From 211856b956d8099ef99b9dbe16ce77dcf78d0bb4 Mon Sep 17 00:00:00 2001
From: Johannes Kron <kron@webrtc.org>
Date: Thu, 6 Sep 2018 12:12:28 +0200
Subject: [PATCH] Make HasAttribute handle partial matching of attribute names.
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Improve HasAttribute to handle the case where the beginning of an
attribute name is also an attribute name in it self. Two attributes
that have this relation are extmap-allow-mixed and extmap.

Bug: webrtc:9712
Change-Id: Iee660cc6e3dc7f2e7c56664a4f0ffb298eca9208
Reviewed-on: https://webrtc-review.googlesource.com/97422
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24640}
---
 pc/webrtcsdp.cc          | 14 +++++++++++++-
 pc/webrtcsdp_unittest.cc | 29 +++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/pc/webrtcsdp.cc b/pc/webrtcsdp.cc
index e392857a8a..665b4d411a 100644
--- a/pc/webrtcsdp.cc
+++ b/pc/webrtcsdp.cc
@@ -541,7 +541,19 @@ static bool GetLineWithType(const std::string& message,
 
 static bool HasAttribute(const std::string& line,
                          const std::string& attribute) {
-  return (line.compare(kLinePrefixLength, attribute.size(), attribute) == 0);
+  if (line.compare(kLinePrefixLength, attribute.size(), attribute) == 0) {
+    // Make sure that the match is not only a partial match. If length of
+    // strings doesn't match, the next character of the line must be ':' or ' '.
+    // This function is also used for media descriptions (e.g., "m=audio 9..."),
+    // hence the need to also allow space in the end.
+    RTC_CHECK_LE(kLinePrefixLength + attribute.size(), line.size());
+    if ((kLinePrefixLength + attribute.size()) == line.size() ||
+        line[kLinePrefixLength + attribute.size()] == kSdpDelimiterColonChar ||
+        line[kLinePrefixLength + attribute.size()] == kSdpDelimiterSpaceChar) {
+      return true;
+    }
+  }
+  return false;
 }
 
 static bool AddSsrcLine(uint32_t ssrc_id,
diff --git a/pc/webrtcsdp_unittest.cc b/pc/webrtcsdp_unittest.cc
index bfae1b9a12..9c10554631 100644
--- a/pc/webrtcsdp_unittest.cc
+++ b/pc/webrtcsdp_unittest.cc
@@ -3566,6 +3566,35 @@ TEST_F(WebRtcSdpTest, IceCredentialsInCandidateStringIgnored) {
   EXPECT_EQ("pwd_voice", c.password());
 }
 
+// Test that attribute lines "a=ice-ufrag-something"/"a=ice-pwd-something" are
+// ignored, and only the "a=ice-ufrag"/"a=ice-pwd" attributes are used.
+// Regression test for:
+// https://bugs.chromium.org/p/webrtc/issues/detail?id=9712
+TEST_F(WebRtcSdpTest, AttributeWithPartialMatchingNameIsIgnored) {
+  static const char kSdpWithFooIceCredentials[] =
+      "v=0\r\n"
+      "o=- 18446744069414584320 18446462598732840960 IN IP4 127.0.0.1\r\n"
+      "s=-\r\n"
+      "t=0 0\r\n"
+      "m=audio 9 RTP/SAVPF 111\r\n"
+      "c=IN IP4 0.0.0.0\r\n"
+      "a=rtcp:9 IN IP4 0.0.0.0\r\n"
+      "a=ice-ufrag-something:foo\r\na=ice-pwd-something:bar\r\n"
+      "a=ice-ufrag:ufrag_voice\r\na=ice-pwd:pwd_voice\r\n"
+      "a=rtpmap:111 opus/48000/2\r\n"
+      "a=candidate:a0+B/1 1 udp 2130706432 192.168.1.5 1234 typ host "
+      "generation 2\r\n";
+
+  JsepSessionDescription jdesc_output(kDummyType);
+  EXPECT_TRUE(SdpDeserialize(kSdpWithFooIceCredentials, &jdesc_output));
+  const IceCandidateCollection* candidates = jdesc_output.candidates(0);
+  ASSERT_NE(nullptr, candidates);
+  ASSERT_EQ(1U, candidates->count());
+  cricket::Candidate c = candidates->at(0)->candidate();
+  EXPECT_EQ("ufrag_voice", c.username());
+  EXPECT_EQ("pwd_voice", c.password());
+}
+
 // Test that SDP with an invalid port number in "a=candidate" lines is
 // rejected, without crashing.
 // Regression test for: