Add support for GCM cipher suites from RFC 7714.

webrtc/base/sslstreamadapter.cc

Index: webrtc/base/sslstreamadapter.cc
diff --git a/webrtc/base/sslstreamadapter.cc b/webrtc/base/sslstreamadapter.cc
index a2cff3e44874678de052e0636c4d695c221094c3..83d83d0299caa216bf08f47995919337633d4816 100644
--- a/webrtc/base/sslstreamadapter.cc
+++ b/webrtc/base/sslstreamadapter.cc
@@ -29,13 +29,22 @@ namespace rtc {
 // webrtc:5043.
 const char CS_AES_CM_128_HMAC_SHA1_80[] = "AES_CM_128_HMAC_SHA1_80";
 const char CS_AES_CM_128_HMAC_SHA1_32[] = "AES_CM_128_HMAC_SHA1_32";
+const char CS_AEAD_AES_128_GCM[] = "AEAD_AES_128_GCM";
+const char CS_AEAD_AES_256_GCM[] = "AEAD_AES_256_GCM";
 
 std::string SrtpCryptoSuiteToName(int crypto_suite) {
-  if (crypto_suite == SRTP_AES128_CM_SHA1_32)
+  switch (crypto_suite) {
+  case SRTP_AES128_CM_SHA1_32:
     return CS_AES_CM_128_HMAC_SHA1_32;
-  if (crypto_suite == SRTP_AES128_CM_SHA1_80)
+  case SRTP_AES128_CM_SHA1_80:
     return CS_AES_CM_128_HMAC_SHA1_80;
-  return std::string();
+  case SRTP_AEAD_AES_128_GCM:
+    return CS_AEAD_AES_128_GCM;
+  case SRTP_AEAD_AES_256_GCM:
+    return CS_AEAD_AES_256_GCM;
+  default:
+    return std::string();
+  }
 }
 
 int SrtpCryptoSuiteFromName(const std::string& crypto_suite) {
@@ -43,9 +52,46 @@ int SrtpCryptoSuiteFromName(const std::string& crypto_suite) {
     return SRTP_AES128_CM_SHA1_32;
   if (crypto_suite == CS_AES_CM_128_HMAC_SHA1_80)
     return SRTP_AES128_CM_SHA1_80;
+  if (crypto_suite == CS_AEAD_AES_128_GCM)
+    return SRTP_AEAD_AES_128_GCM;
+  if (crypto_suite == CS_AEAD_AES_256_GCM)
+    return SRTP_AEAD_AES_256_GCM;
   return SRTP_INVALID_CRYPTO_SUITE;
 }
 
+bool GetSrtpKeyAndSaltLengths(int crypto_suite, int *key_length,
+    int *salt_length) {
+  switch (crypto_suite) {
+  case SRTP_AES128_CM_SHA1_32:
+  case SRTP_AES128_CM_SHA1_80:
+    *key_length = 16;
+    *salt_length = 14;
+    break;
+  case SRTP_AEAD_AES_128_GCM:
+    *key_length = 16;
+    *salt_length = 12;
+    break;
+  case SRTP_AEAD_AES_256_GCM:
+    *key_length = 32;
+    *salt_length = 12;

[pthatcher1, 2016/01/30 00:54:33]

Can you leave a comment saying where these values come from?

[joachim, 2016/01/31 23:39:52]

Done.

+    break;
+  default:
+    return false;
+  }
+  return true;
+}
+
+bool IsGcmCryptoSuite(int crypto_suite) {
+  return (crypto_suite == SRTP_AEAD_AES_256_GCM ||
+          crypto_suite == SRTP_AEAD_AES_128_GCM);
+}
+
+bool IsGcmCryptoSuiteName(const std::string& crypto_suite) {
+  return (crypto_suite == CS_AEAD_AES_256_GCM ||
+          crypto_suite == CS_AEAD_AES_128_GCM);
+}
+
+
 SSLStreamAdapter* SSLStreamAdapter::Create(StreamInterface* stream) {
 #if SSL_USE_OPENSSL
   return new OpenSSLStreamAdapter(stream);