Broadcast Shell

broadcast_shell.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/select.h>

#include <fcntl.h>

int main(int argc, char *argv[])
{
        int fd, logfd, sockfd, newsockfd, i, j;
        struct sockaddr_in server, client;
        int maxfds;
        fd_set master, readfds;
        char buf[400];

        fd = open("/root/typescript", O_RDONLY);
        if (fd < 0)
        {
                perror("open");
                exit(1);
        }

        lseek(fd, SEEK_END, 0);

        logfd = open("/root/logscript", O_WRONLY | O_CREAT | O_TRUNC);
        if (logfd < 0)
        {
                perror("open");
                exit(1);
        }

        sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        if (sockfd < 0)
        {
                perror("socket");
                exit(1);
        }

        server.sin_family = AF_INET;
        server.sin_port = htons(8080);
        server.sin_addr.s_addr = INADDR_ANY;

        if (bind(sockfd, (struct sockaddr *)&server, (socklen_t)sizeof(server)) < 0)
        {
                perror("bind");
                exit(1);
        }

        if (listen(sockfd, 5) < 0)
        {
                perror("listen");
                exit(1);
        }

        maxfds = sockfd;
        FD_ZERO(&master);
        FD_SET(sockfd, &master);
        FD_SET(fd, &master);

        while (1)
        {
                readfds = master;
                if (select(maxfds+1, &readfds, NULL, NULL, NULL) <= 0)
                        continue;

                if (FD_ISSET(sockfd, &readfds))
                {
                        i = sizeof(client);
                        newsockfd = accept(sockfd, (struct sockaddr *)&client, (socklen_t *)&i);
                        if (newsockfd < 0)
                        {
                                perror("accept");
                                continue;
                        }

                        maxfds = (maxfds < newsockfd) ? newsockfd : maxfds;
                        FD_SET(newsockfd, &master);
                }
                else if (FD_ISSET(fd, &readfds))
                {
                        j = read(fd, buf, sizeof(buf));
                        if (j < 0)
                        {
                                perror("read");
                                continue;
                        }
                        if (j == 0)
                                continue;

                        write(logfd, buf, j);

                        for (i=0; i<=maxfds; i++)
                                if (FD_ISSET(i, &master))
                                        if (i != fd && i != sockfd)
                                                send(i, buf, j, 0);
                }
                else
                {
                        for (i=0; i<=maxfds; i++)
                        {
                                if (FD_ISSET(i, &readfds))
                                {
                                        if (recv(i, &j, sizeof(j), 0) <= 0)
                                        {
                                                close(i);
                                                FD_CLR(i, &master);
                                        }
                                }
                        }
                }
        }
}