[adns] / src / reply.c

/*
 * reply.c
 * - main handling and parsing routine for received datagrams
 */
/*
 *  This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software Foundation,
 *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 */

#include "internal.h"

static void cname_recurse(adns_query qu, adns_queryflags xflags) {
  abort(); /* FIXME */
}
    
void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
		     int serv, struct timeval now) {
  int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
  int id, f1, f2, qdcount, ancount, nscount, arcount;
  int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
  int rrtype, rrclass, rdlength, rdstart, ownermatched, l;
  int anstart, nsstart, arstart;
  adns_query qu, nqu;
  dns_rcode rcode;
  adns_status st;
  
  if (dglen<DNS_HDRSIZE) {
    adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
    return;
  }
  GET_W(cbyte,id);
  GET_B(cbyte,f1);
  GET_B(cbyte,f2);
  GET_W(cbyte,qdcount);
  GET_W(cbyte,ancount);
  GET_W(cbyte,nscount);
  GET_W(cbyte,arcount);
  assert(cbyte == DNS_HDRSIZE);

  flg_qr= f1&0x80;
  opcode= (f1&0x78)>>3;
  flg_tc= f1&0x20;
  flg_rd= f1&0x01;
  flg_ra= f2&0x80;
  rcode= (f1&0x0f);

  if (flg_qr) {
    adns__diag(ads,serv,0,"server sent us a query, not a response");
    return;
  }
  if (opcode) {
    adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
    return;
  }
  if (!qdcount) {
    adns__diag(ads,serv,0,"server sent reply without quoting our question");
    return;
  } else if (qdcount>1) {
    adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
	       qdcount);
    return;
  }
  for (qu= ads->timew.head; qu; qu= nqu) {
    nqu= qu->next;
    if (qu->id != id) continue;
    if (dglen < qu->query_dglen) continue;
    if (memcmp(qu->query_dgram+DNS_HDRSIZE,
	       dgram+DNS_HDRSIZE,
	       qu->query_dglen-DNS_HDRSIZE))
      continue;
    break;
  }
  anstart= qu->query_dglen;
  if (!qu) {
    adns__debug(ads,serv,0,"reply not found (id=%02x)",id);
    return;
  }

  LIST_UNLINK(ads->timew,qu);
  /* We're definitely going to do something with this query now */
  
  switch (rcode) {
  case rcode_noerror:
  case rcode_nxdomain:
    break;
  case rcode_formaterror:
    adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
    adns__query_fail(qu,adns_s_serverfaulty);
    return;
  case rcode_servfail:
    adns__query_fail(qu,adns_s_servfail);
    return;
  case rcode_notimp:
    adns__warn(ads,serv,qu,"server claims not to implement our query");
    adns__query_fail(qu,adns_s_notimplemented);
    return;
  case rcode_refused:
    adns__warn(ads,serv,qu,"server refused our query");
    adns__query_fail(qu,adns_s_refused);
    return;
  default:
    adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
    adns__query_fail(qu,adns_s_reasonunknown);
    return;
  }

  /* Now, take a look at the answer section, and see if it is complete.
   * If it has any CNAMEs we stuff them in the answer.
   */
  wantedrrs= 0;
  for (rri= 0; rri<ancount; rri++) {
    rrstart= cbyte;
    st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
		     &rrtype,&rrclass,&rdlength,&rdstart,
		     &ownermatched);
    if (st) adns__query_fail(qu,st);
    if (rrtype == -1) goto x_truncated;

