mongoose/docs/c-api/net.h/mg_connect_opt.md

title	decl_name	symbol_kind	signature
mg_connect_opt()	mg_connect_opt	func	struct mg_connection *mg_connect_opt(struct mg_mgr *mgr, const char *address, mg_event_handler_t handler, struct mg_connect_opts opts);

Connect to a remote host.

address format is [PROTO://]HOST:PORT. PROTO could be tcp or udp. HOST could be an IP address, IPv6 address (if Mongoose is compiled with -DMG_ENABLE_IPV6), or a host name. If HOST is a name, Mongoose will resolve it asynchronously. Examples of valid addresses: google.com:80, udp://1.2.3.4:53, 10.0.0.1:443, [::1]:80

See the mg_connect_opts structure for a description of the optional parameters.

Returns a new outbound connection, or NULL on error.

NOTE: Connection remains owned by the manager, do not free().

NOTE: To enable IPv6 addresses, -DMG_ENABLE_IPV6 should be specified in the compilation flags.

NOTE: New connection will receive MG_EV_CONNECT as it's first event which will report connect success status. If asynchronous resolution fail, or connect() syscall fail for whatever reason (e.g. with ECONNREFUSED or ENETUNREACH), then MG_EV_CONNECT event report failure. Code example below:

static void ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
  int connect_status;

  switch (ev) {
    case MG_EV_CONNECT:
      connect_status = * (int *) ev_data;
      if (connect_status == 0) {
        // Success
      } else  {
        // Error
        printf("connect() error: %s\n", strerror(connect_status));
      }
      break;
    ...
  }
}

  ...
  mg_connect(mgr, "my_site.com:80", ev_handler);