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dname.c
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dname.h
(11.9 KB)
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msgencode.c
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msgencode.h
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msgparse.c
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msgparse.h
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msgreply.c
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msgreply.h
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packed_rrset.c
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packed_rrset.h
(15.91 KB)
Editing: msgencode.c
/* * util/data/msgencode.c - Encode DNS messages, queries and replies. * * Copyright (c) 2007, NLnet Labs. All rights reserved. * * This software is open source. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of the NLNET LABS nor the names of its contributors may * be used to endorse or promote products derived from this software without * specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /** * \file * * This file contains a routines to encode DNS messages. */ #include "config.h" #include "util/data/msgencode.h" #include "util/data/msgreply.h" #include "util/data/msgparse.h" #include "util/data/dname.h" #include "util/log.h" #include "util/regional.h" #include "util/net_help.h" #include "sldns/sbuffer.h" #include "services/localzone.h" #ifdef HAVE_TIME_H #include <time.h> #endif #include <sys/time.h> /** return code that means the function ran out of memory. negative so it does * not conflict with DNS rcodes. */ #define RETVAL_OUTMEM -2 /** return code that means the data did not fit (completely) in the packet */ #define RETVAL_TRUNC -4 /** return code that means all is peachy keen. Equal to DNS rcode NOERROR */ #define RETVAL_OK 0 /** * Data structure to help domain name compression in outgoing messages. * A tree of dnames and their offsets in the packet is kept. * It is kept sorted, not canonical, but by label at least, so that after * a lookup of a name you know its closest match, and the parent from that * closest match. These are possible compression targets. * * It is a binary tree, not a rbtree or balanced tree, as the effort * of keeping it balanced probably outweighs usefulness (given typical * DNS packet size). */ struct compress_tree_node { /** left node in tree, all smaller to this */ struct compress_tree_node* left; /** right node in tree, all larger than this */ struct compress_tree_node* right; /** the parent node - not for tree, but zone parent. One less label */ struct compress_tree_node* parent; /** the domain name for this node. Pointer to uncompressed memory. */ uint8_t* dname; /** number of labels in domain name, kept to help compare func. */ int labs; /** offset in packet that points to this dname */ size_t offset; }; /** * Find domain name in tree, returns exact and closest match. * @param tree: root of tree. * @param dname: pointer to uncompressed dname. * @param labs: number of labels in domain name. * @param match: closest or exact match. * guaranteed to be smaller or equal to the sought dname. * can be null if the tree is empty. * @param matchlabels: number of labels that match with closest match. * can be zero is there is no match. * @param insertpt: insert location for dname, if not found. * @return: 0 if no exact match. */ static int compress_tree_search(struct compress_tree_node** tree, uint8_t* dname, int labs, struct compress_tree_node** match, int* matchlabels, struct compress_tree_node*** insertpt) { int c, n, closen=0; struct compress_tree_node* p = *tree; struct compress_tree_node* close = 0; struct compress_tree_node** prev = tree; while(p) { if((c = dname_lab_cmp(dname, labs, p->dname, p->labs, &n)) == 0) { *matchlabels = n; *match = p; return 1; } if(c<0) { prev = &p->left; p = p->left; } else { closen = n; close = p; /* p->dname is smaller than dname */ prev = &p->right; p = p->right; } } *insertpt = prev; *matchlabels = closen; *match = close; return 0; } /** * Lookup a domain name in compression tree. * @param tree: root of tree (not the node with '.'). * @param dname: pointer to uncompressed dname. * @param labs: number of labels in domain name. * @param insertpt: insert location for dname, if not found. * @return: 0 if not found or compress treenode with best compression. */ static struct compress_tree_node* compress_tree_lookup(struct compress_tree_node** tree, uint8_t* dname, int labs, struct compress_tree_node*** insertpt) { struct compress_tree_node* p; int m; if(labs <= 1) return 0; /* do not compress root node */ if(compress_tree_search(tree, dname, labs, &p, &m, insertpt)) { /* exact match */ return p; } /* return some ancestor of p that compresses well. */ if(m>1) { /* www.example.com. (labs=4) matched foo.example.com.(labs=4) * then matchcount = 3. need to go up. */ while(p && p->labs > m) p = p->parent; return p; } return 0; } /** * Create node for domain name compression tree. * @param dname: pointer to uncompressed dname (stored in tree). * @param labs: number of labels in dname. * @param offset: offset into packet for dname. * @param region: how to allocate memory for new node. * @return new node or 0 on malloc failure. */ static struct compress_tree_node* compress_tree_newnode(uint8_t* dname, int labs, size_t offset, struct regional* region) { struct compress_tree_node* n = (struct compress_tree_node*) regional_alloc(region, sizeof(struct compress_tree_node)); if(!n) return 0; n->left = 0; n->right = 0; n->parent = 0; n->dname = dname; n->labs = labs; n->offset = offset; return n; } /** * Store domain name and ancestors into compression tree. * @param dname: pointer to uncompressed dname (stored in tree). * @param labs: number of labels in dname. * @param offset: offset into packet for dname. * @param region: how to allocate memory for new node. * @param closest: match from previous lookup, used to compress dname. * may be NULL if no previous match. * if the tree has an ancestor of dname already, this must be it. * @param insertpt: where to insert the dname in tree. * @return: 0 on memory error. */ static int compress_tree_store(uint8_t* dname, int labs, size_t offset, struct regional* region, struct compress_tree_node* closest, struct compress_tree_node** insertpt) { uint8_t lablen; struct compress_tree_node* newnode; struct compress_tree_node* prevnode = NULL; int uplabs = labs-1; /* does not store root in tree */ if(closest) uplabs = labs - closest->labs; log_assert(uplabs >= 0); /* algorithms builds up a vine of dname-labels to hang into tree */ while(uplabs--) { if(offset > PTR_MAX_OFFSET) { /* insertion failed, drop vine */ return 1; /* compression pointer no longer useful */ } if(!(newnode = compress_tree_newnode(dname, labs, offset, region))) { /* insertion failed, drop vine */ return 0; } if(prevnode) { /* chain nodes together, last one has one label more, * so is larger than newnode, thus goes right. */ newnode->right = prevnode; prevnode->parent = newnode; } /* next label */ lablen = *dname++; dname += lablen; offset += lablen+1; prevnode = newnode; labs--; } /* if we have a vine, hang the vine into the tree */ if(prevnode) { *insertpt = prevnode; prevnode->parent = closest; } return 1; } /** compress a domain name */ static int write_compressed_dname(sldns_buffer* pkt, uint8_t* dname, int labs, struct compress_tree_node* p) { /* compress it */ int labcopy = labs - p->labs; uint8_t lablen; uint16_t ptr; if(labs == 1) { /* write root label */ if(sldns_buffer_remaining(pkt) < 1) return 0; sldns_buffer_write_u8(pkt, 0); return 1; } /* copy the first couple of labels */ while(labcopy--) { lablen = *dname++; if(sldns_buffer_remaining(pkt) < (size_t)lablen+1) return 0; sldns_buffer_write_u8(pkt, lablen); sldns_buffer_write(pkt, dname, lablen); dname += lablen; } /* insert compression ptr */ if(sldns_buffer_remaining(pkt) < 2) return 0; ptr = PTR_CREATE(p->offset); sldns_buffer_write_u16(pkt, ptr); return 1; } /** compress owner name of RR, return RETVAL_OUTMEM RETVAL_TRUNC */ static int compress_owner(struct ub_packed_rrset_key* key, sldns_buffer* pkt, struct regional* region, struct compress_tree_node** tree, size_t owner_pos, uint16_t* owner_ptr, int owner_labs) { struct compress_tree_node* p; struct compress_tree_node** insertpt = NULL; if(!