Opened 14 years ago

Closed 14 years ago

#1135 closed defect (fixed)

Processing of RTP padding bit (thanks Rafael Maia for the suggestion)

Reported by: bennylp Owned by: nanang
Priority: normal Milestone: release-1.8.5
Component: pjmedia Version: trunk
Keywords: Cc:
Backport to 1.x milestone: Backported:


Currently padding bit in incoming RTP packets are ignored, potentially causing incorrect RTP payload processing.

Also investigate if the padding bit should be used in outgoing RTP transmission.

Change History (1)

comment:1 Changed 14 years ago by nanang

  • Resolution set to fixed
  • Status changed from new to closed

(In [3325]) Fix #1135: added RTP padding checks and RTP payload length adjustment according to padding length.

Payload padding in outgoing RTP investigation results:

  • the RTP does not specify RTP payload alignment.
  • most codecs also do not specify RTP payload alignment, usually only octet-alignment is specified and this seems to be done.
  • SRTP, RFC3711 states:
    • None of the pre-defined SRTP encryption transforms uses any padding; for these, the RTP and SRTP payload sizes match exactly.
    • Message authentication codes define their own padding.
    • Encryption transforms that use padding are vulnerable to subtle attacks, especially when message authentication is not used.

So, currently payload padding in outgoing RTP is not necessary.

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