Review Board 1.7.16


Use the correct IP address in the c and o sdp lines when using an externally mapped IP address

Review Request #566 - Created March 16, 2010 and submitted

ebroad
/trunk
17044
Reviewers
asterisk-dev
Asterisk
The issue stems from a call to ast_rtp_instance_get_local_address() in chan_sip.c in get_our_media_address(). ast_rtp_instance_get_local_address() will always return the internal IP address of the Asterisk machine, which could pose a problem when using NAT.

A simple solution would be to override {v,t}sin->sin_addr in get_our_media_address() with p->ourip.sin_addr.s_addr if it is different(which is what the attached diff does), though I don't know what that might break.

Edit 1: This patch short-circuits some logic later on in get_our_media_address(). ast_rtp_instance_get_local_address() does exactly as the function name suggests, it gets the local address of the machine the Asterisk is running on, which is bad for NAT setups. Should we be calling this in get_our_media_address() or instead just use p->ourip? or should we try to stick with letting the RTP engine decide, and modifying ast_rtp_instance_get_local_address() to return our externally mapped IP when appropriate, which would break from what the function is supposed to do? Comments anyone? 
Applied to trunk, compiled, fax and voice calls made to and from Asterisk successfully.
Review request changed
Updated (Aug. 9, 2010, 4:45 a.m.)
Using media_address when it's not explicitly set is a bad idea, this patch sets a flag(use_externip) and modifies the ast_sockaddr_copy() calls for addr, vaddr, and taddr; essentially using p->ourip when use_externip is set. In hindsight, maybe use_externip should be use_ourip.
Ship it!
Posted (Aug. 10, 2010, 6:46 a.m.)

   

  

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