X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=adns.git;a=blobdiff_plain;f=src%2Freply.c;h=71586688bcba7ac4a238fab575d235c68dcdad0d;hp=63b7033892a2b5e38faf93109f07bc911556948e;hb=0ba0614a998909d8b4f51988d7a8af3ba369a5d9;hpb=4353a5c47b202786905257e520fe570a570e67bc

diff --git a/src/reply.c b/src/reply.c
index 63b7033..7158668 100644
--- a/src/reply.c
+++ b/src/reply.c
@@ -2,7 +2,449 @@
 
 #include "internal.h"
 
-void adns__procdgram(adns_state ads, const byte *dgram, int len, int serv) {
-  /* FIXME do something with incoming datagrams */
+typedef enum {
+  rcode_noerror,
+  rcode_formaterror,
+  rcode_servfail,
+  rcode_nxdomain,
+  rcode_notimp,
+  rcode_refused
+} dns_rcode;
+
+#define GETIL_B(cb) (dgram[*(cb)++])
+#define GET_B(cb,tv) ((tv)= GETIL_B((cb)))
+#define GET_W(cb,tv) ((tv)=0, (tv)|=(GETIL_B((cb))<<8), (tv)|=GETIL_B(cb), (tv))
+
+static void vbuf__append_quoted1035(vbuf *vb, const byte *buf, int len) {
+  char qbuf[10];
+  int i;
+  
+  while (len) {
+    qbuf[0]= 0;
+    for (i=0; i<len; i++) {
+      ch= buf[i];
+      if (ch == '.' || ch == '"' || ch == '(' || ch == ')' ||
+	  ch == '@' || ch == ';' || ch == '$') {
+	sprintf(qbuf,"\\%c",ch);
+	break;
+      } else if (ch <= ' ' || ch >= 127) {
+	sprintf(qbuf,"\\%03o",ch);
+	break;
+      }
+    }
+    if (!adns__vbuf_append(vb,buf,i) || !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
+      return adns_s_nolocalmem;
+    buf+= i; len-= i;
+  }
+}
+
+static adns_status get_label(const byte *dgram, int dglen, int *max_io,
+			     int *cbyte_io, int *lablen_r, int *labstart_r,
+			     int *namelen_io) {
+  /* If succeeds, *lablen_r may be set to -1 to indicate truncation/overrun */
+  int max, cbyte, lablen, namelen;
+
+  max= *max_io;
+  cbyte= *cbyte_io;
+  
+  for (;;) {
+    if (cbyte+2 > max) goto x_truncated;
+    GET_W(cbyte,lablen);
+    if (!(lablen & 0x0c000)) break;
+    if ((lablen & 0x0c000) != 0x0c000) return adns_s_unknownreply;
+    if (cbyte_io) { *cbyte_io= cbyte; cbyte_io= 0; }
+    cbyte= dgram+DNS_HDR_SIZE+(lablen&0x3fff);
+    *max_io= max= dglen;
+  }
+  if (labstart_r) *labstart_r= cbyte;
+  if (lablen) {
+    namelen= *namelen_io;
+    if (namelen) namelen++;
+    namelen+= lablen;
+    if (namelen > DNS_MAXDOMAIN) return adns_s_domaintoolong;
+    *namelen_io= namelen;
+    cbyte+= lablen;
+    if (cbyte > max) goto x_truncated;
+  }
+  if (cbyte_io) *cbyte_io= cbyte;
+  *lablen_r= lablen;
+  return adns_s_ok;
+
+ x_truncated:
+  *lablen_r= -1;
+  return adns_s_ok;
+}
+
+static adns_status get_domain_perm(adns_state ads, adns_query qu, int serv,
+				   const byte *dgram, int dglen,
+				   int *cbyte_io, int max, char **domain_r) {
+  /* Returns 0     for OK (*domain_r set) or truncated (*domain_r null)
+   *      or any other adns_s_* value.
