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monero/external/unbound/util/data/msgparse.c

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/*
* util/data/msgparse.c - parse wireformat DNS messages.
*
* 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
* Routines for message parsing a packet buffer to a descriptive structure.
*/
#include "config.h"
#include "util/data/msgparse.h"
#include "util/data/dname.h"
#include "util/data/packed_rrset.h"
#include "util/storage/lookup3.h"
#include "util/regional.h"
#include "ldns/rrdef.h"
#include "ldns/sbuffer.h"
#include "ldns/parseutil.h"
#include "ldns/wire2str.h"
/** smart comparison of (compressed, valid) dnames from packet */
static int
smart_compare(sldns_buffer* pkt, uint8_t* dnow,
uint8_t* dprfirst, uint8_t* dprlast)
{
if(LABEL_IS_PTR(*dnow)) {
/* ptr points to a previous dname */
uint8_t* p = sldns_buffer_at(pkt, PTR_OFFSET(dnow[0], dnow[1]));
if( p == dprfirst || p == dprlast )
return 0;
/* prev dname is also a ptr, both ptrs are the same. */
if(LABEL_IS_PTR(*dprlast) &&
dprlast[0] == dnow[0] && dprlast[1] == dnow[1])
return 0;
}
return dname_pkt_compare(pkt, dnow, dprlast);
}
/**
* Allocate new rrset in region, fill with data.
*/
static struct rrset_parse*
new_rrset(struct msg_parse* msg, uint8_t* dname, size_t dnamelen,
uint16_t type, uint16_t dclass, hashvalue_t hash,
uint32_t rrset_flags, sldns_pkt_section section,
struct regional* region)
{
struct rrset_parse* p = regional_alloc(region, sizeof(*p));
if(!p) return NULL;
p->rrset_bucket_next = msg->hashtable[hash & (PARSE_TABLE_SIZE-1)];
msg->hashtable[hash & (PARSE_TABLE_SIZE-1)] = p;
p->rrset_all_next = 0;
if(msg->rrset_last)
msg->rrset_last->rrset_all_next = p;
else msg->rrset_first = p;
msg->rrset_last = p;
p->hash = hash;
p->section = section;
p->dname = dname;
p->dname_len = dnamelen;
p->type = type;
p->rrset_class = dclass;
p->flags = rrset_flags;
p->rr_count = 0;
p->size = 0;
p->rr_first = 0;
p->rr_last = 0;
p->rrsig_count = 0;
p->rrsig_first = 0;
p->rrsig_last = 0;
return p;
}
/** See if next rrset is nsec at zone apex */
static int
nsec_at_apex(sldns_buffer* pkt)
{
/* we are at ttl position in packet. */
size_t pos = sldns_buffer_position(pkt);
uint16_t rdatalen;
if(sldns_buffer_remaining(pkt) < 7) /* ttl+len+root */
return 0; /* eek! */
sldns_buffer_skip(pkt, 4); /* ttl */;
rdatalen = sldns_buffer_read_u16(pkt);
if(sldns_buffer_remaining(pkt) < rdatalen) {
sldns_buffer_set_position(pkt, pos);
return 0; /* parse error happens later */
}
/* must validate the nsec next domain name format */
if(pkt_dname_len(pkt) == 0) {
sldns_buffer_set_position(pkt, pos);
return 0; /* parse error */
}
/* see if SOA bit is set. */
if(sldns_buffer_position(pkt) < pos+4+rdatalen) {
/* nsec type bitmap contains items */
uint8_t win, blen, bits;
/* need: windownum, bitmap len, firstbyte */
if(sldns_buffer_position(pkt)+3 > pos+4+rdatalen) {
sldns_buffer_set_position(pkt, pos);
return 0; /* malformed nsec */
}
win = sldns_buffer_read_u8(pkt);
blen = sldns_buffer_read_u8(pkt);
bits = sldns_buffer_read_u8(pkt);
