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src/sbin/unwind/libunbound/util/data/msgencode.c

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/*
* 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;
time_t adjust = 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);
/** Determine relative time adjustment for TTL values.
* For an rrset with a fixed TTL, use the rrset's TTL as given. */
if((key->rk.flags & PACKED_RRSET_FIXEDTTL) != 0)
adjust = 0;
else
adjust = SERVE_ORIGINAL_TTL ? data->ttl_add : timenow;
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] < adjust)
sldns_buffer_write_u32(pkt,
SERVE_EXPIRED?SERVE_EXPIRED_REPLY_TTL:0);
else sldns_buffer_write_u32(pkt, data->rr_ttl[j]-adjust);
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] < adjust)
sldns_buffer_write_u32(pkt,
SERVE_EXPIRED?SERVE_EXPIRED_REPLY_TTL:0);
else sldns_buffer_write_u32(pkt, data->rr_ttl[i]-adjust);
/* 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_inplace_cb_out; opt; opt = opt->next) {
rdatalen += 4 + opt->opt_len;
}
for(opt = edns->opt_list_out; opt; opt = opt->next) {
rdatalen += 4 + opt->opt_len;
}
/* domain root '.' + type + class + ttl + rdatalen */
return 1 + 2 + 2 + 4 + 2 + rdatalen;
}
uint16_t
calc_edns_option_size(struct edns_data* edns, uint16_t code)
{
size_t rdatalen = 0;
struct edns_option* opt;
if(!edns || !edns->edns_present)
return 0;
for(opt = edns->opt_list_inplace_cb_out; opt; opt = opt->next) {
if(opt->opt_code == code)
rdatalen += 4 + opt->opt_len;
}
for(opt = edns->opt_list_out; opt; opt = opt->next) {
if(opt->opt_code == code)
rdatalen += 4 + opt->opt_len;
}
return rdatalen;
}
uint16_t
calc_ede_option_size(struct edns_data* edns, uint16_t* txt_size)
{
size_t rdatalen = 0;
struct edns_option* opt;
*txt_size = 0;
if(!edns || !edns->edns_present)
return 0;
for(opt = edns->opt_list_inplace_cb_out; opt; opt = opt->next) {
if(opt->opt_code == LDNS_EDNS_EDE) {
rdatalen += 4 + opt->opt_len;
if(opt->opt_len > 2) *txt_size += opt->opt_len - 2;
if(opt->opt_len >= 2 && sldns_read_uint16(
opt->opt_data) == LDNS_EDE_OTHER) {
*txt_size += 4 + 2;
}
}
}
for(opt = edns->opt_list_out; opt; opt = opt->next) {
if(opt->opt_code == LDNS_EDNS_EDE) {
rdatalen += 4 + opt->opt_len;
if(opt->opt_len > 2) *txt_size += opt->opt_len - 2;
if(opt->opt_len >= 2 && sldns_read_uint16(
opt->opt_data) == LDNS_EDE_OTHER) {
*txt_size += 4 + 2;
}
}
}
return rdatalen;
}
/* Trims the EDE OPTION-DATA to not include any EXTRA-TEXT data.
* Also removes any LDNS_EDE_OTHER options from the list since they are useless
* without the extra text. */
static void
ede_trim_text(struct edns_option** list)
{
struct edns_option* curr, *prev = NULL;
if(!list || !(*list)) return;
/* Unlink and repoint if LDNS_EDE_OTHER are first in list */
while(list && *list && (*list)->opt_code == LDNS_EDNS_EDE
&& (*list)->opt_len >= 2
&& sldns_read_uint16((*list)->opt_data) == LDNS_EDE_OTHER ) {
*list = (*list)->next;
}
if(!list || !(*list)) return;
curr = *list;
while(curr) {
if(curr->opt_code == LDNS_EDNS_EDE) {
if(curr->opt_len >= 2 && sldns_read_uint16(
curr->opt_data) == LDNS_EDE_OTHER) {
/* LDNS_EDE_OTHER cannot be the first option in
* this while, so prev is always initialized at
* this point from the other branches;
* cut this option off */
prev->next = curr->next;
curr = curr->next;
} else if(curr->opt_len > 2) {
/* trim this option's EXTRA-TEXT */
curr->opt_len = 2;
prev = curr;
curr = curr->next;
} else {
prev = curr;
curr = curr->next;
}
} else {
/* continue */
prev = curr;
curr = curr->next;
}
}
}
static void
attach_edns_record_max_msg_sz(sldns_buffer* pkt, struct edns_data* edns,
uint16_t max_msg_sz)
{
size_t len;
size_t rdatapos;
struct edns_option* opt;
struct edns_option* padding_option = NULL;
/* 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_inplace_cb_out; opt; opt=opt->next) {
if (opt->opt_code == LDNS_EDNS_PADDING) {
padding_option = opt;
continue;
}
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);
}
for(opt=edns->opt_list_out; opt; opt=opt->next) {
if (opt->opt_code == LDNS_EDNS_PADDING) {
padding_option = opt;
continue;
}
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 (padding_option && edns->padding_block_size ) {
size_t pad_pos = sldns_buffer_position(pkt);
size_t msg_sz = ((pad_pos + 3) / edns->padding_block_size + 1)
* edns->padding_block_size;
size_t pad_sz;
if (msg_sz > max_msg_sz)
msg_sz = max_msg_sz;
/* By use of calc_edns_field_size, calling functions should
* have made sure that there is enough space for at least a
* zero sized padding option.
