Add histogram to track NPN/ALPN.

net/socket/ssl_client_socket.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_SOCKET_SSL_CLIENT_SOCKET_H_
 #define NET_SOCKET_SSL_CLIENT_SOCKET_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
@@ skipping 61 matching lines @@
   // connection.
   enum NextProtoStatus {
     // WARNING: These values are serialized to disk. Don't change them.
 
     kNextProtoUnsupported = 0,  // The server doesn't support NPN.
     kNextProtoNegotiated = 1,   // We agreed on a protocol.
     kNextProtoNoOverlap = 2,    // No protocols in common. We requested
                                 // the first protocol in our list.
   };
 
+  // TLS extension used to negotiate protocol.  Recorded in UMA, do not change
+  // or reuse values.
+  enum SSLProtocolNegotiation {
+    // Unknown.
+    PN_UNKNOWN = -1,
+    // Application-Layer Protocol Negotiation.
+    PN_ALPN = 0,
+    // Next Protocol Negotiation used.
+    PN_NPN = 500,
+    // Next Protocol Negotiation used, but there was no overlap between client
+    // and server supported protocols.  Fallback to first one on client's list.
+    PN_NPN_NO_OVERLAP = 1000,

[davidben, 2014/09/19 21:09:17]

It seems strange to have this enum with large numbers and also have a value
(PN_NPN_NO_OVERLAP) that's not set externally. How about just

enum SSLProtocolNegotiation {
  kProtocolNone = 0,
  kProtocolALPN = 1,
  kProtocolNPN = 2,
};

(Our style seems slightly confused as to whether we do kConstantsLikeThis or
CONSTANTS_LIKE_THAT, but this is consistent with the other one in this class.)

And then munge into a single number internally if you want a single histogram.

[Bence, 2014/10/03 10:50:22]

Done.

I changed to kExtension* to better distinguish TLS extensions (NPN, ALPN) from
protocols they negotiate (HTTP/1, SPDY, QUIC).

+  };
+
   // StreamSocket:
   virtual bool WasNpnNegotiated() const OVERRIDE;
   virtual NextProto GetNegotiatedProtocol() const OVERRIDE;
 
   // Computes a unique key string for the SSL session cache.
   virtual std::string GetSessionCacheKey() const = 0;
 
   // Returns true if there is a cache entry in the SSL session cache
   // for the cache key of the SSL socket.
   //
@@ skipping 51 matching lines @@
   static void ClearSessionCache();
 
   virtual bool set_was_npn_negotiated(bool negotiated);
 
   virtual bool was_spdy_negotiated() const;
 
   virtual bool set_was_spdy_negotiated(bool negotiated);
 
   virtual void set_protocol_negotiated(NextProto protocol_negotiated);
 
+  void set_protocol_negotiation(
+      enum SSLProtocolNegotiation protocol_negotiation);

[davidben, 2014/09/19 21:09:17]

No 'enum' prefix in C++.

[Bence, 2014/10/03 10:50:22]

Done.

+
   // Returns the ChannelIDService used by this socket, or NULL if
   // channel ids are not supported.
   virtual ChannelIDService* GetChannelIDService() const = 0;
 
   // Returns true if a channel ID was sent on this connection.
   // This may be useful for protocols, like SPDY, which allow the same
   // connection to be shared between multiple domains, each of which need
   // a channel ID.
   //
   // Public for ssl_client_socket_openssl_unittest.cc.
   virtual bool WasChannelIDSent() const;
 
+  // Record which TLS extension was used to negotiate protocol and protocol
+  // chosen in a UMA histogram.
+  void RecordProtocolNegotiation();
+
  protected:
   virtual void set_channel_id_sent(bool channel_id_sent);
 
   virtual void set_signed_cert_timestamps_received(
       bool signed_cert_timestamps_received);
 
   virtual void set_stapled_ocsp_response_received(
       bool stapled_ocsp_response_received);
 
   // Records histograms for channel id support during full handshakes - resumed
@@ skipping 37 matching lines @@
   // True if NPN successfully negotiated SPDY.
   bool was_spdy_negotiated_;
   // Protocol that we negotiated with the server.
   NextProto protocol_negotiated_;
   // True if a channel ID was sent.
   bool channel_id_sent_;
   // True if SCTs were received via a TLS extension.
   bool signed_cert_timestamps_received_;
   // True if a stapled OCSP response was received.
   bool stapled_ocsp_response_received_;
+  // Protocol negotiation extension used.
+  enum SSLProtocolNegotiation protocol_negotiation_;
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_SSL_CLIENT_SOCKET_H_