1a17240f2Sderaadt /* $NetBSD: inet.c,v 1.4 1995/12/10 10:07:03 mycroft Exp $ */ 2df930be7Sderaadt 3df930be7Sderaadt /* 4df930be7Sderaadt * The mrouted program is covered by the license in the accompanying file 5df930be7Sderaadt * named "LICENSE". Use of the mrouted program represents acceptance of 6df930be7Sderaadt * the terms and conditions listed in that file. 7df930be7Sderaadt * 8df930be7Sderaadt * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of 9df930be7Sderaadt * Leland Stanford Junior University. 10df930be7Sderaadt */ 11df930be7Sderaadt 12df930be7Sderaadt 13df930be7Sderaadt #include "defs.h" 14df930be7Sderaadt 15df930be7Sderaadt 16df930be7Sderaadt /* 17df930be7Sderaadt * Exported variables. 18df930be7Sderaadt */ 19df930be7Sderaadt char s1[19]; /* buffers to hold the string representations */ 20df930be7Sderaadt char s2[19]; /* of IP addresses, to be passed to inet_fmt() */ 21df930be7Sderaadt char s3[19]; /* or inet_fmts(). */ 22df930be7Sderaadt char s4[19]; 23df930be7Sderaadt 24df930be7Sderaadt 25df930be7Sderaadt /* 26df930be7Sderaadt * Verify that a given IP address is credible as a host address. 27df930be7Sderaadt * (Without a mask, cannot detect addresses of the form {subnet,0} or 28df930be7Sderaadt * {subnet,-1}.) 29df930be7Sderaadt */ 30a17240f2Sderaadt int 31*5017e83eSderaadt inet_valid_host(u_int32_t naddr) 32df930be7Sderaadt { 33df930be7Sderaadt register u_int32_t addr; 34df930be7Sderaadt 35df930be7Sderaadt addr = ntohl(naddr); 36df930be7Sderaadt 37df930be7Sderaadt return (!(IN_MULTICAST(addr) || 38df930be7Sderaadt IN_BADCLASS (addr) || 39df930be7Sderaadt (addr & 0xff000000) == 0)); 40df930be7Sderaadt } 41df930be7Sderaadt 42a17240f2Sderaadt /* 43a17240f2Sderaadt * Verify that a given netmask is plausible; 44a17240f2Sderaadt * make sure that it is a series of 1's followed by 45a17240f2Sderaadt * a series of 0's with no discontiguous 1's. 46a17240f2Sderaadt */ 47a17240f2Sderaadt int 48*5017e83eSderaadt inet_valid_mask(u_int32_t mask) 49a17240f2Sderaadt { 50a17240f2Sderaadt if (~(((mask & -mask) - 1) | mask) != 0) { 51a17240f2Sderaadt /* Mask is not contiguous */ 52a17240f2Sderaadt return (FALSE); 53a17240f2Sderaadt } 54a17240f2Sderaadt 55a17240f2Sderaadt return (TRUE); 56a17240f2Sderaadt } 57df930be7Sderaadt 58df930be7Sderaadt /* 59df930be7Sderaadt * Verify that a given subnet number and mask pair are credible. 60df930be7Sderaadt * 61df930be7Sderaadt * With CIDR, almost any subnet and mask are credible. mrouted still 62df930be7Sderaadt * can't handle aggregated class A's, so we still check that, but 63df930be7Sderaadt * otherwise the only requirements are that the subnet address is 64df930be7Sderaadt * within the [ABC] range and that the host bits of the subnet 65df930be7Sderaadt * are all 0. 