/* 0window always first window. bitlen >=1 or parse
error really. bit 0x2 is SOA. */
if(win == 0 && blen >= 1 && (bits & 0x02)) {
sldns_buffer_set_position(pkt, pos);
return 1;
}
}
sldns_buffer_set_position(pkt, pos);
return 0;
}
/** Calculate rrset flags */
static uint32_t
pkt_rrset_flags(sldns_buffer* pkt, uint16_t type, sldns_pkt_section sec)
{
uint32_t f = 0;
if(type == LDNS_RR_TYPE_NSEC && nsec_at_apex(pkt)) {
f |= PACKED_RRSET_NSEC_AT_APEX;
} else if(type == LDNS_RR_TYPE_SOA && sec == LDNS_SECTION_AUTHORITY) {
f |= PACKED_RRSET_SOA_NEG;
}
return f;
}
hashvalue_t
pkt_hash_rrset(sldns_buffer* pkt, uint8_t* dname, uint16_t type,
uint16_t dclass, uint32_t rrset_flags)
{
/* note this MUST be identical to rrset_key_hash in packed_rrset.c */
/* this routine handles compressed names */
hashvalue_t h = 0xab;
h = dname_pkt_hash(pkt, dname, h);
h = hashlittle(&type, sizeof(type), h); /* host order */
h = hashlittle(&dclass, sizeof(dclass), h); /* netw order */
h = hashlittle(&rrset_flags, sizeof(uint32_t), h);
return h;
}
/** create partial dname hash for rrset hash */
static hashvalue_t
pkt_hash_rrset_first(sldns_buffer* pkt, uint8_t* dname)
{
/* works together with pkt_hash_rrset_rest */
/* note this MUST be identical to rrset_key_hash in packed_rrset.c */
/* this routine handles compressed names */
hashvalue_t h = 0xab;
h = dname_pkt_hash(pkt, dname, h);
return h;
}
/** create a rrset hash from a partial dname hash */
static hashvalue_t
pkt_hash_rrset_rest(hashvalue_t dname_h, uint16_t type, uint16_t dclass,
uint32_t rrset_flags)
{
/* works together with pkt_hash_rrset_first */
/* note this MUST be identical to rrset_key_hash in packed_rrset.c */
hashvalue_t h;
h = hashlittle(&type, sizeof(type), dname_h); /* host order */
h = hashlittle(&dclass, sizeof(dclass), h); /* netw order */
h = hashlittle(&rrset_flags, sizeof(uint32_t), h);
return h;
}
/** compare rrset_parse with data */
static int
rrset_parse_equals(struct rrset_parse* p, sldns_buffer* pkt, hashvalue_t h,
uint32_t rrset_flags, uint8_t* dname, size_t dnamelen,
uint16_t type, uint16_t dclass)
{
if(p->hash == h && p->dname_len == dnamelen && p->type == type &&
p->rrset_class == dclass && p->flags == rrset_flags &&
dname_pkt_compare(pkt, dname, p->dname) == 0)
return 1;
return 0;
}
struct rrset_parse*
msgparse_hashtable_lookup(struct msg_parse* msg, sldns_buffer* pkt,
hashvalue_t h, uint32_t rrset_flags, uint8_t* dname, size_t dnamelen,
uint16_t type, uint16_t dclass)
{
struct rrset_parse* p = msg->hashtable[h & (PARSE_TABLE_SIZE-1)];
while(p) {
if(rrset_parse_equals(p, pkt, h, rrset_flags, dname, dnamelen,
type, dclass))
return p;
p = p->rrset_bucket_next;
}
return NULL;
}
/** return type networkformat that rrsig in packet covers */
static int
pkt_rrsig_covered(sldns_buffer* pkt, uint8_t* here, uint16_t* type)
{
size_t pos = sldns_buffer_position(pkt);
sldns_buffer_set_position(pkt, (size_t)(here-sldns_buffer_begin(pkt)));
/* ttl + len + size of small rrsig(rootlabel, no signature) */
if(sldns_buffer_remaining(pkt) < 4+2+19)
return 0;
sldns_buffer_skip(pkt, 4); /* ttl */
