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Deliver partial SCTP messages when the SID is (unexpectedly) changed.

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We're receiving SCTP messages one chunk at a time. The sender is supposed to set the MSG_EOR bit on the last chunk of a message. A crash (RTC_CHECK) happened when the sender started a new message without indicating the end of the previous message. This is likely due to an SCTP implementation that doesn't (correctly) support the MSG_EOR bit.

This change, rather than calling RTC_CHECK, delivers partial messages when SID is (unexpectedly) changed, which is what happened before we paid attention to the MSG_EOR bit ourselves.

TBR=pthatcher@webrtc.org

Bug: chromium:884926
Change-Id: I18c773bb60ae724b735a83933eedd030f6360a3c
Reviewed-on: https://webrtc-review.googlesource.com/c/103023
Commit-Queue: Jeroen de Borst <jeroendb@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24935}
This commit is contained in:
Jeroen de Borst 2018-10-01 15:02:12 -07:00 committed by Commit Bot
parent 5fb245498c
commit ad5465b443
2 changed files with 24 additions and 11 deletions
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32
media/sctp/sctptransport.cc
View File

@ -295,14 +295,31 @@ class SctpTransport::UsrSctpWrapper {
} else {
ReceiveDataParams params;
// Expect only continuation messages belonging to the same sid, usrsctp
// ensures this.
RTC_CHECK(transport->partial_message_.size() == 0 ||
rcv.rcv_sid == transport->partial_message_sid_);
params.sid = rcv.rcv_sid;
params.seq_num = rcv.rcv_ssn;
params.timestamp = rcv.rcv_tsn;
params.type = type;
// Expect only continuation messages belonging to the same sid, the sctp
// stack should ensure this.
if ((transport->partial_message_.size() != 0) &&
(rcv.rcv_sid != transport->partial_params_.sid)) {
// A message with a new sid, but haven't seen the EOR for the
// previous message. Deliver the previous partial message to avoid
// merging messages from different sid's.
transport->invoker_.AsyncInvoke<void>(
RTC_FROM_HERE, transport->network_thread_,
rtc::Bind(&SctpTransport::OnInboundPacketFromSctpToTransport,
transport, transport->partial_message_,
transport->partial_params_, transport->partial_flags_));
transport->partial_message_.Clear();
}
transport->partial_message_.AppendData(reinterpret_cast<uint8_t*>(data),
length);
transport->partial_message_sid_ = rcv.rcv_sid;
transport->partial_params_ = params;
transport->partial_flags_ = flags;
free(data);
@ -315,11 +332,6 @@ class SctpTransport::UsrSctpWrapper {
return 1;
}
params.sid = rcv.rcv_sid;
params.seq_num = rcv.rcv_ssn;
params.timestamp = rcv.rcv_tsn;
params.type = type;
// The ownership of the packet transfers to |invoker_|. Using
// CopyOnWriteBuffer is the most convenient way to do this.
transport->invoker_.AsyncInvoke<void>(

3
media/sctp/sctptransport.h
View File

@ -146,7 +146,8 @@ class SctpTransport : public SctpTransportInternal,
// Track the data received from usrsctp between callbacks until the EOR bit
// arrives.
rtc::CopyOnWriteBuffer partial_message_;
int partial_message_sid_;
ReceiveDataParams partial_params_;
int partial_flags_;
bool was_ever_writable_ = false;
int local_port_ = kSctpDefaultPort;