BSD Sockets Interface Programmer's Guide

Chapter 6 137

Using UNIX Domain Stream Sockets

Sending and Receiving Data

Function result: number of bytes actually sent, –1 if failure occurs.

Example: count = send (s, buf, 10, 0);

send blocks until the speciﬁed number of bytes have been queued to be

sent, unless you are using nonblocking I/O.

When to Send Data

The server or client process should send data after connection is

established. Refer to the send(2) man page for more information on

send.

Receiving Data

recv and its parameters are described in the following table.

Include ﬁles: #include <sys/types.h>

#include <sys/socket.h>

System call: count = recv(s,buf,len,flags)

int s;

char *buf;

int len, flags;

Function result: number of bytes actually received, –1 if failure occurs.

Example: count = recv(s, buf, 10, 0);

recv blocks until there is at least 1 byte of data to be received, unless

you are using nonblocking I/O. The host does not wait for len bytes to be

available; if less than len bytes are available, that number of bytes are

received.

Parameter Description of Contents INPUT Value

s socket descriptor of local

socket

socket descriptor of

socket sending data

buf pointer to data buffer pointer to data to be sent

len maximum number of bytes

that should be received

size of data buffer

ﬂags settings for optional ﬂags 0