-        ufrag.slen = PJ_ICE_UFRAG_LEN;
-
-        pass.ptr = (char*) pj_pool_alloc(pool, PJ_ICE_UFRAG_LEN);
-        pj_create_random_string(pass.ptr, PJ_ICE_UFRAG_LEN);
-        pass.slen = PJ_ICE_UFRAG_LEN;
-
-        status = pj_ice_strans_init_ice(tp_ice->ice_st, ice_role, 
-                                        &ufrag, &pass);
-        if (status != PJ_SUCCESS)
-            return status;
-
-        /* Create ice-ufrag attribute */
-        attr = pjmedia_sdp_attr_create(pool, "ice-ufrag", &ufrag);
-        sdp_local->attr[sdp_local->attr_count++] = attr;
-
-        /* Create ice-pwd attribute */
-        attr = pjmedia_sdp_attr_create(pool, "ice-pwd", &pass);
-        sdp_local->attr[sdp_local->attr_count++] = attr;
-
-        /* Encode all candidates to SDP media */
-
-        buffer = (char*) pj_pool_alloc(pool, MAXLEN);
-
-        for (comp=0; comp < tp_ice->comp_cnt; ++comp) {
-            unsigned cand_cnt;
-            pj_ice_sess_cand cand[PJ_ICE_ST_MAX_CAND];
-
-            cand_cnt = PJ_ARRAY_SIZE(cand);
-            status = pj_ice_strans_enum_cands(tp_ice->ice_st, comp+1,
-                                              &cand_cnt, cand);
-            if (status != PJ_SUCCESS)
-                return status;
-
-            for (i=0; i<cand_cnt; ++i) {
-                pjmedia_sdp_media *m;
-                pj_str_t value;
-
-                value.slen = print_sdp_cand_attr(buffer, MAXLEN, &cand[i]);
-                if (value.slen < 0) {
-                    pj_assert(!"Not enough buffer to print candidate");
-                    return PJ_EBUG;
-                }
-
-                value.ptr = buffer;
-                attr = pjmedia_sdp_attr_create(pool, "candidate", &value);
-                m = sdp_local->media[media_index];
-                m->attr[m->attr_count++] = attr;
-            }
-        }
-    }
-
-    /* Done */
-    return PJ_SUCCESS;
-}
-
-
-/* Parse a=candidate line */
-static pj_status_t parse_cand(pj_pool_t *pool,
-                              const pj_str_t *orig_input,
-                              pj_ice_sess_cand *cand)
-{
-    pj_str_t input;
-    char *token, *host;
-    pj_str_t s;
-    pj_status_t status = PJNATH_EICEINCANDSDP;
-
-    pj_bzero(cand, sizeof(*cand));
-    pj_strdup_with_null(pool, &input, orig_input);
-
-    /* Foundation */
-    token = strtok(input.ptr, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE foundation in candidate"));
-        goto on_return;
-    }
-    pj_strdup2(pool, &cand->foundation, token);
-
-    /* Component ID */
-    token = strtok(NULL, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE component ID in candidate"));
-        goto on_return;
-    }
-    cand->comp_id = (pj_uint8_t) atoi(token);
-
-    /* Transport */
-    token = strtok(NULL, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE transport in candidate"));
-        goto on_return;
-    }
-    if (pj_ansi_stricmp(token, "UDP") != 0) {
-        PJ_LOG(5,(THIS_FILE, 
-                  "Expecting ICE UDP transport only in candidate"));
-        goto on_return;
-    }
-
-    /* Priority */
-    token = strtok(NULL, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE priority in candidate"));
-        goto on_return;
-    }
-    cand->prio = atoi(token);
-
-    /* Host */
-    host = strtok(NULL, " ");
-    if (!host) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE host in candidate"));
-        goto on_return;
-    }
-    if (pj_sockaddr_in_init(&cand->addr.ipv4, pj_cstr(&s, host), 0)) {
-        PJ_LOG(5,(THIS_FILE, 
-                  "Expecting ICE IPv4 transport address in candidate"));
-        goto on_return;
-    }
-
-    /* Port */
-    token = strtok(NULL, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE port number in candidate"));
-        goto on_return;
-    }
-    cand->addr.ipv4.sin_port = pj_htons((pj_uint16_t)atoi(token));
-
-    /* typ */
-    token = strtok(NULL, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE \"typ\" in candidate"));
-        goto on_return;
-    }
-    if (pj_ansi_stricmp(token, "typ") != 0) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE \"typ\" in candidate"));
-        goto on_return;
-    }
-
-    /* candidate type */
-    token = strtok(NULL, " ");
-    if (!token) {
-        PJ_LOG(5,(THIS_FILE, "Expecting ICE candidate type in candidate"));
-        goto on_return;
-    }
-
-    if (pj_ansi_stricmp(token, "host") == 0) {
-        cand->type = PJ_ICE_CAND_TYPE_HOST;
-
-    } else if (pj_ansi_stricmp(token, "srflx") == 0) {
-        cand->type = PJ_ICE_CAND_TYPE_SRFLX;
-
-    } else if (pj_ansi_stricmp(token, "relay") == 0) {
-        cand->type = PJ_ICE_CAND_TYPE_RELAYED;
-
-    } else if (pj_ansi_stricmp(token, "prflx") == 0) {
-        cand->type = PJ_ICE_CAND_TYPE_PRFLX;
-
-    } else {
-        PJ_LOG(5,(THIS_FILE, "Invalid ICE candidate type %s in candidate", 
-                  token));
-        goto on_return;
-    }
-
-
-    status = PJ_SUCCESS;
-
-on_return:
-    return status;
-}
-
-
-/* Disable ICE when SDP from remote doesn't contain a=candidate line */
-static void set_no_ice(struct transport_ice *tp_ice, const char *reason)
-{
-    PJ_LOG(4,(tp_ice->base.name, 
-              "Disabling local ICE, reason=%s", reason));
-    transport_media_stop(&tp_ice->base);
+
+        attr = rem_m->attr[i];
+
+        if (pj_strcmp(&attr->name, &STR_CANDIDATE)!=0)
+            continue;
+
+        /* Parse candidate */
+        status = parse_cand(tp_ice->base.name, tmp_pool, &attr->value, 
+                            &cand[cand_cnt]);
+        if (status != PJ_SUCCESS) {
+            PJ_LOG(4,(tp_ice->base.name, 
+                      "Error in parsing SDP candidate attribute '%.*s', "
+                      "candidate is ignored",
+                      (int)attr->value.slen, attr->value.ptr));
+            continue;
+        }
+
+        cand_cnt++;
+    }
+
+    /* Start ICE */
+    return pj_ice_strans_start_ice(tp_ice->ice_st, &ufrag_attr->value, 
+                                   &pwd_attr->value, cand_cnt, cand);
 }
 
 
 /*
- * Start ICE checks when both offer and answer are available.
+ * Start ICE checks when both offer and answer have been negotiated
+ * by SDP negotiator.
  */
 static pj_status_t transport_media_start(pjmedia_transport *tp,
-                                         pj_pool_t *pool,
-                                         pjmedia_sdp_session *sdp_local,
+                                         pj_pool_t *tmp_pool,
+                                         const pjmedia_sdp_session *sdp_local,
                                          const pjmedia_sdp_session *rem_sdp,
                                          unsigned media_index)
 {
     struct transport_ice *tp_ice = (struct transport_ice*)tp;
-    const pjmedia_sdp_attr *attr;
-    unsigned i, cand_cnt;
-    pj_ice_sess_cand *cand;
-    const pjmedia_sdp_media *sdp_med;
-    pj_bool_t remote_is_lite = PJ_FALSE;
-    pj_bool_t ice_mismatch = PJ_FALSE;
-    pjmedia_sdp_conn *conn = NULL;
-    pj_sockaddr conn_addr;
-    pj_bool_t conn_found_in_candidate = PJ_FALSE;
-    pj_str_t uname, pass;
+    pjmedia_sdp_media *rem_m;
+    enum oa_role current_oa_role;
+    pj_bool_t initial_oa;
     pj_status_t status;
 
-    PJ_ASSERT_RETURN(tp && pool && rem_sdp, PJ_EINVAL);
+    PJ_ASSERT_RETURN(tp && tmp_pool && rem_sdp, PJ_EINVAL);
     PJ_ASSERT_RETURN(media_index < rem_sdp->media_count, PJ_EINVAL);
 
