Socket IPC)

The socket IPC is consistent with the general network communication. There are two types of sock_stream and sock_daram, which are different from the following:

1. the network communication server uses IP/port as the service name, And the IPC uses the socket file path name as the service name. The socket file is different from the general file, and the socket file is created when the program is running, but cannot be created manually.

2. Different domain names: af_inet; af_unix; sockaddr_in and sockaddr_un. struct sockaddr_un {int sun_family; char sun_path [108];}

3. the client and the server can bind a file path. After binding, a socket file is generated. This file does not have any effect. You can delete it directly without affecting communication.

// Server end

# Include <stdio. h>

# Include <stdlib. h>
# Include <sys/socket. h>
# Include <sys/UN. h>
# Include <stddef. h>
# Include <unistd. h>
Int bindsocket (char * servname)
{
Struct sockaddr_un usock;
Int UFD;
Memset (& usock, 0, sizeof (sockaddr_un ));
Usock. sun_family = af_unix;
Strcpy (usock. sun_path, servname );
If (UFD = socket (af_unix, sock_stream, 0) <0)
{
Perror ("socket () error! ");
Exit (-1 );
}
Int Len = offsetof (sockaddr_un, sun_path) + strlen (usock. sun_path );
If (BIND (UFD, (sockaddr *) & usock, Len) <0)
{
Perror ("BIND () error! ");
Exit (-1 );
}

Return UFD;
}
Int acceptsocket (INT ssock, sockaddr_un * UN)
{

Int csock, Len;

Len = sizeof (un); // This statement must exist, because Len is an outgoing parameter. If no size is specified during input, it is possible to pass in the parameter value of the last outgoing parameter.

If (csock = accept (ssock, (sockaddr *) UN, (socklen_t *) & Len) <0)
{
Perror ("accept () error! ");
Exit (-1 );
}
Len-= offsetof (sockaddr_un, sun_path );
Un-> sun_path [Len] = 0;
Printf ("client file: % s \ n", un-> sun_path );
Return csock;

}

Int main (void)
{
Char servname [20];
Sprintf (servname, "server ");
Int SFD = bindsocket (servname );
If (Listen (SFD, 5) <0)
{
Perror ("Listen () error! ");
Exit (-1 );
}
Struct sockaddr_un;
Int CFD = acceptsocket (SFD, & UN );
Char Buf [100];
Int S = read (CFD, Buf, sizeof (BUF ));
Write (stdout_fileno, Buf, S );

}

// Client

# Include <stdio. h>
# Include <sys/socket. h>
# Include <stdlib. h>
# Include <unistd. h>
# Include <string. h>
# Include <sys/UN. h>
# Include <stddef. h>
Int cli_connect (const char * name)
{
Int Len;
Struct sockaddr_un;
Memset (& UN, 0, sizeof (un ));
Un. sun_family = af_unix;
Sprintf (UN. sun_path, "client % 05d", getpid ());
Int CFD;
If (CFD = socket (af_unix, sock_stream, 0) <0)
{
Perror ("socket () error ");
Exit (-1 );
}
Len = offsetof (sockaddr_un, sun_path) + strlen (UN. sun_path );
If (BIND (CFD, (sockaddr *) & UN, Len) <0)
{
Perror ("BIND () error ");
Exit (-1 );
}
Memset (& UN, 0, sizeof (un ));
Un. sun_family = af_unix;
Sprintf (UN. sun_path, name );
Len = offsetof (sockaddr_un, sun_path );
Len + = strlen (UN. sun_path );
Printf ("% s \ n", UN. sun_path );
If (connect (CFD, (sockaddr *) & UN, Len) <0)
{
Perror ("Connect () error ");
Exit (-1 );
}
Return CFD;
}
Int main (void)
{
Int CFD = cli_connect ("QW/Server ");
Char * Buf = "Hello world! ";
If (write (CFD, Buf, strlen (BUF) <0)
Perror ("error ");
Return CFD;
}