+   */
+  int cbyte, sused, lablen, namelen;
+
+  /* If we follow a pointer we set cbyte_io to 0 to indicate that
+   * we've lost our original starting and ending points; we don't
+   * put the end of the pointed-to thing into the original *cbyte_io.
+   */
+  cbyte= *cbyte_io;
+  sused= qu->ans.used;
+  *domain_r= 0;
+  namelen= 0;
+  for (;;) {
+    st= get_label(dgram,dglen,&max, &cbyte,&lablen,&labstart,&namelen);
+    if (st) return st;
+    if (lablen<0) goto x_truncated;
+    if (!lablen) break;
+    if (qu->ans.used != sused)
+      if (!adns__vbuf_append(&qu->ans,".",1)) return adns_s_nolocalmem;
+    if (qu->flags & adns_qf_anyquote) {
+      if (!vbuf__append_quoted1035(&qu->ans,dgram+labstart,lablen))
+	return adns_s_nolocalmem;
+    } else {
+      if (!ctype_isalpha(dgram[labstart])) return adns_s_invaliddomain;
+      for (i= cbyte+1; i<cbyte+lablen; i++) {
+	ch= dgram[cbyte];
+	if (ch != '-' && !ctype_isalpha(ch) && !ctype_isdigit(ch))
+	  return adns_s_invaliddomain;
+      }
+      if (!adns__vbuf_append(&qu->ans,dgram+labstart,lablen))
+	return adns_s_nolocalmem;
+    }
+  }
+  if (cbyte_io) *cbyte_io= cbyte;
+  if (!adns__vbuf_append(&qu->ans,"",1)) return adns_s_nolocalmem;
+  *domain_r= qu->ans.buf+sused;
+  return adns_s_ok;
+
+ x_truncated:
+  return cbyte_io ? -1 : adns_s_serverfaulty;
+}
+    
+static adns_status get_domain_temp(adns_state ads, adns_query qu, int serv,
+				   const byte *dgram, int dglen,
+				   int *cbyte_io, int max, char **domain_r) {
+  int sused;
+  adns_status st;
+
+  sused= qu->ans.used;
+  st= get_domain_perm(ads,qu,serv,dgram,dglen,cbyte_io,max,domain_r);
+  qu->ans.used= sused;
+  return st;
+}
+
+static adns_status get_rr_temp(adns_state ads, adns_query qu, int serv,
+			       const byte *dgram, int dglen, int *cbyte_io,
+			       int *type_r, int *class_r, int *rdlen_r, int *rdstart_r,
+			       const byte *eo_dgram, int eo_dglen, int eo_cbyte,
+			       int *eo_matched_r) {
+  /* _s_ok can have *type_r == -1 and other output invalid, for truncation
+   * type_r and class_r must be !0, other _r may be 0.
+   * eo_dgram==0 for no comparison, otherwise all eo_ must be valid.