-    sdp_med = rem_sdp->media[media_index];
-
-    /* Validate media transport */
-    /* By now, this transport only support RTP/AVP transport */
-    if ((tp_ice->media_option & PJMEDIA_TPMED_NO_TRANSPORT_CHECKING) == 0) {
-        pjmedia_sdp_media *m_rem, *m_loc;
-
-        m_rem = rem_sdp->media[media_index];
-        m_loc = sdp_local->media[media_index];
-
-        if (pj_stricmp(&m_loc->desc.transport, &ID_RTP_AVP) ||
-           (pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP)))
+    rem_m = rem_sdp->media[media_index];
+
+    initial_oa = tp_ice->initial_sdp;
+    current_oa_role = tp_ice->oa_role;
+
+    /* SDP has been negotiated */
+    tp_ice->initial_sdp = PJ_FALSE;
+    tp_ice->oa_role = ROLE_NONE;
+
+    /* Nothing to do if we don't have ICE session */
+    if (pj_ice_strans_has_sess(tp_ice->ice_st) == PJ_FALSE) {
+        return PJ_SUCCESS;
+    }
+
+    /* Processing depends on the offer/answer role */
+    if (current_oa_role == ROLE_OFFERER) {
+        /*
+         * We are offerer. So this will be the first time we see the
+         * remote's SDP.
+         */
+        struct sdp_state answer_state;
+
+        /* Verify the answer */
+        status = verify_ice_sdp(tp_ice, tmp_pool, rem_sdp, media_index, 
+                                PJ_ICE_SESS_ROLE_CONTROLLING, &answer_state);
+        if (status != PJ_SUCCESS) {
+            /* Something wrong in the SDP answer */
+            set_no_ice(tp_ice, "Invalid remote SDP answer", status);
+            return status;
+        }
+
+        /* Does it have ICE? */
+        if (answer_state.match_comp_cnt == 0) {
+            /* Remote doesn't support ICE */
+            set_no_ice(tp_ice, "Remote answer doesn't support ICE", 
+                       PJ_SUCCESS);
+            return PJ_SUCCESS;
+        }
+
+        /* Check if remote has reported ice-mismatch */
+        if (pjmedia_sdp_attr_find(rem_m->attr_count, rem_m->attr, 
+                                  &STR_ICE_MISMATCH, NULL) != NULL)
         {
-            pjmedia_sdp_media_deactivate(pool, m_loc);
-            return PJMEDIA_SDP_EINPROTO;
-        }
-    }
-
-    /* Get the SDP connection for the media stream.
-     * We'll verify later if the SDP connection address is specified 
-     * as one of the candidate.
-     */
-    conn = sdp_med->conn;
-    if (conn == NULL)
-        conn = rem_sdp->conn;
-
-    if (conn == NULL) {
-        /* Unable to find SDP connection */
-        return PJMEDIA_SDP_EMISSINGCONN;
-    }
-
-    pj_sockaddr_in_init(&conn_addr.ipv4, &conn->addr, 
-                        (pj_uint16_t)sdp_med->desc.port);
-
-    /* Find ice-ufrag attribute in media descriptor */
-    attr = pjmedia_sdp_attr_find2(sdp_med->attr_count, sdp_med->attr,
-                                  "ice-ufrag", NULL);
-    if (attr == NULL) {
-        /* Find ice-ufrag attribute in session descriptor */
-        attr = pjmedia_sdp_attr_find2(rem_sdp->attr_count, rem_sdp->attr,
-                                      "ice-ufrag", NULL);
-        if (attr == NULL) {
-            set_no_ice(tp_ice, "ice-ufrag attribute not found");
+            /* Remote has reported ice-mismatch */
+            set_no_ice(tp_ice, 
+                       "Remote answer contains 'ice-mismatch' attribute", 
+                       PJ_SUCCESS);
             return PJ_SUCCESS;
         }
-    }
-    uname = attr->value;
-
-    /* Find ice-pwd attribute in media descriptor */
-    attr = pjmedia_sdp_attr_find2(sdp_med->attr_count, sdp_med->attr,
-                                  "ice-pwd", NULL);
-    if (attr == NULL) {
-        /* Find ice-pwd attribute in session descriptor */
-        attr = pjmedia_sdp_attr_find2(rem_sdp->attr_count, rem_sdp->attr,
-                                      "ice-pwd", NULL);
-        if (attr == NULL) {
-            set_no_ice(tp_ice, "ice-pwd attribute not found");
+
+        /* Check if remote has indicated a restart */
+        if (answer_state.ice_restart) {
+            PJ_LOG(2,(tp_ice->base.name, 
+                      "Warning: remote has signalled ICE restart in SDP "
+                      "answer which is disallowed. Remote ICE negotiation"
+                      " may fail."));
+        }
+
+        /* Check if the answer itself is mismatched */
+        if (answer_state.ice_mismatch) {
+            /* This happens either when a B2BUA modified remote answer but
+             * strangely didn't modify our offer, or remote is not capable
+             * of detecting mismatch in our offer (it didn't put 
+             * 'ice-mismatch' attribute in the answer).
+             */
+            PJ_LOG(2,(tp_ice->base.name, 
+                      "Warning: remote answer mismatch, but it does not "
+                      "reject our offer with 'ice-mismatch'. ICE negotiation "
+                      "may fail"));
+        }
+
+        /* Do nothing if ICE is complete or running */
+        if (pj_ice_strans_sess_is_running(tp_ice->ice_st)) {
+            PJ_LOG(4,(tp_ice->base.name,
+                      "Ignored offer/answer because ICE is running"));
             return PJ_SUCCESS;
         }
-    }
-    pass = attr->value;
-
-    /* Allocate candidate array */
-    cand = (pj_ice_sess_cand*)
-           pj_pool_calloc(pool, PJ_ICE_MAX_CAND, sizeof(pj_ice_sess_cand));
-
-    /* Get all candidates in the media */
-    cand_cnt = 0;
-    for (i=0; i<sdp_med->attr_count && cand_cnt < PJ_ICE_MAX_CAND; ++i) {
-        pjmedia_sdp_attr *attr;
-
-        attr = sdp_med->attr[i];
-
-        /* Detect if remote is ICE lite */
-        if (pj_stricmp(&attr->name, &STR_ICE_LITE)==0) {
-            remote_is_lite = PJ_TRUE;
-            continue;
-        }
-
-        /* Detect if remote has reported ICE mismatch */
-        if (pj_stricmp(&attr->name, &STR_ICE_MISMATCH)==0) {
-            ice_mismatch = PJ_TRUE;
-            continue;
-        }
-
-        if (pj_stricmp(&attr->name, &STR_CANDIDATE)!=0)
-            continue;
-
-        /* Parse candidate */
-        status = parse_cand(pool, &attr->value, &cand[cand_cnt]);
-        if (status != PJ_SUCCESS) {
-            PJ_LOG(4,(THIS_FILE, 
-                      "Error in parsing SDP candidate attribute, "
-                      "candidate is ignored"));
-            continue;
-        }
-
-        /* Check if this candidate is equal to the connection line */
-        if (!conn_found_in_candidate &&
-            pj_memcmp(&conn_addr.ipv4, &cand[cand_cnt].addr.ipv4,
-                      sizeof(pj_sockaddr_in))==0)
-        {
-            conn_found_in_candidate = PJ_TRUE;
-        }
-
-        cand_cnt++;
-    }
-
-    /* Handle ice-mismatch case */
-    if (ice_mismatch) {
-        set_no_ice(tp_ice, "remote reported ice-mismatch");
-        return PJ_SUCCESS;
-    }
-
-    /* Handle case where SDP connection address is not specified as
-     * one of the candidate.
-     */
-    if (!conn_found_in_candidate) {
-        set_no_ice(tp_ice, "local reported ice-mismatch");
-        return PJ_SUCCESS;
-    }
-
-    /* If our role was controlled but it turns out that remote is 
-     * a lite implementation, change our role to controlling.
-     */
-    if (remote_is_lite && 
-        pj_ice_strans_get_role(tp_ice->ice_st) == PJ_ICE_SESS_ROLE_CONTROLLED)
-    {
-        pj_ice_strans_change_role(tp_ice->ice_st, 
-                                  PJ_ICE_SESS_ROLE_CONTROLLING);
-    }
-
-    /* Start ICE */
-    return pj_ice_strans_start_ice(tp_ice->ice_st, &uname, &pass, 
-                                   cand_cnt, cand);
+
+        if (pj_ice_strans_sess_is_complete(tp_ice->ice_st)) {
+            PJ_LOG(4,(tp_ice->base.name, "ICE session unchanged"));
+            return PJ_SUCCESS;
+        }
+
+        /* Start ICE */
+
+    } else {
+        /*
+         * We are answerer. We've seen and negotiated remote's SDP
+         * before, and the result is in "rem_offer_state".
+         */
+        const pjmedia_sdp_attr *ufrag_attr, *pwd_attr;
+
+        /* Check for ICE in remote offer */
+        if (tp_ice->rem_offer_state.match_comp_cnt == 0) {
+            /* No ICE attribute present */
+            set_no_ice(tp_ice, "Remote no longer offers ICE",
+                       PJ_SUCCESS);
+            return PJ_SUCCESS;
+        }
+
+        /* Check for ICE ice_mismatch condition in the offer */
+        if (tp_ice->rem_offer_state.ice_mismatch) {
+            set_no_ice(tp_ice, "Remote offer mismatch: ", 
+                       PJNATH_EICEMISMATCH);
+            return PJ_SUCCESS;
+        }
+
+        /* If ICE is complete and remote doesn't request restart,
+         * then leave the session as is.
+         */
+        if (!initial_oa && tp_ice->rem_offer_state.ice_restart == PJ_FALSE) {
+            /* Remote has not requested ICE restart, so session is
+             * unchanged.
+             */
+            PJ_LOG(4,(tp_ice->base.name, "ICE session unchanged"));
+            return PJ_SUCCESS;
+        }
+
+        /* Either remote has requested ICE restart or this is our
+         * first answer. 
+         */
+
+        /* Stop ICE */
+        if (!initial_oa) {
+            set_no_ice(tp_ice, "restarting by remote request..", PJ_SUCCESS);
+
+            /* We have put new ICE ufrag and pwd in the answer. Now
+             * create a new ICE session with that ufrag/pwd pair.
+             */
+            get_ice_attr(sdp_local, sdp_local->media[media_index], 
+                         &ufrag_attr, &pwd_attr);
+            status = pj_ice_strans_init_ice(tp_ice->ice_st, 
+                                            tp_ice->rem_offer_state.local_role,
+                                            &ufrag_attr->value, 
+                                            &pwd_attr->value);
+            if (status != PJ_SUCCESS) {
+                PJ_LOG(1,(tp_ice->base.name, 
+                          "ICE re-initialization failed (status=%d)!",
+                          status));
+                return status;
+            }
+        }
+
+        /* start ICE */
+    }
+
+    /* Now start ICE */
+    status = start_ice(tp_ice, tmp_pool, rem_sdp, media_index);
+    if (status != PJ_SUCCESS) {
+        PJ_LOG(1,(tp_ice->base.name, 
+                  "ICE restart failed (status=%d)!",
+                  status));
+        return status;
+    }
+
+    /* Done */
+
+    return PJ_SUCCESS;
 }
 
