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hesiod.c revision 1.1.4.3 
      1 /*	$NetBSD: hesiod.c,v 1.1.4.3 1998/11/02 03:29:36 lukem Exp $	*/
      2 
      3 /* This file is part of the Hesiod library.
      4  *
      5  *  Copyright (C) 1988, 1989 by the Massachusetts Institute of Technology
      6  *
      7  *    Export of software employing encryption from the United States of
      8  *    America is assumed to require a specific license from the United
      9  *    States Government.  It is the responsibility of any person or
     10  *    organization contemplating export to obtain such a license before
     11  *    exporting.
     12  *
     13  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
     14  * distribute this software and its documentation for any purpose and
     15  * without fee is hereby granted, provided that the above copyright
     16  * notice appear in all copies and that both that copyright notice and
     17  * this permission notice appear in supporting documentation, and that
     18  * the name of M.I.T. not be used in advertising or publicity pertaining
     19  * to distribution of the software without specific, written prior
     20  * permission.  M.I.T. makes no representations about the suitability of
     21  * this software for any purpose.  It is provided "as is" without express
     22  * or implied warranty.
     23  */
     24 
     25 #include <sys/cdefs.h>
     26 
     27 #ifndef lint
     28 __IDSTRING(rcsid_hesiod_c, "#Header: /afs/rel-eng.athena.mit.edu/project/release/current/source/athena/athena.lib/hesiod/RCS/hesiod.c,v 1.11 93/06/15 10:26:37 mar Exp #");
     29 __IDSTRING(rcsid_resolve_c, "#Header: /afs/rel-eng.athena.mit.edu/project/release/current/source/athena/athena.lib/hesiod/RCS/resolve.c,v 1.7 93/06/15 10:25:45 mar Exp #");
     30 #endif
     31 
     32 #include <sys/types.h>
     33 #include <sys/param.h>
     34 #include <netinet/in.h>
     35 #include <arpa/nameser.h>
     36 
     37 #include <errno.h>
     38 #include <hesiod.h>
     39 #include <resolv.h>
     40 #include <stdio.h>
     41 #include <stdlib.h>
     42 #include <string.h>
     43 #include <stringlist.h>
     44 #include <unistd.h>
     45 
     46 typedef struct rr {
     47 	u_int16_t	 type;		/* RR type */
     48 	u_int16_t	 class;		/* RR class */
     49 	int		 dlen;		/* len of data section */
     50 	u_char		*data;		/* pointer to data */
     51 } rr_t, *rr_p;
     52 
     53 typedef struct nsmsg {
     54 	int	 len;		/* sizeof(msg) */
     55 	int	 ns_off;	/* offset to name server RRs */
     56 	int	 ar_off;	/* offset to additional RRs */
     57 	int	 count;		/* total number of RRs */
     58 	HEADER	*hd;		/* message header */
     59 	rr_t	 rr;		/* vector of (stripped-down) RR descriptors */
     60 } nsmsg_t, *nsmsg_p;
     61 
     62 static int	 Hes_Errno	= HES_ER_UNINIT;
     63 char		*HesConfigFile	= _PATH_HESIOD_CONF;
     64 static char	 Hes_LHS[MAXDNAME + 1];
     65 static char	 Hes_RHS[MAXDNAME + 1];
     66 static u_char	*Hes_eoM;
     67 
     68 #define DEF_RETRANS 4
     69 #define DEF_RETRY 3
     70 
     71 static	caddr_t	_hes_rr_scan __P((u_char *, rr_t *));
     72 static	nsmsg_p	_hes_res_scan __P((u_char *));
     73 static	nsmsg_p	_hes_res __P((u_char *, int, int));
     74 	int	hes_init __P((void));
     75 
     76 static caddr_t
     77 _hes_rr_scan(cp, rr)
     78 	u_char *cp;
     79 	rr_t *rr;
     80 {
