Advanced Programming in the UNIX® Environment

ptg10805159

636 Advanced IPC Chapter 17

socket socket

server process client process

sun_path

Figure 17.6Client and server sockets beforeaconnect

Figure17.6 shows a client process and a server process beforeaconnection exists

between the two. The server has bound its socket to asockaddr_unaddress and is

listening for connection requests. Figure17.7 shows the unique connection between the

client and server after the server has accepted the client’s connection request.

socket socket socket

server process client process

sun_path

Figure 17.7 Client and server sockets after aconnect

We will now develop three functions that can be used to create unique connections

between unrelated processes running on the same machine. These functions mimic the

connection-oriented socket functions discussed in Section 16.4. We use UNIX domain

sockets for the underlying communication mechanism here.

#include "apue.h"

int serv_listen(const char *name);

Returns: file descriptor to listen on if OK, negative value on error

int serv_accept(int listenfd,uid_t *uidptr);

Returns: new file descriptor if OK, negative value on error

int cli_conn(const char *name);

Returns: file descriptor if OK, negative value on error