@@ -642 +1365 @@
 {
     struct transport_ice *tp_ice = (struct transport_ice*)tp;
-    return pj_ice_strans_stop_ice(tp_ice->ice_st);
+    
+    set_no_ice(tp_ice, "media stop requested", PJ_SUCCESS);
+
+    return PJ_SUCCESS;
 }
 

pjproject/trunk/pjmedia/src/pjmedia/transport_srtp.c

@@ -92 +92 @@
     pjmedia_srtp_crypto  rx_policy;
 
+    /* Temporary policy for negotiation */
+    pjmedia_srtp_crypto  tx_policy_neg;
+    pjmedia_srtp_crypto  rx_policy_neg;
+
     /* libSRTP contexts */
     srtp_t               srtp_tx_ctx;
@@ -106 +110 @@
         
     /* Transport information */
-    pjmedia_transport   *real_tp; /**< Underlying transport.       */
+    pjmedia_transport   *member_tp; /**< Underlying transport.       */
+
+    /* When in SRTP optional mode, instead of always offering RTP/AVP,
+     * we should create offer based on remote preference. At the first time,
+     * remote preference is unknown, it is known after media_start() called.
+     * So next time the same session need to create an offer, it will create
+     * SDP with transport type based on remote preference.
+     */
+    pj_bool_t            remote_prefer_rtp_savp;
 
 } transport_srtp;
@@ -152 +164 @@
                                        pj_size_t size);
 static pj_status_t transport_media_create(pjmedia_transport *tp,
-                                       pj_pool_t *pool,
+                                       pj_pool_t *sdp_pool,
                                        unsigned options,
+                                       const pjmedia_sdp_session *sdp_remote,
+                                       unsigned media_index);
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+                                       pj_pool_t *sdp_pool,
                                        pjmedia_sdp_session *sdp_local,
                                        const pjmedia_sdp_session *sdp_remote,
@@ -159 +175 @@
 static pj_status_t transport_media_start (pjmedia_transport *tp,
                                        pj_pool_t *pool,
-                                       pjmedia_sdp_session *sdp_local,
+                                       const pjmedia_sdp_session *sdp_local,
                                        const pjmedia_sdp_session *sdp_remote,
                                        unsigned media_index);
@@ -179 +195 @@
     &transport_send_rtcp2,
     &transport_media_create,
+    &transport_encode_sdp,
     &transport_media_start,
     &transport_media_stop,
@@ -332 +349 @@
     srtp->session_inited = PJ_FALSE;
     srtp->bypass_srtp = PJ_FALSE;
+    srtp->remote_prefer_rtp_savp = PJ_FALSE;
 
     if (opt) {
@@ -368 +386 @@
 
     /* Set underlying transport */
-    srtp->real_tp = tp;
+    srtp->member_tp = tp;
 
     /* Done */
@@ -458 +476 @@
     srtp->tx_policy = *tx;
     pj_strset(&srtp->tx_policy.key,  srtp->tx_key, tx->key.slen);
-    srtp->tx_policy.name = 
-                        pj_str(crypto_suites[get_crypto_idx(&tx->name)].name);
+    srtp->tx_policy.name=pj_str(crypto_suites[get_crypto_idx(&tx->name)].name);
 
 
@@ -492 +509 @@
     srtp->rx_policy = *rx;
     pj_strset(&srtp->rx_policy.key,  srtp->rx_key, rx->key.slen);
-    srtp->rx_policy.name = 
-                        pj_str(crypto_suites[get_crypto_idx(&rx->name)].name);
+    srtp->rx_policy.name=pj_str(crypto_suites[get_crypto_idx(&rx->name)].name);
 
     /* Declare SRTP session initialized */
@@ -551 +567 @@
     PJ_ASSERT_RETURN(tp, NULL);
 
-    return srtp->real_tp;
+    return srtp->member_tp;
 }
 
@@ -578 +594 @@
               sizeof(srtp_info));
 
-    return pjmedia_transport_get_info(srtp->real_tp, info);
+    return pjmedia_transport_get_info(srtp->member_tp, info);
 }
 
@@ -595 +611 @@
 
     /* Attach itself to transport */
-    status = pjmedia_transport_attach(srtp->real_tp, srtp, rem_addr, rem_rtcp,
+    status = pjmedia_transport_attach(srtp->member_tp, srtp, rem_addr, rem_rtcp,
                                       addr_len, &srtp_rtp_cb, &srtp_rtcp_cb);
     if (status != PJ_SUCCESS)
@@ -615 +631 @@
     PJ_ASSERT_ON_FAIL(tp, return);
 
-    if (srtp->real_tp) {
-        pjmedia_transport_detach(srtp->real_tp, srtp);
+    if (srtp->member_tp) {
+        pjmedia_transport_detach(srtp->member_tp, srtp);
     }
 
@@ -635 +651 @@
 
     if (srtp->bypass_srtp)
-        return pjmedia_transport_send_rtp(srtp->real_tp, pkt, size);
+        return pjmedia_transport_send_rtp(srtp->member_tp, pkt, size);
 
     if (!srtp->session_inited)
@@ -648 +664 @@
     err = srtp_protect(srtp->srtp_tx_ctx, srtp->tx_buffer, &len);
     if (err == err_status_ok) {
-        status = pjmedia_transport_send_rtp(srtp->real_tp, srtp->tx_buffer, len);
+        status = pjmedia_transport_send_rtp(srtp->member_tp, srtp->tx_buffer, len);
     } else {
         status = PJMEDIA_ERRNO_FROM_LIBSRTP(err);
@@ -677 +693 @@
 
     if (srtp->bypass_srtp) {
-        return pjmedia_transport_send_rtcp2(srtp->real_tp, addr, addr_len, 
+        return pjmedia_transport_send_rtcp2(srtp->member_tp, addr, addr_len, 
                                             pkt, size);
     }
@@ -693 +709 @@
     
     if (err == err_status_ok) {
-        status = pjmedia_transport_send_rtcp2(srtp->real_tp, addr, addr_len,
+        status = pjmedia_transport_send_rtcp2(srtp->member_tp, addr, addr_len,
                                               srtp->tx_buffer, len);
     } else {
@@ -711 +727 @@
     transport_srtp *srtp = (transport_srtp *) tp;
 
