149 lines
4.2 KiB
C
149 lines
4.2 KiB
C
/*
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** igmpproxy - IGMP proxy based multicast router
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** Copyright (C) 2005 Johnny Egeland <johnny@rlo.org>
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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**
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**----------------------------------------------------------------------------
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**
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** This software is derived work from the following software. The original
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** source code has been modified from it's original state by the author
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** of igmpproxy.
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**
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** smcroute 0.92 - Copyright (C) 2001 Carsten Schill <carsten@cschill.de>
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** - Licensed under the GNU General Public License, version 2
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**
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** mrouted 3.9-beta3 - COPYRIGHT 1989 by The Board of Trustees of
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** Leland Stanford Junior University.
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** - Original license can be found in the Stanford.txt file.
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**
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*/
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#include "igmpproxy.h"
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/*
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* Exported variables.
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*/
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char s1[19]; /* buffers to hold the string representations */
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char s2[19]; /* of IP addresses, to be passed to inet_fmt() */
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char s3[19]; /* or inet_fmts(). */
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char s4[19];
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/*
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** Formats 'InAdr' into a dotted decimal string.
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**
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** returns: - pointer to 'St'
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**
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*/
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char *fmtInAdr( char *St, struct in_addr InAdr ) {
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sprintf( St, "%u.%u.%u.%u",
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((uint8_t *)&InAdr.s_addr)[ 0 ],
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((uint8_t *)&InAdr.s_addr)[ 1 ],
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((uint8_t *)&InAdr.s_addr)[ 2 ],
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((uint8_t *)&InAdr.s_addr)[ 3 ] );
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return St;
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}
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/*
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* Convert an IP address in u_long (network) format into a printable string.
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*/
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char *inetFmt(uint32_t addr, char *s) {
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register u_char *a;
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a = (u_char *)&addr;
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sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
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return(s);
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}
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/*
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* Convert an IP subnet number in u_long (network) format into a printable
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* string including the netmask as a number of bits.
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*/
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char *inetFmts(uint32_t addr, uint32_t mask, char *s) {
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register u_char *a, *m;
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int bits;
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if ((addr == 0) && (mask == 0)) {
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sprintf(s, "default");
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return(s);
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}
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a = (u_char *)&addr;
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m = (u_char *)&mask;
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bits = 33 - ffs(ntohl(mask));
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if (m[3] != 0) sprintf(s, "%u.%u.%u.%u/%d", a[0], a[1], a[2], a[3],
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bits);
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else if (m[2] != 0) sprintf(s, "%u.%u.%u/%d", a[0], a[1], a[2], bits);
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else if (m[1] != 0) sprintf(s, "%u.%u/%d", a[0], a[1], bits);
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else sprintf(s, "%u/%d", a[0], bits);
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return(s);
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}
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/*
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* inet_cksum extracted from:
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* P I N G . C
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*
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* Author -
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* Mike Muuss
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* U. S. Army Ballistic Research Laboratory
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* December, 1983
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* Modified at Uc Berkeley
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*
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* (ping.c) Status -
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* Public Domain. Distribution Unlimited.
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*
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* I N _ C K S U M
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*
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* Checksum routine for Internet Protocol family headers (C Version)
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*
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*/
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uint16_t inetChksum(uint16_t *addr, int len) {
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register int nleft = len;
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register uint16_t *w = addr;
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uint16_t answer = 0;
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register int32_t sum = 0;
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/*
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* Our algorithm is simple, using a 32 bit accumulator (sum),
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* we add sequential 16 bit words to it, and at the end, fold
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* back all the carry bits from the top 16 bits into the lower
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* 16 bits.
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*/
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while (nleft > 1) {
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sum += *w++;
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nleft -= 2;
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}
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/* mop up an odd byte, if necessary */
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if (nleft == 1) {
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*(uint8_t *) (&answer) = *(uint8_t *)w ;
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sum += answer;
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}
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/*
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* add back carry outs from top 16 bits to low 16 bits
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*/
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sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
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sum += (sum >> 16); /* add carry */
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answer = ~sum; /* truncate to 16 bits */
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return(answer);
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}
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