    if (rrclass != DNS_CLASS_IN) {
      adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
		 rrclass,DNS_CLASS_IN);
      continue;
    }
    if (!ownermatched) {
      if (ads->iflags & adns_if_debug) {
	adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
		    adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
				      dgram,dglen,rrstart));
      }
      continue;
    }
    if (rrtype == adns_r_cname &&
	(qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
      if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
	qu->cname_dgram= adns__alloc_mine(qu,dglen);
	if (!qu->cname_dgram) return;
	qu->cname_begin= rdstart;
	qu->cname_dglen= dglen;
	st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
			       dgram,dglen, &rdstart,rdstart+rdlength);
	if (!qu->vb.used) goto x_truncated;
	if (st) { adns__query_fail(qu,st); return; }
	l= strlen(qu->vb.buf)+1;
	qu->answer->cname= adns__alloc_interim(qu,l);
	if (!qu->answer->cname) return;
	memcpy(qu->answer->cname,qu->vb.buf,l);
	/* If we find the answer section truncated after this point we restart
	 * the query at the CNAME; if beforehand then we obviously have to use
	 * TCP.  If there is no truncation we can use the whole answer if
	 * it contains the relevant info.
	 */
      } else {
	adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
		    adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
				      dgram,dglen,rdstart),
		    qu->answer->cname);
      }
    } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
      wantedrrs++;
    } else {
      adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
    }
  }

  /* If we got here then the answer section is intact. */
  nsstart= cbyte;

  if (!wantedrrs) {
    /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
    
    if (rcode == rcode_nxdomain) {
      adns__query_fail(qu,adns_s_nxdomain);
      return;
    }

    /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
    foundsoa= 0; foundns= 0;
    for (rri= 0; rri<nscount; rri++) {
      rrstart= cbyte;
      st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
		       &rrtype,&rrclass,&rdlength,&rdstart, 0);
      if (st) { adns__query_fail(qu,st); return; }
      if (rrtype==-1) goto x_truncated;
      if (rrclass != DNS_CLASS_IN) {
	adns__diag(ads,serv,qu,
		   "ignoring authority RR with wrong class %d (expected IN=%d)",
		   rrclass,DNS_CLASS_IN);
	continue;
      }
      if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
      else if (rrtype == adns_r_ns_raw) { foundns= 1; }
    }

    if (foundsoa || !foundns) {
      /* Aha !  A NODATA response, good. */
      adns__query_fail(qu,adns_s_nodata);
      return;
    }

    /* Now what ?  No relevant answers, no SOA, and at least some NS's.
     * Looks like a referral.  Just one last chance ... if we came across
     * a CNAME in this datagram then we should probably do our own CNAME
     * lookup now in the hope that we won't get a referral again.
     */
    if (qu->cname_dgram == dgram) { cname_recurse(qu,0); return; }

    /* Bloody hell, I thought we asked for recursion ? */
    if (flg_rd) {
      adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
    }
    if (!flg_ra) {
      adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
      adns__query_fail(qu,adns_s_norecurse);
    } else {
      adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
      adns__query_fail(qu,adns_s_serverfaulty);
    }
    return;
  }

  /* Now, we have some RRs which we wanted. */

  qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
  if (!qu->answer->rrs.untyped) return;

  cbyte= anstart;
  arstart= -1;
  for (rri=0; rri<ancount; rri++) {
    st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
		     &rrtype,&rrclass,&rdlength,&rdstart,
		     &ownermatched);
    assert(!st); assert(rrtype != -1);
    if (rrclass != DNS_CLASS_IN ||
	rrtype != (qu->typei->type & adns__rrt_typemask) ||
	!ownermatched)
      continue;
    assert(qu->answer->nrrs<wantedrrs);
    st= qu->typei->parse(qu,serv,
			 dgram,dglen, rdstart,rdstart+rdlength,
			 qu->answer->rrs.bytes+qu->answer->nrrs*qu->typei->rrsz);
    if (st) { adns__query_fail(qu,st); return; }
    if (rdstart==-1) goto x_truncated;
  }

