X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Freply.c;h=90314763f656b1f6a9cdaef4f08818b824593a83;hb=4b707d8b1701aec2cec7431d4656f771b96a9f00;hp=63b7033892a2b5e38faf93109f07bc911556948e;hpb=4353a5c47b202786905257e520fe570a570e67bc;p=adns.git

diff --git a/src/reply.c b/src/reply.c
index 63b7033..9031476 100644
--- a/src/reply.c
+++ b/src/reply.c
@@ -1,8 +1,330 @@
-/**/
+/*
+ * 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 <stdlib.h>
+#include <string.h>
 
 #include "internal.h"
+    
+void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
+		     int serv, struct timeval now) {
+  int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
+  int id, f1, f2, qdcount, ancount, nscount, arcount;
+  int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
+  int rrtype, rrclass, rdlength, rdstart;
+  int anstart, nsstart, arstart;
+  int ownermatched, l, nrrs;
+  const typeinfo *typei;
+  adns_query qu, nqu;
+  dns_rcode rcode;
+  adns_status st;
+  vbuf tempvb;
+  byte *newquery, *rrsdata;
+  parseinfo pai;
+  
+  if (dglen<DNS_HDRSIZE) {
+    adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
+    return;
+  }
+  cbyte= 0;
+  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&0x02;
+  flg_rd= f1&0x01;
+  flg_ra= f2&0x80;
+  rcode= (f2&0x0f);
+
+  cname_here= 0;
+  
+  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;
+  }
+  if (!qu) {
+    if (ads->iflags & adns_if_debug) {
+      adns__vbuf_init(&tempvb);
+      adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
+		  id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
+      adns__vbuf_free(&tempvb);
+    }
+    return;
+  }
+  anstart= qu->query_dglen;
+  arstart= -1;
+
+  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_rcodeformaterror);
+    return;
+  case rcode_servfail:
+    adns__query_fail(qu,adns_s_rcodeservfail);
+    return;
+  case rcode_notimp:
+    adns__warn(ads,serv,qu,"server claims not to implement our query");
+    adns__query_fail(qu,adns_s_rcodenotimplemented);
+    return;
+  case rcode_refused:
+    adns__warn(ads,serv,qu,"server refused our query");
+    adns__query_fail(qu,adns_s_rcoderefused);
+    return;
+  default:
+    adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
+    adns__query_fail(qu,adns_s_rcodeunknown);
+    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;
+  cbyte= anstart;
+  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); return; }
+    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, dgram,dglen,rrstart));
+      }
+      continue;
+    }
+    if (rrtype == adns_r_cname && /* fixme - implement adns_qf_nocname */
+	(qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
+      if (qu->flags & adns_qf_cname_forbid) {
+	adns__query_fail(qu,adns_s_prohibitedcname);
+	return;
+      } else if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
+	qu->cname_begin= rdstart;
+	qu->cname_dglen= dglen;
+	st= adns__parse_domain(ads,serv,qu, &qu->vb,
+			       qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0,
+			       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) { adns__query_fail(qu,adns_s_nomemory); return; }
+
+	qu->cname_dgram= adns__alloc_mine(qu,dglen);
+	memcpy(qu->cname_dgram,dgram,dglen);
+
+	memcpy(qu->answer->cname,qu->vb.buf,l);
+	cname_here= 1;
+	/* 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, 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);
+    }
+  }
+
+  /* We defer handling truncated responses here, in case there was a CNAME
+   * which we could use.
+   */
+  if (flg_tc) goto x_truncated;
+  
+  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 (cname_here) goto x_restartquery;
+
+    /* 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_invalidresponse);
+    }
+    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) { adns__query_fail(qu,adns_s_nomemory); return; }
+
+  typei= qu->typei;
+  cbyte= anstart;
+  rrsdata= qu->answer->rrs.bytes;
+
+  pai.ads= qu->ads;
+  pai.qu= qu;
+  pai.serv= serv;
+  pai.dgram= dgram;
+  pai.dglen= dglen;
+  pai.nsstart= nsstart;
+  pai.nscount= nscount;
+  pai.arcount= arcount;
+  pai.now= now;
+
+  for (rri=0, nrrs=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;
+    st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
+    if (st) { adns__query_fail(qu,st); return; }
+    if (rdstart==-1) goto x_truncated;
+    nrrs++;
+  }
+  assert(nrrs==wantedrrs);
+  qu->answer->nrrs= nrrs;
+
+  /* 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;
 
-void adns__procdgram(adns_state ads, const byte *dgram, int len, int serv) {
-  /* FIXME do something with incoming datagrams */
-  adns__diag(ads,serv,"received datagram size %d",len);
+ x_truncated:
+  
+  if (!flg_tc) {
+    adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
+    adns__query_fail(qu,adns_s_invalidresponse);
+    return;
+  }
+  qu->flags |= adns_qf_usevc;
+  
+ x_restartquery:
+  
+  if (qu->cname_dgram) {
+    st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
+			      qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
+			      qu->typei->type, qu->flags);
+    if (st) { adns__query_fail(qu,st); return; }
+    
+    newquery= realloc(qu->query_dgram,qu->vb.used);
+    if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
+    
+    qu->query_dgram= newquery;
+    qu->query_dglen= qu->vb.used;
+    memcpy(newquery,qu->vb.buf,qu->vb.used);
+  }
+  
+  adns__reset_cnameonly(qu);
+  adns__query_udp(qu,now);
 }