     81 	int n;
     82 
     83 	if ((n = dn_skipname(cp, Hes_eoM)) < 0) {
     84 		errno = EINVAL;
     85 		return((u_char *)NULL);
     86 	}
     87 
     88 	cp += n;
     89 	rr->type = _getshort(cp);
     90 	cp += sizeof(u_int16_t /*type*/);
     91 
     92 	rr->class = _getshort(cp);
     93 	cp += sizeof(u_int16_t /*class*/) + sizeof(u_int32_t /*ttl*/);
     94 
     95 	rr->dlen = (int)_getshort(cp);
     96 	rr->data = cp + sizeof(u_int16_t /*dlen*/);
     97 
     98 	return(rr->data + rr->dlen);
     99 }
    100 
    101 
    102 static nsmsg_p
    103 _hes_res_scan(msg)
    104 	u_char *msg;
    105 {
    106 	static u_char	 bigmess[sizeof(nsmsg_t) + sizeof(rr_t) *
    107 				((PACKETSZ-sizeof(HEADER))/RRFIXEDSZ)];
    108 	static u_char	 datmess[PACKETSZ-sizeof(HEADER)];
    109 	u_char		*cp;
    110 	rr_t		*rp;
    111 	HEADER		*hp;
    112 	u_char		*data = datmess;
    113 	int	 	 n, n_an, n_ns, n_ar, nrec;
    114 	nsmsg_t		*mess = (nsmsg_t *)bigmess;
    115 
    116 	hp = (HEADER *)msg;
    117 	cp = msg + sizeof(HEADER);
    118 	n_an = ntohs(hp->ancount);
    119 	n_ns = ntohs(hp->nscount);
    120 	n_ar = ntohs(hp->arcount);
    121 	nrec = n_an + n_ns + n_ar;
    122 
    123 	mess->len = 0;
    124 	mess->hd = hp;
    125 	mess->ns_off = n_an;
    126 	mess->ar_off = n_an + n_ns;
    127 	mess->count = nrec;
    128 	rp = &mess->rr;
    129 
    130 	/* skip over questions */
    131 	if ((n = ntohs(hp->qdcount) != 0)) {
    132 		while (--n >= 0) {
    133 			int i;
    134 			if ((i = dn_skipname(cp, Hes_eoM)) < 0)
    135 				return((nsmsg_t *)NULL);
    136 			cp += i + (sizeof(u_int16_t /*type*/)
    137 				+ sizeof(u_int16_t /*class*/));
    138 		}
    139 	}
    140 
    141 	/* scan answers */
    142 	if ((n = n_an) != 0) {
    143 		while (--n >= 0) {
    144 			if ((cp = _hes_rr_scan(cp, rp)) == NULL)
    145 				return((nsmsg_t *)NULL);
    146 			(void) strncpy(data, rp->data, rp->dlen);
    147 			rp->data = data;
    148 			data += rp->dlen;
    149 			*data++ = '\0';
    150 			rp++;
    151 		}
    152 	}
    153 
    154 	/* scan name servers */
    155 	if ((n = n_ns) != 0) {
    156 		while (--n >= 0) {
    157 			if ((cp = _hes_rr_scan(cp, rp)) == NULL)
    158 				return((nsmsg_t *)NULL);
    159 			(void) strncpy(data, rp->data, rp->dlen);
    160 			rp->data = data;
    161 			data += rp->dlen;
    162 			*data++ = '\0';
    163 			rp++;
    164 		}
    165 	}
    166 
    167 	/* scan additional records */
    168 	if ((n = n_ar) != 0) {
    169 		while (--n >= 0) {
    170 			if ((cp = _hes_rr_scan(cp, rp)) == NULL)
    171 				return((nsmsg_t *)NULL);
    172 			(void) strncpy(data, rp->data, rp->dlen);
    173 			rp->data = data;
    174 			data += rp->dlen;
    175 			*data++ = '\0';
    176 			rp++;
    177 		}
    178 	}
    179 
    180 	mess->len = (int)cp - (int)msg;
    181 
    182 	return(mess);
    183 }
    184 
    185 /*
    186  * Resolve name into data records
    187  */
    188 
    189 static nsmsg_p
    190 _hes_res(name, class, type)
    191 	u_char *name;
    192 	int class, type;
    193 {
    194 	static u_char		qbuf[PACKETSZ], abuf[PACKETSZ];
    195 	int			n;
    196 	u_int32_t		res_options = _res.options;
    197 	int			res_retrans = _res.retrans;
    198 	int			res_retry = _res.retry;
    199 
    200 #ifdef DEBUG
    201 	if (_res.options & RES_DEBUG)
    202 		printf("_hes_res: class = %d, type = %d\n", class, type);
