#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <sys/socket.h>

#define handle_error(msg) do { perror(msg); exit(EXIT_FAILURE); } while(0)

static int conn;

int
main(int argc, char *argv[]) {
	pid_t pid;
        char buf[64] = {0};
        int sfd, cfd, ret;
        struct sockaddr_un addr;

        sfd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (sfd == -1)
                handle_error ("Failed to create socket");

        if (unlink ("/tmp/fd-pass.socket") == -1 && errno != ENOENT)
                handle_error ("Removing socket file failed");

        memset(&addr, 0, sizeof(struct sockaddr_un));
        addr.sun_family = AF_UNIX;
        strncpy(addr.sun_path, "/tmp/fd-pass.socket", sizeof(addr.sun_path) - 1);

        if (bind(sfd, (struct sockaddr *) &addr, sizeof(struct sockaddr_un)) == -1)
                handle_error ("Failed to bind to socket");

        if (listen(sfd, 5) == -1)
                handle_error ("Failed to listen on socket");

	while (1) {
		cfd = accept(sfd, NULL, NULL);
		if (cfd == -1)
			handle_error ("Failed to accept incoming connection");

		conn++;
		fprintf(stdout, "%d CONNECTION/S ESTABLISHED\n", conn);

		pid = fork();
		if (pid == -1) {
			handle_error ("Failed to fork after accepting connection");
		} else if (pid == 0) {
			if (close(sfd) == -1)
				handle_error ("Failed to close server socket in child");

			ret = recv (cfd, buf, 64, 0);
			if (ret == -1)
				handle_error ("Failed to receive data from client in child");

			ret = send (cfd, buf, ret, 0);
			if (ret == -1)
				handle_error ("Failed to send data to client in child");

			if (close(cfd) == -1)
				handle_error ("Failed to close server socket in child");

			exit(0);
		}
		waitpid (-1, NULL, 0);
		if (close(cfd) == -1)
			handle_error ("Failed to close client socket");
	}

        return 0;
}