-    return pjmedia_transport_simulate_lost(srtp->real_tp, dir, pct_lost);
+    return pjmedia_transport_simulate_lost(srtp->member_tp, dir, pct_lost);
 }
 
@@ -723 +739 @@
     pjmedia_transport_detach(tp, NULL);
     
-    if (srtp->setting.close_member_tp && srtp->real_tp) {
-        pjmedia_transport_close(srtp->real_tp);
+    if (srtp->setting.close_member_tp && srtp->member_tp) {
+        pjmedia_transport_close(srtp->member_tp);
     }
 
@@ -956 +972 @@
 
 static pj_status_t transport_media_create(pjmedia_transport *tp,
-                                          pj_pool_t *pool,
+                                          pj_pool_t *sdp_pool,
                                           unsigned options,
-                                          pjmedia_sdp_session *sdp_local,
                                           const pjmedia_sdp_session *sdp_remote,
                                           unsigned media_index)
+{
+    struct transport_srtp *srtp = (struct transport_srtp*) tp;
+    unsigned member_tp_option;
+
+    PJ_ASSERT_RETURN(tp, PJ_EINVAL);
+    
+    pj_bzero(&srtp->rx_policy_neg, sizeof(srtp->rx_policy_neg));
+    pj_bzero(&srtp->tx_policy_neg, sizeof(srtp->tx_policy_neg));
+
+    srtp->media_option = options;
+    member_tp_option = options | PJMEDIA_TPMED_NO_TRANSPORT_CHECKING;
+
+    srtp->offerer_side = sdp_remote == NULL;
+
+    /* Validations */
+    if (srtp->offerer_side) {
+
+        if (srtp->setting.use == PJMEDIA_SRTP_DISABLED)
+            goto BYPASS_SRTP;
+
+    } else {
+
+        pjmedia_sdp_media *m_rem;
+        
+        m_rem = sdp_remote->media[media_index];
+
+        /* Nothing to do on inactive media stream */
+        if (pjmedia_sdp_media_find_attr(m_rem, &ID_INACTIVE, NULL))
+            goto BYPASS_SRTP;
+
+        /* Validate remote media transport based on SRTP usage option.
+         */
+        switch (srtp->setting.use) {
+            case PJMEDIA_SRTP_DISABLED:
+                if (pj_stricmp(&m_rem->desc.transport, &ID_RTP_SAVP) == 0)
+                    return PJMEDIA_SRTP_ESDPINTRANSPORT;
+                goto BYPASS_SRTP;
+            case PJMEDIA_SRTP_OPTIONAL:
+                break;
+            case PJMEDIA_SRTP_MANDATORY:
+                if (pj_stricmp(&m_rem->desc.transport, &ID_RTP_SAVP) != 0)
+                    return PJMEDIA_SRTP_ESDPINTRANSPORT;
+                break;
+        }
+
+    }
+    goto PROPAGATE_MEDIA_CREATE;
+
+BYPASS_SRTP:
+    srtp->bypass_srtp = PJ_TRUE;
+    member_tp_option &= ~PJMEDIA_TPMED_NO_TRANSPORT_CHECKING;
+
+PROPAGATE_MEDIA_CREATE:
+    return pjmedia_transport_media_create(srtp->member_tp, sdp_pool, 
+                                          member_tp_option, sdp_remote,
+                                          media_index);
+}
+
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+                                        pj_pool_t *sdp_pool,
+                                        pjmedia_sdp_session *sdp_local,
+                                        const pjmedia_sdp_session *sdp_remote,
+                                        unsigned media_index)
 {
     struct transport_srtp *srtp = (struct transport_srtp*) tp;
@@ -971 +1049 @@
     pj_str_t attr_value;
     unsigned i, j;
-    unsigned member_tp_option;
-
-    PJ_ASSERT_RETURN(tp && pool && sdp_local, PJ_EINVAL);
+
+    PJ_ASSERT_RETURN(tp && sdp_pool && sdp_local, PJ_EINVAL);
     
-    srtp->media_option = options;
-    member_tp_option = options | PJMEDIA_TPMED_NO_TRANSPORT_CHECKING;
-
-    pj_bzero(&srtp->rx_policy, sizeof(srtp->tx_policy));
-    pj_bzero(&srtp->tx_policy, sizeof(srtp->rx_policy));
+    srtp->offerer_side = sdp_remote == NULL;
 
     m_rem = sdp_remote ? sdp_remote->media[media_index] : NULL;
     m_loc = sdp_local->media[media_index];
 
-    /* bypass if media transport is not RTP/AVP or RTP/SAVP */
+    /* Bypass if media transport is not RTP/AVP or RTP/SAVP */
     if (pj_stricmp(&m_loc->desc.transport, &ID_RTP_AVP)  != 0 && 
         pj_stricmp(&m_loc->desc.transport, &ID_RTP_SAVP) != 0)
@@ -992 +1065 @@
     if (pjmedia_sdp_media_find_attr(m_loc, &ID_INACTIVE, NULL) || 
         (m_rem && pjmedia_sdp_media_find_attr(m_rem, &ID_INACTIVE, NULL)))
-    {
         goto BYPASS_SRTP;
-    }
-
-    srtp->offerer_side = !sdp_remote;
 
