ns_name.c 8.79 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
/*
 * Copyright (c) 1996,1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#include "config.h"

#include <sys/types.h>

#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_NAMESER_H
# include <arpa/nameser.h>
#endif

#include <ctype.h>
#include <errno.h>
#ifdef HAVE_RESOLV_H
# include <resolv.h>
#endif
#include <string.h>
#include <ctype.h>

/* Data. */

static const char	digits[] = "0123456789";

/* Forward. */

static int		special(int);
static int		printable(int);

/* Public. */

/*
 * dns_ns_name_ntop(src, dst, dstsiz)
 *	Convert an encoded domain name to printable ascii as per RFC1035.
 * return:
 *	Number of bytes written to buffer, or -1 (with errno set)
 * notes:
 *	The root is returned as "."
 *	All other domains are returned in non absolute form
 */
57
static int
58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234
dns_ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
	const u_char *cp;
	char *dn, *eom;
	u_char c;
	u_int n;

	cp = src;
	dn = dst;
	eom = dst + dstsiz;

	while ((n = *cp++) != 0) {
		if ((n & NS_CMPRSFLGS) != 0 && n != 0x41) {
			/* Some kind of compression pointer. */
			return (-1);
		}
		if (dn != dst) {
			if (dn >= eom) {
				return (-1);
			}
			*dn++ = '.';
		}

		if (n == 0x41) {
			n = *cp++ / 8;
			if (dn + n * 2 + 4 >= eom) {
				return (-1);
			}
			*dn++ = '\\';
			*dn++ = '[';
			*dn++ = 'x';

			while (n-- > 0) {
                unsigned u;
				c = *cp++;
				u = c >> 4;
				*dn++ = u > 9 ? 'a' + u - 10 : '0' + u;
				u = c & 0xf;
				*dn++ = u > 9 ? 'a' + u - 10 : '0' + u;
			}

			*dn++ = ']';
			continue;
		}

		if (dn + n >= eom) {
			return (-1);
		}
		for ((void)NULL; n > 0; n--) {
			c = *cp++;
			if (special(c)) {
				if (dn + 1 >= eom) {
					return (-1);
				}
				*dn++ = '\\';
				*dn++ = (char)c;
			} else if (!printable(c)) {
				if (dn + 3 >= eom) {
					return (-1);
				}
				*dn++ = '\\';
				*dn++ = digits[c / 100];
				*dn++ = digits[(c % 100) / 10];
				*dn++ = digits[c % 10];
			} else {
				if (dn >= eom) {
					return (-1);
				}
				*dn++ = (char)c;
			}
		}
	}
	if (dn == dst) {
		if (dn >= eom) {
			return (-1);
		}
		*dn++ = '.';
	}
	if (dn >= eom) {
		return (-1);
	}
	*dn++ = '\0';
	return (dn - dst);
}

/*
 * dns_ns_name_pton(src, dst, dstsiz)
 *	Convert a ascii string into an encoded domain name as per RFC1035.
 * return:
 *	-1 if it fails
 *	1 if string was fully qualified
 *	0 is string was not fully qualified
 * notes:
 *	Enforces label and domain length limits.
 */

int
dns_ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
	u_char *label, *bp, *eom;
	int c, n, escaped;
	char *cp;

	escaped = 0;
	bp = dst;
	eom = dst + dstsiz;
	label = bp++;

	while ((c = *src++) != 0) {
		if (escaped) {
			if ((cp = strchr(digits, c)) != NULL) {
				n = (cp - digits) * 100;
				if ((c = *src++) == 0 ||
				    (cp = strchr(digits, c)) == NULL) {
					return (-1);
				}
				n += (cp - digits) * 10;
				if ((c = *src++) == 0 ||
				    (cp = strchr(digits, c)) == NULL) {
					return (-1);
				}
				n += (cp - digits);
				if (n > 255) {
					return (-1);
				}
				c = n;
			} else if (c == '[' && label == bp - 1 && *src == 'x') {
				/* Theoretically we would have to handle \[o
				   as well but we do not since we do not need
				   it internally.  */
				*label = 0x41;
				label = bp++;
				++src;
				while (isxdigit (*src)) {
					n = *src > '9' ? *src - 'a' + 10 : *src - '0';
					++src;
					if (! isxdigit(*src)) {
						return (-1);
					}
					n <<= 4;
					n += *src > '9' ? *src - 'a' + 10 : *src - '0';
					if (bp + 1 >= eom) {
						return (-1);
					}
					*bp++ = n;
					++src;
				}
				*label = (bp - label - 1) * 8;
				if (*src++ != ']' || *src++ != '.') {
					return (-1);
				}
				escaped = 0;
				label = bp++;
				if (bp >= eom) {
					return (-1);
				}
				continue;
			}
			escaped = 0;
		} else if (c == '\\') {
			escaped = 1;
			continue;
		} else if (c == '.') {
			c = (bp - label - 1);
			if ((c & NS_CMPRSFLGS) != 0) {	/* Label too big. */
				return (-1);
			}
			if (label >= eom) {
				return (-1);
			}
			*label = c;
			/* Fully qualified ? */
			if (*src == '\0') {
				if (c != 0) {
					if (bp >= eom) {
						return (-1);
					}
					*bp++ = '\0';
				}
235
				if ((bp - dst) > NS_MAXCDNAME) {
236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264
					return (-1);
				}
				return (1);
			}
			if (c == 0 || *src == '.') {
				return (-1);
			}
			label = bp++;
			continue;
		}
		if (bp >= eom) {
			return (-1);
		}
		*bp++ = (u_char)c;
	}
	c = (bp - label - 1);
	if ((c & NS_CMPRSFLGS) != 0) {		/* Label too big. */
		return (-1);
	}
	if (label >= eom) {
		return (-1);
	}
	*label = c;
	if (c != 0) {
		if (bp >= eom) {
			return (-1);
		}
		*bp++ = 0;
	}
265
	if ((bp - dst) > NS_MAXCDNAME) {	/* src too big */
266 267 268 269 270 271 272 273 274 275 276 277
		return (-1);
	}
	return (0);
}