  /* This may have generated some child queries ... */
  if (qu->children.head) {
    qu->state= query_child;
    LIST_LINK_TAIL(ads->childw,qu);
    return;
  }

  adns__query_done(qu);
  return;

 x_truncated:
  if (!flg_tc) {
    adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
    adns__query_fail(qu,adns_s_serverfaulty);
    return;
  }
  if (qu->cname_dgram) { cname_recurse(qu,adns_qf_usevc); return; }
  adns__reset_cnameonly(qu);
  qu->flags |= adns_qf_usevc;
  adns__query_udp(qu,now);
}
Commit	Line	Data
e576be50	1	/*
	2	* reply.c
	3	* - main handling and parsing routine for received datagrams
	4	*/
	5	/*
	6	* This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2, or (at your option)
	11	* any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License
	19	* along with this program; if not, write to the Free Software Foundation,
	20	* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	21	*/
4353a5c4	22
	23	#include "internal.h"
	24
3955725c	25	static void cname_recurse(adns_query qu, adns_queryflags xflags) {
98a3f706	26	abort(); /* FIXME */
b9de380c	27	}
b9de380c	28
98a3f706	29	void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
	30	int serv, struct timeval now) {
	31	int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
3955725c	32	int id, f1, f2, qdcount, ancount, nscount, arcount;
	33	int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
	34	int rrtype, rrclass, rdlength, rdstart, ownermatched, l;
98a3f706	35	int anstart, nsstart, arstart;
98a3f706	36	adns_query qu, nqu;
98a3f706	37	dns_rcode rcode;
b9de380c	38	adns_status st;
ec477b9e	39
98a3f706	40	if (dglen<DNS_HDRSIZE) {
3955725c	41	adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
ec477b9e	42	return;
ec477b9e	43	}
b9de380c	44	GET_W(cbyte,id);
	45	GET_B(cbyte,f1);
	46	GET_B(cbyte,f2);
	47	GET_W(cbyte,qdcount);
	48	GET_W(cbyte,ancount);
	49	GET_W(cbyte,nscount);
	50	GET_W(cbyte,arcount);
98a3f706	51	assert(cbyte == DNS_HDRSIZE);
ec477b9e	52
31144a72	53	flg_qr= f1&0x80;
31144a72	54	opcode= (f1&0x78)>>3;
98a3f706	55	flg_tc= f1&0x20;
31144a72	56	flg_rd= f1&0x01;
0ba0614a	57	flg_ra= f2&0x80;
31144a72	58	rcode= (f1&0x0f);
0ba0614a	59
31144a72	60	if (flg_qr) {
3955725c	61	adns__diag(ads,serv,0,"server sent us a query, not a response");
ec477b9e	62	return;
ec477b9e	63	}
31144a72	64	if (opcode) {
3955725c	65	adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
ec477b9e	66	return;
	67	}
	68	if (!qdcount) {
3955725c	69	adns__diag(ads,serv,0,"server sent reply without quoting our question");
ec477b9e	70	return;
ec477b9e	71	} else if (qdcount>1) {
3955725c	72	adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
ec477b9e	73	qdcount);
	74	return;
	75	}
98a3f706	76	for (qu= ads->timew.head; qu; qu= nqu) {
ec477b9e	77	nqu= qu->next;
ec477b9e	78	if (qu->id != id) continue;
3955725c	79	if (dglen < qu->query_dglen) continue;
	80	if (memcmp(qu->query_dgram+DNS_HDRSIZE,
	81	dgram+DNS_HDRSIZE,
	82	qu->query_dglen-DNS_HDRSIZE))
b9de380c	83	continue;
ec477b9e	84	break;
ec477b9e	85	}
3955725c	86	anstart= qu->query_dglen;
ec477b9e	87	if (!qu) {
3955725c	88	adns__debug(ads,serv,0,"reply not found (id=%02x)",id);
ec477b9e	89	return;
ec477b9e	90	}
98a3f706	91
	92	LIST_UNLINK(ads->timew,qu);
	93	/* We're definitely going to do something with this query now */
	94
b9de380c	95	switch (rcode) {
	96	case rcode_noerror:
	97	case rcode_nxdomain:
ec477b9e	98	break;
b9de380c	99	case rcode_formaterror:
31144a72	100	adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
3955725c	101	adns__query_fail(qu,adns_s_serverfaulty);
ec477b9e	102	return;
98a3f706	103	case rcode_servfail:
3955725c	104	adns__query_fail(qu,adns_s_servfail);
ec477b9e	105	return;
b9de380c	106	case rcode_notimp:
31144a72	107	adns__warn(ads,serv,qu,"server claims not to implement our query");
3955725c	108	adns__query_fail(qu,adns_s_notimplemented);
b9de380c	109	return;
b9de380c	110	case rcode_refused:
31144a72	111	adns__warn(ads,serv,qu,"server refused our query");
3955725c	112	adns__query_fail(qu,adns_s_refused);
b9de380c	113	return;
b9de380c	114	default:
31144a72	115	adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
3955725c	116	adns__query_fail(qu,adns_s_reasonunknown);
b9de380c	117	return;
	118	}
	119
	120	/* Now, take a look at the answer section, and see if it is complete.
	121	* If it has any CNAMEs we stuff them in the answer.
	122	*/
	123	wantedrrs= 0;
	124	for (rri= 0; rri<ancount; rri++) {
	125	rrstart= cbyte;
3955725c	126	st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
	127	&rrtype,&rrclass,&rdlength,&rdstart,
	128	&ownermatched);
	129	if (st) adns__query_fail(qu,st);
0ba0614a	130	if (rrtype == -1) goto x_truncated;
0ba0614a	131
b9de380c	132	if (rrclass != DNS_CLASS_IN) {
31144a72	133	adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
b9de380c	134	rrclass,DNS_CLASS_IN);
	135	continue;
	136	}
0ba0614a	137	if (!ownermatched) {
98a3f706	138	if (ads->iflags & adns_if_debug) {
31144a72	139	adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
3955725c	140	adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
3955725c	141	dgram,dglen,rrstart));
0ba0614a	142	}
b9de380c	143	continue;
b9de380c	144	}
31144a72	145	if (rrtype == adns_r_cname &&
31144a72	146	(qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
3955725c	147	if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
	148	qu->cname_dgram= adns__alloc_mine(qu,dglen);
	149	if (!qu->cname_dgram) return;
31144a72	150	qu->cname_begin= rdstart;
31144a72	151	qu->cname_dglen= dglen;
3955725c	152	st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
31144a72	153	dgram,dglen, &rdstart,rdstart+rdlength);
3955725c	154	if (!qu->vb.used) goto x_truncated;
	155	if (st) { adns__query_fail(qu,st); return; }
	156	l= strlen(qu->vb.buf)+1;
	157	qu->answer->cname= adns__alloc_interim(qu,l);
8e5b0abb	158	if (!qu->answer->cname) return;
3955725c	159	memcpy(qu->answer->cname,qu->vb.buf,l);
31144a72	160	/* If we find the answer section truncated after this point we restart
	161	* the query at the CNAME; if beforehand then we obviously have to use
	162	* TCP. If there is no truncation we can use the whole answer if
	163	* it contains the relevant info.
	164	*/
	165	} else {
	166	adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
3955725c	167	adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
	168	dgram,dglen,rdstart),
	169	qu->answer->cname);
31144a72	170	}
98a3f706	171	} else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
b9de380c	172	wantedrrs++;
b9de380c	173	} else {
31144a72	174	adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
b9de380c	175	}
	176	}
	177
	178	/* If we got here then the answer section is intact. */
	179	nsstart= cbyte;
	180
	181	if (!wantedrrs) {
	182	/* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
	183
	184	if (rcode == rcode_nxdomain) {
3955725c	185	adns__query_fail(qu,adns_s_nxdomain);
b9de380c	186	return;
	187	}
	188
