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

src/tool_cfgable.h

@@ -214,6 +214,8 @@ struct Configurable {
   bool test_event_based;
 #endif
   char *xoauth2_bearer;       /* XOAUTH2 bearer token */
+  bool nonpn;                 /* enable/disable TLS NPN extension */
+  bool noalpn;                /* enable/disable TLS ALPN extension */
 
   struct Configurable* prev;
   struct Configurable* next;  /* Always last in the struct */

src/tool_getparam.c

@@ -90,7 +90,9 @@ static const struct LongShort aliases[]= {
 #endif
   {"*F", "dns-servers",              TRUE},
   {"*g", "trace",                    TRUE},
+  {"*G", "npn",                      FALSE},
   {"*h", "trace-ascii",              TRUE},
+  {"*H", "alpn",                     FALSE},
   {"*i", "limit-rate",               TRUE},
   {"*j", "compressed",               FALSE},
   {"*J", "tr-encoding",              FALSE},
@@ -554,6 +556,9 @@ ParameterError getparameter(char *flag,    /* f or -long-flag */
           warnf(config, "--trace overrides an earlier trace/verbose option\n");
         config->tracetype = TRACE_BIN;
         break;
+      case 'G': /* --npn */
+        config->nonpn = (!toggle)?TRUE:FALSE;
+        break;
       case 'h': /* --trace-ascii */
         GetStr(&config->trace_dump, nextarg);
         if(config->tracetype && (config->tracetype != TRACE_ASCII))
@@ -561,6 +566,9 @@ ParameterError getparameter(char *flag,    /* f or -long-flag */
                 "--trace-ascii overrides an earlier trace/verbose option\n");
         config->tracetype = TRACE_ASCII;
         break;
+      case 'H': /* --alpn */
+        config->noalpn = (!toggle)?TRUE:FALSE;
+        break;
       case 'i': /* --limit-rate */
       {
         /* We support G, M, K too */

src/tool_help.c

@@ -105,6 +105,8 @@ static const char *const helptext[] = {
   " -0, --http1.0       Use HTTP 1.0 (H)",
   "     --http1.1       Use HTTP 1.1 (H)",
   "     --http2         Use HTTP 2 (H)",
+  "     --no-npn        Disable the NPN TLS extension",
+  "     --no-alpn       Disable the ALPN TLS extension",
   "     --ignore-content-length  Ignore the HTTP Content-Length header",
   " -i, --include       Include protocol headers in the output (H/F)",
   " -k, --insecure      Allow connections to SSL sites without certs (H)",

src/tool_operate.c

@@ -1350,6 +1350,14 @@ static int operate_do(struct Configurable *config)
         if(config->sasl_ir)
           my_setopt(curl, CURLOPT_SASL_IR, 1L);
 
+        if(config->nonpn) {
+          my_setopt(curl, CURLOPT_SSL_ENABLE_NPN, 0L);
+        }
+
+        if(config->noalpn) {
+          my_setopt(curl, CURLOPT_SSL_ENABLE_ALPN, 0L);
+        }
+
         /* initialize retry vars for loop below */
         retry_sleep_default = (config->retry_delay) ?
           config->retry_delay*1000L : RETRY_SLEEP_DEFAULT; /* ms */

src/tool_setopt.c

@@ -145,6 +145,8 @@ const NameValue setopt_nv_CURLPROTO[] = {
 static const NameValue setopt_nv_CURLNONZERODEFAULTS[] = {
   NV1(CURLOPT_SSL_VERIFYPEER, 1),
   NV1(CURLOPT_SSL_VERIFYHOST, 1),
+  NV1(CURLOPT_SSL_ENABLE_NPN, 1),
+  NV1(CURLOPT_SSL_ENABLE_ALPN, 1),
   NVEND
 };