     /* Check remote media transport & set local media transport 
@@ -1002 +1071 @@
      */
     if (srtp->offerer_side) {
-        if (srtp->setting.use == PJMEDIA_SRTP_DISABLED) {
-            goto BYPASS_SRTP;
-        } else if (srtp->setting.use == PJMEDIA_SRTP_OPTIONAL) {
-            m_loc->desc.transport = ID_RTP_AVP;
-        } else if (srtp->setting.use == PJMEDIA_SRTP_MANDATORY) {
-            m_loc->desc.transport = ID_RTP_SAVP;
+
+        /* Generate transport */
+        switch (srtp->setting.use) {
+            case PJMEDIA_SRTP_DISABLED:
+                goto BYPASS_SRTP;
+            case PJMEDIA_SRTP_OPTIONAL:
+                m_loc->desc.transport = srtp->remote_prefer_rtp_savp?
+                                        ID_RTP_SAVP : ID_RTP_AVP;
+                break;
+            case PJMEDIA_SRTP_MANDATORY:
+                m_loc->desc.transport = ID_RTP_SAVP;
+                break;
         }
+
+        /* Generate crypto attribute if not yet */
+        if (pjmedia_sdp_media_find_attr(m_loc, &ID_CRYPTO, NULL) == NULL) {
+            for (i=0; i<srtp->setting.crypto_count; ++i) {
+                /* Offer crypto-suites based on setting. */
+                buffer_len = MAXLEN;
+                status = generate_crypto_attr_value(srtp->pool, buffer, &buffer_len,
+                                                    &srtp->setting.crypto[i],
+                                                    i+1);
+                if (status != PJ_SUCCESS)
+                    return status;
+
+                /* If buffer_len==0, just skip the crypto attribute. */
+                if (buffer_len) {
+                    pj_strset(&attr_value, buffer, buffer_len);
+                    attr = pjmedia_sdp_attr_create(srtp->pool, ID_CRYPTO.ptr, 
+                                                   &attr_value);
+                    m_loc->attr[m_loc->attr_count++] = attr;
+                }
+            }
+        }
+
     } else {
-        if (srtp->setting.use == PJMEDIA_SRTP_DISABLED) {
-            if (pj_stricmp(&m_rem->desc.transport, &ID_RTP_SAVP) == 0) {
-                DEACTIVATE_MEDIA(pool, m_loc);
-                return PJMEDIA_SRTP_ESDPINTRANSPORT;
+        /* Answerer side */
+
+        pj_assert(sdp_remote && m_rem);
+
+        /* Generate transport */
+        switch (srtp->setting.use) {
+            case PJMEDIA_SRTP_DISABLED:
+                if (pj_stricmp(&m_rem->desc.transport, &ID_RTP_SAVP) == 0)
+                    return PJMEDIA_SRTP_ESDPINTRANSPORT;
+                goto BYPASS_SRTP;
+            case PJMEDIA_SRTP_OPTIONAL:
+                m_loc->desc.transport = m_rem->desc.transport;
+                break;
+            case PJMEDIA_SRTP_MANDATORY:
+                if (pj_stricmp(&m_rem->desc.transport, &ID_RTP_SAVP) != 0)
+                    return PJMEDIA_SRTP_ESDPINTRANSPORT;
+                m_loc->desc.transport = ID_RTP_SAVP;
+                break;
+        }
+
+        /* Generate crypto attribute if not yet */
+        if (pjmedia_sdp_media_find_attr(m_loc, &ID_CRYPTO, NULL) == NULL) {
+
+            pjmedia_srtp_crypto tmp_rx_crypto;
+            pj_bool_t has_crypto_attr = PJ_FALSE;
+            int matched_idx = -1;
+            int chosen_tag = 0;
+            int tags[64]; /* assume no more than 64 crypto attrs in a media */
+            int cr_attr_count = 0;
+
+            /* Find supported crypto-suite, get the tag, and assign policy_local */
+            for (i=0; i<m_rem->attr_count; ++i) {
+                if (pj_stricmp(&m_rem->attr[i]->name, &ID_CRYPTO) != 0)
+                    continue;
+
+                has_crypto_attr = PJ_TRUE;
+
+                status = parse_attr_crypto(srtp->pool, m_rem->attr[i], 
+                                           &tmp_rx_crypto, &tags[cr_attr_count]);
+                if (status != PJ_SUCCESS)
+                    return status;
+         
+                /* Check duplicated tag */
+                for (j=0; j<cr_attr_count; ++j) {
+                    if (tags[j] == tags[cr_attr_count]) {
+                        DEACTIVATE_MEDIA(sdp_pool, m_loc);
+                        return PJMEDIA_SRTP_ESDPDUPCRYPTOTAG;
+                    }
+                }
+
+                if (matched_idx == -1) {
+                    /* lets see if the crypto-suite offered is supported */
+                    for (j=0; j<srtp->setting.crypto_count; ++j)
+                        if (pj_stricmp(&tmp_rx_crypto.name, 
+                                       &srtp->setting.crypto[j].name) == 0)
+                        {
+                            int cs_idx = get_crypto_idx(&tmp_rx_crypto.name);
+
+                            /* Force to use test key */
+                            /* bad keys for snom: */
+                            //char *hex_test_key = "58b29c5c8f42308120ce857e439f2d"
+                            //               "7810a8b10ad0b1446be5470faea496";
+                            //char *hex_test_key = "20a26aac7ba062d356ff52b61e3993"
+                            //               "ccb78078f12c64db94b9c294927fd0";
+                            //pj_str_t *test_key = &srtp->setting.crypto[j].key;
+                            //char  *raw_test_key = pj_pool_zalloc(srtp->pool, 64);
+                            //hex_string_to_octet_string(
+                            //          raw_test_key,
+                            //          hex_test_key,
+                            //          strlen(hex_test_key));
+                            //pj_strset(test_key, raw_test_key, 
+                            //    crypto_suites[cs_idx].cipher_key_len);
+                            /* EO Force to use test key */
+
+                            if (tmp_rx_crypto.key.slen != 
+                                (int)crypto_suites[cs_idx].cipher_key_len)
+                                return PJMEDIA_SRTP_EINKEYLEN;
+
+                            srtp->rx_policy_neg = tmp_rx_crypto;
+                            chosen_tag = tags[cr_attr_count];
+                            matched_idx = j;
+                            break;
+                        }
+                }
+                cr_attr_count++;
             }
-            goto BYPASS_SRTP;
-        } else if (srtp->setting.use == PJMEDIA_SRTP_OPTIONAL) {
-                m_loc->desc.transport = m_rem->desc.transport;
-        } else if (srtp->setting.use == PJMEDIA_SRTP_MANDATORY) {
-            if (pj_stricmp(&m_rem->desc.transport, &ID_RTP_SAVP) != 0) {
-                DEACTIVATE_MEDIA(pool, m_loc);
-                return PJMEDIA_SRTP_ESDPINTRANSPORT;
+
+            /* Check crypto negotiation result */
+            switch (srtp->setting.use) {
+                case PJMEDIA_SRTP_DISABLED:
+                    pj_assert(!"Should never reach here");
+                    break;
+
+                case PJMEDIA_SRTP_OPTIONAL:
+                    /* bypass SRTP when no crypto-attr and remote uses RTP/AVP */
+                    if (!has_crypto_attr && 
+                        pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP) == 0)
+                        goto BYPASS_SRTP;
+                    /* bypass SRTP when nothing match and remote uses RTP/AVP */
+                    else if (matched_idx == -1 && 
+                        pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP) == 0)
+                        goto BYPASS_SRTP;
+                    break;
+
+                case PJMEDIA_SRTP_MANDATORY:
+                    /* Do nothing, intentional */
+                    break;
             }
-            m_loc->desc.transport = ID_RTP_SAVP;
-        }
-    }
-
-    /* Generate crypto attribute */
-    if (srtp->offerer_side) {
-        for (i=0; i<srtp->setting.crypto_count; ++i) {
-            /* Offer crypto-suites based on setting. */
+
+            /* No crypto attr */
+            if (!has_crypto_attr) {
+                DEACTIVATE_MEDIA(sdp_pool, m_loc);
+                return PJMEDIA_SRTP_ESDPREQCRYPTO;
+            }
+
+            /* No crypto match */
+            if (matched_idx == -1) {
+                DEACTIVATE_MEDIA(sdp_pool, m_loc);
+                return PJMEDIA_SRTP_ENOTSUPCRYPTO;
+            }
+
+            /* we have to generate crypto answer, 
+             * with srtp->tx_policy_neg matched the offer
+             * and rem_tag contains matched offer tag.
+             */
             buffer_len = MAXLEN;
             status = generate_crypto_attr_value(srtp->pool, buffer, &buffer_len,
-                                                &srtp->setting.crypto[i],
-                                                i+1);
+                                                &srtp->setting.crypto[matched_idx],
+                                                chosen_tag);
             if (status != PJ_SUCCESS)
                 return status;
 
