C Echo Server (utilizing linux namespaces)

echo.c

/*Required Headers*/
#define _GNU_SOURCE 
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sched.h>
#include <stdlib.h>
#include <sys/wait.h>

#define STACK_SIZE 1024*1024*5


void sig_handler(int signo)
{
  if (signo == SIGINT)
      exit(0);
}

int echo_server()
{
    printf("Child:  PID=%ld PPID=%ld\n", (long) getpid(), (long) getppid());
    char str[100];
    int listen_fd, comm_fd;
 
    struct sockaddr_in servaddr;
 
    listen_fd = socket(AF_INET, SOCK_STREAM, 0);
 
    bzero( &servaddr, sizeof(servaddr));
 
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htons(INADDR_ANY);
    servaddr.sin_port = htons(7);
 
    bind(listen_fd, (struct sockaddr *) &servaddr, sizeof(servaddr));
    setuid(65534);
    signal(SIGINT, sig_handler);
 
    listen(listen_fd, 10);
 
    comm_fd = accept(listen_fd, (struct sockaddr*) NULL, NULL);
 
    bzero( str, 100);
    read(comm_fd,str,100);
    printf("Echoing back - %s",str);
    write(comm_fd, str, strlen(str)+1);

    return 0;
}



int main() {
	char *stack;
	char *stackTop;
	
	stack = malloc(STACK_SIZE);
	if (stack == NULL) {
		printf("malloc(2) failed\n");
		return 1;
	}

	signal(SIGCHLD, SIG_IGN);

	stackTop = stack + STACK_SIZE;
	pid_t child_pid = clone(echo_server, stackTop, CLONE_NEWPID | SIGCHLD, NULL);
	waitpid(child_pid, NULL, 0);
	return 0;
}