+   */
+  int cbyte, tmp, rdlen, mismatch;
+  int max, lablen, labstart, namelen;
+  int eo_max, eo_lablen, eo_labstart, eo_namelen;
+
+  cbyte= *cbyte_io;
+  mismatch= eo_dgram ? 1 : 0;
+
+  namelen= 0; eo_namelen= 0;
+  max= dglen; eo_max= eo_dglen;
+  for (;;) {
+    st= get_label(dgram,dglen,&max,
+		  &cbyte,&lablen,&labstart,&namelen);
+    if (st) return st;
+    if (lablen<0) goto x_truncated;
+
+    if (!mismatch) {
+      st= get_label(eo_dgram,eo_dglen,&eo_max,
+		    &eo_cbyte,&eo_lablen,&eo_labstart,&eo_namelen);
+      if (st) return st;
+      assert(eo_lablen>=0);
+      if (lablen != eo_lablen) mismatch= 1;
+      while (!mismatch && lablen-- > 0) {
+	ch= dgram[labstart++]; if (ctype_isalpha(ch)) ch &= ~32;
+	eo_ch= eo_dgram[eo_labstart++]; if (ctype_isalpha(eo_ch)) eo_ch &= ~32;
+	if (ch != eo_ch) mismatch= 1
+      }
+    }
+  }
+  if (eo_matched_r) *eo_matched_r= !mismatch;
+  
+  if (cbyte+10>len) goto x_truncated;
+  GET_W(cbyte,tmp); *type_r= tmp;
+  GET_W(cbyte,tmp); *class_r= tmp;
+  cbyte+= 4; /* we skip the TTL */
+  GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= tmp;
+  if (rdstart_r) *rdstart_r= cbyte;
+  cbyte+= rdlen;
+  if (cbyte>dglen) goto x_truncated;
+  *cbyte_io= cbyte;
+  return adns_s_ok;
+
+ x_truncated:
+  *type_r= -1;
+  return 0;;
+}
+    
+void adns__procdgram(adns_state ads, const byte *dgram, int dglen, int serv) {
+  int cbyte, anstart, rrstart, lablen, wantedrrs, get_t, cnamestart;
+
+  cbyte= 0;
+  
+  if (dglen<DNS_HDR_SIZE) {
+    adns__diag(ads,serv,"received datagram too short for message header (%d)",len);
+    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_HDR_SIZE);
+
+  flg_ra= f2&0x80;
+
+  if (f1&0x80) {
+    adns__diag(ads,serv,"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);
+    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; qu= nqu; qu++) {
+    nqu= qu->next;
+    if (qu->id != id) continue;
+    if (len < qu->querylen) continue;
+    if (memcmp(qu->querymsg+DNSHDRSIZE,dgram+DNSHDRSIZE,qu->querylen-DNSHDRSIZE))
+      continue;
+    break;
+  }
+  anstart= qu->querylen;
+  if (!qu) {
+    adns__debug(ads,serv,"reply not found (id=%02x)",id);
+    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);
+    return;
+  }
+
+  rcode= (f1&0x0f);
+  switch (rcode) {
+  case rcode_noerror:
+  case rcode_nxdomain:
+    break;
+  case rcode_formaterror:
+    adns__warn(ads,serv,"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_serverfailure);
+    return;
+  case rcode_notimp:
+    adns__warn(ads,serv,"server claims not to implement our query");
+    adns__query_fail(ads,qu,adns_s_notimplemented);
+    return;
+  case rcode_refused:
+    adns__warn(ads,serv,"server refused our query");
+    adns__query_fail(ads,qu,adns_s_refused);
+    return;
+  default:
+    adns__warn(ads,serv,"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) {
+      st= get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
+		      &rrtype,&rrclass,&rdlength,&rdstart,
+		      dgram,dglen,cnamestart, &ownermatched);
+    } else {
+      st= get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
+		      &rrtype,&rrclass,&rdlength,&rdstart,
+		      qu->querymsg,qu->querylen,DNS_HDR_SIZE, &ownermatched);
+    }
+    if (st) adns__query_fail(ads,qu,st);
+    if (rrtype == -1) goto x_truncated;
+
+    if (rrclass != DNS_CLASS_IN) {
+      adns__diag(ads,serv,"ignoring answer RR with wrong class %d (expected IN=%d)",
+		 rrclass,DNS_CLASS_IN);
+      continue;
+    }
+    if (!ownermatched) {
+      if (ads->iflag & adns_if_debug) {
+	st= get_domain_temp(ads,qu,serv, dgram,dglen,&rrstart,dglen, &cowner);
+	if (st) adns__debug(ads,serv,"ignoring RR with an irrelevant owner, code %d",st);
+	else adns__debug(ads,serv,"ignoring RR with an irrelevant owner \"%s\"",cowner);
+      }
+      continue;
+    }
+    if (!qu->cname &&
+	(qu->type & adns__rrt_typemask) != adns_cname &&
+	rrtype == adns_cname) { /* Ignore second and subsequent CNAMEs */
+      st= get_domain_perm(ads,qu,serv, dgram,dglen,
+			  &rdstart,rdstart+rdlength,&qu->cname);
+      if (st) return st;
+      if (!qu->cname) goto x_truncated;
+      /* 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->type & adns__rrt_typemask)) {
+      wantedrrs++;
+    } else {
+      adns__debug(ads,serv,"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= get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
+		      &rrtype,&rrclass, &rdlength,&rdstart, 0,0,0,0);
+      if (st) return st;
+      if (rrtype==-1) goto x_truncated;
+      if (rrclass != DNS_CLASS_IN) {
+	adns__diag(ads,serv,"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 then perhaps we should do our own CNAME lookup.