+            srtp->tx_policy_neg = srtp->setting.crypto[matched_idx];
+            
             /* If buffer_len==0, just skip the crypto attribute. */
             if (buffer_len) {
                 pj_strset(&attr_value, buffer, buffer_len);
-                attr = pjmedia_sdp_attr_create(srtp->pool, ID_CRYPTO.ptr, 
+                attr = pjmedia_sdp_attr_create(sdp_pool, ID_CRYPTO.ptr, 
                                                &attr_value);
                 m_loc->attr[m_loc->attr_count++] = attr;
             }
+
+            /* At this point, we get valid rx_policy_neg & tx_policy_neg. */
         }
-    } else {
-        /* find supported crypto-suite, get the tag, and assign policy_local */
-        pjmedia_srtp_crypto tmp_rx_crypto;
-        pj_bool_t has_crypto_attr = PJ_FALSE;
-        pj_bool_t has_match = PJ_FALSE;
-        int chosen_tag = 0;
-        int tags[64]; /* assume no more than 64 crypto attrs in a media */
-        int cr_attr_count = 0;
-        int k;
-
-        for (i=0; i<m_rem->attr_count; ++i) {
-            if (pj_stricmp(&m_rem->attr[i]->name, &ID_CRYPTO) != 0)
-                continue;
-
-            has_crypto_attr = PJ_TRUE;
-
-            status = parse_attr_crypto(srtp->pool, m_rem->attr[i], 
-                                       &tmp_rx_crypto, &tags[cr_attr_count]);
-            if (status != PJ_SUCCESS)
-                return status;
-         
-            /* Check duplicated tag */
-            for (k=0; k<cr_attr_count; ++k) {
-                if (tags[k] == tags[cr_attr_count]) {
-                    DEACTIVATE_MEDIA(pool, m_loc);
-                    return PJMEDIA_SRTP_ESDPDUPCRYPTOTAG;
-                }
-            }
-
-            if (!has_match) {
-                /* lets see if the crypto-suite offered is supported */
-                for (j=0; j<srtp->setting.crypto_count; ++j)
-                    if (pj_stricmp(&tmp_rx_crypto.name, 
-                                   &srtp->setting.crypto[j].name) == 0)
-                    {
-                        int cs_idx = get_crypto_idx(&tmp_rx_crypto.name);
-
-                        /* Force to use test key */
-                        /* bad keys for snom: */
-                        //char *hex_test_key = "58b29c5c8f42308120ce857e439f2d"
-                        //                   "7810a8b10ad0b1446be5470faea496";
-                        //char *hex_test_key = "20a26aac7ba062d356ff52b61e3993"
-                        //                   "ccb78078f12c64db94b9c294927fd0";
-                        //pj_str_t *test_key = &srtp->setting.crypto[j].key;
-                        //char  *raw_test_key = pj_pool_zalloc(srtp->pool, 64);
-                        //hex_string_to_octet_string(
-                        //              raw_test_key,
-                        //              hex_test_key,
-                        //              strlen(hex_test_key));
-                        //pj_strset(test_key, raw_test_key, 
-                        //        crypto_suites[cs_idx].cipher_key_len);
-                        /* EO Force to use test key */
-
-                        if (tmp_rx_crypto.key.slen != 
-                            (int)crypto_suites[cs_idx].cipher_key_len)
-                            return PJMEDIA_SRTP_EINKEYLEN;
-
-                        srtp->tx_policy = srtp->setting.crypto[j];
-                        srtp->rx_policy = tmp_rx_crypto;
-                        chosen_tag = tags[cr_attr_count];
-                        has_match = PJ_TRUE;
-                        break;
-                    }
-            }
-            cr_attr_count++;
-        }
-
-        if (srtp->setting.use == PJMEDIA_SRTP_DISABLED) {
-            /* bypass when remote uses RTP/AVP and we disable SRTP */
-            goto BYPASS_SRTP;
-        } else if (srtp->setting.use == PJMEDIA_SRTP_OPTIONAL) {
-            /* bypass SRTP when no crypto-attr but remote uses RTP/AVP */
-            if (!has_crypto_attr && 
-                pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP) == 0)
-                goto BYPASS_SRTP;
-            /* bypass SRTP when nothing match but remote uses RTP/AVP */
-            if (!has_match && 
-                pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP) == 0)
-                goto BYPASS_SRTP;
-        } else if (srtp->setting.use == PJMEDIA_SRTP_MANDATORY) {
-            /* do nothing, this is intended */
-        }
-
-        /* No crypto attr */
-        if (!has_crypto_attr) {
-            DEACTIVATE_MEDIA(pool, m_loc);
-            return PJMEDIA_SRTP_ESDPREQCRYPTO;
-        }
-
-        /* No crypto match */
-        if (!has_match) {
-            DEACTIVATE_MEDIA(pool, m_loc);
-            return PJMEDIA_SRTP_ENOTSUPCRYPTO;
-        }
-
-        /* we have to generate crypto answer, 
-         * with srtp->tx_policy matched the offer
-         * and rem_tag contains matched offer tag.
-         */
-        buffer_len = MAXLEN;
-        status = generate_crypto_attr_value(srtp->pool, buffer, &buffer_len,
-                                            &srtp->tx_policy,
-                                            chosen_tag);
-        if (status != PJ_SUCCESS)
-            return status;
-
-        /* If buffer_len==0, just skip the crypto attribute. */
-        if (buffer_len) {
-            pj_strset(&attr_value, buffer, buffer_len);
-            attr = pjmedia_sdp_attr_create(srtp->pool, ID_CRYPTO.ptr, 
-                                           &attr_value);
-            m_loc->attr[m_loc->attr_count++] = attr;
-        }
-
-        /* At this point,
-         * we should have valid rx_policy & tx_policy.
-         */
+            
     }
     goto PROPAGATE_MEDIA_CREATE;
@@ -1168 +1257 @@
 BYPASS_SRTP:
     srtp->bypass_srtp = PJ_TRUE;
-    member_tp_option &= ~PJMEDIA_TPMED_NO_TRANSPORT_CHECKING;
 
 PROPAGATE_MEDIA_CREATE:
-    return pjmedia_transport_media_create(srtp->real_tp, pool, 
-                            member_tp_option,
-                            sdp_local, sdp_remote, media_index);
+    return pjmedia_transport_encode_sdp(srtp->member_tp, sdp_pool, 
+                                        sdp_local, sdp_remote, media_index);
 }
 
@@ -1180 +1267 @@
 static pj_status_t transport_media_start(pjmedia_transport *tp,
                                          pj_pool_t *pool,
-                                         pjmedia_sdp_session *sdp_local,
+                                         const pjmedia_sdp_session *sdp_local,
                                          const pjmedia_sdp_session *sdp_remote,
                                          unsigned media_index)
@@ -1196 +1283 @@
     m_rem = sdp_remote->media[media_index];
     m_loc = sdp_local->media[media_index];
+
+    srtp->remote_prefer_rtp_savp = (pj_stricmp(&m_rem->desc.transport, 
+                                   &ID_RTP_SAVP) == 0);
 
     /* For answerer side, this function will just have to start SRTP */
@@ -1264 +1354 @@
             }
 
-            srtp->tx_policy = srtp->setting.crypto[rem_tag-1];
-            srtp->rx_policy = tmp_tx_crypto;
+            srtp->tx_policy_neg = srtp->setting.crypto[rem_tag-1];
+            srtp->rx_policy_neg = tmp_tx_crypto;
         }
 
@@ -1281 +1371 @@
         }
 
-        /* At this point,
-         * we should have valid rx_policy & tx_policy.
-         */
+        /* At this point, we get valid rx_policy_neg & tx_policy_neg. */
     }
 
     /* Got policy_local & policy_remote, let's initalize the SRTP */
-    status = pjmedia_transport_srtp_start(tp, &srtp->tx_policy, &srtp->rx_policy);
+    status = pjmedia_transport_srtp_start(tp, &srtp->tx_policy_neg, &srtp->rx_policy_neg);
     if (status != PJ_SUCCESS)
         return status;
@@ -1297 +1385 @@
 
 PROPAGATE_MEDIA_START:
-    return pjmedia_transport_media_start(srtp->real_tp, pool, 
+    return pjmedia_transport_media_start(srtp->member_tp, pool, 
                                          sdp_local, sdp_remote,
                                          media_index);
@@ -1307 +1395 @@
     pj_status_t status;
 
-    status = pjmedia_transport_media_stop(srtp->real_tp);
+    status = pjmedia_transport_media_stop(srtp->member_tp);
     if (status != PJ_SUCCESS)
         PJ_LOG(4, (srtp->pool->obj_name, 

pjproject/trunk/pjmedia/src/pjmedia/transport_udp.c

@@ -130 +130 @@
                                        pj_pool_t *pool,
                                        unsigned options,
-                                       pjmedia_sdp_session *sdp_local,
                                        const pjmedia_sdp_session *sdp_remote,
                                        unsigned media_index);
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+                                        pj_pool_t *pool,
+                                        pjmedia_sdp_session *sdp_local,
+                                        const pjmedia_sdp_session *rem_sdp,
+                                        unsigned media_index);
 static pj_status_t transport_media_start (pjmedia_transport *tp,
                                        pj_pool_t *pool,
-                                       pjmedia_sdp_session *sdp_local,
+                                       const pjmedia_sdp_session *sdp_local,
                                        const pjmedia_sdp_session *sdp_remote,
                                        unsigned media_index);
@@ -154 +158 @@
     &transport_send_rtcp2,
     &transport_media_create,
+    &transport_encode_sdp,
     &transport_media_start,
     &transport_media_stop,
@@ -791 +796 @@
                                   pj_pool_t *pool,
                                   unsigned options,
-                                  pjmedia_sdp_session *sdp_local,
                                   const pjmedia_sdp_session *sdp_remote,
                                   unsigned media_index)
@@ -797 +801 @@
     struct transport_udp *udp = (struct transport_udp*)tp;
 
-    PJ_ASSERT_RETURN(tp && pool && sdp_local, PJ_EINVAL);
+    PJ_ASSERT_RETURN(tp && pool, PJ_EINVAL);
     udp->media_options = options;
+
+    PJ_UNUSED_ARG(sdp_remote);
+    PJ_UNUSED_ARG(media_index);
+
+    return PJ_SUCCESS;
+}
+
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+                                        pj_pool_t *pool,
+                                        pjmedia_sdp_session *sdp_local,
+                                        const pjmedia_sdp_session *rem_sdp,
+                                        unsigned media_index)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
 
     /* Validate media transport */
@@ -805 +823 @@
         pjmedia_sdp_media *m_rem, *m_loc;
 
-        m_rem = sdp_remote? sdp_remote->media[media_index] : NULL;
+        m_rem = rem_sdp? rem_sdp->media[media_index] : NULL;
         m_loc = sdp_local->media[media_index];
 
