NPN/ALPN: allow disabling via command line

when using --http2 one can now selectively disable NPN or ALPN with
--no-alpn and --no-npn. for now honored with NSS only.

TODO: honor this option with GnuTLS and OpenSSL

1 files changed, 35 insertions, 20 deletions

diff --git a/lib/vtls/nss.c b/lib/vtls/nss.c
index b679c12bb..c784109f7 100644
--- a/lib/vtls/nss.c
+++ b/lib/vtls/nss.c
@@ -616,15 +616,16 @@ static void HandshakeCallback(PRFileDesc *sock, void *arg)
 {
   struct connectdata *conn = (struct connectdata*) arg;
 
-#ifndef USE_NGHTTP2
-  (void)sock;
-  (void)conn;
-#else
+#ifdef USE_NGHTTP2
   unsigned int buflenmax = 50;
   unsigned char buf[50];
   unsigned int buflen;
   SSLNextProtoState state;
 
+  if(!conn->data->set.ssl_enable_npn && !conn->data->set.ssl_enable_alpn) {
+    return;
+  }
+
   if(SSL_GetNextProto(sock, &state, buf, &buflen, buflenmax) == SECSuccess) {
 
     switch(state) {
@@ -1311,6 +1312,7 @@ CURLcode Curl_nss_connect(struct connectdata *conn, int sockindex)
 #endif
 #endif
 
+
   if(connssl->state == ssl_connection_complete)
     return CURLE_OK;
 
@@ -1485,32 +1487,45 @@ CURLcode Curl_nss_connect(struct connectdata *conn, int sockindex)
   }
 
 #ifdef USE_NGHTTP2
+  if(data->set.httpversion == CURL_HTTP_VERSION_2_0) {
 #ifdef SSL_ENABLE_NPN
-  if(SSL_OptionSet(connssl->handle, SSL_ENABLE_NPN, PR_TRUE) != SECSuccess)
-    goto error;
+    if(data->set.ssl_enable_npn) {
+      if(SSL_OptionSet(connssl->handle, SSL_ENABLE_NPN, PR_TRUE) != SECSuccess)
+        goto error;
+    }
 #endif
 
 #ifdef SSL_ENABLE_ALPN
-  if(SSL_OptionSet(connssl->handle, SSL_ENABLE_ALPN, PR_TRUE) != SECSuccess)
-    goto error;
+    if(data->set.ssl_enable_alpn) {
+      if(SSL_OptionSet(connssl->handle, SSL_ENABLE_ALPN, PR_TRUE)
+          != SECSuccess)
+        goto error;
+    }
 #endif
 
 #if defined(SSL_ENABLE_NPN) || defined(SSL_ENABLE_ALPN)
-  alpn_protos[cur] = NGHTTP2_PROTO_VERSION_ID_LEN;
-  cur++;
-  memcpy(&alpn_protos[cur], NGHTTP2_PROTO_VERSION_ID,
-      NGHTTP2_PROTO_VERSION_ID_LEN);
-  cur += NGHTTP2_PROTO_VERSION_ID_LEN;
-  alpn_protos[cur] = ALPN_HTTP_1_1_LENGTH;
-  cur++;
-  memcpy(&alpn_protos[cur], ALPN_HTTP_1_1, ALPN_HTTP_1_1_LENGTH);
-
-  if(SSL_SetNextProtoNego(connssl->handle, alpn_protos, alpn_protos_len)
-      != SECSuccess)
-    goto error;
+    if(data->set.ssl_enable_npn || data->set.ssl_enable_alpn) {
+      alpn_protos[cur] = NGHTTP2_PROTO_VERSION_ID_LEN;
+      cur++;
+      memcpy(&alpn_protos[cur], NGHTTP2_PROTO_VERSION_ID,
+          NGHTTP2_PROTO_VERSION_ID_LEN);
+      cur += NGHTTP2_PROTO_VERSION_ID_LEN;
+      alpn_protos[cur] = ALPN_HTTP_1_1_LENGTH;
+      cur++;
+      memcpy(&alpn_protos[cur], ALPN_HTTP_1_1, ALPN_HTTP_1_1_LENGTH);
+
+      if(SSL_SetNextProtoNego(connssl->handle, alpn_protos, alpn_protos_len)
+          != SECSuccess)
+        goto error;
+    }
+    else {
+      infof(data, "SSL, can't negotiate HTTP/2.0 with neither NPN nor ALPN\n");
+    }
 #endif
+  }
 #endif
 
+
   /* Force handshake on next I/O */
   SSL_ResetHandshake(connssl->handle, /* asServer */ PR_FALSE);