server-client-killer

// message-types.h

#pragma once

typedef struct message_from_client {
    long mtype;
    struct info_from_client {
        float a;
        int b;
        long pid;
    } info;
} message_from_client;

typedef struct message_from_server {
    long mtype;
    struct info_from_server {
        float c;
    } info;
} message_from_server;



// server.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/stat.h>
#include <errno.h>

#include "message-types.h"

int main()
{
    int msqid;
    char pathname[] = "server.c";
    key_t key = ftok(pathname, 0);

    (void) umask(0000);
    if ((msqid = msgget(key, 0666 | IPC_CREAT | IPC_EXCL)) < 0) {
        if (errno == EEXIST) { printf("Error1s\n"); exit(-1); }
        else { printf("Error2s\n"); exit(-1); }
    }

    message_from_server snd;
    message_from_client rcv;
    int maxlen_c = sizeof(struct info_from_client);
    int maxlen_s = sizeof(struct info_from_server);

    while (1) {
        if (msgrcv(msqid, (message_from_client*) &rcv, maxlen_c, 1, 0) < 0) { printf("Error3s\n"); exit(-1); }
        printf("Server received from %ld, contents: a = %f, b = %d\n", rcv.info.pid, rcv.info.a, rcv.info.b);

        if (rcv.info.pid < 0)
            break;

        snd.mtype = rcv.info.pid;
        snd.info.c = (float) rcv.info.a * rcv.info.b;

        if (msgsnd(msqid, (message_from_server*) &snd, maxlen_s, 0) < 0) { printf("Error4s\n"); exit(-1); }
        printf("Server sent to %ld, result: c = %f\n", snd.mtype, snd.info.c);
    }

    if (msgctl(msqid, IPC_RMID, (struct msqid_ds*) NULL) < 0) { printf("Error5s\n"); exit(-1); }

    return 0;
}



// client.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

#include <sys/ipc.h>
#include <sys/msg.h>
#include <time.h>

#include "message-types.h"

int main() {
    char pathname[] = "server.c";
    key_t key = ftok(pathname, 0);

    int msqid;
    if ((msqid = msgget(key, 0)) < 0) { printf("Error1c\n"); exit(-1); }

    message_from_client snd;

    snd.mtype = 1;
    srand(time(0));
    snd.info.b = rand() % 512;
    snd.info.a = (float) rand() / RAND_MAX;
    snd.info.pid = (long) getpid();

    if (msgsnd(msqid, (message_from_client*) &snd, sizeof (struct info_from_client), 0) < 0) { printf("Error2c\n"); exit(-1); }
    printf ("Client %ld sent numbers a = %f, b = %d to the server\n", snd.info.pid, snd.info.a, snd.info.b);

    message_from_server rcv;
    if (msgrcv(msqid, (message_from_server*) &rcv, sizeof (struct info_from_server), (int) getpid(), 0) < 0) { printf("Error3c\n"); exit(-1); }
    printf ("Client %d received from the server, type: %ld, result: c = %f\n", (int) getpid(), rcv.mtype, rcv.info.c);

    return 0;
}



// killer.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

#include <sys/ipc.h>
#include <sys/msg.h>

#include "message-types.h"

int main() {
    char pathname[] = "server.c";
    key_t key = ftok(pathname, 0);

    int msqid;
    if ((msqid = msgget(key, 0)) < 0) { printf("Error1k\n"); exit(-1); }

    message_from_client snd;

    snd.mtype = 1;
    snd.info.pid = -1;

    if (msgsnd(msqid, (message_from_client*) &snd, sizeof (struct info_from_client), 0) < 0) { printf("Error2c\n"); exit(-1); }

    return 0;
}