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Add instructions for converting SCTP verbose log to pcap file.

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This is pretty useful if you need to debug an SCTP issue. SCTP goes
over DTLS, which is encrypted, which means you need a private key
in order to decrypt a normal packet capture. We don't log this key,
for understandable reasons. So the alternative is to turn on SCTP
verbose logging, then turn the text log into a pcap file.

NOTRY=True
TBR=zhihuang@webrtc.org

Bug: None
Change-Id: If3380d7953ea829b3ae9945326d3c820ce7cc6a3
Reviewed-on: https://webrtc-review.googlesource.com/14561
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Commit-Queue: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20380}
This commit is contained in:
Taylor Brandstetter 2017-10-22 16:09:34 -07:00 committed by Commit Bot
parent cb423c43b0
commit 5526687dfc
1 changed files with 17 additions and 0 deletions
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17
media/sctp/sctptransport.cc
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@ -186,6 +186,23 @@ bool GetDataMediaType(PayloadProtocolIdentifier ppid,
}
// Log the packet in text2pcap format, if log level is at LS_VERBOSE.
//
// In order to turn these logs into a pcap file you can use, first filter the
// "SCTP_PACKET" log lines:
//
// cat chrome_debug.log | grep SCTP_PACKET > filtered.log
//
// Then run through text2pcap:
//
// text2pcap -t "%H:%M:%S." -D -u 1024,1024 filtered.log filtered.pcap
//
// The value "1024" isn't important, we just need a port for the dummy UDP
// headers generated. Lastly, you should be able to open filtered.pcap in
// Wireshark, then right click a packet and "Decode As..." SCTP.
//
// Why do all this? Because SCTP goes over DTLS, which is encrypted. So just
// getting a normal packet capture won't help you, unless you have the DTLS
// keying material.
void VerboseLogPacket(const void* data, size_t length, int direction) {
if (LOG_CHECK_LEVEL(LS_VERBOSE) && length > 0) {
char* dump_buf;