/* * The mrouted program is covered by the license in the accompanying file * named "LICENSE". Use of the mrouted program represents acceptance of * the terms and conditions listed in that file. * * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of * Leland Stanford Junior University. * * * $Id: inet.c,v 1.2 1995/06/01 02:25:54 mycroft Exp $ */ #include "defs.h" /* * Exported variables. */ char s1[19]; /* buffers to hold the string representations */ char s2[19]; /* of IP addresses, to be passed to inet_fmt() */ char s3[19]; /* or inet_fmts(). */ char s4[19]; /* * Verify that a given IP address is credible as a host address. * (Without a mask, cannot detect addresses of the form {subnet,0} or * {subnet,-1}.) */ int inet_valid_host(naddr) u_int32_t naddr; { register u_int32_t addr; addr = ntohl(naddr); return (!(IN_MULTICAST(addr) || IN_BADCLASS (addr) || (addr & 0xff000000) == 0)); } /* * Verify that a given subnet number and mask pair are credible. * * With CIDR, almost any subnet and mask are credible. mrouted still * can't handle aggregated class A's, so we still check that, but * otherwise the only requirements are that the subnet address is * within the [ABC] range and that the host bits of the subnet * are all 0. */ int inet_valid_subnet(nsubnet, nmask) u_int32_t nsubnet, nmask; { register u_int32_t subnet, mask; subnet = ntohl(nsubnet); mask = ntohl(nmask); if ((subnet & mask) != subnet) return (FALSE); if (subnet == 0 && mask == 0) return (TRUE); if (IN_CLASSA(subnet)) { if (mask < 0xff000000 || (subnet & 0xff000000) == 0x7f000000) return (FALSE); } else if (IN_CLASSD(subnet) || IN_BADCLASS(subnet)) { /* Above Class C address space */ return (FALSE); } else if (subnet & ~mask) { /* Host bits are set in the subnet */ return (FALSE); } return (TRUE); } /* * Convert an IP address in u_long (network) format into a printable string. */ char *inet_fmt(addr, s) u_int32_t addr; char *s; { register u_char *a; a = (u_char *)&addr; sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]); return (s); } /* * Convert an IP subnet number in u_long (network) format into a printable * string including the netmask as a number of bits. */ char *inet_fmts(addr, mask, s) u_int32_t addr, mask; char *s; { register u_char *a, *m; int bits; if ((addr == 0) && (mask == 0)) { sprintf(s, "default"); return (s); } a = (u_char *)&addr; m = (u_char *)&mask; bits = 33 - ffs(ntohl(mask)); if (m[3] != 0) sprintf(s, "%u.%u.%u.%u/%d", a[0], a[1], a[2], a[3], bits); else if (m[2] != 0) sprintf(s, "%u.%u.%u/%d", a[0], a[1], a[2], bits); else if (m[1] != 0) sprintf(s, "%u.%u/%d", a[0], a[1], bits); else sprintf(s, "%u/%d", a[0], bits); return (s); } /* * Convert the printable string representation of an IP address into the * u_long (network) format. Return 0xffffffff on error. (To detect the * legal address with that value, you must explicitly compare the string * with "255.255.255.255".) */ u_int32_t inet_parse(s) char *s; { u_int32_t a = 0; u_int a0, a1, a2, a3; char c; if (sscanf(s, "%u.%u.%u.%u%c", &a0, &a1, &a2, &a3, &c) != 4 || a0 > 255 || a1 > 255 || a2 > 255 || a3 > 255) return (0xffffffff); ((u_char *)&a)[0] = a0; ((u_char *)&a)[1] = a1; ((u_char *)&a)[2] = a2; ((u_char *)&a)[3] = a3; return (a); } /* * inet_cksum extracted from: * P I N G . C * * Author - * Mike Muuss * U. S. Army Ballistic Research Laboratory * December, 1983 * Modified at Uc Berkeley * * (ping.c) Status - * Public Domain. Distribution Unlimited. * * I N _ C K S U M * * Checksum routine for Internet Protocol family headers (C Version) * */ int inet_cksum(addr, len) u_short *addr; u_int len; { register int nleft = (int)len; register u_short *w = addr; u_short answer = 0; register int sum = 0; /* * Our algorithm is simple, using a 32 bit accumulator (sum), * we add sequential 16 bit words to it, and at the end, fold * back all the carry bits from the top 16 bits into the lower * 16 bits. */ while( nleft > 1 ) { sum += *w++; nleft -= 2; } /* mop up an odd byte, if necessary */ if( nleft == 1 ) { *(u_char *) (&answer) = *(u_char *)w ; sum += answer; } /* * add back carry outs from top 16 bits to low 16 bits */ sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ sum += (sum >> 16); /* add carry */ answer = ~sum; /* truncate to 16 bits */ return (answer); }