if(sldns_buffer_read_u16(pkt) < 19) /* too short */ {
sldns_buffer_set_position(pkt, pos);
return 0;
}
*type = sldns_buffer_read_u16(pkt);
sldns_buffer_set_position(pkt, pos);
return 1;
}
/** true if covered type equals prevtype */
static int
pkt_rrsig_covered_equals(sldns_buffer* pkt, uint8_t* here, uint16_t type)
{
uint16_t t;
if(pkt_rrsig_covered(pkt, here, &t) && t == type)
return 1;
return 0;
}
void
msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset)
{
struct rrset_parse** p;
p = &msg->hashtable[ rrset->hash & (PARSE_TABLE_SIZE-1) ];
while(*p) {
if(*p == rrset) {
*p = rrset->rrset_bucket_next;
return;
}
p = &( (*p)->rrset_bucket_next );
}
}
/** change section of rrset from previous to current section */
static void
change_section(struct msg_parse* msg, struct rrset_parse* rrset,
sldns_pkt_section section)
{
struct rrset_parse *p, *prev;
/* remove from list */
if(section == rrset->section)
return;
p = msg->rrset_first;
prev = 0;
while(p) {
if(p == rrset) {
if(prev) prev->rrset_all_next = p->rrset_all_next;
else msg->rrset_first = p->rrset_all_next;
if(msg->rrset_last == rrset)
msg->rrset_last = prev;
break;
}
prev = p;
p = p->rrset_all_next;
}
/* remove from count */
switch(rrset->section) {
case LDNS_SECTION_ANSWER: msg->an_rrsets--; break;
case LDNS_SECTION_AUTHORITY: msg->ns_rrsets--; break;
case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets--; break;
default: log_assert(0);
}
/* insert at end of list */
rrset->rrset_all_next = 0;
if(msg->rrset_last)
msg->rrset_last->rrset_all_next = rrset;
else msg->rrset_first = rrset;
msg->rrset_last = rrset;
/* up count of new section */
switch(section) {
case LDNS_SECTION_AUTHORITY: msg->ns_rrsets++; break;
case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets++; break;
default: log_assert(0);
}
rrset->section = section;
}
/** see if rrset of type RRSIG contains sig over given type */
static int
rrset_has_sigover(sldns_buffer* pkt, struct rrset_parse* rrset, uint16_t type,
int* hasother)
{
int res = 0;
struct rr_parse* rr = rrset->rr_first;
log_assert( rrset->type == LDNS_RR_TYPE_RRSIG );
while(rr) {
if(pkt_rrsig_covered_equals(pkt, rr->ttl_data, type))
res = 1;
else *hasother = 1;
rr = rr->next;
}
return res;
}
/** move rrsigs from sigset to dataset */
static int
moveover_rrsigs(sldns_buffer* pkt, struct regional* region,
struct rrset_parse* sigset, struct rrset_parse* dataset, int duplicate)
{
struct rr_parse* sig = sigset->rr_first;
struct rr_parse* prev = NULL;
struct rr_parse* insert;
struct rr_parse* nextsig;
while(sig) {
nextsig = sig->next;
if(pkt_rrsig_covered_equals(pkt, sig->ttl_data,
dataset->type)) {
if(duplicate) {
/* new */
insert = (struct rr_parse*)regional_alloc(
region, sizeof(struct rr_parse));
if(!insert) return 0;
insert->outside_packet = 0;
insert->ttl_data = sig->ttl_data;
insert->size = sig->size;
/* prev not used */
} else {
/* remove from sigset */
if(prev) prev->next = sig->next;
else sigset->rr_first = sig->next;
if(sigset->rr_last == sig)
sigset->rr_last = prev;
sigset->rr_count--;
sigset->size -= sig->size;
insert = sig;
/* prev not changed */
}
