xref: /csrg-svn/lib/libc/net/res_comp.c (revision 18342)
118140Sralph #ifndef lint
2*18342Sralph static char sccsid[] = "@(#)res_comp.c	4.2 (Berkeley) 03/15/85";
318140Sralph #endif
418140Sralph 
518140Sralph #include <sys/types.h>
618140Sralph #include <stdio.h>
718140Sralph #include <ctype.h>
818140Sralph #include <nameser.h>
918140Sralph 
1018140Sralph 
1118140Sralph /*
12*18342Sralph  * Expand compressed domain name 'comp_dn' to full domain name.
13*18342Sralph  * Expanded names are converted to upper case.
14*18342Sralph  * 'msg' is a pointer to the begining of the message,
15*18342Sralph  * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
1618140Sralph  * Return size of compressed name or -1 if there was an error.
1718140Sralph  */
1818140Sralph dn_expand(msg, comp_dn, exp_dn, length)
1918140Sralph 	char *msg, *comp_dn, *exp_dn;
2018140Sralph 	int length;
2118140Sralph {
2218140Sralph 	register char *cp, *dn;
2318140Sralph 	register int n, c;
2418140Sralph 	char *eom;
25*18342Sralph 	int len = -1;
2618140Sralph 
2718140Sralph 	dn = exp_dn;
2818140Sralph 	cp = comp_dn;
2918140Sralph 	eom = exp_dn + length - 1;
3018140Sralph 	/*
3118140Sralph 	 * fetch next label in domain name
3218140Sralph 	 */
3318140Sralph 	while (n = *cp++) {
3418140Sralph 		/*
3518140Sralph 		 * Check for indirection
3618140Sralph 		 */
3718140Sralph 		switch (n & INDIR_MASK) {
3818140Sralph 		case 0:
39*18342Sralph 			if (dn != exp_dn) {
40*18342Sralph 				if (dn >= eom)
41*18342Sralph 					return (-1);
4218140Sralph 				*dn++ = '.';
43*18342Sralph 			}
4418140Sralph 			if (dn+n >= eom)
4518140Sralph 				return (-1);
4618140Sralph 			while (--n >= 0)
4718140Sralph 				if (islower(c = *cp++))
4818140Sralph 					*dn++ = toupper(c);
49*18342Sralph 				else {
50*18342Sralph 					if (c == '.') {
51*18342Sralph 						if (dn+n+1 >= eom)
52*18342Sralph 							return (-1);
53*18342Sralph 						*dn++ = '\\';
54*18342Sralph 					}
5518140Sralph 					*dn++ = c;
56*18342Sralph 				}
5718140Sralph 			break;
5818140Sralph 
5918140Sralph 		case INDIR_MASK:
60*18342Sralph 			if (len < 0)
6118140Sralph 				len = cp - comp_dn + 1;
6218140Sralph 			cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
6318140Sralph 			break;
6418140Sralph 
6518140Sralph 		default:
6618140Sralph 			return (-1);			/* flag error */
6718140Sralph 		}
6818140Sralph 	}
6918140Sralph 	*dn = '\0';
70*18342Sralph 	if (len < 0)
7118140Sralph 		len = cp - comp_dn;
7218140Sralph 	return (len);
7318140Sralph }
7418140Sralph 
7518140Sralph /*
76*18342Sralph  * Compress domain name 'exp_dn' into 'comp_dn'.
77*18342Sralph  * Return the size of the compressed name or -1.
78*18342Sralph  * 'length' is the size of the array pointed to by 'comp_dn'.
79*18342Sralph  * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0]
8018140Sralph  * is a pointer to the beginning of the message. The list ends with NULL.
81*18342Sralph  * 'lastdnptr' is a pointer to the end of the arrary pointed to
82*18342Sralph  * by 'dnptrs'. Side effect is to update the list of pointers for
83*18342Sralph  * labels inserted into the message as we compress the name.
84*18342Sralph  * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
85*18342Sralph  * is NULL, we don't update the list.
