Data commit

Task/Echo-server/C/echo-server.c

@@ -0,0 +1,118 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <signal.h>
+
+#define MAX_ENQUEUED 20
+#define BUF_LEN 256
+#define PORT_STR "12321"
+
+/* ------------------------------------------------------------ */
+/* How to clean up after dead child processes                   */
+/* ------------------------------------------------------------ */
+
+void wait_for_zombie(int s)
+{
+    while(waitpid(-1, NULL, WNOHANG) > 0) ;
+}
+
+/* ------------------------------------------------------------ */
+/* Core of implementation of a child process                    */
+/* ------------------------------------------------------------ */
+
+void echo_lines(int csock)
+{
+    char buf[BUF_LEN];
+    int r;
+
+    while( (r = read(csock, buf, BUF_LEN)) > 0 ) {
+        (void)write(csock, buf, r);
+    }
+    exit(EXIT_SUCCESS);
+}
+
+/* ------------------------------------------------------------ */
+/* Core of implementation of the parent process                 */
+/* ------------------------------------------------------------ */
+
+void take_connections_forever(int ssock)
+{
+    for(;;) {
+        struct sockaddr addr;
+        socklen_t addr_size = sizeof(addr);
+        int csock;
+
+        /* Block until we take one connection to the server socket */
+        csock = accept(ssock, &addr, &addr_size);
+
+        /* If it was a successful connection, spawn a worker process to service it */
+        if ( csock == -1 ) {
+            perror("accept");
+        } else if ( fork() == 0 ) {
+            close(ssock);
+            echo_lines(csock);
+        } else {
+            close(csock);
+        }
+    }
+}
+
+/* ------------------------------------------------------------ */
+/* The server process's one-off setup code                      */
+/* ------------------------------------------------------------ */
+
+int main()
+{
+    struct addrinfo hints, *res;
+    struct sigaction sa;
+    int sock;
+
+    /* Look up the address to bind to */
+    memset(&hints, 0, sizeof(struct addrinfo));
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_PASSIVE;
+    if ( getaddrinfo(NULL, PORT_STR, &hints, &res) != 0 ) {
+        perror("getaddrinfo");
+        exit(EXIT_FAILURE);
+    }
+
+    /* Make a socket */
+    if ( (sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1 ) {
+        perror("socket");
+        exit(EXIT_FAILURE);
+    }
+
+    /* Arrange to clean up child processes (the workers) */
+    sa.sa_handler = wait_for_zombie;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = SA_RESTART;
+    if ( sigaction(SIGCHLD, &sa, NULL) == -1 ) {
+        perror("sigaction");
+        exit(EXIT_FAILURE);
+    }
+
+    /* Associate the socket with its address */
+    if ( bind(sock, res->ai_addr, res->ai_addrlen) != 0 ) {
+        perror("bind");
+        exit(EXIT_FAILURE);
+    }
+
+    freeaddrinfo(res);
+
+    /* State that we've opened a server socket and are listening for connections */
+    if ( listen(sock, MAX_ENQUEUED) != 0 ) {
+        perror("listen");
+        exit(EXIT_FAILURE);
+    }
+
+    /* Serve the listening socket until killed */
+    take_connections_forever(sock);
+    return EXIT_SUCCESS;
+}