The recv() call receives data on a socket with descriptor s and stores it in a buffer. The recv() call applies only to connected sockets.

This call returns the length of the incoming message or data. If data is not available for socket s, and s is in blocking mode, the recv() call blocks the caller until data arrives. If data is not available and s is in nonblocking mode, recv() returns a -1 and sets errno to EWOULDBLOCK. See fcntl() or ioctl() for a description of how to set nonblocking mode.

If a datagram packet is too long to fit in the supplied buffer, datagram sockets discard extra bytes. Stream sockets act like streams of information with no boundaries separating data. For example, if applications A and B are connected with a stream socket and Application A sends 1000 bytes, each call to this function can return 1 byte, or 10 bytes, or the entire 1000 bytes. Therefore, applications using stream sockets should place this call in a loop and call this function until all data has been received.

#include <manifest.h>
#include <bsdtypes.h>
#include <socket.h>
 
int recv(int s, char *buf, int len, int flags)

Parameter

Description

s

Socket descriptor.

buf

Points to the buffer that receives the data.

len

Length in bytes of the buffer pointed to by buf.

flags

Set the flags parameter by specifying one or more of the following flags. If more than one flag is specified, the logical OR operator (|) must be used to separate them. Setting this parameter is supported only for sockets in the AF_INET domain. Setting these flags is not supported for sockets in the AF_IUCV domain.

MSG_OOB

Reads any out-of-band data on the socket. This is valid for stream (TCP) sockets only.

MSG_PEEK

Peeks at the data present on the socket; the data is returned but not consumed, so that a subsequent receive operation sees the same data.

Return values

Related calls

connect(), fcntl(), getsockopt(), ioctl(), read(), readv(), recvfrom(), recvmsg(), select(), selectex(), send(), sendmsg(), sendto(), setsockopt(), socket(), write(), writev()