	189	/* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
0ba0614a	190	foundsoa= 0; foundns= 0;
b9de380c	191	for (rri= 0; rri<nscount; rri++) {
0ba0614a	192	rrstart= cbyte;
3955725c	193	st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
	194	&rrtype,&rrclass,&rdlength,&rdstart, 0);
	195	if (st) { adns__query_fail(qu,st); return; }
0ba0614a	196	if (rrtype==-1) goto x_truncated;
0ba0614a	197	if (rrclass != DNS_CLASS_IN) {
31144a72	198	adns__diag(ads,serv,qu,
31144a72	199	"ignoring authority RR with wrong class %d (expected IN=%d)",
0ba0614a	200	rrclass,DNS_CLASS_IN);
	201	continue;
	202	}
	203	if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
	204	else if (rrtype == adns_r_ns_raw) { foundns= 1; }
b9de380c	205	}
0ba0614a	206
	207	if (foundsoa \|\| !foundns) {
	208	/* Aha ! A NODATA response, good. */
3955725c	209	adns__query_fail(qu,adns_s_nodata);
0ba0614a	210	return;
	211	}
	212
	213	/* Now what ? No relevant answers, no SOA, and at least some NS's.
	214	* Looks like a referral. Just one last chance ... if we came across
31144a72	215	* a CNAME in this datagram then we should probably do our own CNAME
31144a72	216	* lookup now in the hope that we won't get a referral again.
0ba0614a	217	*/
3955725c	218	if (qu->cname_dgram == dgram) { cname_recurse(qu,0); return; }
0ba0614a	219
0ba0614a	220	/* Bloody hell, I thought we asked for recursion ? */
31144a72	221	if (flg_rd) {
	222	adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
	223	}
0ba0614a	224	if (!flg_ra) {
31144a72	225	adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
3955725c	226	adns__query_fail(qu,adns_s_norecurse);
31144a72	227	} else {
31144a72	228	adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
3955725c	229	adns__query_fail(qu,adns_s_serverfaulty);
0ba0614a	230	}
b9de380c	231	return;
	232	}
	233
0ba0614a	234	/* Now, we have some RRs which we wanted. */
b9de380c	235
3955725c	236	qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
3955725c	237	if (!qu->answer->rrs.untyped) return;
98a3f706	238
98a3f706	239	cbyte= anstart;
98a3f706	240	arstart= -1;
98a3f706	241	for (rri=0; rri<ancount; rri++) {
3955725c	242	st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
	243	&rrtype,&rrclass,&rdlength,&rdstart,
	244	&ownermatched);
98a3f706	245	assert(!st); assert(rrtype != -1);
98a3f706	246	if (rrclass != DNS_CLASS_IN \|\|
31144a72	247	rrtype != (qu->typei->type & adns__rrt_typemask) \|\|
31144a72	248	!ownermatched)
98a3f706	249	continue;
3955725c	250	assert(qu->answer->nrrs<wantedrrs);
	251	st= qu->typei->parse(qu,serv,
	252	dgram,dglen, rdstart,rdstart+rdlength,
	253	qu->answer->rrs.bytes+qu->answer->nrrs*qu->typei->rrsz);
	254	if (st) { adns__query_fail(qu,st); return; }
31144a72	255	if (rdstart==-1) goto x_truncated;
98a3f706	256	}
b9de380c	257
98a3f706	258	/* This may have generated some child queries ... */
	259	if (qu->children.head) {
	260	qu->state= query_child;
	261	LIST_LINK_TAIL(ads->childw,qu);
	262	return;
b9de380c	263	}
ec477b9e	264
3955725c	265	adns__query_done(qu);
98a3f706	266	return;
0ba0614a	267
e576be50	268	x_truncated:
98a3f706	269	if (!flg_tc) {
31144a72	270	adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
3955725c	271	adns__query_fail(qu,adns_s_serverfaulty);
98a3f706	272	return;
98a3f706	273	}
3955725c	274	if (qu->cname_dgram) { cname_recurse(qu,adns_qf_usevc); return; }
3955725c	275	adns__reset_cnameonly(qu);
98a3f706	276	qu->flags \|= adns_qf_usevc;
3955725c	277	adns__query_udp(qu,now);
98a3f706	278	}