Make the VER tag required in QUIC CHLO and SHLO messages.

net/quic/crypto/quic_crypto_client_config.cc

 // Copyright 2013 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 "net/quic/crypto/quic_crypto_client_config.h"
 
 #include "base/stl_util.h"
 #include "net/quic/crypto/cert_compressor.h"
 #include "net/quic/crypto/channel_id.h"
 #include "net/quic/crypto/common_cert_set.h"
@@ skipping 630 matching lines @@
     string* error_details) {
   DCHECK(error_details != NULL);
 
   if (server_hello.tag() != kSHLO) {
     *error_details = "Bad tag";
     return QUIC_INVALID_CRYPTO_MESSAGE_TYPE;
   }
 
   const QuicTag* supported_version_tags;
   size_t num_supported_versions;
-  // TODO(rch): Once QUIC_VERSION_12 is removed, then make it a failure
-  // if the server does not have a version list.
+
   if (server_hello.GetTaglist(kVER, &supported_version_tags,
-                              &num_supported_versions) == QUIC_NO_ERROR) {
-    if (!negotiated_versions.empty()) {
-      bool mismatch = num_supported_versions != negotiated_versions.size();
-      for (size_t i = 0; i < num_supported_versions && !mismatch; ++i) {
-        mismatch = QuicTagToQuicVersion(supported_version_tags[i]) !=
-            negotiated_versions[i];
-      }
-      // The server sent a list of supported versions, and the connection
-      // reports that there was a version negotiation during the handshake.
+                              &num_supported_versions) != QUIC_NO_ERROR) {
+    *error_details = "server hello missing version list";
+    return QUIC_INVALID_CRYPTO_MESSAGE_PARAMETER;
+  }
+  if (!negotiated_versions.empty()) {
+    bool mismatch = num_supported_versions != negotiated_versions.size();
+    for (size_t i = 0; i < num_supported_versions && !mismatch; ++i) {
+      mismatch = QuicTagToQuicVersion(supported_version_tags[i]) !=
+          negotiated_versions[i];
+    }
+    // The server sent a list of supported versions, and the connection
+    // reports that there was a version negotiation during the handshake.
       // Ensure that these two lists are identical.
-      if (mismatch) {
-        *error_details = "Downgrade attack detected";
-        return QUIC_VERSION_NEGOTIATION_MISMATCH;
-      }
+    if (mismatch) {
+      *error_details = "Downgrade attack detected";
+      return QUIC_VERSION_NEGOTIATION_MISMATCH;
     }
   }
 
   // Learn about updated source address tokens.
   StringPiece token;
   if (server_hello.GetStringPiece(kSourceAddressTokenTag, &token)) {
     cached->set_source_address_token(token);
   }
 
   // TODO(agl):
@@ skipping 51 matching lines @@
   CachedState* canonical_cached =
       canonical_crypto_config->LookupOrCreate(canonical_server_hostname);
   if (!canonical_cached->proof_valid()) {
     return;
   }
   CachedState* cached = LookupOrCreate(server_hostname);
   cached->InitializeFrom(*canonical_cached);
 }
 
 }  // namespace net