commit 5150ee40f45fe9cdef03b4454bfde7e099860673
author Seth Hampson <shampson@webrtc.org> Thu Apr 05 00:39:19 2018
committer Commit Bot <commit-bot@chromium.org> Thu Apr 05 20:08:05 2018
tree d1d6b44bcbea794be42aba3c181ebeaa89753dc6
parent 09a6cd55416e9ff8826d98c4de024b1cfa22104d

Changing MTU size for SCTP socket options.

With the latest usrsctp roll, the MTU value you provide is the space
avaiable for chunks in the packet. We previously specified this to be the
MTU for the entire SCTP packet, so we were logging errors when the SCTP
packets were 12 bytes larger than expected (the size of the SCTP header).
This fix updates our MTU specified to account for the SCTP header size
as well.

Bug: webrtc:9082
Change-Id: Id3bfa839d4e7662230111ebbdf33bd81ccdc7cf4
Reviewed-on: https://webrtc-review.googlesource.com/66943
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Commit-Queue: Seth Hampson <shampson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22754}

media/sctp/sctptransport.cc

diff --git a/media/sctp/sctptransport.cc b/media/sctp/sctptransport.cc
index bcfb4f4..6e047e2 100644
--- a/media/sctp/sctptransport.cc
+++ b/media/sctp/sctptransport.cc
@@ -656,7 +656,9 @@
   sctp_paddrparams params = {{0}};
   memcpy(&params.spp_address, &remote_sconn, sizeof(remote_sconn));
   params.spp_flags = SPP_PMTUD_DISABLE;
-  params.spp_pathmtu = kSctpMtu;
+  // The MTU value provided specifies the space available for chunks in the
+  // packet, so we subtract the SCTP header size.
+  params.spp_pathmtu = kSctpMtu - sizeof(struct sctp_common_header);
   if (usrsctp_setsockopt(sock_, IPPROTO_SCTP, SCTP_PEER_ADDR_PARAMS, &params,
                          sizeof(params))) {
     RTC_LOG_ERRNO(LS_ERROR) << debug_name_ << "->Connect(): "