@@ -821 +839 @@
 static pj_status_t transport_media_start(pjmedia_transport *tp,
                                   pj_pool_t *pool,
-                                  pjmedia_sdp_session *sdp_local,
+                                  const pjmedia_sdp_session *sdp_local,
                                   const pjmedia_sdp_session *sdp_remote,
                                   unsigned media_index)
 {
-    struct transport_udp *udp = (struct transport_udp*)tp;
-
     PJ_ASSERT_RETURN(tp && pool && sdp_local, PJ_EINVAL);
 
-    /* Validate media transport */
-    /* By now, this transport only support RTP/AVP transport */
-    if ((udp->media_options & PJMEDIA_TPMED_NO_TRANSPORT_CHECKING) == 0) {
-        pjmedia_sdp_media *m_rem, *m_loc;
-
-        m_rem = sdp_remote->media[media_index];
-        m_loc = sdp_local->media[media_index];
-
-        if (pj_stricmp(&m_loc->desc.transport, &ID_RTP_AVP) ||
-            pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP))
-        {
-            pjmedia_sdp_media_deactivate(pool, m_loc);
-            return PJMEDIA_SDP_EINPROTO;
-        }
-    }
+    PJ_UNUSED_ARG(tp);
+    PJ_UNUSED_ARG(pool);
+    PJ_UNUSED_ARG(sdp_local);
+    PJ_UNUSED_ARG(sdp_remote);
+    PJ_UNUSED_ARG(media_index);
 
     return PJ_SUCCESS;

pjproject/trunk/pjsip/include/pjsua-lib/pjsua_internal.h

@@ -26 +26 @@
 
 PJ_BEGIN_DECL
+
+/** 
+ * Media transport state.
+ */
+typedef enum pjsua_med_tp_st
+{
+    /** Not initialized */
+    PJSUA_MED_TP_IDLE,
+
+    /** Initialized (media_create() has been called) */
+    PJSUA_MED_TP_INIT,
+
+    /** Running (media_start() has been called) */
+    PJSUA_MED_TP_RUNNING
+
+} pjsua_med_tp_st;
 
 /** 
@@ -53 +69 @@
                                          call was triggered by xfer.        */
     pjmedia_transport   *med_tp;    /**< Current media transport.           */
-    pj_status_t          med_tp_st; /**< Media transport status.            */
+    pj_status_t          med_tp_ready;/**< Media transport status.          */
     pjmedia_transport   *med_orig;  /**< Original media transport           */
+    pjsua_med_tp_st      med_tp_st; /**< Media transport state              */
     pj_timer_entry       refresh_tm;/**< Timer to send re-INVITE.           */
     pj_timer_entry       hangup_tm; /**< Timer to hangup call.              */
@@ -322 +339 @@
                                      pjsip_role_e role,
                                      int security_level,
+                                     pj_pool_t *tmp_pool,
+                                     const pjmedia_sdp_session *rem_sdp,
                                      int *sip_err_code);
 pj_status_t pjsua_media_channel_create_sdp(pjsua_call_id call_id, 
@@ -329 +348 @@
                                            int *sip_err_code);
 pj_status_t pjsua_media_channel_update(pjsua_call_id call_id,
-                                       pjmedia_sdp_session *local_sdp,
+                                       const pjmedia_sdp_session *local_sdp,
                                        const pjmedia_sdp_session *remote_sdp);
 pj_status_t pjsua_media_channel_deinit(pjsua_call_id call_id);

pjproject/trunk/pjsip/src/pjsua-lib/pjsua_call.c

@@ -213 +213 @@
 
 
-#define LATE_SDP    0
-
 /* Allocate one call id */
 static pjsua_call_id alloc_call_id(void)
@@ -288 +286 @@
 }
 
+/*
 static int call_get_secure_level(pjsua_call *call)
 {
@@ -317 +316 @@
     return 0;
 }
+*/
 
 
@@ -450 +450 @@
     /* Init media channel */
     status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAC, 
-                                      call->secure_level, NULL);
+                                      call->secure_level, dlg->pool,
+                                      NULL, NULL);
     if (status != PJ_SUCCESS) {
         pjsua_perror(THIS_FILE, "Error initializing media channel", status);
@@ -456 +457 @@
     }
 
-    /* Create SDP offer */
-#if LATE_SDP
-    offer = NULL;
-#else
-    status = pjsua_media_channel_create_sdp(call->index, dlg->pool, NULL, 
+    /* Create offer */
+    status = pjsua_media_channel_create_sdp(call->index, dlg->pool, NULL,
                                             &offer, NULL);
     if (status != PJ_SUCCESS) {
-        pjsua_perror(THIS_FILE, "pjmedia unable to create SDP", status);
+        pjsua_perror(THIS_FILE, "Error initializing media channel", status);
         goto on_error;
     }
-#endif
 
     /* Create the INVITE session: */
@@ -719 +716 @@
         call->secure_level = 0;
 
-    /* Init media channel */
-    status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAS, 
-                                      call->secure_level, &sip_err_code);
-    if (status != PJ_SUCCESS) {
-        pjsua_perror(THIS_FILE, "Error initializing media channel", status);
-        pjsip_endpt_respond_stateless(pjsua_var.endpt, rdata, 
-                                      sip_err_code, NULL,
-                                      NULL, NULL);
-        PJSUA_UNLOCK();
-        return PJ_TRUE;
-    }
-
     /* Parse SDP from incoming request */
     if (rdata->msg_info.msg->body) {
@@ -740 +725 @@
             pjsua_perror(THIS_FILE, "Error parsing SDP in incoming INVITE", 
                          status);
-            pjsip_endpt_respond_stateless(pjsua_var.endpt, rdata, 400, &reason,
-                                          NULL, NULL);
-            pjsua_media_channel_deinit(call->index);
+            pjsip_endpt_respond(pjsua_var.endpt, NULL, rdata, 400, 
+                                &reason, NULL, NULL, NULL);
             PJSUA_UNLOCK();
             return PJ_TRUE;
@@ -762 +746 @@
     }
 
-    /* Get media capability from media endpoint: */
+    /* Init media channel */
+    status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAS, 
+                                      call->secure_level, 
+                                      rdata->tp_info.pool, offer,
+                                      &sip_err_code);
+    if (status != PJ_SUCCESS) {
+        pjsua_perror(THIS_FILE, "Error initializing media channel", status);
+        pjsip_endpt_respond(pjsua_var.endpt, NULL, rdata,
+                            sip_err_code, NULL, NULL, NULL, NULL);
+        PJSUA_UNLOCK();
+        return PJ_TRUE;
+    }
+
+    /* Create answer */
     status = pjsua_media_channel_create_sdp(call->index, rdata->tp_info.pool, 
                                             offer, &answer, &sip_err_code);
     if (status != PJ_SUCCESS) {
         pjsua_perror(THIS_FILE, "Error creating SDP answer", status);
-        pjsip_endpt_respond_stateless(pjsua_var.endpt, rdata, 
-                                      sip_err_code, NULL,
-                                      NULL, NULL);
-        pjsua_media_channel_deinit(call->index);
+        pjsip_endpt_respond(pjsua_var.endpt, NULL, rdata,
+                            sip_err_code, NULL, NULL, NULL, NULL);
         PJSUA_UNLOCK();
         return PJ_TRUE;
     }
+
 
     /* Verify that we can handle the request. */
@@ -795 +791 @@
 
         } else {
-
             /* Respond with 500 (Internal Server Error) */
-            pjsip_endpt_respond_stateless(pjsua_var.endpt, rdata, 500, NULL,
-                                          NULL, NULL);
+            pjsip_endpt_respond(pjsua_var.endpt, NULL, rdata, 500, NULL,
+                                NULL, NULL, NULL);
         }
 
@@ -1475 +1470 @@
     }
 
-    /* Update call secure level */
-    call->secure_level = call_get_secure_level(call);
-
-    /* Init media channel */
-    status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAC,
-                                      call->secure_level, NULL);
-    if (status != PJ_SUCCESS) {
-        pjsua_perror(THIS_FILE, "Error initializing media channel", status);
-        pjsip_dlg_dec_lock(dlg);
-        return PJSIP_ESESSIONSTATE;
-    }
-
     /* Create SDP */
     PJ_UNUSED_ARG(unhold);
@@ -1548 +1531 @@
         return status;
 
-    /* Update call's secure level */
-    call->secure_level = call_get_secure_level(call);
-
-    /* Init media channel */
-    status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAC,
-                                      call->secure_level, NULL);
-    if (status != PJ_SUCCESS) {
-        pjsua_perror(THIS_FILE, "Error initializing media channel", status);
-        pjsip_dlg_dec_lock(dlg);
-        return PJSIP_ESESSIONSTATE;
-    }
-
     /* Create SDP */
     status = pjsua_media_channel_create_sdp(call->index, call->inv->pool, 
@@ -1570 +1541 @@
     }
 
