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- Committer: ivan.a.zorin at gmail
- Date: 2011-08-20 10:58:21 UTC
- Revision ID: ivan.a.zorin@gmail.com-20110820105821-qf3pzwgifu2b6yih
book source code examples: Guide to Network Programming
- files added:
- examples
- guide
added
removed
examples/selectserver.c
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/*
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** selectserver.c -- a cheezy multiperson chat server
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <netdb.h>
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#define PORT "9034" // port we're listening on
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// get sockaddr, IPv4 or IPv6:
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void *get_in_addr(struct sockaddr *sa)
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{
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if (sa->sa_family == AF_INET) {
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return &(((struct sockaddr_in*)sa)->sin_addr);
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}
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return &(((struct sockaddr_in6*)sa)->sin6_addr);
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}
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int main(void)
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{
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fd_set master; // master file descriptor list
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fd_set read_fds; // temp file descriptor list for select()
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int fdmax; // maximum file descriptor number
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int listener; // listening socket descriptor
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int newfd; // newly accept()ed socket descriptor
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struct sockaddr_storage remoteaddr; // client address
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socklen_t addrlen;
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char buf[256]; // buffer for client data
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int nbytes;
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char remoteIP[INET6_ADDRSTRLEN];
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int yes=1; // for setsockopt() SO_REUSEADDR, below
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int i, j, rv;
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struct addrinfo hints, *ai, *p;
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FD_ZERO(&master); // clear the master and temp sets
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FD_ZERO(&read_fds);
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// get us a socket and bind it
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memset(&hints, 0, sizeof hints);
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hints.ai_family = AF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_flags = AI_PASSIVE;
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if ((rv = getaddrinfo(NULL, PORT, &hints, &ai)) != 0) {
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fprintf(stderr, "selectserver: %s\n", gai_strerror(rv));
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exit(1);
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}
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for(p = ai; p != NULL; p = p->ai_next) {
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listener = socket(p->ai_family, p->ai_socktype, p->ai_protocol);
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if (listener < 0) {
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continue;
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}
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// lose the pesky "address already in use" error message
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setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));
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if (bind(listener, p->ai_addr, p->ai_addrlen) < 0) {
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close(listener);
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continue;
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}
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break;
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}
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// if we got here, it means we didn't get bound
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if (p == NULL) {
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fprintf(stderr, "selectserver: failed to bind\n");
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exit(2);
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}
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freeaddrinfo(ai); // all done with this
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// listen
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if (listen(listener, 10) == -1) {
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perror("listen");
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exit(3);
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}
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// add the listener to the master set
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FD_SET(listener, &master);
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// keep track of the biggest file descriptor
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fdmax = listener; // so far, it's this one
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// main loop
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for(;;) {
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read_fds = master; // copy it
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if (select(fdmax+1, &read_fds, NULL, NULL, NULL) == -1) {
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perror("select");
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exit(4);
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}
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// run through the existing connections looking for data to read
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for(i = 0; i <= fdmax; i++) {
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if (FD_ISSET(i, &read_fds)) { // we got one!!
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if (i == listener) {
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// handle new connections
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addrlen = sizeof remoteaddr;
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newfd = accept(listener,
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(struct sockaddr *)&remoteaddr,
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&addrlen);
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if (newfd == -1) {
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perror("accept");
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} else {
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FD_SET(newfd, &master); // add to master set
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if (newfd > fdmax) { // keep track of the max
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fdmax = newfd;
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}
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printf("selectserver: new connection from %s on "
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"socket %d\n",
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inet_ntop(remoteaddr.ss_family,
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get_in_addr((struct sockaddr*)&remoteaddr),
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remoteIP, INET6_ADDRSTRLEN),
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newfd);
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}
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} else {
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// handle data from a client
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if ((nbytes = recv(i, buf, sizeof buf, 0)) <= 0) {
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// got error or connection closed by client
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if (nbytes == 0) {
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// connection closed
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printf("selectserver: socket %d hung up\n", i);
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} else {
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perror("recv");
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}
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close(i); // bye!
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FD_CLR(i, &master); // remove from master set
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} else {
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// we got some data from a client
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for(j = 0; j <= fdmax; j++) {
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// send to everyone!
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if (FD_ISSET(j, &master)) {
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// except the listener and ourselves
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if (j != listener && j != i) {
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if (send(j, buf, nbytes, 0) == -1) {
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perror("send");
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}
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}
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}
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}
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}
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} // END handle data from client
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} // END got new incoming connection
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} // END looping through file descriptors
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} // END for(;;)--and you thought it would never end!
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return 0;
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}
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