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95 lines
3.2 KiB
C
95 lines
3.2 KiB
C
/*************************************************************************\
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* Copyright (C) Michael Kerrisk, 2018. *
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* *
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* This program is free software. You may use, modify, and redistribute it *
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* under the terms of the GNU General Public License as published by the *
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* Free Software Foundation, either version 3 or (at your option) any *
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* later version. This program is distributed without any warranty. See *
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* the file COPYING.gpl-v3 for details. *
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\*************************************************************************/
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/* Solution for Exercise 59-2:b */
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/* is_seqnum_v2_sv.c
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A simple Internet stream socket server. Our service is to provide unique
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sequence numbers to the client.
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This program is the same as is_seqnum_cl.c, except that it uses the functions
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in our inet_sockets.c library to simplify set up of the server's socket.
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Usage: is_seqnum_sv [init-seq-num] (default = 0)
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See also is_seqnum_v2_cl.c.
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*/
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#include "is_seqnum_v2.h"
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int
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main(int argc, char *argv[])
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{
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uint32_t seqNum;
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char reqLenStr[INT_LEN]; /* Length of requested sequence */
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char seqNumStr[INT_LEN]; /* Start of granted sequence */
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struct sockaddr *claddr;
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int lfd, cfd, reqLen;
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socklen_t addrlen, alen;
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char addrStr[IS_ADDR_STR_LEN];
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if (argc > 1 && strcmp(argv[1], "--help") == 0)
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usageErr("%s [init-seq-num]\n", argv[0]);
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seqNum = (argc > 1) ? getInt(argv[1], 0, "init-seq-num") : 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) errExit("signal");
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lfd = inetListen(PORT_NUM_STR, 5, &addrlen);
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if (lfd == -1)
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fatal("inetListen() failed");
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/* Allocate a buffer large enough to hold the client's socket address */
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claddr = malloc(addrlen);
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if (claddr == NULL)
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errExit("malloc");
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for (;;) { /* Handle clients iteratively */
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/* Accept a client connection, obtaining client's address */
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alen = addrlen;
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cfd = accept(lfd, (struct sockaddr *) claddr, &alen);
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if (cfd == -1) {
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errMsg("accept");
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continue;
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}
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printf("Connection from %s\n", inetAddressStr(claddr, alen,
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addrStr, IS_ADDR_STR_LEN));
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/* Read client request, send sequence number back */
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if (readLine(cfd, reqLenStr, INT_LEN) <= 0) {
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close(cfd);
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continue; /* Failed read; skip request */
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}
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reqLen = atoi(reqLenStr);
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if (reqLen <= 0) { /* Watch for misbehaving clients */
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close(cfd);
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continue; /* Bad request; skip it */
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}
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snprintf(seqNumStr, INT_LEN, "%d\n", seqNum);
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if (write(cfd, seqNumStr, strlen(seqNumStr)) != strlen(seqNumStr))
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fprintf(stderr, "Error on write");
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seqNum += reqLen; /* Update sequence number */
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if (close(cfd) == -1) /* Close connection */
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errMsg("close");
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}
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}
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