*owner_ptr) { /* compress first time dname */ if((p = compress_tree_lookup(tree, key->rk.dname, owner_labs, &insertpt))) { if(p->labs == owner_labs) /* avoid ptr chains, since some software is * not capable of decoding ptr after a ptr. */ *owner_ptr = htons(PTR_CREATE(p->offset)); if(!write_compressed_dname(pkt, key->rk.dname, owner_labs, p)) return RETVAL_TRUNC; /* check if typeclass+4 ttl + rdatalen is available */ if(sldns_buffer_remaining(pkt) < 4+4+2) return RETVAL_TRUNC; } else { /* no compress */ if(sldns_buffer_remaining(pkt) < key->rk.dname_len+4+4+2) return RETVAL_TRUNC; sldns_buffer_write(pkt, key->rk.dname, key->rk.dname_len); if(owner_pos <= PTR_MAX_OFFSET) *owner_ptr = htons(PTR_CREATE(owner_pos)); } if(!compress_tree_store(key->rk.dname, owner_labs, owner_pos, region, p, insertpt)) return RETVAL_OUTMEM; } else { /* always compress 2nd-further RRs in RRset */ if(owner_labs == 1) { if(sldns_buffer_remaining(pkt) < 1+4+4+2) return RETVAL_TRUNC; sldns_buffer_write_u8(pkt, 0); } else { if(sldns_buffer_remaining(pkt) < 2+4+4+2) return RETVAL_TRUNC; sldns_buffer_write(pkt, owner_ptr, 2); } } return RETVAL_OK; } /** compress any domain name to the packet, return RETVAL_* */ static int compress_any_dname(uint8_t* dname, sldns_buffer* pkt, int labs, struct regional* region, struct compress_tree_node** tree) { struct compress_tree_node* p; struct compress_tree_node** insertpt = NULL; size_t pos = sldns_buffer_position(pkt); if((p = compress_tree_lookup(tree, dname, labs, &insertpt))) { if(!write_compressed_dname(pkt, dname, labs, p)) return RETVAL_TRUNC; } else { if(!dname_buffer_write(pkt, dname)) return RETVAL_TRUNC; } if(!compress_tree_store(dname, labs, pos, region, p, insertpt)) return RETVAL_OUTMEM; return RETVAL_OK; } /** return true if type needs domain name compression in rdata */ static const sldns_rr_descriptor* type_rdata_compressable(struct ub_packed_rrset_key* key) { uint16_t t = ntohs(key->rk.type); if(sldns_rr_descript(t) && sldns_rr_descript(t)->_compress == LDNS_RR_COMPRESS) return sldns_rr_descript(t); return 0; } /** compress domain names in rdata, return RETVAL_* */ static int compress_rdata(sldns_buffer* pkt, uint8_t* rdata, size_t todolen, struct regional* region, struct compress_tree_node** tree, const sldns_rr_descriptor* desc) { int labs, r, rdf = 0; size_t dname_len, len, pos = sldns_buffer_position(pkt); uint8_t count = desc->_dname_count; sldns_buffer_skip(pkt, 2); /* rdata len fill in later */ /* space for rdatalen checked for already */ rdata += 2; todolen -= 2; while(todolen > 0 && count) { switch(desc->_wireformat[rdf]) { case LDNS_RDF_TYPE_DNAME: labs = dname_count_size_labels(rdata, &dname_len); if((r=compress_any_dname(rdata, pkt, labs, region, tree)) != RETVAL_OK) return r; rdata += dname_len; todolen -= dname_len; count--; len = 0; break; case LDNS_RDF_TYPE_STR: len = *rdata + 1; break; default: len = get_rdf_size(desc->_wireformat[rdf]); } if(len) { /* copy over */ if(sldns_buffer_remaining(pkt) < len) return RETVAL_TRUNC; sldns_buffer_write(pkt, rdata, len); todolen -= len; rdata += len; } rdf++; } /* copy remainder */ if(todolen > 0) { if(sldns_buffer_remaining(pkt) < todolen) return RETVAL_TRUNC; sldns_buffer_write(pkt, rdata, todolen); } /* set rdata len */ sldns_buffer_write_u16_at(pkt, pos, sldns_buffer_position(pkt)-pos-2); return RETVAL_OK; } /** Returns true if RR type should be included */ static int rrset_belongs_in_reply(sldns_pkt_section s, uint16_t rrtype, uint16_t qtype, int