diff options
Diffstat (limited to 'adns-0.6/src/reply.c')
| -rw-r--r-- | adns-0.6/src/reply.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/adns-0.6/src/reply.c b/adns-0.6/src/reply.c new file mode 100644 index 0000000..246d52d --- /dev/null +++ b/adns-0.6/src/reply.c @@ -0,0 +1,357 @@ +/* + * reply.c + * - main handling and parsing routine for received datagrams + */ +/* + * This file is + * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk> + * + * It is part of adns, which is + * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk> + * Copyright (C) 1999 Tony Finch <dot@dotat.at> + * + * 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 "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, arstart; + 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 (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= 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) { + 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; + + if (viatcp) LIST_UNLINK(ads->tcpw,qu); + else LIST_UNLINK(ads->udpw,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,&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->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 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_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_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->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) */ + + /* 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) { + 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_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,&ttl, &rdlength,&rdstart, + &ownermatched); + assert(!st); assert(rrtype != -1); + if (rrclass != DNS_CLASS_IN || + rrtype != (qu->typei->type & adns__rrt_typemask) || + !ownermatched) + continue; + adns__update_expires(qu,ttl,now); + 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_childw; + 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_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); + } + + if (qu->state == query_tcpw) qu->state= query_tosend; + qu->retries= 0; + adns__reset_preserved(qu); + adns__query_send(qu,now); +} |