    203 #endif
    204 
    205 	if (class < 0 || type < 0) {
    206 		errno = EINVAL;
    207 		return((nsmsg_t *)NULL);
    208 	}
    209 
    210 	_res.options |= RES_IGNTC;
    211 
    212 	n = res_mkquery(QUERY, name, class, type, (u_char *)NULL, 0,
    213 	    NULL, qbuf, PACKETSZ);
    214 	if (n < 0) {
    215 		errno = EMSGSIZE;
    216 		return((nsmsg_t *)NULL);
    217 	}
    218 
    219 	_res.retrans = DEF_RETRANS;
    220 	_res.retry = DEF_RETRY;
    221 
    222 	n = res_send(qbuf, n, abuf, PACKETSZ);
    223 
    224 	_res.options = res_options;
    225 	_res.retrans = res_retrans;
    226 	_res.retry = res_retry;
    227 
    228 	if (n < 0) {
    229 		errno = ECONNREFUSED;
    230 		return((nsmsg_t *)NULL);
    231 	}
    232 	Hes_eoM = abuf+n;
    233 
    234 	return(_hes_res_scan(abuf));
    235 }
    236 
    237 int
    238 hes_init()
    239 {
    240 	FILE	*fp;
    241 	char	*key, *cp, *cpp;
    242 	char	 buf[MAXDNAME+7];
    243 
    244 	Hes_Errno = HES_ER_UNINIT;
    245 	Hes_LHS[0] = '\0';
    246 	Hes_RHS[0] = '\0';
    247 	if ((fp = fopen(HesConfigFile, "r")) == NULL) {
    248 		/* use defaults compiled in */
    249 		/* no file or no access uses defaults */
    250 		/* but poorly formed file returns error */
    251 		if (DEF_LHS) strncpy(Hes_LHS, DEF_LHS, MAXDNAME);
    252 		if (DEF_RHS) strncpy(Hes_RHS, DEF_RHS, MAXDNAME);
    253 
    254 		/* if DEF_RHS == "", use getdomainname() */
    255 		if (Hes_RHS[0] == '\0')
    256 			(void)getdomainname(Hes_RHS, MAXDNAME);
    257 	} else {
    258 		while(fgets(buf, MAXDNAME+7, fp) != NULL) {
    259 			cp = buf;
    260 			if (*cp == '#' || *cp == '\n')
    261 				continue;
    262 			while(*cp == ' ' || *cp == '\t')
    263 				cp++;
    264 			key = cp;
    265 			while(*cp != ' ' && *cp != '\t' && *cp != '=')
    266 				cp++;
    267 			*cp++ = '\0';
    268 			if (strcmp(key, "lhs") == 0)
    269 				cpp = Hes_LHS;
    270 			else if (strcmp(key, "rhs") == 0)
    271 				cpp = Hes_RHS;
    272 			else
    273 				continue;
    274 			while(*cp == ' ' || *cp == '\t' || *cp == '=')
    275 				cp++;
    276 			if (*cp != '.' && *cp != '\n') {
    277 				Hes_Errno = HES_ER_CONFIG;
    278 				fclose(fp);
    279 				return(Hes_Errno);
    280 			}
    281 			(void) strncpy(cpp, cp, strlen(cp)-1);
    282 		}
    283 		fclose(fp);
    284 	}
    285 	/* see if the RHS is overridden by environment variable */
    286 	if ((cp = getenv("HES_DOMAIN")) != NULL)
    287 		strncpy(Hes_RHS, cp, MAXDNAME);
    288 	/* the LHS may be null, the RHS must not be null */
    289 	if (Hes_RHS[0] == '\0')
    290 		Hes_Errno = HES_ER_CONFIG;
    291 	else
    292 		Hes_Errno = HES_ER_OK;
    293 	return(Hes_Errno);
    294 }
    295 
    296 char *
    297 hes_to_bind(HesiodName, HesiodNameType)
    298 	char *HesiodName, *HesiodNameType;
    299 {
    300 	static char	 bindname[MAXDNAME];
    301 	char		*cp, **cpp, *x;
    302 	char		*RHS;
    303 	int		 bni = 0;
    304 
    305 #define STRADDBIND(y)	for (x = y; *x; x++, bni++) { \
    306 				if (bni >= MAXDNAME) \
    307 					return NULL; \
    308 				bindname[bni] = *x; \
    309 			}
    310 
    311 	if (Hes_Errno == HES_ER_UNINIT || Hes_Errno == HES_ER_CONFIG)
    312 		(void) hes_init();
    313 	if (Hes_Errno == HES_ER_CONFIG)
    314 		return(NULL);
    315 	if ((cp = strchr(HesiodName,'@')) != NULL) {
    316 		if (strchr(++cp,'.'))
