188 lines
4.1 KiB
C
188 lines
4.1 KiB
C
/*
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* The mrouted program is covered by the license in the accompanying file
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* named "LICENSE". Use of the mrouted program represents acceptance of
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* the terms and conditions listed in that file.
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*
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* The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
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* Leland Stanford Junior University.
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*
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*
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* $Id: inet.c,v 1.4 1993/05/30 01:36:38 deering Exp $
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*/
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#include "defs.h"
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/*
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* Exported variables.
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*/
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char s1[16]; /* buffers to hold the string representations */
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char s2[16]; /* of IP addresses, to be passed to inet_fmt() */
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char s3[16]; /* or inet_fmts(). */
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/*
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* Verify that a given IP address is credible as a host address.
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* (Without a mask, cannot detect addresses of the form {subnet,0} or
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* {subnet,-1}.)
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*/
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int inet_valid_host(naddr)
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u_long naddr;
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{
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register u_long addr;
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addr = ntohl(naddr);
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return (!(IN_MULTICAST(addr) ||
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IN_BADCLASS (addr) ||
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(addr & 0xff000000) == 0));
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}
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/*
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* Verify that a given subnet number and mask pair are credible.
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*/
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int inet_valid_subnet(nsubnet, nmask)
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u_long nsubnet, nmask;
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{
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register u_long subnet, mask;
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subnet = ntohl(nsubnet);
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mask = ntohl(nmask);
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if ((subnet & mask) != subnet) return (FALSE);
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if (IN_CLASSA(subnet)) {
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if (mask < 0xff000000 ||
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(subnet & 0xff000000) == 0 ||
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(subnet & 0xff000000) == 0x7f000000) return (FALSE);
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}
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else if (IN_CLASSB(subnet)) {
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if (mask < 0xffff0000) return (FALSE);
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}
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else if (IN_CLASSC(subnet)) {
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if (mask < 0xffffff00) return (FALSE);
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}
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else return (FALSE);
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return (TRUE);
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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 *inet_fmt(addr, s)
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u_long addr;
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char *s;
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{
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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.
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*/
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char *inet_fmts(addr, mask, s)
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u_long addr, mask;
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char *s;
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{
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register u_char *a, *m;
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a = (u_char *)&addr;
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m = (u_char *)&mask;
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if (m[3] != 0) sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
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else if (m[2] != 0) sprintf(s, "%u.%u.%u", a[0], a[1], a[2]);
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else if (m[1] != 0) sprintf(s, "%u.%u", a[0], a[1]);
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else sprintf(s, "%u", a[0]);
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return (s);
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}
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/*
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* Convert the printable string representation of an IP address into the
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* u_long (network) format. Return 0xffffffff on error. (To detect the
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* legal address with that value, you must explicitly compare the string
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* with "255.255.255.255".)
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*/
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u_long inet_parse(s)
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char *s;
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{
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u_long a;
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u_int a0, a1, a2, a3;
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char c;
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if (sscanf(s, "%u.%u.%u.%u%c", &a0, &a1, &a2, &a3, &c) != 4 ||
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a0 > 255 || a1 > 255 || a2 > 255 || a3 > 255)
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return (0xffffffff);
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((u_char *)&a)[0] = a0;
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((u_char *)&a)[1] = a1;
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((u_char *)&a)[2] = a2;
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((u_char *)&a)[3] = a3;
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return (a);
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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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int inet_cksum(addr, len)
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u_short *addr;
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u_int len;
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{
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register int nleft = (int)len;
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register u_short *w = addr;
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u_short answer = 0;
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register int 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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*(u_char *) (&answer) = *(u_char *)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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