66df930be7Sderaadt */ 67a17240f2Sderaadt int 68*5017e83eSderaadt inet_valid_subnet(u_int32_t nsubnet, u_int32_t nmask) 69df930be7Sderaadt { 70df930be7Sderaadt register u_int32_t subnet, mask; 71df930be7Sderaadt 72df930be7Sderaadt subnet = ntohl(nsubnet); 73df930be7Sderaadt mask = ntohl(nmask); 74df930be7Sderaadt 75df930be7Sderaadt if ((subnet & mask) != subnet) return (FALSE); 76df930be7Sderaadt 77a17240f2Sderaadt if (subnet == 0) 78a17240f2Sderaadt return (mask == 0); 79df930be7Sderaadt 80df930be7Sderaadt if (IN_CLASSA(subnet)) { 81df930be7Sderaadt if (mask < 0xff000000 || 82a17240f2Sderaadt (subnet & 0xff000000) == 0x7f000000 || 83a17240f2Sderaadt (subnet & 0xff000000) == 0x00000000) return (FALSE); 84df930be7Sderaadt } 85df930be7Sderaadt else if (IN_CLASSD(subnet) || IN_BADCLASS(subnet)) { 86df930be7Sderaadt /* Above Class C address space */ 87df930be7Sderaadt return (FALSE); 88df930be7Sderaadt } 89a17240f2Sderaadt if (subnet & ~mask) { 90df930be7Sderaadt /* Host bits are set in the subnet */ 91df930be7Sderaadt return (FALSE); 92df930be7Sderaadt } 93a17240f2Sderaadt if (!inet_valid_mask(mask)) { 94a17240f2Sderaadt /* Netmask is not contiguous */ 95a17240f2Sderaadt return (FALSE); 96a17240f2Sderaadt } 97df930be7Sderaadt 98df930be7Sderaadt return (TRUE); 99df930be7Sderaadt } 100df930be7Sderaadt 101df930be7Sderaadt 102df930be7Sderaadt /* 103df930be7Sderaadt * Convert an IP address in u_long (network) format into a printable string. 104df930be7Sderaadt */ 105a17240f2Sderaadt char * 106*5017e83eSderaadt inet_fmt(u_int32_t addr, char *s) 107df930be7Sderaadt { 108df930be7Sderaadt register u_char *a; 109df930be7Sderaadt 110df930be7Sderaadt a = (u_char *)&addr; 111df930be7Sderaadt sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]); 112df930be7Sderaadt return (s); 113df930be7Sderaadt } 114df930be7Sderaadt 115df930be7Sderaadt 116df930be7Sderaadt /* 117df930be7Sderaadt * Convert an IP subnet number in u_long (network) format into a printable 118df930be7Sderaadt * string including the netmask as a number of bits. 119df930be7Sderaadt */ 120a17240f2Sderaadt char * 121*5017e83eSderaadt inet_fmts(u_int32_t addr, u_int32_t mask, char *s) 122df930be7Sderaadt { 123df930be7Sderaadt register u_char *a, *m; 124df930be7Sderaadt int bits; 125df930be7Sderaadt 126df930be7Sderaadt if ((addr == 0) && (mask == 0)) { 127df930be7Sderaadt sprintf(s, "default"); 128df930be7Sderaadt return (s); 129df930be7Sderaadt } 130df930be7Sderaadt a = (u_char *)&addr; 131df930be7Sderaadt m = (u_char *)&mask; 132df930be7Sderaadt bits = 33 - ffs(ntohl(mask)); 133df930be7Sderaadt 134df930be7Sderaadt if (m[3] != 0) sprintf(s, "%u.%u.%u.%u/%d", a[0], a[1], a[2], a[3], 135df930be7Sderaadt bits); 136df930be7Sderaadt else if (m[2] != 0) sprintf(s, "%u.%u.%u/%d", a[0], a[1], a[2], bits); 137df930be7Sderaadt else if (m[1] != 0) sprintf(s, "%u.%u/%d", a[0], a[1], bits); 138df930be7Sderaadt else sprintf(s, "%u/%d", a[0], bits); 139df930be7Sderaadt 140df930be7Sderaadt return (s); 141df930be7Sderaadt } 142df930be7Sderaadt 143df930be7Sderaadt /* 144df930be7Sderaadt * Convert the printable string representation of an IP address into the 145df930be7Sderaadt * u_long (network) format. Return 0xffffffff on error. (To detect the 146df930be7Sderaadt * legal address with that value, you must explicitly compare the string 147df930be7Sderaadt * with "255.255.255.255".) 