- Phil Blundell added the CURLOPT_SCOPE option, as well as adjusted the URL

parser to allow numerical IPv6-addresses to be specified with the scope
  given, as per RFC4007 - with a percent letter that itself needs to be URL
  escaped. For example, for an address of fe80::1234%1 the HTTP URL is:
  "http://[fe80::1234%251]/"

lib/connect.c

@@ -773,6 +773,13 @@ singleipconnect(struct connectdata *conn,
 
   *connected = FALSE; /* default is not connected */
 
+#ifdef CURLRES_IPV6
+  if (conn->scope && (addr->family == AF_INET6)) {
+    struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)&addr->addr;
+    in6->sin6_scope_id = conn->scope;
+  }
+#endif
+
   /* FIXME: do we have Curl_printable_address-like with struct sockaddr* as
      argument? */
 #if defined(HAVE_SYS_UN_H) && defined(AF_UNIX)