X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/adns/blobdiff_plain/4353a5c47b202786905257e520fe570a570e67bc..31144a72ed24e2d3cd62f5f1239e219737beeff4:/src/reply.c

diff --git a/src/reply.c b/src/reply.c
index 63b7033..0bcc3fa 100644
--- a/src/reply.c
+++ b/src/reply.c
@@ -2,7 +2,274 @@
 
 #include "internal.h"
 
-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);
+static void cname_recurse(adns_state ads, 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, flg_ra, flg_rd, flg_tc, opcode;
+  int rrtype, rrclass, rdlength, rdstart, ownermatched, ownerstart;
+  int anstart, nsstart, arstart;
+  int currentrrs;
+  adns_query qu, nqu;
+  dns_rcode rcode;
+  adns_status st;
+  vbuf vb;
+#error init and free vb properly
+  
+  if (dglen<DNS_HDRSIZE) {
+    adns__diag(ads,serv,"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,"server sent us a query, not a response");
+    return;
+  }
+  if (opcode) {
+    adns__diag(ads,serv,"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;
+  }
+  for (qu= ads->timew.head; qu; qu= nqu) {
+    nqu= qu->next;
+    if (qu->id != id) continue;
+    if (dglen < qu->querylen) continue;
+    if (memcmp(qu->querymsg+DNS_HDRSIZE,dgram+DNS_HDRSIZE,qu->querylen-DNS_HDRSIZE))
+      continue;
+    break;
+  }
+  assert(qu->cnameoff == -1);
+  anstart= qu->querylen;
+  if (!qu) {
+    adns__debug(ads,serv,"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(ads,qu,adns_s_serverfaulty);
+    return;
+  case rcode_servfail:
+    adns__query_fail(ads,qu,adns_s_servfail);
+    return;
+  case rcode_notimp:
+    adns__warn(ads,serv,qu,"server claims not to implement our query");
+    adns__query_fail(ads,qu,adns_s_notimplemented);
+    return;
+  case rcode_refused:
+    adns__warn(ads,serv,qu,"server refused our query");
+    adns__query_fail(ads,qu,adns_s_refused);
+    return;
+  default:
+    adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
+    adns__query_fail(ads,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;
+    if (qu->cname_dgram >= 0) {
+      st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
+		       &rrtype,&rrclass,&rdlength,&rdstart,
+		       qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
+    } else {
+      st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
+		       &rrtype,&rrclass,&rdlength,&rdstart,
+		       qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
+    }
+    if (st) adns__query_fail(ads,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,&vb,qu->flags,
+				      dgram,dglen,rrstart,dglen));
+      }
+      continue;
+    }
+    if (rrtype == adns_r_cname &&
+	(qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
+      if (!qu->cname_str) { /* Ignore second and subsequent CNAMEs */
+	qu->cname_begin= rdstart;
+	qu->cname_dgram= dgram;
+	qu->cname_dglen= dglen;
+	st= adns__parse_domain(ads,serv,&vb,qu->flags,
+			       dgram,dglen, &rdstart,rdstart+rdlength);
+	if (!vb.used) goto x_truncated;
+	if (st) { adns__query_fail(ads,qu,st); return; }
+	qu->cname_str= adns__vbuf_extractstring(&vb);
+	/* 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,&vb,qu->flags,
+				      dgram,dglen, rdstart,rdstart+rdlength),
+		    qu->cname_str);
+      }
+    } 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_finish(ads,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(ads,serv, dgram,dglen,&cbyte,
+		       &rrtype,&rrclass,&rdlength,&rdstart,
+		       0,0,0,0);
+      if (st) { adns__query_fail(ads,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_finish(ads,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(ads,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(ads,qu,adns_s_norecurse);
+    } else {
+      adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
+      adns__query_fail(ads,qu,adns_s_serverfaulty);
+    }
+    return;
+  }
+
+  /* Now, we have some RRs which we wanted. */
+
+  if (!adns__vbuf_ensure(&qu->ansbuf,qu->typei->rrsz*wantedrrs)) {
+    adns__query_fail(ads,qu,adns_s_nolocalmem);
+    return;
+  }
+
+  cbyte= anstart;
+  currentrrs= 0;
+  arstart= -1;
+  qu->ansbuf.used= 0;
+  for (rri=0; rri<ancount; rri++) {
+    if (qu->cname_dgram >= 0) {
+      st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
+		       &rrtype,&rrclass,&rdlength,&rdstart,
+		       qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
+    } else {
+      st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
+		       &rrtype,&rrclass,&rdlength,&rdstart,
+		       qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
+    }
+    assert(!st); assert(rrtype != -1);
+    if (rrclass != DNS_CLASS_IN ||
+	rrtype != (qu->typei->type & adns__rrt_typemask) ||
+	!ownermatched)
+      continue;
+    assert(currentrrs<wantedrrs);
+    qu->ansbuf.used += quj->typei->rrsz;
+    st= qu->typei->parse(ads,qu,serv,&vb,
+			 dgram,dglen, &rdstart,rdstart+rdlength,
+			 (void*)(qu->ansbuf.buf+qu->ansbuf.used));
+    if (st) { adns__query_fail(ads,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_finish(ads,qu,adns_s_ok);
+  return;
+
+x_truncated:
+  if (!flg_tc) {
+    adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
+    adns__query_fail(ads,qu,adns_s_serverfaulty);
+    return;
+  }
+  if (qu->cname_dgram) { cname_recurse(ads,qu,adns_qf_usevc); return; }
+  ans= (adns_answer*)qu->ans.buf;
+  ans->nrrs= 0;
+  qu->ans.used= sizeof(adns_answer);
+  qu->flags |= adns_qf_usevc;
+  adns__query_udp(ads,qu,now);
 }