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WS_RECVL(3)		   libdill Library Functions		   WS_RECVL(3)

       ws_recvl	- receives a WebSocket message

	      #include <libdill.h>

	      ssize_t ws_recvl(
		  int s,
		  int* flags,
		  struct iolist* first,
		  struct iolist* last,
		  int64_t deadline);

       WARNING:	 This  is experimental functionality and the API may change in
       the future.

       WebSocket is a message-based protocol defined in	RFC 6455.  It  can  be
       used  as	a bidirectional	communication channel for communication	with a
       web server.

       This function receives one WebSocket message.  It is very much the same
       as  mrecvl  except that it returns the type of the message (either text
       or binary).

       This function accepts a linked list of I/O buffers instead of a	single
       buffer.	 Argument  first  points  to  the first	item in	the list, last
       points to the last buffer in the	list.  The list	represents  a  single,
       fragmented  message, not	a list of multiple messages.  Structure	iolist
       has the following members:

	      void *iol_base;	       /* Pointer to the buffer. */
	      size_t iol_len;	       /* Size of the buffer. */
	      struct iolist *iol_next; /* Next buffer in the list. */
	      int iol_rsvd;	       /* Reserved. Must be set	to zero. */

       When receiving, iol_base	equal to NULL means that iol_len bytes	should
       be skipped.

       The function returns EINVAL error in the	case the list is malformed:

       o If last->iol_next is not NULL.

       o If first and last don't belong	to the same list.

       o If there's a loop in the list.

       o If iol_rsvd of	any item is non-zero.

       The  list  (but not the buffers themselves) can be temporarily modified
       while the function is in	progress.  However, once the function  returns
       the list	is guaranteed to be the	same as	before the call.

       s: Handle of the	UDP socket.

       flags: Out parameter.  Possible values are either WS_BINARYor WS_TEXT.

       first: Pointer to the first item	of a linked list of I/O	buffers.

       last: Pointer to	the last item of a linked list of I/O buffers.

       deadline:  A  point in time when	the operation should time out, in mil-
       liseconds.  Use the now function	to get your current point in time.   0
       means immediate timeout,	i.e., perform the operation if possible	or re-
       turn without blocking if	not.  -1 means no  deadline,  i.e.,  the  call
       will block forever if the operation cannot be performed.

       This  function  is  not	available  if  libdill is compiled with	--dis-
       able-sockets option.

       In case of success the function returns size of the  received  message,
       in  bytes.  In case of error it returns -1 and sets errno to one	of the
       values below.

       o EBADF:	Invalid	handle.

       o EBUSY:	The handle is currently	being used by a	different coroutine.

       o ECANCELED: Current coroutine was canceled.

       o ECONNRESET: Broken connection.

       o EINVAL: Invalid argument.

       o EMSGSIZE: The data won't fit into the supplied	buffer.

       o ENOTSUP: The handle does not support this operation.

       o ETIMEDOUT: Deadline was reached.

	      struct ipaddr addr;
	      ipaddr_remote(&addr, "", 80, 0, -1);
	      int s = tcp_connect(&addr, -1);
	      s	= ws_attach_client(s, "/", "", WS_TEXT, -1);
	      ws_send(s, WS_TEXT, "Hello, world!", 13, -1);
	      int flags;
	      char buf[256];
	      ssize_t sz = ws_recv(s, &flags, buf, sizeof(buf),	-1);
	      assert(flags & WS_TEXT);
	      s	= ws_detach(s, -1);
	      tcp_close(s, -1);

       mrecv(3)	mrecvl(3) msend(3) msendl(3) now(3) ws_attach_client(3)	ws_at-
       tach_client_mem(3)  ws_attach_server(3)	ws_attach_server_mem(3)	ws_de-
       tach(3)	ws_done(3)  ws_recv(3)	ws_request_key(3)   ws_response_key(3)
       ws_send(3) ws_sendl(3) ws_status(3)

libdill								   WS_RECVL(3)


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