A Client Process in the Unix Domain (in C)
Consider a simple client process wishing to establish a connection with a
server process in the Unix domain.
When communicating within the Unix domain,
the data frames never leave the single computer,
and never get lost (other than on an extremely busy machine).
In this example,
the client program sends commands to a 3D printer which is directly connected
to the same computer.
The client process simply connects to the server process
and then writes the bytes to be printed to the socket
(note that this example is far from how print spooling works in
practice!)
#include <many-header-files.h>
int write_file_to_server(int sd, const char filenm[])
{
// ENSURE THAT WE CAN OPEN PROVIDED FILE
int fd = open(filenm, O_RDWR, 0);
if(fd >= 0) {
char buffer[1024];
int nbytes;
// COPY BYTES FROM FILE-DESCRIPTOR TO SOCKET-DESCRIPTOR
while( (nbytes = read(fd, buffer, sizeof(buffer) ) ) {
if(write(sd, buffer, nbytes) != nbytes) {
close(fd);
return 1;
}
}
close(fd);
return 0;
}
return 1;
}
int main(int argc, char *argv[])
{
// ASK OUR OS KERNEL TO ALLOCATE RESOURCES FOR A SOCKET
int sd = socket(AF_UNIX, SOCK_STREAM, 0);
if(sd < 0) {
perror(argv[0]); // issue a standard error message
exit(EXIT_FAILURE);
}
// FIND AND CONNECT TO THE SERVICE ADVERTISED WITH "THREEDsocket"
if(connect(sd,"THREEDsocket",strlen("THREEDsocket")) == -1) {
perror(argv[0]); // issue a standard error message
exit(EXIT_FAILURE);
}
write_file_to_server(sd, FILENM_OF_COMMANDS);
shutdown(sd, SHUT_RDWR);
close(sd);
exit(EXIT_SUCCESS);
}
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CITS3002 Computer Networks, Lecture 8, Transport layer protocols and APIs, p15, 24th April 2024.
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CITS3002