| 1 | /* |
| 2 | * The mrouted program is covered by the license in the accompanying file |
| 3 | * named "LICENSE". Use of the mrouted program represents acceptance of |
| 4 | * the terms and conditions listed in that file. |
| 5 | * |
| 6 | * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of |
| 7 | * Leland Stanford Junior University. |
| 8 | * |
| 9 | * |
| 10 | * $Id: inet.c,v 1.4 1993/05/30 01:36:38 deering Exp $ |
| 11 | */ |
| 12 | |
| 13 | |
| 14 | #include "defs.h" |
| 15 | |
| 16 | |
| 17 | /* |
| 18 | * Exported variables. |
| 19 | */ |
| 20 | char s1[16]; /* buffers to hold the string representations */ |
| 21 | char s2[16]; /* of IP addresses, to be passed to inet_fmt() */ |
| 22 | char s3[16]; /* or inet_fmts(). */ |
| 23 | |
| 24 | |
| 25 | /* |
| 26 | * Verify that a given IP address is credible as a host address. |
| 27 | * (Without a mask, cannot detect addresses of the form {subnet,0} or |
| 28 | * {subnet,-1}.) |
| 29 | */ |
| 30 | int inet_valid_host(naddr) |
| 31 | u_long naddr; |
| 32 | { |
| 33 | register u_long addr; |
| 34 | |
| 35 | addr = ntohl(naddr); |
| 36 | |
| 37 | return (!(IN_MULTICAST(addr) || |
| 38 | IN_BADCLASS (addr) || |
| 39 | (addr & 0xff000000) == 0)); |
| 40 | } |
| 41 | |
| 42 | |
| 43 | /* |
| 44 | * Verify that a given subnet number and mask pair are credible. |
| 45 | */ |
| 46 | int inet_valid_subnet(nsubnet, nmask) |
| 47 | u_long nsubnet, nmask; |
| 48 | { |
| 49 | register u_long subnet, mask; |
| 50 | |
| 51 | subnet = ntohl(nsubnet); |
| 52 | mask = ntohl(nmask); |
| 53 | |
| 54 | if ((subnet & mask) != subnet) return (FALSE); |
| 55 | |
| 56 | if (IN_CLASSA(subnet)) { |
| 57 | if (mask < 0xff000000 || |
| 58 | (subnet & 0xff000000) == 0 || |
| 59 | (subnet & 0xff000000) == 0x7f000000) return (FALSE); |
| 60 | } |
| 61 | else if (IN_CLASSB(subnet)) { |
| 62 | if (mask < 0xffff0000) return (FALSE); |
| 63 | } |
| 64 | else if (IN_CLASSC(subnet)) { |
| 65 | if (mask < 0xffffff00) return (FALSE); |
| 66 | } |
| 67 | else return (FALSE); |
| 68 | |
| 69 | return (TRUE); |
| 70 | } |
| 71 | |
| 72 | |
| 73 | /* |
| 74 | * Convert an IP address in u_long (network) format into a printable string. |
| 75 | */ |
| 76 | char *inet_fmt(addr, s) |
| 77 | u_long addr; |
| 78 | char *s; |
| 79 | { |
| 80 | register u_char *a; |
| 81 | |
| 82 | a = (u_char *)&addr; |
| 83 | sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]); |
| 84 | return (s); |
| 85 | } |
| 86 | |
| 87 | |
| 88 | /* |
| 89 | * Convert an IP subnet number in u_long (network) format into a printable |
| 90 | * string. |
| 91 | */ |
| 92 | char *inet_fmts(addr, mask, s) |
| 93 | u_long addr, mask; |
| 94 | char *s; |
| 95 | { |
| 96 | register u_char *a, *m; |
| 97 | |
| 98 | a = (u_char *)&addr; |
| 99 | m = (u_char *)&mask; |
| 100 | |
| 101 | if (m[3] != 0) sprintf(s, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]); |
| 102 | else if (m[2] != 0) sprintf(s, "%u.%u.%u", a[0], a[1], a[2]); |
| 103 | else if (m[1] != 0) sprintf(s, "%u.%u", a[0], a[1]); |
| 104 | else sprintf(s, "%u", a[0]); |
| 105 | |
| 106 | return (s); |
| 107 | } |
| 108 | |
| 109 | |
| 110 | /* |
| 111 | * Convert the printable string representation of an IP address into the |
| 112 | * u_long (network) format. Return 0xffffffff on error. (To detect the |
| 113 | * legal address with that value, you must explicitly compare the string |
| 114 | * with "255.255.255.255".) |
| 115 | */ |
| 116 | u_long inet_parse(s) |
| 117 | char *s; |
| 118 | { |
| 119 | u_long a; |
| 120 | u_int a0, a1, a2, a3; |
| 121 | char c; |
| 122 | |
| 123 | if (sscanf(s, "%u.%u.%u.%u%c", &a0, &a1, &a2, &a3, &c) != 4 || |
| 124 | a0 > 255 || a1 > 255 || a2 > 255 || a3 > 255) |
| 125 | return (0xffffffff); |
| 126 | |
| 127 | ((u_char *)&a)[0] = a0; |
| 128 | ((u_char *)&a)[1] = a1; |
| 129 | ((u_char *)&a)[2] = a2; |
| 130 | ((u_char *)&a)[3] = a3; |
| 131 | |
| 132 | return (a); |
| 133 | } |
| 134 | |
| 135 | |
| 136 | /* |
| 137 | * inet_cksum extracted from: |
| 138 | * P I N G . C |
| 139 | * |
| 140 | * Author - |
| 141 | * Mike Muuss |
| 142 | * U. S. Army Ballistic Research Laboratory |
| 143 | * December, 1983 |
| 144 | * Modified at Uc Berkeley |
| 145 | * |
| 146 | * (ping.c) Status - |
| 147 | * Public Domain. Distribution Unlimited. |
| 148 | * |
| 149 | * I N _ C K S U M |
| 150 | * |
| 151 | * Checksum routine for Internet Protocol family headers (C Version) |
| 152 | * |
| 153 | */ |
| 154 | int inet_cksum(addr, len) |
| 155 | u_short *addr; |
| 156 | u_int len; |
| 157 | { |
| 158 | register int nleft = (int)len; |
| 159 | register u_short *w = addr; |
| 160 | u_short answer = 0; |
| 161 | register int sum = 0; |
| 162 | |
| 163 | /* |
| 164 | * Our algorithm is simple, using a 32 bit accumulator (sum), |
| 165 | * we add sequential 16 bit words to it, and at the end, fold |
| 166 | * back all the carry bits from the top 16 bits into the lower |
| 167 | * 16 bits. |
| 168 | */ |
| 169 | while( nleft > 1 ) { |
| 170 | sum += *w++; |
| 171 | nleft -= 2; |
| 172 | } |
| 173 | |
| 174 | /* mop up an odd byte, if necessary */ |
| 175 | if( nleft == 1 ) { |
| 176 | *(u_char *) (&answer) = *(u_char *)w ; |
| 177 | sum += answer; |
| 178 | } |
| 179 | |
| 180 | /* |
| 181 | * add back carry outs from top 16 bits to low 16 bits |
| 182 | */ |
| 183 | sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ |
| 184 | sum += (sum >> 16); /* add carry */ |
| 185 | answer = ~sum; /* truncate to 16 bits */ |
| 186 | return (answer); |
| 187 | } |