*/
log_assert(pad_pos + 4 <= msg_sz);
pad_sz = msg_sz - pad_pos - 4;
sldns_buffer_write_u16(pkt, LDNS_EDNS_PADDING);
sldns_buffer_write_u16(pkt, pad_sz);
if (pad_sz) {
memset(sldns_buffer_current(pkt), 0, pad_sz);
sldns_buffer_skip(pkt, pad_sz);
}
}
sldns_buffer_write_u16_at(pkt, rdatapos,
sldns_buffer_position(pkt)-rdatapos-2);
sldns_buffer_flip(pkt);
}
void
attach_edns_record(sldns_buffer* pkt, struct edns_data* edns)
{
if(!edns || !edns->edns_present)
return;
attach_edns_record_max_msg_sz(pkt, edns, edns->udp_size);
}
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;
uint16_t edns_field_size, ede_size, ede_txt_size;
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;
/* currently edns does not change during calculations;
* calculate sizes once here */
edns_field_size = calc_edns_field_size(edns);
ede_size = calc_ede_option_size(edns, &ede_txt_size);
if(sldns_buffer_capacity(pkt) < udpsize)
udpsize = sldns_buffer_capacity(pkt);
if(!edns || !edns->edns_present) {
attach_edns = 0;
/* EDEs are optional, try to fit anything else before them */
} else if(udpsize < LDNS_HEADER_SIZE + edns_field_size - ede_size) {
/* packet too small to contain edns, omit it. */
attach_edns = 0;
} else {
/* reserve space for edns record */
attach_edns = (unsigned int)edns_field_size - ede_size;
}
if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
udpsize - attach_edns, dnssec, MINIMAL_RESPONSES)) {
log_err("reply encode: out of memory");
return 0;
}
if(attach_edns) {
if(udpsize >= sldns_buffer_limit(pkt) + edns_field_size)
attach_edns_record_max_msg_sz(pkt, edns, udpsize);
else if(udpsize >= sldns_buffer_limit(pkt) + edns_field_size - ede_txt_size) {
ede_trim_text(&edns->opt_list_inplace_cb_out);
ede_trim_text(&edns->opt_list_out);
attach_edns_record_max_msg_sz(pkt, edns, udpsize);
} else if(udpsize >= sldns_buffer_limit(pkt) + edns_field_size - ede_size) {
edns_opt_list_remove(&edns->opt_list_inplace_cb_out, LDNS_EDNS_EDE);
edns_opt_list_remove(&edns->opt_list_out, LDNS_EDNS_EDE);
attach_edns_record_max_msg_sz(pkt, edns, udpsize);
}
}
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
extended_error_encode(sldns_buffer* buf, uint16_t rcode,
struct query_info* qinfo, uint16_t qid, uint16_t qflags,
uint16_t xflags, 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 | (rcode & 0xF)); /* QR and retcode*/
flags |= xflags;
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 = (uint8_t)(rcode >> 4);
es.bits &= EDNS_DO;
if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
edns->udp_size) {
edns_opt_list_remove(&es.opt_list_inplace_cb_out, LDNS_EDNS_EDE);
edns_opt_list_remove(&es.opt_list_out, LDNS_EDNS_EDE);
if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
edns->udp_size) {
return;
}
}
attach_edns_record(buf, &es);
}
}
void
error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
uint16_t qid, uint16_t qflags, struct edns_data* edns)
{
extended_error_encode(buf, (r & 0x000F), qinfo, qid, qflags,
(r & 0xFFF0), edns);
}
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