Add support for GCM cipher suites from RFC 7714.

webrtc/pc/srtpfilter.cc

 /*
  *  Copyright 2009 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 36 matching lines @@
 extern "C" debug_module_t mod_aes_icm;
 extern "C" debug_module_t mod_aes_hmac;
 #endif
 #else
 // SrtpFilter needs that constant.
 #define SRTP_MASTER_KEY_LEN 30
 #endif  // HAVE_SRTP
 
 namespace cricket {
 
-const int SRTP_MASTER_KEY_BASE64_LEN = SRTP_MASTER_KEY_LEN * 4 / 3;
-const int SRTP_MASTER_KEY_KEY_LEN = 16;
-const int SRTP_MASTER_KEY_SALT_LEN = 14;
-
 #ifndef HAVE_SRTP
 
 // This helper function is used on systems that don't (yet) have SRTP,
 // to log that the functions that require it won't do anything.
 namespace {
 bool SrtpNotAvailable(const char *func) {
   LOG(LS_ERROR) << func << ": SRTP is not available on your system.";
   return false;
 }
 }  // anonymous namespace
@@ skipping 580 matching lines @@
                   << "SRTP session already created";
     return false;
   }
 
   if (!Init()) {
     return false;
   }
 
   srtp_policy_t policy;
   memset(&policy, 0, sizeof(policy));
-
   if (cs == rtc::SRTP_AES128_CM_SHA1_80) {
     crypto_policy_set_aes_cm_128_hmac_sha1_80(&policy.rtp);
     crypto_policy_set_aes_cm_128_hmac_sha1_80(&policy.rtcp);
   } else if (cs == rtc::SRTP_AES128_CM_SHA1_32) {
     crypto_policy_set_aes_cm_128_hmac_sha1_32(&policy.rtp);   // rtp is 32,
     crypto_policy_set_aes_cm_128_hmac_sha1_80(&policy.rtcp);  // rtcp still 80
+  } else if (cs == rtc::SRTP_AEAD_AES_128_GCM) {
+    crypto_policy_set_aes_gcm_128_16_auth(&policy.rtp);
+    crypto_policy_set_aes_gcm_128_16_auth(&policy.rtcp);
+  } else if (cs == rtc::SRTP_AEAD_AES_256_GCM) {
+    crypto_policy_set_aes_gcm_256_16_auth(&policy.rtp);
+    crypto_policy_set_aes_gcm_256_16_auth(&policy.rtcp);
   } else {
     LOG(LS_WARNING) << "Failed to create SRTP session: unsupported"
                     << " cipher_suite " << cs;
     return false;
   }
 
-  if (!key || len != SRTP_MASTER_KEY_LEN) {
+  int expected_key_len;
+  int expected_salt_len;
+  if (!rtc::GetSrtpKeyAndSaltLengths(cs, &expected_key_len,
+      &expected_salt_len)) {
+    // This should never happen.
+    LOG(LS_WARNING) << "Failed to create SRTP session: unsupported"
+                    << " cipher_suite without length information" << cs;
+    return false;
+  }
+
+  if (!key || len != (expected_key_len + expected_salt_len)) {
     LOG(LS_WARNING) << "Failed to create SRTP session: invalid key";
     return false;
   }
 
   policy.ssrc.type = static_cast<ssrc_type_t>(type);
   policy.ssrc.value = 0;
   policy.key = const_cast<uint8_t*>(key);
   // TODO(astor) parse window size from WSH session-param
   policy.window_size = 1024;
   policy.allow_repeat_tx = 1;
   // If external authentication option is enabled, supply custom auth module
   // id EXTERNAL_HMAC_SHA1 in the policy structure.
   // We want to set this option only for rtp packets.
   // By default policy structure is initialized to HMAC_SHA1.
 #if defined(ENABLE_EXTERNAL_AUTH)
   // Enable external HMAC authentication only for outgoing streams.
   if (type == ssrc_any_outbound) {
     policy.rtp.auth_type = EXTERNAL_HMAC_SHA1;
   }
 #endif
   policy.next = NULL;
 
   int err = srtp_create(&session_, &policy);
   if (err != err_status_ok) {
     session_ = NULL;
     LOG(LS_ERROR) << "Failed to create SRTP session, err=" << err;
     return false;
   }
 
-
   rtp_auth_tag_len_ = policy.rtp.auth_tag_len;
   rtcp_auth_tag_len_ = policy.rtcp.auth_tag_len;
   return true;
 }
 
 bool SrtpSession::Init() {
   rtc::GlobalLockScope ls(&lock_);
 
   if (!inited_) {
     int err;
@@ skipping 211 matching lines @@
   SrtpNotAvailable(__FUNCTION__);
 }
 
 void SrtpStat::HandleSrtpResult(const SrtpStat::FailureKey& key) {
   SrtpNotAvailable(__FUNCTION__);
 }
 
 #endif  // HAVE_SRTP
 
 }  // namespace cricket