sample unix client and server program

unixsocket.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <sys/un.h>
#include <sys/socket.h>

const char* SOCKET_FILE = "/tmp/fgfgdgdgff";

#define BUFFER_SPACE 100


static void do_client(void) {
	pid_t child = fork();
	if (child != 0) {
		return;
	}
    struct sockaddr_un addr;

    int sfd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (sfd == -1) {
    	fprintf(stderr, "Could not create socket, err=%d\n", errno);
    	exit(4);
    }


    memset(&addr, 0, sizeof(struct sockaddr_un));
    addr.sun_family = AF_UNIX;
    strncpy(addr.sun_path, SOCKET_FILE, sizeof(addr.sun_path) - 1);



    while (connect(sfd, (struct sockaddr *) &addr, sizeof(struct sockaddr_un)) == -1) {
    	if (errno == ECONNREFUSED) {
    		fprintf(stderr, "connection refused, retrying\n");
    		continue;
    	} 
    	fprintf(stderr, "Failed to connect to socket, err=%d\n", errno);
    	exit(4);
    }



    if (write(sfd, "Foody", 5) != 5) {
    	fprintf(stderr, "Failed to write to socket, err=%d\n", errno);
    	exit(5);
    }

    if (write(sfd, "Foody", 5) != 5) {
    	fprintf(stderr, "Failed to write to socket, err=%d\n", errno);
    	exit(5);
    }

    if (write(sfd, "Foody", 5) != 5) {
    	fprintf(stderr, "Failed to write to socket, err=%d\n", errno);
    	exit(5);
    }


	exit(0);
}

int main(int argc, char const *argv[])
{
	puts("Unix Socket");
	signal(SIGPIPE, SIG_IGN);
	// Make sure to handle removal of socket 
    if (remove(SOCKET_FILE) == -1 && errno != ENOENT) {
    	fprintf(stderr, "Failed to remove socket path %s\n", SOCKET_FILE);
    	exit(4);
    }
    struct sockaddr_un addr;
    int sfd;
    int cfd;
    ssize_t numRead;
    char buf[BUFFER_SPACE];



    sfd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (sfd == -1) {
    	fprintf(stderr, "Failed to create socket, err=%d\n", errno);
    	exit(4);
    }

    if (strlen(SOCKET_FILE) > sizeof(addr.sun_path) - 1) {
    	fprintf(stderr, "Socket name too long, socket sun path is size %zu\n", sizeof(addr.sun_path) - 1);
    	exit(1);
    }

    memset(&addr, 0, sizeof(struct sockaddr_un));
    addr.sun_family = AF_UNIX;
    strncpy(addr.sun_path, SOCKET_FILE, sizeof(addr.sun_path) - 1);

    if (bind(sfd, (struct sockaddr *) &addr, sizeof(struct sockaddr_un)) == -1) {
    	fprintf(stderr, "Failed to bind, err=%d\n", errno);
    	exit(3);
    }

    if (listen(sfd, 5) == -1) {
    	fprintf(stderr, "Failed to listen err=%d\n", errno);
    	exit(2);
    }

    do_client();
    while (1) {
    	cfd = accept(sfd, NULL, NULL);
    	if (cfd == -1) {
    		fprintf(stderr, "Cannot accept, err=%d\n", errno);
    		exit(5);
    	}

    	while ((numRead = read(cfd, buf, BUFFER_SPACE)) > 0) {
    		if (write(STDOUT_FILENO, buf, numRead) != numRead) {
    			fprintf(stderr, "Cannot write to stdout, err=%d\n", errno);
    			exit(6);
    		}
    	}

    	if (numRead == -1) {
    		fprintf(stderr, "Error while reading, err=%d\n", errno);
    		exit(8);
    	}

    	if (close(cfd) == -1) {
    		fprintf(stderr, "Cannot close connected fd, err=%d\n", errno);
    		exit(9);
    	}
    }

	return 0;
}