Simple HTTP client implementation (thanks Johan Lantz for the suggestion)

[bennylp]

A simple HTTP client implementation will make way for XCAP client implementation.

Specifications

Assorted specifications:

• Supported HTTP method(s):
  • GET
  • PUT
  • DELETE
• Asynchronous:
  • application create/build the HTTP request
  • the request is submitted
  • application will be notified when the request is complete and complete response has been received.
• Application may cancel the request once it has been submitted
• Options:
  • request timeout support
  • ability to add custom headers
  • HTTPS (optional)

[ming]

Implemented in r3087

• pjlib-util:
  • implement http_client
• pjlib-util-test:
  • unit test for http_client
• pjsip-apps/samples:
  • sample http client implementation
• build:
  • added http_client support on VS6, VS2005, MMP, and Makefile

[ming]

In r3089:

• httpdemo: make the 2nd parameter (output filename) optional (result will be printed to stdout if output file is not provided.
• remove trailing "\n" from PJ_LOG.
• change response.status_code from pj_str_t to pj_uint16_t.
• remove PJ_EPENDING status checking from on_complete.

[bennylp]

In r3092:

• fixed gcc warning about incompatible pointer types

[bennylp]

In r3095:

• fixed some more warnings about pointer conversions, or errors if the library is compiled in C++ mode (thanks Atik Khan for the report)

[ming]

In r3098:

• Immediately process response body after receiving the header.
• Fix GET method when Content-Length header is not specified.
• Fix checking when HTTP request is cancelled.

[bennylp]

In r3147:

• fixed failure in pjlib-util-test due to the use of hardcoded port in HTTP client test

[ming]

In r3227:
Application may now destroy pj_http_req inside on_complete callback.