How to send broadcast messages with named pipe using C? - c

Question

I want to write a program with 1 sender and 3 receivers. The sender can send individual message to each receivers and group message to all receivers. I am using named pipes to achieve this but can't send group message to all receivers synchronously. Any idea to send broadcast message with named pipe?
Sender program:
/* Sender */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
char pipename1[] = "/tmp/pipe1";
char pipename2[] = "/tmp/pipe2";
char pipename3[] = "/tmp/pipe3";
char pipename4[] = "/tmp/pipe4";
char buf1[80];
char buf2[80];
char buf3[80];
char buf4[80];
int fd1, fd2, fd3, fd4;
int select1, select2;
int n,pid;
/* Pipe Creation */
if (access(pipename1, F_OK) == -1) {
fd1 = mkfifo(pipename1, 0700);
if (fd1 != 0) {
printf("Pipe creation error\n");
exit(1);
}
}
if (access(pipename2, F_OK) == -1) {
fd2 = mkfifo(pipename2, 0700);
if (fd2 != 0) {
printf("Pipe creation error\n");
exit(1);
}
}
if (access(pipename3, F_OK) == -1) {
fd3 = mkfifo(pipename3, 0700);
if (fd3 != 0) {
printf("Pipe creation error\n");
exit(1);
}
}
if (access(pipename4, F_OK) == -1) {
fd4 = mkfifo(pipename4, 0700);
if (fd4 != 0) {
printf("Pipe creation error\n");
exit(1);
}
}
pid = fork();
if (pid < 0) {
printf("Fork failed\n");
exit(1);
} else if (pid == 0) {
printf("1. Send individual message\n");
printf("2. Send group message\n");
printf("Please select an option: ");
scanf("%d", &select1);
switch(select1) {
case 1:
printf("1. Receiver 1 (Mary)\n");
printf("2. Receiver 2 (John)\n");
printf("3. Receiver 3 (Peter)\n");
printf("Please select a receiver: ");
scanf("%d", &select2);
switch(select2) {
case 1:
/* Open pipe for writing */
if ((fd1 = open(pipename1, O_WRONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while (1) {
printf("Send message to Mary: \n");
n = read(STDIN_FILENO,buf1,80);
if (n <= 0) break;
buf1[--n] = 0;
printf("Sending message [%s] to Mary\n",buf1);
write(fd1,buf1,n);
}
close(fd1);
break;
case 2:
/* Open pipe for writing */
if ((fd2 = open(pipename2, O_WRONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while (1) {
printf("Send message to John: \n");
n = read(STDIN_FILENO,buf2,80);
if (n <= 0) break;
buf2[--n] = 0;
printf("Sending message [%s] to John\n",buf2);
write(fd2,buf2,n);
}
break;
case 3:
/* Open pipe for writing */
if ((fd3 = open(pipename3, O_WRONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while (1) {
printf("Send message to Peter: \n");
n = read(STDIN_FILENO,buf3,80);
if (n <= 0) break;
buf3[--n] = 0;
printf("Sending message [%s] to Peter\n",buf3);
write(fd3,buf3,n);
}
break;
default:
printf("Receiver not found\n");
break;
}
case 2:
/* Open pipe for writing */
if ((fd4 = open(pipename4, O_WRONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while (1) {
printf("Send message to Group: \n");
n = read(STDIN_FILENO,buf4,80);
if (n <= 0) break;
buf4[--n] = 0;
printf("Sending message [%s] to Group\n",buf4);
write(fd4,buf4,n);
}
break;
default:
printf("Wrong Input!\n");
break;
}
} else {
wait(NULL);
}
unlink(pipename1);
unlink(pipename2);
unlink(pipename3);
unlink(pipename4);
exit(0);
}
Receiver1 program:
/* Receiver1 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
char pipename1[] = "/tmp/pipe1";
char pipename4[] = "/tmp/pipe4";
char buf1[80];
char buf4[80];
int fd1, fd4;
int n, pid;
printf("Mary is online\n");
pid = fork();
if (pid < 0) {
printf("Fork failed\n");
exit(1);
} else if (pid == 0) {
/* Open pipe for reading */
if ((fd1 = open(pipename1, O_RDONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while ((n = read(fd1, buf1, 80)) > 0) {
buf1[n] = 0;
printf("[Message received:] %s\n", buf1, n);
}
close(fd1);
exit(0);
} else {
/* Open pipe for reading */
if ((fd4 = open(pipename4, O_RDONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while ((n = read(fd4, buf4, 80)) > 0) {
buf4[n] = 0;
printf("[Message received:] %s\n", buf4, n);
}
close(fd4);
wait(NULL);
exit(0);
}
}
Receiver2 program:
/* Receiver2 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
char pipename2[] = "/tmp/pipe2";
char pipename4[] = "/tmp/pipe4";
char buf2[80];
char buf4[80];
int fd2, fd4;
int n, pid;
printf("John is online\n");
pid = fork();
if (pid < 0) {
printf("Fork failed\n");
exit(1);
} else if (pid == 0) {
/* Open pipe for reading */
if ((fd2 = open(pipename2, O_RDONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while ((n = read(fd2, buf2, 80)) > 0) {
buf2[n] = 0;
printf("[Message received:] %s\n", buf2, n);
}
close(fd2);
exit(0);
} else {
/* Open pipe for reading */
if ((fd4 = open(pipename4, O_RDONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while ((n = read(fd4, buf4, 80)) > 0) {
buf4[n] = 0;
printf("[Message received:] %s\n", buf4, n);
}
close(fd4);
wait(NULL);
exit(0);
}
}
Receiver3 program:
/* Receiver3 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
char pipename3[] = "/tmp/pipe3";
char pipename4[] = "/tmp/pipe4";
char buf3[80];
char buf4[80];
int fd3, fd4;
int n, pid;
printf("Peter is online\n");
pid = fork();
if (pid < 0) {
printf("Fork failed\n");
exit(1);
} else if (pid == 0) {
/* Open pipe for reading */
if ((fd3 = open(pipename3, O_RDONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while ((n = read(fd3, buf3, 80)) > 0) {
buf3[n] = 0;
printf("[Message received:] %s\n", buf3, n);
}
close(fd3);
exit(0);
} else {
/* Open pipe for reading */
if ((fd6 = open(pipename4, O_RDONLY)) < 0) {
printf("Pipe open error\n");
exit(1);
}
while ((n = read(fd4, buf4, 80)) > 0) {
buf4[n] = 0;
printf("[Message received:] %s\n", buf4, n);
}
close(fd4);
wait(NULL);
exit(0);
}
}