Annotation of embedaddon/pimd/inet.c, revision 1.1
1.1 ! misho 1: /*
! 2: * The mrouted program is covered by the license in the accompanying file
! 3: * named "LICENSE.mrouted". 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: * inet.c,v 3.8.4.1 1997/01/29 19:49:33 fenner Exp
! 11: */
! 12: #define C(x) ((x) & 0xff)
! 13:
! 14: #include "defs.h"
! 15:
! 16:
! 17: /*
! 18: * Exported variables.
! 19: */
! 20: char s1[MAX_INET_BUF_LEN]; /* buffers to hold the string representations */
! 21: char s2[MAX_INET_BUF_LEN]; /* of IP addresses, to be passed to inet_fmt() */
! 22: char s3[MAX_INET_BUF_LEN];
! 23: char s4[MAX_INET_BUF_LEN];
! 24:
! 25:
! 26: /*
! 27: * Verify that a given IP address is credible as a host address.
! 28: * (Without a mask, cannot detect addresses of the form {subnet,0} or
! 29: * {subnet,-1}.)
! 30: */
! 31: int inet_valid_host(uint32_t naddr)
! 32: {
! 33: uint32_t addr;
! 34:
! 35: addr = ntohl(naddr);
! 36:
! 37: return !(IN_MULTICAST(addr) ||
! 38: IN_BADCLASS (addr) ||
! 39: (addr & 0xff000000) == 0);
! 40: }
! 41:
! 42: /*
! 43: * Verify that a given netmask is plausible;
! 44: * make sure that it is a series of 1's followed by
! 45: * a series of 0's with no discontiguous 1's.
! 46: */
! 47: int inet_valid_mask(uint32_t mask)
! 48: {
! 49: if (~(((mask & -mask) - 1) | mask) != 0) {
! 50: /* Mask is not contiguous */
! 51: return FALSE;
! 52: }
! 53:
! 54: return TRUE;
! 55: }
! 56:
! 57: /*
! 58: * Verify that a given subnet number and mask pair are credible.
! 59: *
! 60: * With CIDR, almost any subnet and mask are credible. mrouted still
! 61: * can't handle aggregated class A's, so we still check that, but
! 62: * otherwise the only requirements are that the subnet address is
! 63: * within the [ABC] range and that the host bits of the subnet
! 64: * are all 0.
! 65: */
! 66: int inet_valid_subnet(uint32_t nsubnet, uint32_t nmask)
! 67: {
! 68: uint32_t subnet, mask;
! 69:
! 70: subnet = ntohl(nsubnet);
! 71: mask = ntohl(nmask);
! 72:
! 73: if ((subnet & mask) != subnet)
! 74: return FALSE;
! 75:
! 76: if (subnet == 0)
! 77: return mask == 0;
! 78:
! 79: if (IN_CLASSA(subnet)) {
! 80: if (mask < 0xff000000 ||
! 81: (subnet & 0xff000000) == 0x7f000000 ||
! 82: (subnet & 0xff000000) == 0x00000000)
! 83: return FALSE;
! 84: }
! 85: else if (IN_CLASSD(subnet) || IN_BADCLASS(subnet)) {
! 86: /* Above Class C address space */
! 87: return FALSE;
! 88: }
! 89: if (subnet & ~mask) {
! 90: /* Host bits are set in the subnet */
! 91: return FALSE;
! 92: }
! 93: if (!inet_valid_mask(mask)) {
! 94: /* Netmask is not contiguous */
! 95: return FALSE;
! 96: }
! 97:
! 98: return TRUE;
! 99: }
! 100:
! 101:
! 102: /*
! 103: * Convert an IP address in uint32_t (network) format into a printable string.
! 104: */
! 105: char *inet_fmt(uint32_t addr, char *s, size_t len)
! 106: {
! 107: uint8_t *a;
! 108:
! 109: a = (uint8_t *)&addr;
! 110: snprintf(s, len, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
! 111:
! 112: return s;
! 113: }
! 114:
! 115: /*
! 116: * Convert the printable string representation of an IP address into the
! 117: * uint32_t (network) format. Return 0xffffffff on error. (To detect the
! 118: * legal address with that value, you must explicitly compare the string
! 119: * with "255.255.255.255".)
! 120: * The return value is in network order.
! 121: */
! 122: uint32_t inet_parse(char *s, int n)
! 123: {
! 124: uint32_t a = 0;
! 125: u_int a0 = 0, a1 = 0, a2 = 0, a3 = 0;
! 126: int i;
! 127: char c;
! 128:
! 129: i = sscanf(s, "%u.%u.%u.%u%c", &a0, &a1, &a2, &a3, &c);
! 130: if (i < n || i > 4 || a0 > 255 || a1 > 255 || a2 > 255 || a3 > 255)
! 131: return 0xffffffff;
! 132:
! 133: ((uint8_t *)&a)[0] = a0;
! 134: ((uint8_t *)&a)[1] = a1;
! 135: ((uint8_t *)&a)[2] = a2;
! 136: ((uint8_t *)&a)[3] = a3;
! 137:
! 138: return a;
! 139: }
! 140:
! 141:
! 142: /*
! 143: * inet_cksum extracted from:
! 144: * P I N G . C
! 145: *
! 146: * Author -
! 147: * Mike Muuss
! 148: * U. S. Army Ballistic Research Laboratory
! 149: * December, 1983
! 150: * Modified at Uc Berkeley
! 151: *
! 152: * (ping.c) Status -
! 153: * Public Domain. Distribution Unlimited.