dnssec) { if(dnssec) return 1; /* skip non DNSSEC types, except if directly queried for */ if(s == LDNS_SECTION_ANSWER) { if(qtype == LDNS_RR_TYPE_ANY || qtype == rrtype) return 1; } /* check DNSSEC-ness */ switch(rrtype) { case LDNS_RR_TYPE_SIG: case LDNS_RR_TYPE_KEY: case LDNS_RR_TYPE_NXT: case LDNS_RR_TYPE_DS: case LDNS_RR_TYPE_RRSIG: case LDNS_RR_TYPE_NSEC: case LDNS_RR_TYPE_DNSKEY: case LDNS_RR_TYPE_NSEC3: case LDNS_RR_TYPE_NSEC3PARAMS: return 0; } return 1; } /** store rrset in buffer in wireformat, return RETVAL_* */ static int packed_rrset_encode(struct ub_packed_rrset_key* key, sldns_buffer* pkt, uint16_t* num_rrs, time_t timenow, struct regional* region, int do_data, int do_sig, struct compress_tree_node** tree, sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset) { size_t i, j, owner_pos; int r, owner_labs; uint16_t owner_ptr = 0; struct packed_rrset_data* data = (struct packed_rrset_data*) key->entry.data; /* does this RR type belong in the answer? */ if(!rrset_belongs_in_reply(s, ntohs(key->rk.type), qtype, dnssec)) return RETVAL_OK; owner_labs = dname_count_labels(key->rk.dname); owner_pos = sldns_buffer_position(pkt); /* For an rrset with a fixed TTL, use the rrset's TTL as given */ if((key->rk.flags & PACKED_RRSET_FIXEDTTL) != 0) timenow = 0; if(do_data) { const sldns_rr_descriptor* c = type_rdata_compressable(key); for(i=0; i<data->count; i++) { /* rrset roundrobin */ j = (i + rr_offset) % data->count; if((r=compress_owner(key, pkt, region, tree, owner_pos, &owner_ptr, owner_labs)) != RETVAL_OK) return r; sldns_buffer_write(pkt, &key->rk.type, 2); sldns_buffer_write(pkt, &key->rk.rrset_class, 2); if(data->rr_ttl[j] < timenow) sldns_buffer_write_u32(pkt, SERVE_EXPIRED?SERVE_EXPIRED_REPLY_TTL:0); else sldns_buffer_write_u32(pkt, data->rr_ttl[j]-timenow); if(c) { if((r=compress_rdata(pkt, data->rr_data[j], data->rr_len[j], region, tree, c)) != RETVAL_OK) return r; } else { if(sldns_buffer_remaining(pkt) < data->rr_len[j]) return RETVAL_TRUNC; sldns_buffer_write(pkt, data->rr_data[j], data->rr_len[j]); } } } /* insert rrsigs */ if(do_sig && dnssec) { size_t total = data->count+data->rrsig_count; for(i=data->count; i<total; i++) { if(owner_ptr && owner_labs != 1) { if(sldns_buffer_remaining(pkt) < 2+4+4+data->rr_len[i]) return RETVAL_TRUNC; sldns_buffer_write(pkt, &owner_ptr, 2); } else { if((r=compress_any_dname(key->rk.dname, pkt, owner_labs, region, tree)) != RETVAL_OK) return r; if(sldns_buffer_remaining(pkt) < 4+4+data->rr_len[i]) return RETVAL_TRUNC; } sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_RRSIG); sldns_buffer_write(pkt, &key->rk.rrset_class, 2); if(data->rr_ttl[i] < timenow) sldns_buffer_write_u32(pkt, SERVE_EXPIRED?SERVE_EXPIRED_REPLY_TTL:0); else sldns_buffer_write_u32(pkt, data->rr_ttl[i]-timenow); /* rrsig rdata cannot be compressed, perform 100+ byte * memcopy. */ sldns_buffer_write(pkt, data->rr_data[i], data->rr_len[i]); } } /* change rrnum only after we are sure it fits */ if(do_data) *num_rrs += data->count; if(do_sig && dnssec) *num_rrs += data->rrsig_count; return RETVAL_OK; } /** store msg section in wireformat buffer, return RETVAL_* */ static int insert_section(struct reply_info* rep, size_t num_rrsets, uint16_t* num_rrs, sldns_buffer* pkt, size_t rrsets_before, time_t timenow, struct regional* region, struct compress_tree_node** tree, sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset) { int r; size_t i, setstart; /* we now allow this function to be called multiple times for the * same section, incrementally updating num_rrs. The caller is * responsible for initializing it (which is the case in the current * implementation). */ if(s != LDNS_SECTION_ADDITIONAL) { if(s == LDNS_SECTION_ANSWER && qtype == LDNS_RR_TYPE_ANY) dnssec = 1; /* include all types in ANY answer */ for(i=0; i<num_rrsets; i++) { setstart = sldns_buffer_position(pkt); if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i], pkt, num_rrs, timenow, region, 1, 