bug 807435 telemetry for server TLS NPN support r=bsmith r=honzab

security/manager/ssl/src/nsNSSCallbacks.cpp

@@ -921,16 +921,18 @@ void HandshakeCallback(PRFileDesc* fd, void* client_data) {
     status->mSecretKeyLength = encryptBits;
     status->mCipherName.Assign(cipherName);
 
-    // Get the NPN value. Do this on the stack and copy it into
-    // a string rather than preallocating the string because right
-    // now we expect NPN to fail more often than it succeeds.
+    // Get the NPN value.
     SSLNextProtoState state;
     unsigned char npnbuf[256];
     unsigned int npnlen;
     
-    if (SSL_GetNextProto(fd, &state, npnbuf, &npnlen, 256) == SECSuccess &&
-        state == SSL_NEXT_PROTO_NEGOTIATED)
-      infoObject->SetNegotiatedNPN(reinterpret_cast<char *>(npnbuf), npnlen);
+    if (SSL_GetNextProto(fd, &state, npnbuf, &npnlen, 256) == SECSuccess) {
+      if (state == SSL_NEXT_PROTO_NEGOTIATED)
+        infoObject->SetNegotiatedNPN(reinterpret_cast<char *>(npnbuf), npnlen);
+      else
+        infoObject->SetNegotiatedNPN(nullptr, 0);
+      mozilla::Telemetry::Accumulate(Telemetry::SSL_NPN_TYPE, state);
+    }
     else
       infoObject->SetNegotiatedNPN(nullptr, 0);
 

toolkit/components/telemetry/Histograms.json

@@ -711,6 +711,11 @@
     "n_values": 16,
     "description": "SSL Version (0=ssl3, 1=tls1, 2=tls1.1, 3=tls1.2)"
   },
+  "SSL_NPN_TYPE": {
+    "kind": "enumerated",
+    "n_values": 16,
+    "description": "NPN Results (0=none, 1=negotiated, 2=no-overlap)"
+  },
   "WEBSOCKETS_HANDSHAKE_TYPE": {
     "kind": "enumerated",
     "n_values": 16,