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_CB(mg_event_handler_t handler, void *user_data);

Connects to a remote host.

The 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: The 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: The new connection will receive MG_EV_CONNECT as its first event which will report the connect success status. If the asynchronous resolution fails or the connect() syscall fails for whatever reason (e.g. with ECONNREFUSED or ENETUNREACH), then MG_EV_CONNECT event will 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);