Miscellany

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>

#define PORT   666
#define BACKLOG 10

void sigchld_handler(int s)
{
        while(waitpid(-1, NULL, WNOHANG) > 0);
}

int main(void)

{
        struct sockaddr_in server;
        struct sockaddr_in client;
        struct sigaction sa;
        socklen_t sin_size;
        int sockfd, sockfd2;
        int addr_len;
        int opt = 1;

        if ((sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
        {
              perror("socket");
              exit(1);
        }

        if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *) &opt, sizeof(opt)) == -1)
        {
                perror("setsockopt");

                exit(1);
        }

        server.sin_family = AF_INET;
        server.sin_addr.s_addr = INADDR_ANY;
        server.sin_port = htons(PORT);
        bzero(&(server.sin_zero),8);



        if (bind(sockfd, (struct sockaddr * )&server, sizeof(server)) == -1)
        {
                perror("bind");
                exit(1);
        }

        if (listen(sockfd, BACKLOG) == -1)
        {
                perror("listen");
                exit(1);
        }

        sa.sa_handler = sigchld_handler;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;

        if (sigaction(SIGCHLD, &sa, NULL) == -1)
        {
                perror("sigaction");
                exit(1);
        }

        while(1)
        {
                sin_size = sizeof(struct sockaddr_in);
                if ((sockfd2 = accept(sockfd, (struct sockaddr *)&client, &sin_size)) == -1)
                {
                        perror("accept");
                        continue;
                }

                printf("Connection from %s\n", inet_ntoa(client.sin_addr));

                if (!fork())
                {
                        close(sockfd);

                        if (send(sockfd2, "Smash The Stack\n", 16, 0) == -1)

                            perror("send");
                            close(sockfd2);
                            exit(0);

                }

                close(sockfd2);
        }

        return 0;
}