#include <stdio.h>
#include <stdlib.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <sys/select.h>

/* do not create sockets in tmp directory
* To show a socket example – it is fine.
* creating sockets in tmp directory is a security
* vulnerability */

const char *path= “/tmp/unix_socket.sock”;

struct sockaddr_un *servaddr = NULL;
/* create a list of client connections */
struct sockaddr_un clientaddr[10] = {0};
int sockserver, sockclient[10] = {0};

/* Interrupt_handler so that CTRL +C can be used
* to exit the program */
void interrupt_handler (int signum) {
        int index =0;
        close(sockserver);
        free(servaddr);
        for(index = 0; index < 10; index++) {
                if(sockclient[index] > 0)
                        close(sockclient[index]);
        }
        printf(“socket connection closed\n”);
        exit(0);
}

int main () {

        int length, max_fd, index=0, sel_ready;
        char buffer[50];
        char *string = “Hello from server”;
        fd_set read_fd;

        /* signal handler to exit out of while 1 loop */
        signal (SIGINT, interrupt_handler);
        signal (SIGPIPE, interrupt_handler);

        /* Part 1 – create the socket */
        sockserver = socket(AF_UNIX, SOCK_STREAM, 0);
        if (sockserver < 0) {
                printf(“creating server socket failed\n”);
                exit(0);
        }
        /* Part 2 – fill the structure and bind to the socket path
        * Remove/unlink any previous socket file creation
        */

        remove(path);

        servaddr = (struct sockaddr_un *)malloc(sizeof(struct sockaddr_un));

        if (servaddr == NULL) {
                printf(“Unable to allocate memory\n”);
                goto end;
        }

        servaddr->sun_family = AF_UNIX;

        if ((strlen(path)) > sizeof(servaddr->sun_path)) {
                printf(“Path is too long\n”);
                goto end1;
        }
        snprintf(servaddr->sun_path, (strlen(path)+1), “%s”, path);

        if (0 != (bind(sockserver,(struct sockaddr *)servaddr, sizeof(struct sockaddr_un)))) {
                printf(“Unable to bind to the socket path\n”);
                goto end1;
        }

        /* Part 3 – make the server socket a passive socket and accept connections
        * from client stations */
        if(-1 == listen(sockserver, 10)) {
                printf(“Listen Failed\n”);
                goto end1;
        }
        FD_ZERO(&read_fd);
        /* set max_fd */
        max_fd = sockserver + 1;
        while (1) {
                FD_SET(sockserver, &read_fd);
                /* wait on read_fd and time is set as NULL – so wait infinite time */
                sel_ready = select(max_fd, &read_fd, NULL, NULL, NULL);
                if (FD_ISSET(sockserver, &read_fd)) {
                        sockclient[index] = accept(sockserver, (struct sockaddr *)&clientaddr[index], &length);

                        if (sockclient[index] < 0) {
                                printf(“unable to accept client connection\n”);
                                goto end2;
                        }
                }
                /* read one packet from client and write one packet to client */
               memset(buffer, 0, sizeof(buffer));
               read(sockclient[index], buffer, sizeof(buffer));
               printf(“%s\n”, buffer);

               memset(buffer, 0, sizeof(buffer));
               snprintf(buffer, (strlen(string)+1), “%s”, string);
               write(sockclient[index], buffer, sizeof(buffer));
               index++;
        }
end2:
        for(index = 0; index < 10; index++) {
                if(sockclient[index] > 0)
                        close(sockclient[index]);
        }
end1:
       free(servaddr);
end:
       close(sockserver);
       return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>

/* do not create sockets in tmp directory
* To show a socket example – it is fine.
* creating sockets in tmp directory is a security
* vulnerability */

const char *path= “/tmp/unix_socket.sock”;

struct sockaddr_un *servaddr = NULL;
int sockserver;

int main () {
        int length;
        char buffer[50];
        char *string = “Hello from client”;

        /* Part 1 – create the socket */
        sockserver = socket(AF_UNIX, SOCK_STREAM, 0);
        if (sockserver < 0) {
                printf(“creating client socket failed\n”);
                exit(0);
        }
        /* Part 2 – fill the structure and bind to the socket path
        * Remove/unlink any previous socket file creation
        */

        servaddr = (struct sockaddr_un *)malloc(sizeof(struct sockaddr_un));
        if(servaddr == NULL) {
                printf(“unable to allocate memory\n”);
                goto end;
        }
        servaddr->sun_family = AF_UNIX;

        if ((strlen(path)) > sizeof(servaddr->sun_path)) {
                printf(“Path is too long\n”);
                goto end1;
        }
        snprintf(servaddr->sun_path, (strlen(path)+1), “%s”, path);

        if (0 != (connect(sockserver, (struct sockaddr *)servaddr, sizeof(struct sockaddr_un)))) {
                printf(“unable to connect to the server\n”);
                goto end1;
        }

        /* write and read one packet from server */
        memset(buffer, 0, sizeof(buffer));
        snprintf(buffer, (strlen(string)+1), “%s”, string);
        write(sockserver, buffer, sizeof(buffer));

        memset(buffer, 0, sizeof(buffer));
        read(sockserver, buffer, sizeof(buffer));
        printf(“%s\n”, buffer);
end1:
        free(servaddr);
end:
        close(sockserver);
        return 0;
}