Cast: Reject old RTCP packets

media/cast/net/rtcp/rtcp.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/cast/net/rtcp/rtcp.h"
 
 #include "media/cast/cast_config.h"
 #include "media/cast/cast_defines.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/net/cast_transport_defines.h"
 #include "media/cast/net/rtcp/rtcp_defines.h"
 #include "media/cast/net/rtcp/rtcp_sender.h"
 #include "media/cast/net/rtcp/rtcp_utility.h"
 
 using base::TimeDelta;
 
 namespace media {
 namespace cast {
 
 static const int32 kMaxRttMs = 10000;  // 10 seconds.
+// Reject packets that are older than 0.5 seconds older than
+// the newest packet we've seen so far. This protect internal
+// states from crazy routers. (Based on RRTR)
+static const int32 kOutOfOrderMaxAgeMs = 500;
 
 namespace {
 
 // A receiver frame event is identified by frame RTP timestamp, event timestamp
 // and event type.
 // A receiver packet event is identified by all of the above plus packet id.
 // The key format is as follows:
 // First uint64:
 //   bits 0-11: zeroes (unused).
 //   bits 12-15: event type ID.
@@ skipping 74 matching lines @@
   // Check if this packet is to us.
   uint32 ssrc_of_sender = GetSsrcOfSender(data, length);
   if (ssrc_of_sender != remote_ssrc_) {
     return false;
   }
 
   // Parse this packet.
   RtcpParser parser(local_ssrc_, remote_ssrc_);
   base::BigEndianReader reader(reinterpret_cast<const char*>(data), length);
   if (parser.Parse(&reader)) {
+    if (parser.has_receiver_reference_time_report()) {
+      base::TimeTicks t = ConvertNtpToTimeTicks(
+          parser.receiver_reference_time_report().ntp_seconds,
+          parser.receiver_reference_time_report().ntp_fraction);
+      if (t > largest_seen_timestamp_) {
+        largest_seen_timestamp_ = t;
+      } else if ((largest_seen_timestamp_ - t).InMilliseconds() >
+                 kOutOfOrderMaxAgeMs) {
+        // Reject packet, it is too old.
+        VLOG(1) << "Rejecting RTCP packet as it is too old ("
+                << (largest_seen_timestamp_ - t).InMilliseconds()
+                << " ms)";
+        return true;
+      }
+
+      OnReceivedNtp(parser.receiver_reference_time_report().ntp_seconds,
+                    parser.receiver_reference_time_report().ntp_fraction);
+    }
     if (parser.has_sender_report()) {
       OnReceivedNtp(parser.sender_report().ntp_seconds,
                     parser.sender_report().ntp_fraction);
       OnReceivedLipSyncInfo(parser.sender_report().rtp_timestamp,
                             parser.sender_report().ntp_seconds,
                             parser.sender_report().ntp_fraction);
     }
-    if (parser.has_receiver_reference_time_report()) {
-      OnReceivedNtp(parser.receiver_reference_time_report().ntp_seconds,
-                    parser.receiver_reference_time_report().ntp_fraction);
-    }
     if (parser.has_receiver_log()) {
       if (DedupeReceiverLog(parser.mutable_receiver_log())) {
         OnReceivedReceiverLog(parser.receiver_log());
       }
     }
     if (parser.has_last_report()) {
       OnReceivedDelaySinceLastReport(parser.last_report(),
                                      parser.delay_since_last_report());
     }
     if (parser.has_cast_message()) {
@@ skipping 278 matching lines @@
 }
 
 void Rtcp::OnReceivedReceiverLog(const RtcpReceiverLogMessage& receiver_log) {
   if (log_callback_.is_null())
     return;
   log_callback_.Run(receiver_log);
 }
 
 }  // namespace cast
 }  // namespace media