1, tree, s, qtype, dnssec, rr_offset)) != RETVAL_OK) { /* Bad, but if due to size must set TC bit */ /* trim off the rrset neatly. */ sldns_buffer_set_position(pkt, setstart); return r; } } } else { for(i=0; i<num_rrsets; i++) { setstart = sldns_buffer_position(pkt); if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i], pkt, num_rrs, timenow, region, 1, 0, tree, s, qtype, dnssec, rr_offset)) != RETVAL_OK) { sldns_buffer_set_position(pkt, setstart); return r; } } if(dnssec) for(i=0; i<num_rrsets; i++) { setstart = sldns_buffer_position(pkt); if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i], pkt, num_rrs, timenow, region, 0, 1, tree, s, qtype, dnssec, rr_offset)) != RETVAL_OK) { sldns_buffer_set_position(pkt, setstart); return r; } } } return RETVAL_OK; } /** store query section in wireformat buffer, return RETVAL */ static int insert_query(struct query_info* qinfo, struct compress_tree_node** tree, sldns_buffer* buffer, struct regional* region) { uint8_t* qname = qinfo->local_alias ? qinfo->local_alias->rrset->rk.dname : qinfo->qname; size_t qname_len = qinfo->local_alias ? qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len; if(sldns_buffer_remaining(buffer) < qinfo->qname_len+sizeof(uint16_t)*2) return RETVAL_TRUNC; /* buffer too small */ /* the query is the first name inserted into the tree */ if(!compress_tree_store(qname, dname_count_labels(qname), sldns_buffer_position(buffer), region, NULL, tree)) return RETVAL_OUTMEM; if(sldns_buffer_current(buffer) == qname) sldns_buffer_skip(buffer, (ssize_t)qname_len); else sldns_buffer_write(buffer, qname, qname_len); sldns_buffer_write_u16(buffer, qinfo->qtype); sldns_buffer_write_u16(buffer, qinfo->qclass); return RETVAL_OK; } static int positive_answer(struct reply_info* rep, uint16_t qtype) { size_t i; if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR) return 0; for(i=0;i<rep->an_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == qtype) { /* for priming queries, type NS, include addresses */ if(qtype == LDNS_RR_TYPE_NS) return 0; /* in case it is a wildcard with DNSSEC, there will * be NSEC/NSEC3 records in the authority section * that we cannot remove */ for(i=rep->an_numrrsets; i<rep->an_numrrsets+ rep->ns_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC || ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC3) return 0; } return 1; } } return 0; } static int negative_answer(struct reply_info* rep) { size_t i; int ns_seen = 0; if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN) return 1; if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR && rep->an_numrrsets != 0) return 0; /* positive */ if(FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR && FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NXDOMAIN) return 0; for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++){ if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_SOA) return 1; if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS) ns_seen = 1; } if(ns_seen) return 0; /* could be referral, NS, but no SOA */ return 1; } int reply_info_encode(struct query_info* qinfo, struct reply_info* rep, uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow, struct regional* region, uint16_t udpsize, int dnssec, int minimise) { uint16_t ancount=0, nscount=0, arcount=0; struct compress_tree_node* tree = 0; int r; size_t rr_offset; sldns_buffer_clear(buffer); if(udpsize < sldns_buffer_limit(buffer)) sldns_buffer_set_limit(buffer, udpsize); if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE) return 0; sldns_buffer_write(buffer, &id, sizeof(uint16_t)); sldns_buffer_write_u16(buffer, flags); sldns_buffer_write_u16(buffer, rep->qdcount); /* set an, ns, ar counts to zero in case of small packets */ sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6); /* insert query section */ if(rep->qdcount) { if((r=insert_query(qinfo, &tree, buffer, region)) != RETVAL_OK) { if(r == RETVAL_TRUNC) { /* create truncated message */ sldns_buffer_write_u16_at(buffer, 4, 0); LDNS_TC_SET(sldns_buffer_begin(buffer)); sldns_buffer_flip(buffer); return 1; } return 0; } } /* roundrobin offset. using query id for random number. With ntohs * for different roundrobins for sequential id client senders. */ rr_offset = RRSET_ROUNDROBIN?ntohs(id)+(timenow?timenow:time(NULL)):0; /* "prepend" any local alias records in the answer section if this * response is supposed to be authoritative. Currently it should * be a single CNAME record (sanity-checked in worker_handle_request()) * but it can be extended if and when we support more variations of * aliases. */ if(qinfo->local_alias && (flags & BIT_AA)) { struct reply_info arep; time_t timezero = 0; /* to use the 'authoritative' TTL */ memset(&arep, 0, sizeof(arep)); arep.flags = rep->flags; arep.an_numrrsets = 1; arep.rrset_count = 1; arep.rrsets = &qinfo->local_alias->rrset; if((r=insert_section(&arep, 1, &ancount, buffer, 0, timezero, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) { if(r == RETVAL_TRUNC) { /* create truncated message */ sldns_buffer_write_u16_at(buffer, 6, ancount); LDNS_TC_SET(sldns_buffer_begin(buffer)); sldns_buffer_flip(buffer); return 1; } return 0; } } /* insert answer section */ if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer, 0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) { if(r == RETVAL_TRUNC) { /* create truncated message */ sldns_buffer_write_u16_at(buffer, 6, ancount); LDNS_TC_SET(sldns_buffer_begin(buffer)); sldns_buffer_flip(buffer); return 1; } return 0; } sldns_buffer_write_u16_at(buffer, 6, ancount); /* if response is positive answer, auth/add sections are not required */ if( ! (minimise && positive_answer(rep, qinfo->qtype)) ) { /* insert auth section */ if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer, rep->an_numrrsets, timenow, region, &tree, LDNS_SECTION_AUTHORITY, qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) { if(r == RETVAL_TRUNC) { /* create truncated message */ sldns_buffer_write_u16_at(buffer, 8, nscount); LDNS_TC_SET(sldns_buffer_begin(buffer)); sldns_buffer_flip(buffer); return 1; } return 0; } sldns_buffer_write_u16_at(buffer, 8, nscount); if(! (minimise && negative_answer(rep))) { /* insert add section */ if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer, rep->an_numrrsets + rep->ns_numrrsets, timenow, region, &tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) { if(r == RETVAL_TRUNC) { /* no need to set TC bit, this is the additional */ sldns_buffer_write_u16_at(buffer, 10, arcount); sldns_buffer_flip(buffer); return 1; } return 0; } sldns_buffer_write_u16_at(buffer, 10, arcount); } } sldns_buffer_flip(buffer); return 1; } uint16_t calc_edns_field_size(struct edns_data* edns) { size_t rdatalen = 0; struct edns_option* opt; if(!edns || !edns->edns_present) return 0; for(opt = edns->opt_list; opt; opt = opt->next) { rdatalen += 4 + opt->opt_len; } /* domain root '.' + type + class + ttl + rdatalen */ return 1 + 2 + 2 + 4 + 2 + rdatalen; } void attach_edns_record(sldns_buffer* pkt, struct edns_data* edns) { size_t len; size_t rdatapos; struct edns_option* opt; if(!edns || !edns->edns_present) return; /* inc additional count */ sldns_buffer_write_u16_at(pkt, 10, sldns_buffer_read_u16_at(pkt, 10) + 1); len = sldns_buffer_limit(pkt); sldns_buffer_clear(pkt); sldns_buffer_set_position(pkt, len); /* write EDNS record */ sldns_buffer_write_u8(pkt, 0); /* '.' label */ sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */ sldns_buffer_write_u16(pkt, edns->udp_size); /* class */ sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */ sldns_buffer_write_u8(pkt, edns->edns_version); sldns_buffer_write_u16(pkt, edns->bits); rdatapos = sldns_buffer_position(pkt); sldns_buffer_write_u16(pkt, 0); /* rdatalen */ /* write rdata */ for(opt=edns->opt_list; opt; opt=opt->next) { sldns_buffer_write_u16(pkt, opt->opt_code); sldns_buffer_write_u16(pkt, opt->opt_len); if(opt->opt_len != 0) sldns_buffer_write(pkt, opt->opt_data, opt->opt_len); } if(edns->opt_list) sldns_buffer_write_u16_at(pkt, rdatapos, sldns_buffer_position(pkt)-rdatapos-2); sldns_buffer_flip(pkt); } int reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep, uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow, int cached, struct regional* region, uint16_t udpsize, struct edns_data* edns, int dnssec, int secure) { uint16_t flags; unsigned int attach_edns = 0; if(!cached || rep->authoritative) { /* original flags, copy RD and CD bits from query. */ flags = rep->flags | (qflags & (BIT_RD|BIT_CD)); } else { /* remove AA bit, copy RD and CD bits from query. */ flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD)); } if(secure && (dnssec || (qflags&BIT_AD))) flags |= BIT_AD; /* restore AA bit if we have a local alias and the response can be * authoritative. Also clear AD bit if set as the local data is the * primary answer. */ if(qinf->local_alias && (FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR || FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)) { flags |= BIT_AA; flags &= ~BIT_AD; } log_assert(flags & BIT_QR); /* QR bit must be on in our replies */ if(udpsize < LDNS_HEADER_SIZE) return 0; if(sldns_buffer_capacity(pkt) < udpsize) udpsize = sldns_buffer_capacity(pkt); if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) { /* packet too small to contain edns, omit it. */ attach_edns = 0; } else { /* reserve space for edns record */ attach_edns = (unsigned int)calc_edns_field_size(edns); udpsize -= attach_edns; } if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region, udpsize, dnssec, MINIMAL_RESPONSES)) { log_err("reply encode: out of memory"); return 0; } if(attach_edns && sldns_buffer_capacity(pkt) >= sldns_buffer_limit(pkt)+attach_edns) attach_edns_record(pkt, edns); return 1; } void qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo) { uint16_t flags = 0; /* QUERY, NOERROR */ const uint8_t* qname = qinfo->local_alias ? qinfo->local_alias->rrset->rk.dname : qinfo->qname; size_t qname_len = qinfo->local_alias ? qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len; sldns_buffer_clear(pkt); log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/); sldns_buffer_skip(pkt, 2); /* id done later */ sldns_buffer_write_u16(pkt, flags); sldns_buffer_write_u16(pkt, 1); /* query count */ sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */ sldns_buffer_write(pkt, qname, qname_len); sldns_buffer_write_u16(pkt, qinfo->qtype); sldns_buffer_write_u16(pkt, qinfo->qclass); sldns_buffer_flip(pkt); } void error_encode(sldns_buffer* buf, int r, struct query_info* qinfo, uint16_t qid, uint16_t qflags, struct edns_data* edns) { uint16_t flags; sldns_buffer_clear(buf); sldns_buffer_write(buf, &qid, sizeof(uint16_t)); flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/ flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */ sldns_buffer_write_u16(buf, flags); if(qinfo) flags = 1; else flags = 0; sldns_buffer_write_u16(buf, flags); flags = 0; sldns_buffer_write(buf, &flags, sizeof(uint16_t)); sldns_buffer_write(buf, &flags, sizeof(uint16_t)); sldns_buffer_write(buf, &flags, sizeof(uint16_t)); if(qinfo) { const uint8_t* qname = qinfo->local_alias ? qinfo->local_alias->rrset->rk.dname : qinfo->qname; size_t qname_len = qinfo->local_alias ? qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len; if(sldns_buffer_current(buf) == qname) sldns_buffer_skip(buf, (ssize_t)qname_len); else sldns_buffer_write(buf, qname, qname_len); sldns_buffer_write_u16(buf, qinfo->qtype); sldns_buffer_write_u16(buf, qinfo->qclass); } sldns_buffer_flip(buf); if(edns) { struct edns_data es = *edns; es.edns_version = EDNS_ADVERTISED_VERSION; es.udp_size = EDNS_ADVERTISED_SIZE; es.ext_rcode = 0; es.bits &= EDNS_DO; if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) > edns->udp_size) return; attach_edns_record(buf, &es); } }
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