8618140Sralph  */
8718140Sralph dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
8818140Sralph 	char *exp_dn, *comp_dn;
8918140Sralph 	int length;
9018140Sralph 	char **dnptrs, **lastdnptr;
9118140Sralph {
9218140Sralph 	register char *cp, *dn;
9318140Sralph 	register int c, l;
9418140Sralph 	char **cpp, **lpp, *sp, *eob;
9518140Sralph 	char *msg;
9618140Sralph 
9718140Sralph 	dn = exp_dn;
9818140Sralph 	cp = comp_dn;
9918140Sralph 	eob = comp_dn + length;
10018140Sralph 	if (dnptrs != NULL) {
10118140Sralph 		if ((msg = *dnptrs++) != NULL) {
10218140Sralph 			for (cpp = dnptrs; *cpp != NULL; cpp++)
10318140Sralph 				;
10418140Sralph 			lpp = cpp;	/* end of list to search */
10518140Sralph 		}
10618140Sralph 	} else
10718140Sralph 		msg = NULL;
10818140Sralph 	for (c = *dn++; c != '\0'; ) {
10918140Sralph 		/* look to see if we can use pointers */
11018140Sralph 		if (msg != NULL) {
11118140Sralph 			if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) {
11218140Sralph 				if (cp+1 >= eob)
11318140Sralph 					return (-1);
11418140Sralph 				*cp++ = (l >> 8) | INDIR_MASK;
11518140Sralph 				*cp++ = l;
11618140Sralph 				return (cp - comp_dn);
11718140Sralph 			}
11818140Sralph 			/* not found, save it */
11918140Sralph 			if (lastdnptr != NULL && cpp < lastdnptr-1) {
12018140Sralph 				*cpp++ = cp;
12118140Sralph 				*cpp = NULL;
12218140Sralph 			}
12318140Sralph 		}
12418140Sralph 		sp = cp++;	/* save ptr to length byte */
12518140Sralph 		do {
12618140Sralph 			if (c == '.') {
12718140Sralph 				c = *dn++;
12818140Sralph 				break;
12918140Sralph 			}
130*18342Sralph 			if (c == '\\') {
131*18342Sralph 				if ((c = *dn++) == '\0')
132*18342Sralph 					break;
133*18342Sralph 			}
13418140Sralph 			if (cp >= eob)
13518140Sralph 				return (-1);
13618140Sralph 			*cp++ = c;
13718140Sralph 		} while ((c = *dn++) != '\0');
138*18342Sralph 		/* catch trailing '.'s but not '..' */
139*18342Sralph 		if ((l = cp - sp - 1) == 0 && c == '\0') {
140*18342Sralph 			cp--;
141*18342Sralph 			break;
142*18342Sralph 		}
143*18342Sralph 		if (l <= 0 || l > MAXLABEL)
14418140Sralph 			return (-1);
14518140Sralph 		*sp = l;
14618140Sralph 	}
14718140Sralph 	if (cp >= eob)
14818140Sralph 		return (-1);
14918140Sralph 	*cp++ = '\0';
15018140Sralph 	return (cp - comp_dn);
15118140Sralph }
15218140Sralph 
15318140Sralph /*
154*18342Sralph  * Skip over a compressed domain name. Return the size or -1.
15518140Sralph  */
156*18342Sralph dn_skip(comp_dn)
157*18342Sralph 	char *comp_dn;
15818140Sralph {
15918140Sralph 	register char *cp;
16018140Sralph 	register int n;
16118140Sralph 
162*18342Sralph 	cp = comp_dn;
16318140Sralph 	while (n = *cp++) {
16418140Sralph 		/*
16518140Sralph 		 * check for indirection
16618140Sralph 		 */
16718140Sralph 		switch (n & INDIR_MASK) {
16818140Sralph 		case 0:		/* normal case, n == len */
16918140Sralph 			cp += n;
17018140Sralph 			continue;
17118140Sralph 		default:	/* illegal type */
17218140Sralph 			return (-1);
17318140Sralph 		case INDIR_MASK:	/* indirection */
17418140Sralph 			cp++;
17518140Sralph 		}
17618140Sralph 		break;
17718140Sralph 	}
178*18342Sralph 	return (cp - comp_dn);
17918140Sralph }
18018140Sralph 
18118140Sralph /*
18218140Sralph  * Search for expanded name from a list of previously compressed names.
18318140Sralph  * Return the offset from msg if found or -1.
18418140Sralph  */
18518140Sralph dn_find(exp_dn, msg, dnptrs, lastdnptr)
18618140Sralph 	char *exp_dn, *msg;
18718140Sralph 	char **dnptrs, **lastdnptr;
18818140Sralph {
18918140Sralph 	register char *dn, *cp, **cpp;
19018140Sralph 	register int n;
19118140Sralph 	char *sp;
19218140Sralph 
19318140Sralph 	for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
19418140Sralph 		dn = exp_dn;
19518140Sralph 		sp = cp = *cpp;
19618140Sralph 		while (n = *cp++) {
19718140Sralph 			/*
19818140Sralph 			 * check for indirection
19918140Sralph 			 */
20018140Sralph 			switch (n & INDIR_MASK) {
20118140Sralph 			case 0:		/* normal case, n == len */
202*18342Sralph 				while (--n >= 0) {
203*18342Sralph 					if (*dn == '\\')
204*18342Sralph 						dn++;
20518140Sralph 					if (*dn++ != *cp++)
20618140Sralph 						goto next;
207*18342Sralph 				}
20818140Sralph 				if ((n = *dn++) == '\0' && *cp == '\0')
20918140Sralph 					return (sp - msg);
21018140Sralph 				if (n == '.')
21118140Sralph 					continue;
21218140Sralph 				goto next;
21318140Sralph 
21418140Sralph 			default:	/* illegal type */
21518140Sralph 				return (-1);
21618140Sralph 
21718140Sralph 			case INDIR_MASK:	/* indirection */
21818140Sralph 				cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
21918140Sralph 			}
22018140Sralph 		}
22118140Sralph 		if (*dn == '\0')
22218140Sralph 			return (sp - msg);
22318140Sralph 	next:	;
22418140Sralph 	}
22518140Sralph 	return (-1);
22618140Sralph }
227