/* add to dataset */
dataset->rrsig_count++;
insert->next = 0;
if(dataset->rrsig_last)
dataset->rrsig_last->next = insert;
else dataset->rrsig_first = insert;
dataset->rrsig_last = insert;
dataset->size += insert->size;
} else {
prev = sig;
}
sig = nextsig;
}
return 1;
}
/** change an rrsig rrset for use as data rrset */
static struct rrset_parse*
change_rrsig_rrset(struct rrset_parse* sigset, struct msg_parse* msg,
sldns_buffer* pkt, uint16_t datatype, uint32_t rrset_flags,
int hasother, sldns_pkt_section section, struct regional* region)
{
struct rrset_parse* dataset = sigset;
hashvalue_t hash = pkt_hash_rrset(pkt, sigset->dname, datatype,
sigset->rrset_class, rrset_flags);
log_assert( sigset->type == LDNS_RR_TYPE_RRSIG );
log_assert( datatype != LDNS_RR_TYPE_RRSIG );
if(hasother) {
/* need to make new rrset to hold data type */
dataset = new_rrset(msg, sigset->dname, sigset->dname_len,
datatype, sigset->rrset_class, hash, rrset_flags,
section, region);
if(!dataset)
return NULL;
switch(section) {
case LDNS_SECTION_ANSWER: msg->an_rrsets++; break;
case LDNS_SECTION_AUTHORITY: msg->ns_rrsets++; break;
case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets++; break;
default: log_assert(0);
}
if(!moveover_rrsigs(pkt, region, sigset, dataset,
msg->qtype == LDNS_RR_TYPE_RRSIG ||
(msg->qtype == LDNS_RR_TYPE_ANY &&
section != LDNS_SECTION_ANSWER) ))
return NULL;
return dataset;
}
/* changeover the type of the rrset to data set */
msgparse_bucket_remove(msg, dataset);
/* insert into new hash bucket */
dataset->rrset_bucket_next = msg->hashtable[hash&(PARSE_TABLE_SIZE-1)];
msg->hashtable[hash&(PARSE_TABLE_SIZE-1)] = dataset;
dataset->hash = hash;
/* use section of data item for result */
change_section(msg, dataset, section);
dataset->type = datatype;
dataset->flags = rrset_flags;
dataset->rrsig_count += dataset->rr_count;
dataset->rr_count = 0;
/* move sigs to end of siglist */
if(dataset->rrsig_last)
dataset->rrsig_last->next = dataset->rr_first;
else dataset->rrsig_first = dataset->rr_first;
dataset->rrsig_last = dataset->rr_last;
dataset->rr_first = 0;
dataset->rr_last = 0;
return dataset;
}
/** Find rrset. If equal to previous it is fast. hash if not so.
* @param msg: the message with hash table.
* @param pkt: the packet in wireformat (needed for compression ptrs).
* @param dname: pointer to start of dname (compressed) in packet.
* @param dnamelen: uncompressed wirefmt length of dname.
* @param type: type of current rr.
* @param dclass: class of current rr.
* @param hash: hash value is returned if the rrset could not be found.
* @param rrset_flags: is returned if the rrset could not be found.
* @param prev_dname_first: dname of last seen RR. First seen dname.
* @param prev_dname_last: dname of last seen RR. Last seen dname.
* @param prev_dnamelen: dname len of last seen RR.
* @param prev_type: type of last seen RR.
* @param prev_dclass: class of last seen RR.
* @param rrset_prev: last seen RRset.
* @param section: the current section in the packet.
* @param region: used to allocate temporary parsing data.
* @return 0 on out of memory.
