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