recv(3XNET)					   X/Open Networking Services Library Functions 				       recv(3XNET)

NAME

       recv - receive a message from a connected socket

SYNOPSIS

       cc [ flag ... ] file ... -lxnet [ library ... ]
       #include <sys/socket.h>

       ssize_t recv(int socket, void *buffer, size_t length, int flags);

DESCRIPTION

       The   recv()  function  receives a message from a connection-mode or connectionless-mode socket. It is normally used with connected sockets
       because it does not permit the application to retrieve the source address of received data. The function takes the following arguments:

       socket	 Specifies the socket file descriptor.

       buffer	 Points to a buffer where the message should be stored.

       length	 Specifies the length in bytes of the buffer pointed to by the buffer argument.

       flags	 Specifies the type of message reception.  Values of this argument are formed by logically OR'ing zero or more	of  the  following
		 values:

		 MSG_PEEK	Peeks  at  an  incoming message.  The data is treated as unread and the next recv() or similar function will still
				return this data.

		 MSG_OOB	Requests out-of-band data. The significance and semantics of out-of-band data are protocol-specific.

		 MSG_WAITALL	Requests that the function block until the full amount of data requested can be returned.  The function may return
				a smaller amount of data if a signal is caught, if the connection is terminated,  if MSG_PEEK was specified, or if
				an error is pending for the socket.

       The recv() function returns the length of the message written to the buffer pointed to by the buffer argument.  For  message-based  sockets
       such  as SOCK_DGRAM and SOCK_SEQPACKET, the entire message must be read in a single operation.  If a message is too long to fit in the sup-
       plied buffer, and MSG_PEEK is not set in the flags argument, the excess bytes are discarded.  For stream-based sockets such as SOCK_STREAM,
       message boundaries are ignored.	In this case, data is returned to the user as soon as it becomes available, and no data is discarded.

       If the MSG_WAITALL flag is not set, data will be returned only up to the end of the first message.

       If  no  messages  are  available  at  the  socket  and O_NONBLOCK is not set on the socket's file descriptor, recv() blocks until a message
       arrives.  If no messages are available at the socket and O_NONBLOCK is set on the socket's file descriptor, recv() fails and sets errno	to
       EAGAIN or EWOULDBLOCK.

USAGE

       The recv() function is identical to recvfrom(3XNET) with a zero address_len argument, and to read() if no flags are used.

       The select(3C) and poll(2) functions can be used to determine when data is available to be received.

RETURN VALUES

       Upon  successful  completion,  recv() returns the length of the message in bytes.  If no messages are available to be received and the peer
       has performed an orderly shutdown, recv() returns 0.  Otherwise, -1 is returned and errno is set to indicate the error.

ERRORS

       The recv() function will fail if:

       EAGAIN	      The socket's file descriptor is marked O_NONBLOCK and no data is waiting to be received; or MSG_OOB is set  and  no  out-of-
       EWOULDBLOCK    band  data is available and either the socket's file descriptor is marked O_NONBLOCK or the socket does not support blocking
		      to await out-of-band data.

       EBADF	      The socket argument is not a valid file descriptor.

       ECONNRESET     A connection was forcibly closed by a peer.

       EFAULT	      The  buffer parameter can not be accessed or written.

       EINTR	      The recv() function was interrupted by a signal that was caught, before any data was available.

       EINVAL	      The MSG_OOB flag is set and no out-of-band data is available.

       ENOTCONN       A receive is attempted on a connection-mode socket that is not connected.

       ENOTSOCK       The socket argument does not refer to a socket.

       EOPNOTSUPP     The specified flags are not supported for this socket type or protocol.

       ETIMEDOUT      The connection timed out during connection establishment, or due to a transmission timeout on active connection.

       The recv() function may fail if:

       EIO	  An I/O error occurred while reading from or writing to the file system.

       ENOBUFS	  Insufficient resources were available in the system to perform the operation.

       ENOMEM	  Insufficient memory was available to fulfill the request.

       ENOSR	  There were insufficient STREAMS resources available for the operation to complete.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       poll(2),  recvmsg(3XNET),  recvfrom(3XNET),  select(3C),  send(3XNET),  sendmsg(3XNET),	sendto(3XNET),	 shutdown(3XNET),   socket(3XNET),
       attributes(5), standards(5)

SunOS 5.11							    10 Jun 2002 						       recv(3XNET)