+     */
+    if (qu->cname) {
+      cname_recurse(ads,qu);
+      return;
+    }
+
+    /* Bloody hell, I thought we asked for recursion ? */
+    if (!flg_ra) {
+      adns__diag(ads,serv,"server is not willing to do recursive lookups for us");
+      adns__query_fail(ads,qu,adns_s_norecurse);
+      return;
+    }
+    adns__diag(ads,serv,"server claims to do recursion, but gave us a referral");
+    adns__query_fail(ads,qu,adns_s_serverfault);
+    return;
+  }
+
+  /* Now, we have some RRs which we wanted. */
+  rrs= 
+    
+    }
+    } else {
+      
+{ truncated(ads,qu,flg_ra); return; }    
+  
+	) {
+    if (type 
+      if (cbyte+lab
+      if (anstart > dgend) { truncated(ads,qu,f1); return; }
+  }
+    for    
+
+    /* Look for CNAMEs in the answer section */
+
+  }
+  
+    
+    adns__diag(ads,serv,"server refused our query");
+    
+    case rcode_
+    
+  case 0: /* NOERROR 
+    break;
+  case 1: /* Format error */
+  case 3: /* Name Error */
+  
+  qr= f1&0x80;
+  
+	      
   adns__diag(ads,serv,"received datagram size %d",len);
+
 }
+
+  while (
+  switch (type) {
+  case adns_r_a:  
+  adns_r_a_mf=                  adns_r_a|adns__qtf_masterfmt,
+  
+  adns_r_ns_raw=             2,
+  adns_r_ns=                    adns_r_ns_raw|adns__qtf_deref,
+  adns_r_ns_mf=                 adns_r_ns_raw|adns__qtf_masterfmt,
+  
+  adns_r_cname=              5,
+  adns_r_cname_mf=              adns_r_cname|adns__qtf_masterfmt,
+  
+  adns_r_soa_raw=            6,
+  adns_r_soa=                   adns_r_soa_raw|adns__qtf_mail822, 
+  adns_r_soa_mf=                adns_r_soa_raw|adns__qtf_masterfmt,
+  
+  adns_r_null=              10,
+  adns_r_null_mf=               adns_r_null|adns__qtf_masterfmt,
+  
+  adns_r_ptr_raw=           12,
+  adns_r_ptr=                   adns_r_ptr_raw|adns__qtf_deref,
+  adns_r_ptr_mf=                adns_r_ptr_raw|adns__qtf_masterfmt,
+  
+  adns_r_hinfo=             13,  
+  adns_r_hinfo_mf=              adns_r_hinfo|adns__qtf_masterfmt,
+  
+  adns_r_mx_raw=            15,
+  adns_r_mx=                    adns_r_mx_raw|adns__qtf_deref,
+  adns_r_mx_mf=                 adns_r_mx_raw|adns__qtf_masterfmt,
+  
+  adns_r_txt=               16,
+  adns_r_txt_mf=                adns_r_txt|adns__qtf_masterfmt,
+  
+  adns_r_rp_raw=            17,
+  adns_r_rp=                    adns_r_rp_raw|adns__qtf_mail822,
+  adns_r_rp_mf=                 adns_r_rp_raw|adns__qtf_masterfmt
+    
+