X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=adns.git;a=blobdiff_plain;f=src%2Freply.c;h=486dd37ea997bc6695ce56add139f66ae82b2c77;hp=6aacd2b820c160c9706e5919c0a00a80b98aa3a6;hb=ced2f0cf2a351f8d30b800c915eeee042658d235;hpb=ec477b9e0921b754a2edcee988d16a6339be1708

diff --git a/src/reply.c b/src/reply.c
index 6aacd2b..486dd37 100644
--- a/src/reply.c
+++ b/src/reply.c
@@ -1,84 +1,389 @@
-/**/
+/*
+ * reply.c
+ * - main handling and parsing routine for received datagrams
+ */
+/*
+ *  This file is part of adns, which is
+ *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
+ *    Copyright (C) 1999-2000,2003,2006  Tony Finch
+ *    Copyright (C) 1991 Massachusetts Institute of Technology
+ *  (See the file INSTALL for full details.)
+ *  
+ *  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 3, 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.
+ */
 
-#include "internal.h"
+#include <stdlib.h>
 
-typedef enum {
-  rcode_noerror,
-  rcode_formaterror,
-  rcode_serverfail,
-  rcode_nxdomain,
-  rcode_notimp,
-  rcode_refused
-} dns_rcode;
-
-void adns__procdgram(adns_state ads, const byte *dgram, int len, int serv) {
-  unsigned char *rpp;
+#include "internal.h"
+    
+void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
+		     int serv, int viatcp, 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;
+  int ownermatched, l, nrrs;
+  unsigned long ttl, soattl;
+  const typeinfo *typei;
+  adns_query qu, nqu;
+  dns_rcode rcode;
+  adns_status st;
+  vbuf tempvb;
+  byte *newquery, *rrsdata;
+  parseinfo pai;
   
