wolfssl: Use ECC supported curves extension

https://github.com/wolfSSL/wolfssl/issues/366

configure.ac

@@ -2206,11 +2206,13 @@ if test "$curl_ssl_msg" = "$init_ssl_msg"; then
         dnl Recent WolfSSL versions build without SSLv3 by default
         dnl WolfSSL needs configure --enable-opensslextra to have *get_peer*
         AC_CHECK_FUNCS(wolfSSLv3_client_method \
+                       wolfSSL_CTX_UseSupportedCurve \
                        wolfSSL_get_peer_certificate \
                        wolfSSL_UseALPN)
       else
         dnl Cyassl needs configure --enable-opensslextra to have *get_peer*
-        AC_CHECK_FUNCS(CyaSSL_get_peer_certificate)
+        AC_CHECK_FUNCS(CyaSSL_CTX_UseSupportedCurve \
+                       CyaSSL_get_peer_certificate)
       fi
 
       if test -n "$cyassllib"; then

lib/vtls/cyassl.c

@@ -112,6 +112,15 @@ and that's a problem since options.h hasn't been included yet. */
 #endif
 #endif
 
+/* HAVE_SUPPORTED_CURVES is wolfSSL's build time symbol for enabling the ECC
+   supported curve extension in options.h. Note ECC is enabled separately. */
+#ifndef HAVE_SUPPORTED_CURVES
+#if defined(HAVE_CYASSL_CTX_USESUPPORTEDCURVE) || \
+    defined(HAVE_WOLFSSL_CTX_USESUPPORTEDCURVE)
+#define HAVE_SUPPORTED_CURVES
+#endif
+#endif
+
 static Curl_recv cyassl_recv;
 static Curl_send cyassl_send;
 
@@ -313,6 +322,16 @@ cyassl_connect_step1(struct connectdata *conn,
   }
 #endif
 
+#ifdef HAVE_SUPPORTED_CURVES
+  /* CyaSSL/wolfSSL does not send the supported ECC curves ext automatically:
+     https://github.com/wolfSSL/wolfssl/issues/366
+     The supported curves below are those also supported by OpenSSL 1.0.2 and
+     in the same order. */
+  CyaSSL_CTX_UseSupportedCurve(conssl->ctx, 0x17); /* secp256r1 */
+  CyaSSL_CTX_UseSupportedCurve(conssl->ctx, 0x19); /* secp521r1 */
+  CyaSSL_CTX_UseSupportedCurve(conssl->ctx, 0x18); /* secp384r1 */
+#endif
+
   /* give application a chance to interfere with SSL set up. */
   if(data->set.ssl.fsslctx) {
     CURLcode result = CURLE_OK;

projects/wolfssl_options.h

@@ -30,6 +30,7 @@ C_EXTRA_FLAGS="\
   --enable-sha512 \
   --enable-sni \
   --enable-sslv3 \
+  --enable-supportedcurves \
   --enable-testcert \
   > config.out 2>&1
 
@@ -158,6 +159,9 @@ extern "C" {
 #undef  HAVE_TLS_EXTENSIONS
 #define HAVE_TLS_EXTENSIONS
 
+#undef  HAVE_SUPPORTED_CURVES
+#define HAVE_SUPPORTED_CURVES
+
 #undef  WOLFSSL_TEST_CERT
 #define WOLFSSL_TEST_CERT