rendered paste body/*** selectserver.c -- a cheezy multiperson chat server*/#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#define PORT 9034 // port we're listening onint main(void){ fd_set master; // master file descriptor list fd_set read_fds; // temp file descriptor list for select() struct sockaddr_in myaddr; // server address struct sockaddr_in remoteaddr; // client address int fdmax; // maximum file descriptor number int listener; // listening socket descriptor int newfd; // newly accept()ed socket descriptor char buf[256]; // buffer for client data int nbytes; int yes=1; // for setsockopt() SO_REUSEADDR, below socklen_t addrlen; int i, j; FD_ZERO(&master); // clear the master and temp sets FD_ZERO(&read_fds); // get the listener if ((listener = socket(PF_INET, SOCK_STREAM, 0)) == -1) { perror("socket"); exit(1); } // lose the pesky "address already in use" error message if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) { perror("setsockopt"); exit(1); } // bind myaddr.sin_family = AF_INET; myaddr.sin_addr.s_addr = INADDR_ANY; myaddr.sin_port = htons(PORT); memset(&(myaddr.sin_zero), '\0', 8); if (bind(listener, (struct sockaddr *)&myaddr, sizeof(myaddr)) == -1) { perror("bind"); exit(1); } // listen if (listen(listener, 10) == -1) { perror("listen"); exit(1); } // add the listener to the master set FD_SET(listener, &master); // keep track of the biggest file descriptor fdmax = listener; // so far, it's this one // main loop for(;;) { read_fds = master; // copy it if (select(fdmax+1, &read_fds, NULL, NULL, NULL) == -1) { perror("select"); exit(1); } // run through the existing connections looking for data to read for(i = 0; i <= fdmax; i++) { if (FD_ISSET(i, &read_fds)) { // we got one!! if (i == listener) { // handle new connections addrlen = sizeof(remoteaddr); if ((newfd = accept(listener, (struct sockaddr *)&remoteaddr,&addrlen)) == -1) { perror("accept"); } else { FD_SET(newfd, &master); // add to master set if (newfd > fdmax) { // keep track of the maximum fdmax = newfd; } printf("selectserver: new connection from %s on socket %d\n", inet_ntoa(remoteaddr.sin_addr), newfd); } } else { // handle data from a client if ((nbytes = recv(i, buf, sizeof(buf), 0)) <= 0) { // got error or connection closed by client if (nbytes == 0) { // connection closed printf("selectserver: socket %d hung up\n", i); } else { perror("recv"); } close(i); // bye! FD_CLR(i, &master); // remove from master set } else { // we got some data from a client for(j = 0; j <= fdmax; j++) { // send to everyone! if (FD_ISSET(j, &master)) { // except the listener and ourselves if (j != listener && j != i) { // printf("socket %i says: %s",j,i); if (send(j, buf, nbytes, 0) == -1) { perror("send"); } } } } } } // it's SO UGLY! } } } return 0;}