! 154: *
! 155: * I N _ C K S U M
! 156: *
! 157: * Checksum routine for Internet Protocol family headers (C Version)
! 158: *
! 159: */
! 160: int inet_cksum(uint16_t *addr, u_int len)
! 161: {
! 162: int sum = 0;
! 163: int nleft = (int)len;
! 164: uint16_t *w = addr;
! 165: uint16_t answer = 0;
! 166:
! 167: /*
! 168: * Our algorithm is simple, using a 32 bit accumulator (sum),
! 169: * we add sequential 16 bit words to it, and at the end, fold
! 170: * back all the carry bits from the top 16 bits into the lower
! 171: * 16 bits.
! 172: */
! 173: while (nleft > 1) {
! 174: sum += *w++;
! 175: nleft -= 2;
! 176: }
! 177:
! 178: /* mop up an odd byte, if necessary */
! 179: if (nleft == 1) {
! 180: *(uint8_t *) (&answer) = *(uint8_t *)w ;
! 181: sum += answer;
! 182: }
! 183:
! 184: /*
! 185: * add back carry outs from top 16 bits to low 16 bits
! 186: */
! 187: sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
! 188: sum += (sum >> 16); /* add carry */
! 189: answer = ~sum; /* truncate to 16 bits */
! 190:
! 191: return answer;
! 192: }
! 193:
! 194: /*
! 195: * Called by following netname() to create a mask specified network address.
! 196: */
! 197: void trimdomain(char *cp)
! 198: {
! 199: static char domain[MAXHOSTNAMELEN + 1];
! 200: static int first = 1;
! 201: char *s;
! 202:
! 203: if (first) {
! 204: first = 0;
! 205: if (gethostname(domain, MAXHOSTNAMELEN) == 0 &&
! 206: (s = strchr(domain, '.')))
! 207: (void) strlcpy(domain, s + 1, sizeof(domain));
! 208: else
! 209: domain[0] = 0;
! 210: }
! 211:
! 212: if (domain[0]) {
! 213: while ((cp = strchr(cp, '.'))) {
! 214: if (!strcasecmp(cp + 1, domain)) {
! 215: *cp = 0;
! 216: break;
! 217: }
! 218: cp++;
! 219: }
! 220: }
! 221: }
! 222:
! 223: static uint32_t forgemask(uint32_t a)
! 224: {
! 225: uint32_t m;
! 226:
! 227: if (IN_CLASSA(a))
! 228: m = IN_CLASSA_NET;
! 229: else if (IN_CLASSB(a))
! 230: m = IN_CLASSB_NET;
! 231: else
! 232: m = IN_CLASSC_NET;
! 233:
! 234: return (m);
! 235: }
! 236:
! 237: static void domask(char *dst, size_t len, uint32_t addr, uint32_t mask)
! 238: {
! 239: int b, i;
! 240:
! 241: if (!mask || (forgemask(addr) == mask)) {
! 242: *dst = '\0';
! 243: return;
! 244: }
! 245:
! 246: i = 0;
! 247: for (b = 0; b < 32; b++) {
! 248: if (mask & (1 << b)) {
! 249: int bb;
! 250:
! 251: i = b;
! 252: for (bb = b+1; bb < 32; bb++) {
! 253: if (!(mask & (1 << bb))) {
! 254: i = -1; /* noncontig */
! 255: break;
! 256: }
! 257: }
! 258: break;
! 259: }
! 260: }
! 261:
! 262: if (i == -1)
! 263: snprintf(dst, len, "&0x%x", mask);
! 264: else
! 265: snprintf(dst, len, "/%d", 32 - i);
! 266: }
! 267:
! 268: /*
! 269: * Return the name of the network whose address is given.
! 270: * The address is assumed to be that of a net or subnet, not a host.
! 271: */
! 272: char *netname(uint32_t addr, uint32_t mask)
! 273: {
! 274: static char line[MAXHOSTNAMELEN + 4];
! 275: uint32_t omask;
! 276: uint32_t i;
! 277:
! 278: i = ntohl(addr);
! 279: omask = mask = ntohl(mask);
! 280: if ((i & 0xffffff) == 0)
! 281: snprintf(line, sizeof(line), "%u", C(i >> 24));
! 282: else if ((i & 0xffff) == 0)
! 283: snprintf(line, sizeof(line), "%u.%u", C(i >> 24) , C(i >> 16));
! 284: else if ((i & 0xff) == 0)
! 285: snprintf(line, sizeof(line), "%u.%u.%u", C(i >> 24), C(i >> 16), C(i >> 8));
! 286: else
! 287: snprintf(line, sizeof(line), "%u.%u.%u.%u", C(i >> 24),
! 288: C(i >> 16), C(i >> 8), C(i));
! 289: domask(line + strlen(line), sizeof(line) - strlen(line), i, omask);
! 290:
! 291: return line;
! 292: }
! 293:
! 294: /**
! 295: * Local Variables:
! 296: * version-control: t
! 297: * indent-tabs-mode: t
! 298: * c-file-style: "ellemtel"
! 299: * c-basic-offset: 4
! 300: * End:
! 301: */
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