    317 			RHS = cp;
    318 		else
    319 			if ((cpp = hes_resolve(cp, "rhs-extension")) != NULL)
    320 				RHS = *cpp;
    321 			else {
    322 				Hes_Errno = HES_ER_NOTFOUND;
    323 				return(NULL);
    324 			}
    325 		STRADDBIND(HesiodName);
    326 		*strchr(bindname,'@') = '\0';
    327 	} else {
    328 		RHS = Hes_RHS;
    329 		STRADDBIND(HesiodName);
    330 	}
    331 	STRADDBIND(".");
    332 	STRADDBIND(HesiodNameType);
    333 	if (Hes_LHS && Hes_LHS[0]) {
    334 		if (Hes_LHS[0] != '.')
    335 			STRADDBIND(".");
    336 		STRADDBIND(Hes_LHS);
    337 	}
    338 	if (RHS[0] != '.')
    339 		STRADDBIND(".");
    340 	STRADDBIND(RHS);
    341 	if (bni == MAXDNAME)
    342 		bni--;
    343 	bindname[bni] = '\0';
    344 	return(bindname);
    345 }
    346 
    347 /* XXX: convert to resolv directly */
    348 char **
    349 hes_resolve(HesiodName, HesiodNameType)
    350 	char *HesiodName, *HesiodNameType;
    351 {
    352 	char		**retvec;
    353 	char		 *cp, *ocp, *dst;
    354 	int		  i, n;
    355 	struct nsmsg	 *ns;
    356 	rr_t		 *rp;
    357 	StringList	 *sl;
    358 
    359 	sl = sl_init();
    360 
    361 	cp = hes_to_bind(HesiodName, HesiodNameType);
    362 	if (cp == NULL)
    363 		return(NULL);
    364 	errno = 0;
    365 	ns = _hes_res(cp, C_HS, T_TXT);
    366 	if (errno == ETIMEDOUT || errno == ECONNREFUSED) {
    367 		Hes_Errno = HES_ER_NET;
    368 		return(NULL);
    369 	}
    370 	if (ns == NULL || ns->ns_off <= 0) {
    371 		Hes_Errno = HES_ER_NOTFOUND;
    372 		return(NULL);
    373 	}
    374 	for(i = 0, rp = &ns->rr; i < ns->ns_off; rp++, i++) {
    375 		if (rp->class == C_HS && rp->type == T_TXT) {
    376 			dst = calloc(rp->dlen + 1, sizeof(char));
    377 			if (dst == NULL) {
    378 				sl_free(sl, 1);
    379 				return NULL;
    380 			}
    381 			sl_add(sl, dst);
    382 			ocp = cp = rp->data;
    383 			while (cp < ocp + rp->dlen) {
    384 				n = (unsigned char) *cp++;
    385 				(void) memmove(dst, cp, n);
    386 				cp += n;
    387 				dst += n;
    388 			}
    389 			*dst = 0;
    390 		}
    391 	}
    392 	sl_add(sl, NULL);
    393 	retvec = sl->sl_str;	/* XXX: nasty, knows stringlist internals */
    394 	free(sl);
    395 	return(retvec);
    396 }
    397 
    398 int
    399 hes_error()
    400 {
    401 	return(Hes_Errno);
    402 }
    403 
    404 void
    405 hes_free(hp)
    406 	char **hp;
    407 {
    408 	int i;
    409 	if (!hp)
    410 		return;
    411 	for (i = 0; hp[i]; i++)
    412 		free(hp[i]);
    413 	free(hp);
    414 }
    415