*/
static int
find_rrset(struct msg_parse* msg, sldns_buffer* pkt, uint8_t* dname,
size_t dnamelen, uint16_t type, uint16_t dclass, hashvalue_t* hash,
uint32_t* rrset_flags,
uint8_t** prev_dname_first, uint8_t** prev_dname_last,
size_t* prev_dnamelen, uint16_t* prev_type,
uint16_t* prev_dclass, struct rrset_parse** rrset_prev,
sldns_pkt_section section, struct regional* region)
{
hashvalue_t dname_h = pkt_hash_rrset_first(pkt, dname);
uint16_t covtype;
if(*rrset_prev) {
/* check if equal to previous item */
if(type == *prev_type && dclass == *prev_dclass &&
dnamelen == *prev_dnamelen &&
smart_compare(pkt, dname, *prev_dname_first,
*prev_dname_last) == 0 &&
type != LDNS_RR_TYPE_RRSIG) {
/* same as previous */
*prev_dname_last = dname;
return 1;
}
/* check if rrsig over previous item */
if(type == LDNS_RR_TYPE_RRSIG && dclass == *prev_dclass &&
pkt_rrsig_covered_equals(pkt, sldns_buffer_current(pkt),
*prev_type) &&
smart_compare(pkt, dname, *prev_dname_first,
*prev_dname_last) == 0) {
/* covers previous */
*prev_dname_last = dname;
return 1;
}
}
/* find by hashing and lookup in hashtable */
*rrset_flags = pkt_rrset_flags(pkt, type, section);
/* if rrsig - try to lookup matching data set first */
if(type == LDNS_RR_TYPE_RRSIG && pkt_rrsig_covered(pkt,
sldns_buffer_current(pkt), &covtype)) {
*hash = pkt_hash_rrset_rest(dname_h, covtype, dclass,
*rrset_flags);
*rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash,
*rrset_flags, dname, dnamelen, covtype, dclass);
if(!*rrset_prev && covtype == LDNS_RR_TYPE_NSEC) {
/* if NSEC try with NSEC apex bit twiddled */
*rrset_flags ^= PACKED_RRSET_NSEC_AT_APEX;
*hash = pkt_hash_rrset_rest(dname_h, covtype, dclass,
*rrset_flags);
*rrset_prev = msgparse_hashtable_lookup(msg, pkt,
*hash, *rrset_flags, dname, dnamelen, covtype,
dclass);
if(!*rrset_prev) /* untwiddle if not found */
*rrset_flags ^= PACKED_RRSET_NSEC_AT_APEX;
}
if(!*rrset_prev && covtype == LDNS_RR_TYPE_SOA) {
/* if SOA try with SOA neg flag twiddled */
*rrset_flags ^= PACKED_RRSET_SOA_NEG;
*hash = pkt_hash_rrset_rest(dname_h, covtype, dclass,
*rrset_flags);
*rrset_prev = msgparse_hashtable_lookup(msg, pkt,
*hash, *rrset_flags, dname, dnamelen, covtype,
dclass);
if(!*rrset_prev) /* untwiddle if not found */
*rrset_flags ^= PACKED_RRSET_SOA_NEG;
}
if(*rrset_prev) {
*prev_dname_first = (*rrset_prev)->dname;
*prev_dname_last = dname;
*prev_dnamelen = dnamelen;
*prev_type = covtype;
*prev_dclass = dclass;
return 1;
}
}
if(type != LDNS_RR_TYPE_RRSIG) {
int hasother = 0;
/* find matching rrsig */
*hash = pkt_hash_rrset_rest(dname_h, LDNS_RR_TYPE_RRSIG,
dclass, 0);
*rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash,
0, dname, dnamelen, LDNS_RR_TYPE_RRSIG,
dclass);
if(*rrset_prev && rrset_has_sigover(pkt, *rrset_prev, type,
&hasother)) {
/* yes! */
*prev_dname_first = (*rrset_prev)->dname;
*prev_dname_last = dname;
*prev_dnamelen = dnamelen;
*prev_type = type;
*prev_dclass = dclass;
*rrset_prev = change_rrsig_rrset(*rrset_prev, msg,
pkt, type, *rrset_flags, hasother, section,
region);
if(!*rrset_prev) return 0;
return 1;
}
}
*hash = pkt_hash_rrset_rest(dname_h, type, dclass, *rrset_flags);
*rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash, *rrset_flags,
dname, dnamelen, type, dclass);
if(*rrset_prev)
*prev_dname_first = (*rrset_prev)->dname;
else *prev_dname_first = dname;
*prev_dname_last = dname;
*prev_dnamelen = dnamelen;
*prev_type = type;
*prev_dclass = dclass;
return 1;
}
/**
* Parse query section.
* @param pkt: packet, position at call must be at start of query section.
* at end position is after query section.
* @param msg: store results here.
* @return: 0 if OK, or rcode on error.