-  if (len<12) {
-    adns__diag(ads,serv,"received datagram too short for message header (%d)",len);
+  if (dglen<DNS_HDRSIZE) {
+    adns__diag(ads,serv,0,"received datagram"
+	       " too short for message header (%d)",dglen);
     return;
   }
-  id= GFREPLYW;
-  f1= GFREPLYB;
-  f2= GFREPLYB;
-  qdcount= GFREPLYW;
-  ancount= GFREPLYW;
-  nscount= GFREPLYW;
-  arcount= GFREPLYW;
-
-  if (f1&0x80) {
-    adns__diag(ads,serv,"server sent us a query, not a response");
+  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 (f1&0x70) {
-    adns__diag(ads,serv,"server sent us unknown opcode %d (wanted 0=QUERY)",
-	       (f1>>4)&0x70);
+  if (opcode) {
+    adns__diag(ads,serv,0,"server sent us unknown opcode"
+	       " %d (wanted 0=QUERY)",opcode);
     return;
   }
-  if (!qdcount) {
-    adns__diag(ads,serv,"server sent reply without quoting our question");
-    return;
-  } else if (qdcount>1) {
-    adns__diag(ads,serv,"server claimed to answer %d questions with one message",
-	       qdcount);
-    return;
+
+  qu= 0;
+  /* See if we can find the relevant query, or leave qu=0 otherwise ... */   
+
+  if (qdcount == 1) {
+    for (qu= viatcp ? ads->tcpw.head : ads->udpw.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;
+      if (viatcp) {
+	assert(qu->state == query_tcpw);
+      } else {
+	assert(qu->state == query_tosend);
+	if (!(qu->udpsent & (1<<serv))) continue;
+      }
+      break;
+    }
+    if (qu) {
+      /* We're definitely going to do something with this query now */
+      if (viatcp) LIST_UNLINK(ads->tcpw,qu);
+      else LIST_UNLINK(ads->udpw,qu);
+    }
   }
-  for (qu= ads->timew; qu= nqu; qu++) {
-    nqu= qu->next;
-    if (qu->id != id) continue;
-    if (len < qu->querylen) continue;
-    if (memcmp(qu->querymsg+12,rpp,qu->querylen-12)) continue;
+  
+  /* If we're going to ignore the packet, we return as soon as we have
+   * failed the query (if any) and printed the warning message (if
+   * any).
+   */
+  switch (rcode) {
+  case rcode_noerror:
+  case rcode_nxdomain:
     break;
+  case rcode_formaterror:
+    adns__warn(ads,serv,qu,"server cannot understand our query"
+	       " (Format Error)");
+    if (qu) adns__query_fail(qu,adns_s_rcodeformaterror);
+    return;
+  case rcode_servfail:
+    if (qu) adns__query_fail(qu,adns_s_rcodeservfail);
+    else adns__debug(ads,serv,qu,"server failure on unidentifiable query");
+    return;
+  case rcode_notimp:
+    adns__warn(ads,serv,qu,"server claims not to implement our query");
+    if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented);
+    return;
+  case rcode_refused:
+    adns__debug(ads,serv,qu,"server refused our query");
+    if (qu) adns__query_fail(qu,adns_s_rcoderefused);
+    return;
+  default:
+    adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
+    if (qu) adns__query_fail(qu,adns_s_rcodeunknown);
+    return;
   }
+
   if (!qu) {
-    adns__debug(ads,serv,"reply not found (id=%02x)",id);
+    if (!qdcount) {
+      adns__diag(ads,serv,0,"server sent reply without quoting our question");
+    } else if (qdcount>1) {
+      adns__diag(ads,serv,0,"server claimed to answer %d"
+		 " questions with one message", qdcount);
+    } else 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;
   }
-  if (!(f2&0x80)) {
-    adns__diag(ads,serv,"server is not willing to do recursive lookups for us");
-    adns__query_fail(ads,qu,adns_s_norecurse);
+
+  /* We're definitely going to do something with this packet and this
+   * query now. */
+  
+  anstart= qu->query_dglen;
+
+  /* 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,&ttl, &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 &&
+	(qu->answer->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 CNAME(s) */
+	adns__debug(ads,serv,qu,"allegedly canonical name %s"
+		    " is actually alias for %s", qu->answer->cname,
+		    adns__diag_domain(ads,serv,qu, &qu->vb,
+				      dgram,dglen,rdstart));
+	adns__query_fail(qu,adns_s_prohibitedcname);
+	return;
+      } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
+	adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
+		    adns__diag_domain(ads,serv,qu, &qu->vb,
+				      dgram,dglen,rdstart));
+      } else {
+	qu->cname_begin= rdstart;
+	qu->cname_dglen= dglen;
+	st= adns__parse_domain(ads,serv,qu, &qu->vb,
+			       qu->flags & adns_qf_quotefail_cname
+			       ? 0 : pdf_quoteok,
+			       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_preserved(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;
+	adns__update_expires(qu,ttl,now);
+	/* 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 if (rrtype == (qu->answer->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) */
+
+    /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records
+     * in authority section */
+    foundsoa= 0; soattl= 0; foundns= 0;
+    for (rri= 0; rri<nscount; rri++) {
+      rrstart= cbyte;
+      st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
+		       &rrtype,&rrclass,&ttl, &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; soattl= ttl; break; }
+      else if (rrtype == adns_r_ns_raw) { foundns= 1; }
+    }
+    
+    if (rcode == rcode_nxdomain) {
+      /* We still wanted to look for the SOA so we could find the TTL. */
+      adns__update_expires(qu,soattl,now);
+
+      if (qu->flags & adns_qf_search && !qu->cname_dgram) {
+	adns__search_next(ads,qu,now);
+      } else {
+	adns__query_fail(qu,adns_s_nxdomain);
+      }
+      return;
+    }
+
+    if (foundsoa || !foundns) {
+      /* Aha !  A NODATA response, good. */
+      adns__update_expires(qu,soattl,now);
+      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_ra) {
+      adns__diag(ads,serv,qu,"server is not willing"
+		 " to do recursive lookups for us");
+      adns__query_fail(qu,adns_s_norecurse);
+    } else {
+      if (!flg_rd)
+	adns__diag(ads,serv,qu,"server thinks"
+		   " we didn't ask for recursive lookup");
+      else
+	adns__debug(ads,serv,qu,"server claims to do recursion,"
+		    " but gave us a referral");
+      adns__query_fail(qu,adns_s_invalidresponse);
+    }
     return;
   }
-  if (!(f1&0x01)) {
-    adns__diag(ads,serv,"server thinks we didn't ask for recursive lookup");
-    adns__query_fail(ads,qu,adns_s_serverfaulty);
+
+  /* Now, we have some RRs which we wanted. */
+
+  qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->answer->rrsz*wantedrrs);
+  if (!qu->answer->rrs.untyped) {
+    adns__query_fail(qu,adns_s_nomemory);
     return;
   }
-  switch (f1&0x0f) {
-  case 0: /* NOERROR */
-    break;
-  case 1: /* Format error */
-    adns__diag(ads,serv,"server cannot understand our query (Format Error)");
-    adns__query_fail(ads,qu,adns_s_serverfaulty);
+
+  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,&ttl, &rdlength,&rdstart,
+		     &ownermatched);
+    assert(!st); assert(rrtype != -1);
+    if (rrclass != DNS_CLASS_IN ||
+	rrtype != (qu->answer->type & adns_rrt_typemask) ||
+	!ownermatched)
+      continue;
+    adns__update_expires(qu,ttl,now);
+    st= typei->parse(&pai, rdstart,rdstart+rdlength,
+		     rrsdata+nrrs*qu->answer->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_childw;
+    LIST_LINK_TAIL(ads->childw,qu);
     return;
-  case 2: /* Server failure */
-    adns__query_fail(ads,qu,adns_s_serverfailure);
+  }
+  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_invalidresponse);
     return;
-  case 3: /* Name Error */
+  }
+  qu->flags |= adns_qf_usevc;
   
-  qr= f1&0x80;
+ 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->answer->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__diag(ads,serv,"received datagram size %d",len);
-
+  if (qu->state == query_tcpw) qu->state= query_tosend;
+  qu->retries= 0;
+  adns__reset_preserved(qu);
+  adns__query_send(qu,now);
 }