/*
 * dns_ns_name_unpack(msg, eom, src, dst, dstsiz)
 *	Unpack a domain name from a message, source may be compressed.
 * return:
 *	-1 if it fails, or consumed octets if it succeeds.
 */
278
static int
279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444
dns_ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
	       u_char *dst, size_t dstsiz)
{
	const u_char *srcp, *dstlim;
	u_char *dstp;
	int n, len, checked;

	len = -1;
	checked = 0;
	dstp = dst;
	srcp = src;
	dstlim = dst + dstsiz;
	if (srcp < msg || srcp >= eom) {
		return (-1);
	}
	/* Fetch next label in domain name. */
	while ((n = *srcp++) != 0) {
		/* Check for indirection. */
		switch (n & NS_CMPRSFLGS) {
		case 0x40:
			if (n == 0x41) {
				if (dstp + 1 >= dstlim) {
					return (-1);
			  	}
				*dstp++ = 0x41;
				n = *srcp++ / 8;
				++checked;
			} else {
				return (-1);		/* flag error */
			}
			/* FALLTHROUGH */
		case 0:
			/* Limit checks. */
			if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
				return (-1);
			}
			checked += n + 1;
			dstp = memcpy(dstp, srcp - 1, n + 1);
			dstp += n + 1;
			srcp += n;
			break;

		case NS_CMPRSFLGS:
			if (srcp >= eom) {
				return (-1);
			}
			if (len < 0)
				len = srcp - src + 1;
			srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
			if (srcp < msg || srcp >= eom) {  /* Out of range. */
				return (-1);
			}
			checked += 2;
			/*
			 * Check for loops in the compressed name;
			 * if we've looked at the whole message,
			 * there must be a loop.
			 */
			if (checked >= eom - msg) {
				return (-1);
			}
			break;

		default:
			return (-1);			/* flag error */
		}
	}
	*dstp = '\0';
	if (len < 0)
		len = srcp - src;
	return (len);
}


/*
 * dns_ns_name_uncompress(msg, eom, src, dst, dstsiz)
 *	Expand compressed domain name to presentation format.
 * return:
 *	Number of bytes read out of `src', or -1 (with errno set).
 * note:
 *	Root domain returns as "." not "".
 */
int
dns_ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
		   char *dst, size_t dstsiz)
{
	u_char tmp[NS_MAXCDNAME];
	int n;

	if ((n = dns_ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
		return (-1);
	if (dns_ns_name_ntop(tmp, dst, dstsiz) == -1)
		return (-1);
	return (n);
}


/*
 * dns_ns_name_skip(ptrptr, eom)
 *	Advance *ptrptr to skip over the compressed name it points at.
 * return:
 *	0 on success, -1 (with errno set) on failure.
 */
int
dns_ns_name_skip(const u_char **ptrptr, const u_char *eom) {
	const u_char *cp;
	u_int n;

	cp = *ptrptr;
	while (cp < eom && (n = *cp++) != 0) {
		/* Check for indirection. */
		switch (n & NS_CMPRSFLGS) {
		case 0:			/* normal case, n == len */
			cp += n;
			continue;
		case NS_CMPRSFLGS:	/* indirection */
			cp++;
			break;
		default:		/* illegal type */
			return (-1);
		}
		break;
	}
	if (cp > eom) {
		return (-1);
	}
	*ptrptr = cp;
	return (0);
}

/* Private. */

/*
 * special(ch)
 *	Thinking in noninternationalized USASCII (per the DNS spec),
 *	is this characted special ("in need of quoting") ?
 * return:
 *	boolean.
 */
static int
special(int ch) {
	switch (ch) {
	case 0x22: /* '"' */
	case 0x2E: /* '.' */
	case 0x3B: /* ';' */
	case 0x5C: /* '\\' */
	/* Special modifiers in zone files. */
	case 0x40: /* '@' */
	case 0x24: /* '$' */
		return (1);
	default:
		return (0);
	}
}

/*
 * printable(ch)
 *	Thinking in noninternationalized USASCII (per the DNS spec),
 *	is this character visible and not a space when printed ?
 * return:
 *	boolean.
 */
static int
printable(int ch) {
	return (ch > 0x20 && ch < 0x7f);
}