148df930be7Sderaadt */ 149a17240f2Sderaadt u_int32_t 150*5017e83eSderaadt inet_parse(char *s) 151df930be7Sderaadt { 152df930be7Sderaadt u_int32_t a = 0; 153df930be7Sderaadt u_int a0, a1, a2, a3; 154df930be7Sderaadt char c; 155df930be7Sderaadt 156df930be7Sderaadt if (sscanf(s, "%u.%u.%u.%u%c", &a0, &a1, &a2, &a3, &c) != 4 || 157df930be7Sderaadt a0 > 255 || a1 > 255 || a2 > 255 || a3 > 255) 158df930be7Sderaadt return (0xffffffff); 159df930be7Sderaadt 160df930be7Sderaadt ((u_char *)&a)[0] = a0; 161df930be7Sderaadt ((u_char *)&a)[1] = a1; 162df930be7Sderaadt ((u_char *)&a)[2] = a2; 163df930be7Sderaadt ((u_char *)&a)[3] = a3; 164df930be7Sderaadt 165df930be7Sderaadt return (a); 166df930be7Sderaadt } 167df930be7Sderaadt 168df930be7Sderaadt 169df930be7Sderaadt /* 170df930be7Sderaadt * inet_cksum extracted from: 171df930be7Sderaadt * P I N G . C 172df930be7Sderaadt * 173df930be7Sderaadt * Author - 174df930be7Sderaadt * Mike Muuss 175df930be7Sderaadt * U. S. Army Ballistic Research Laboratory 176df930be7Sderaadt * December, 1983 177df930be7Sderaadt * Modified at Uc Berkeley 178df930be7Sderaadt * 179df930be7Sderaadt * (ping.c) Status - 180df930be7Sderaadt * Public Domain. Distribution Unlimited. 181df930be7Sderaadt * 182df930be7Sderaadt * I N _ C K S U M 183df930be7Sderaadt * 184df930be7Sderaadt * Checksum routine for Internet Protocol family headers (C Version) 185df930be7Sderaadt * 186df930be7Sderaadt */ 187a17240f2Sderaadt int 188*5017e83eSderaadt inet_cksum(u_int16_t *addr, u_int len) 189df930be7Sderaadt { 190df930be7Sderaadt register int nleft = (int)len; 19108c1e0f4Sitojun register u_int16_t *w = addr; 19208c1e0f4Sitojun u_int16_t answer = 0; 19308c1e0f4Sitojun register int32_t sum = 0; 194df930be7Sderaadt 195df930be7Sderaadt /* 196df930be7Sderaadt * Our algorithm is simple, using a 32 bit accumulator (sum), 197df930be7Sderaadt * we add sequential 16 bit words to it, and at the end, fold 198df930be7Sderaadt * back all the carry bits from the top 16 bits into the lower 199df930be7Sderaadt * 16 bits. 200df930be7Sderaadt */ 201df930be7Sderaadt while (nleft > 1) { 202df930be7Sderaadt sum += *w++; 203df930be7Sderaadt nleft -= 2; 204df930be7Sderaadt } 205df930be7Sderaadt 206df930be7Sderaadt /* mop up an odd byte, if necessary */ 207df930be7Sderaadt if (nleft == 1) { 208df930be7Sderaadt *(u_char *) (&answer) = *(u_char *)w ; 209df930be7Sderaadt sum += answer; 210df930be7Sderaadt } 211df930be7Sderaadt 212df930be7Sderaadt /* 213df930be7Sderaadt * add back carry outs from top 16 bits to low 16 bits 214df930be7Sderaadt */ 215df930be7Sderaadt sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ 216df930be7Sderaadt sum += (sum >> 16); /* add carry */ 217df930be7Sderaadt answer = ~sum; /* truncate to 16 bits */ 218df930be7Sderaadt return (answer); 219df930be7Sderaadt } 220