/* is_seqnum_sv.c
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A simple Internet stream socket server. Our service is to provide
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unique sequence numbers to clients.
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Usage: is_seqnum_sv [init-seq-num]
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(default = 0)
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See also is_seqnum_cl.c.
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*/
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#define _BSD_SOURCE /* To get definitions of NI_MAXHOST and
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NI_MAXSERV from <netdb.h> */
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#include <netdb.h>
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#include "is_seqnum.h"
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#define BACKLOG 50
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int
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main(int argc, char *argv[])
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{
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char line[1024]; /* Length of requested sequence */
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struct sockaddr_storage claddr;
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int lfd, cfd, optval;
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socklen_t addrlen;
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struct addrinfo hints;
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struct addrinfo *result, *rp;
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#define ADDRSTRLEN (NI_MAXHOST + NI_MAXSERV + 10)
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char addrStr[ADDRSTRLEN];
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char host[NI_MAXHOST];
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char service[NI_MAXSERV];
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if (argc > 1 && strcmp(argv[1], "--help") == 0)
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printf("%s [init-seq-num]\n", argv[0]);
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/* Ignore the SIGPIPE signal, so that we find out about broken connection
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errors via a failure from write(). */
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if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) err_exit(errno, "signal");
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/* Call getaddrinfo() to obtain a list of addresses that
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we can try binding to */
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memset(&hints, 0, sizeof(struct addrinfo));
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hints.ai_canonname = NULL;
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hints.ai_addr = NULL;
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hints.ai_next = NULL;
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_family = AF_UNSPEC; /* Allows IPv4 or IPv6 */
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hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV;
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/* Wildcard IP address; service name is numeric */
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if (getaddrinfo(NULL, PORT_NUM, &hints, &result) != 0)
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err_exit(errno, "getaddrinfo");
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/* Walk through returned list until we find an address structure
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that can be used to successfully create and bind a socket */
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optval = 1;
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for (rp = result; rp != NULL; rp = rp->ai_next) {
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lfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
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if (lfd == -1)
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continue; /* On error, try next address */
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if (setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) == -1)
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err_exit(errno, "setsockopt");
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if (bind(lfd, rp->ai_addr, rp->ai_addrlen) == 0)
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break; /* Success */
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/* bind() failed: close this socket and try next address */
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close(lfd);
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}
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if (rp == NULL)
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err_exit(errno, "Could not bind socket to any address");
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if (listen(lfd, BACKLOG) == -1)
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err_exit(errno, "listen");
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freeaddrinfo(result);
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for (;;) { /* Handle clients iteratively */
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/* Accept a client connection, obtaining client's address */
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addrlen = sizeof(struct sockaddr_storage);
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cfd = accept(lfd, (struct sockaddr *) &claddr, &addrlen);
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if (cfd == -1) {
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err_msg(errno, "accept");
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continue;
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}
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if (getnameinfo((struct sockaddr *) &claddr, addrlen,
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host, NI_MAXHOST, service, NI_MAXSERV, 0) == 0)
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snprintf(addrStr, ADDRSTRLEN, "(%s, %s)", host, service);
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else
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snprintf(addrStr, ADDRSTRLEN, "(?UNKNOWN?)");
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printf("Connection from %s\n", addrStr);
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/* Read client request, send sequence number back */
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if (readLine(cfd, line, 1024) <= 0) {
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close(cfd);
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continue; /* Failed read; skip request */
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}
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if (write(cfd, line, strlen(line)) != strlen(line))
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fprintf(stderr, "Error on write");
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if (close(cfd) == -1)
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err_msg(errno, "close");
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}
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}
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