-    /* Create re-INVITE with new offer */
+    update_sdp_version(call, sdp);
+
+    /* Create UPDATE with new offer */
     status = pjsip_inv_update(call->inv, NULL, sdp, &tdata);
     if (status != PJ_SUCCESS) {
@@ -2538 +2511 @@
 {
     pjsua_call *call;
-    const pjmedia_sdp_session *c_local;
-    pjmedia_sdp_session *local_sdp;
+    const pjmedia_sdp_session *local_sdp;
     const pjmedia_sdp_session *remote_sdp;
 
@@ -2568 +2540 @@
 
     /* Get local and remote SDP */
-    status = pjmedia_sdp_neg_get_active_local(call->inv->neg, &c_local);
+    status = pjmedia_sdp_neg_get_active_local(call->inv->neg, &local_sdp);
     if (status != PJ_SUCCESS) {
         pjsua_perror(THIS_FILE, 
@@ -2577 +2549 @@
         return;
     }
-    local_sdp = (pjmedia_sdp_session*) c_local;
 
     status = pjmedia_sdp_neg_get_active_remote(call->inv->neg, &remote_sdp);
@@ -2713 +2684 @@
                   call->index));
 
-        /* Update call's secure level */
-        call->secure_level = call_get_secure_level(call);
-
-        /* Init media channel */
-        status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAS,
-                                          call->secure_level, NULL);
-        if (status != PJ_SUCCESS) {
-            pjsua_perror(THIS_FILE, "Error initializing media channel", status);
-            PJSUA_UNLOCK();
-            return;
-        }
-
         status = pjsua_media_channel_create_sdp(call->index, call->inv->pool, 
                                                 offer, &answer, NULL);
@@ -2768 +2727 @@
         PJ_LOG(4,(THIS_FILE, "Call %d: asked to send a new offer",
                   call->index));
-
-        /* Update call's secure level */
-        call->secure_level = call_get_secure_level(call);
-
-        /* Init media channel */
-        status = pjsua_media_channel_init(call->index, PJSIP_ROLE_UAC,
-                                          call->secure_level, NULL);
-        if (status != PJ_SUCCESS) {
-            pjsua_perror(THIS_FILE, "Error initializing media channel", status);
-            PJSUA_UNLOCK();
-            return;
-        }
 
         status = pjsua_media_channel_create_sdp(call->index, call->inv->pool, 

pjproject/trunk/pjsip/src/pjsua-lib/pjsua_media.c

@@ -653 +653 @@
     switch (op) {
     case PJ_ICE_STRANS_OP_INIT:
-        pjsua_var.calls[id].med_tp_st = result;
+        pjsua_var.calls[id].med_tp_ready = result;
         break;
     case PJ_ICE_STRANS_OP_NEGOTIATION:
@@ -753 +753 @@
         ice_cb.on_ice_complete = &on_ice_complete;
         pj_ansi_snprintf(name, sizeof(name), "icetp%02d", i);
-        pjsua_var.calls[i].med_tp_st = PJ_EPENDING;
+        pjsua_var.calls[i].med_tp_ready = PJ_EPENDING;
 
         comp_cnt = 1;
@@ -770 +770 @@
         /* Wait until transport is initialized, or time out */
         PJSUA_UNLOCK();
-        while (pjsua_var.calls[i].med_tp_st == PJ_EPENDING) {
+        while (pjsua_var.calls[i].med_tp_ready == PJ_EPENDING) {
             pjsua_handle_events(100);
         }
         PJSUA_LOCK();
-        if (pjsua_var.calls[i].med_tp_st != PJ_SUCCESS) {
+        if (pjsua_var.calls[i].med_tp_ready != PJ_SUCCESS) {
             pjsua_perror(THIS_FILE, "Error initializing ICE media transport",
-                         pjsua_var.calls[i].med_tp_st);
-            status = pjsua_var.calls[i].med_tp_st;
+                         pjsua_var.calls[i].med_tp_ready);
+            status = pjsua_var.calls[i].med_tp_ready;
             goto on_error;
         }
@@ -848 +848 @@
                                      pjsip_role_e role,
                                      int security_level,
+                                     pj_pool_t *tmp_pool,
+                                     const pjmedia_sdp_session *rem_sdp,
                                      int *sip_err_code)
 {
+    enum { MEDIA_IDX = 0 };
     pjsua_call *call = &pjsua_var.calls[call_id];
+    pj_status_t status;
 
 #if defined(PJMEDIA_HAS_SRTP) && (PJMEDIA_HAS_SRTP != 0)
@@ -856 +860 @@
     pjmedia_srtp_setting srtp_opt;
     pjmedia_transport *srtp;
-    pj_status_t status;
 #endif
 
@@ -905 +908 @@
 #endif
 
+    /* Create the media transport */
+    status = pjmedia_transport_media_create(call->med_tp, tmp_pool, 0,
+                                            rem_sdp, MEDIA_IDX);
+    if (status != PJ_SUCCESS) {
+        if (sip_err_code) *sip_err_code = PJSIP_SC_NOT_ACCEPTABLE;
+        pjsua_media_channel_deinit(call_id);
+        return status;
+    }
+
+    call->med_tp_st = PJSUA_MED_TP_INIT;
     return PJ_SUCCESS;
 }
@@ -927 +940 @@
     }
 
+    /* Create media if it's not created. This could happen when call is
+     * currently on-hold
+     */
+    if (call->med_tp_st == PJSUA_MED_TP_IDLE) {
+        pjsip_role_e role;
+        role = (rem_sdp ? PJSIP_ROLE_UAS : PJSIP_ROLE_UAC);
+        status = pjsua_media_channel_init(call_id, role, call->secure_level, 
+                                          pool, rem_sdp, sip_status_code);
+        if (status != PJ_SUCCESS)
+            return status;
+    }
+
     /* Get media socket info */
     pjmedia_transport_info_init(&tpinfo);
@@ -936 +961 @@
     if (status != PJ_SUCCESS) {
         if (sip_status_code) *sip_status_code = 500;
-        goto on_error;
+        return status;
     }
 
@@ -964 +989 @@
 
     /* Give the SDP to media transport */
-    status = pjmedia_transport_media_create(call->med_tp, pool, 0,
-                                            sdp, rem_sdp, MEDIA_IDX);
+    status = pjmedia_transport_encode_sdp(call->med_tp, pool, sdp, rem_sdp, 
+                                          MEDIA_IDX);
     if (status != PJ_SUCCESS) {
         if (sip_status_code) *sip_status_code = PJSIP_SC_NOT_ACCEPTABLE;
-        goto on_error;
+        return status;
     }
 
     *p_sdp = sdp;
     return PJ_SUCCESS;
-
-on_error:
-    pjsua_media_channel_deinit(call_id);
-    return status;
-
 }
 
@@ -984 +1004 @@
 {
     pjsua_call *call = &pjsua_var.calls[call_id];
-
-    //see ticket #525
-    //pjmedia_transport_media_stop(call->med_tp);
 
     if (call->conf_slot != PJSUA_INVALID_ID) {
@@ -1017 +1034 @@
     stop_media_session(call_id);
 
-    pjmedia_transport_media_stop(call->med_tp);
+    if (call->med_tp_st != PJSUA_MED_TP_IDLE) {
+        pjmedia_transport_media_stop(call->med_tp);
+        call->med_tp_st = PJSUA_MED_TP_IDLE;
+    }
 
     if (call->med_orig && call->med_tp != call->med_orig) {
@@ -1049 +1069 @@
 
 pj_status_t pjsua_media_channel_update(pjsua_call_id call_id,
-                                       pjmedia_sdp_session *local_sdp,
+                                       const pjmedia_sdp_session *local_sdp,
                                        const pjmedia_sdp_session *remote_sdp)
 {
@@ -1113 +1133 @@
         /* Shutdown transport's session */
         pjmedia_transport_media_stop(call->med_tp);
+        call->med_tp_st = PJSUA_MED_TP_IDLE;
 
         /* No need because we need keepalive? */
@@ -1123 +1144 @@
 
     } else {
-        /* Start media transport */
+        /* Start/restart media transport */
         status = pjmedia_transport_media_start(call->med_tp, 
                                                call->inv->pool,
@@ -1129 +1150 @@
         if (status != PJ_SUCCESS)
             return status;
+
+        call->med_tp_st = PJSUA_MED_TP_RUNNING;
 
         /* Override ptime, if this option is specified. */