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  fol-
		       lowing values:

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

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

		       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  termi-
					       nated,  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
       EWOULDBLOCK	       out-of-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 5.10							    10 Jun 2002 						       recv(3XNET)