119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netdb.h>
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#include <unistd.h>
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#include <sys/wait.h>
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#include <signal.h>
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#define MAX_ENQUEUED 20
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#define BUF_LEN 256
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#define PORT_STR "12321"
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/* ------------------------------------------------------------ */
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/* How to clean up after dead child processes */
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/* ------------------------------------------------------------ */
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void wait_for_zombie(int s)
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{
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while(waitpid(-1, NULL, WNOHANG) > 0) ;
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}
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/* ------------------------------------------------------------ */
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/* Core of implementation of a child process */
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/* ------------------------------------------------------------ */
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void echo_lines(int csock)
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{
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char buf[BUF_LEN];
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int r;
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while( (r = read(csock, buf, BUF_LEN)) > 0 ) {
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(void)write(csock, buf, r);
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}
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exit(EXIT_SUCCESS);
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}
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/* ------------------------------------------------------------ */
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/* Core of implementation of the parent process */
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/* ------------------------------------------------------------ */
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void take_connections_forever(int ssock)
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{
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for(;;) {
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struct sockaddr addr;
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socklen_t addr_size = sizeof(addr);
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int csock;
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/* Block until we take one connection to the server socket */
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csock = accept(ssock, &addr, &addr_size);
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/* If it was a successful connection, spawn a worker process to service it */
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if ( csock == -1 ) {
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perror("accept");
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} else if ( fork() == 0 ) {
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close(ssock);
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echo_lines(csock);
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} else {
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close(csock);
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}
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}
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}
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/* ------------------------------------------------------------ */
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/* The server process's one-off setup code */
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/* ------------------------------------------------------------ */
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int main()
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{
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struct addrinfo hints, *res;
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struct sigaction sa;
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int sock;
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/* Look up the address to bind to */
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memset(&hints, 0, sizeof(struct addrinfo));
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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 ( getaddrinfo(NULL, PORT_STR, &hints, &res) != 0 ) {
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perror("getaddrinfo");
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exit(EXIT_FAILURE);
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}
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/* Make a socket */
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if ( (sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1 ) {
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perror("socket");
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exit(EXIT_FAILURE);
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}
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/* Arrange to clean up child processes (the workers) */
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sa.sa_handler = wait_for_zombie;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_RESTART;
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if ( sigaction(SIGCHLD, &sa, NULL) == -1 ) {
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perror("sigaction");
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exit(EXIT_FAILURE);
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}
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/* Associate the socket with its address */
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if ( bind(sock, res->ai_addr, res->ai_addrlen) != 0 ) {
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perror("bind");
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exit(EXIT_FAILURE);
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}
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freeaddrinfo(res);
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/* State that we've opened a server socket and are listening for connections */
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if ( listen(sock, MAX_ENQUEUED) != 0 ) {
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perror("listen");
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exit(EXIT_FAILURE);
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}
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/* Serve the listening socket until killed */
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take_connections_forever(sock);
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return EXIT_SUCCESS;
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}
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