BSD Sockets Interface Programmer's Guide

92 Chapter 4

Using Internet Datagram Sockets

Writing the Server and Client Processes

This section explains the calls your server and client processes must

make.

Creating Sockets

Both processes must call socket to create communication endpoints.

socket and its parameters are described in the following table.

Include ﬁles: #include <sys/types.h>

#include <sys/socket.h>

System call: s = socket(af, type, protocol)

int s, af, type, protocol;

Function result: socket number (HP-UX ﬁle descriptor), –1 if failure

occurs.

Example:

ls = socket (AF_INET, SOCK_DGRAM, 0);

The socket number returned is the socket descriptor for the newly

created socket. This number is an HP-UX ﬁle descriptor and can be used

for reading, writing or any standard ﬁle system calls. A socket descriptor

is treated like a ﬁle descriptor for an open ﬁle.

NOTE To use write(2) with a datagram socket, you must declare a default

address. Refer to the “Specifying a Default Socket Address” section of the

“Advanced Topics for Internet Datagram Sockets” chapter for more

information.

Parameter Description of Contents INPUT Value

af address family AF_INET

type socket type SOCK_DGRAM

protocol underlying protocol to be

used

0 (default) or value

returned by

getprotobyname