*/
static int
parse_query_section(sldns_buffer* pkt, struct msg_parse* msg)
{
if(msg->qdcount == 0)
return 0;
if(msg->qdcount > 1)
return LDNS_RCODE_FORMERR;
log_assert(msg->qdcount == 1);
if(sldns_buffer_remaining(pkt) <= 0)
return LDNS_RCODE_FORMERR;
msg->qname = sldns_buffer_current(pkt);
if((msg->qname_len = pkt_dname_len(pkt)) == 0)
return LDNS_RCODE_FORMERR;
if(sldns_buffer_remaining(pkt) < sizeof(uint16_t)*2)
return LDNS_RCODE_FORMERR;
msg->qtype = sldns_buffer_read_u16(pkt);
msg->qclass = sldns_buffer_read_u16(pkt);
return 0;
}
size_t
get_rdf_size(sldns_rdf_type rdf)
{
switch(rdf) {
case LDNS_RDF_TYPE_CLASS:
case LDNS_RDF_TYPE_ALG:
case LDNS_RDF_TYPE_INT8:
return 1;
break;
case LDNS_RDF_TYPE_INT16:
case LDNS_RDF_TYPE_TYPE:
case LDNS_RDF_TYPE_CERT_ALG:
return 2;
break;
case LDNS_RDF_TYPE_INT32:
case LDNS_RDF_TYPE_TIME:
case LDNS_RDF_TYPE_A:
case LDNS_RDF_TYPE_PERIOD:
return 4;
break;
case LDNS_RDF_TYPE_TSIGTIME:
return 6;
break;
case LDNS_RDF_TYPE_AAAA:
return 16;
break;
default:
log_assert(0); /* add type above */
/* only types that appear before a domain *
* name are needed. rest is simply copied. */
}
return 0;
}
/** calculate the size of one rr */
static int
calc_size(sldns_buffer* pkt, uint16_t type, struct rr_parse* rr)
{
const sldns_rr_descriptor* desc;
uint16_t pkt_len; /* length of rr inside the packet */
rr->size = sizeof(uint16_t); /* the rdatalen */
sldns_buffer_skip(pkt, 4); /* skip ttl */
pkt_len = sldns_buffer_read_u16(pkt);
if(sldns_buffer_remaining(pkt) < pkt_len)
return 0;
desc = sldns_rr_descript(type);
if(pkt_len > 0 && desc && desc->_dname_count > 0) {
int count = (int)desc->_dname_count;
int rdf = 0;
size_t len;
size_t oldpos;
/* skip first part. */
while(pkt_len > 0 && count) {
switch(desc->_wireformat[rdf]) {
case LDNS_RDF_TYPE_DNAME:
/* decompress every domain name */
oldpos = sldns_buffer_position(pkt);
if((len = pkt_dname_len(pkt)) == 0)
return 0; /* malformed dname */
if(sldns_buffer_position(pkt)-oldpos > pkt_len)
return 0; /* dname exceeds rdata */
pkt_len -= sldns_buffer_position(pkt)-oldpos;
rr->size += len;
count--;
len = 0;
break;
case LDNS_RDF_TYPE_STR:
if(pkt_len < 1) {
/* NOTREACHED, due to 'while(>0)' */
return 0; /* len byte exceeds rdata */
}
len = sldns_buffer_current(pkt)[0] + 1;
break;
default:
len = get_rdf_size(desc->_wireformat[rdf]);
}
if(len) {
if(pkt_len < len)
return 0; /* exceeds rdata */
pkt_len -= len;
sldns_buffer_skip(pkt, (ssize_t)len);
rr->size += len;
}
rdf++;
}
}
/* remaining rdata */
rr->size += pkt_len;
sldns_buffer_skip(pkt, (ssize_t)pkt_len);
return 1;
}
/** skip rr ttl and rdata */
static int
skip_ttl_rdata(sldns_buffer* pkt)
{
uint16_t rdatalen;
if(sldns_buffer_remaining(pkt) < 6) /* ttl + rdatalen */
return 0;
sldns_buffer_skip(pkt, 4); /* ttl */
rdatalen = sldns_buffer_read_u16(pkt);
if(sldns_buffer_remaining(pkt) < rdatalen)
return 0;
sldns_buffer_skip(pkt, (ssize_t)rdatalen);
return 1;
}
/** see if RRSIG is a duplicate of another */
static int
sig_is_double(sldns_buffer* pkt, struct rrset_parse* rrset, uint8_t* ttldata)
{
uint16_t rlen, siglen;
size_t pos = sldns_buffer_position(pkt);
struct rr_parse* sig;
if(sldns_buffer_remaining(pkt) < 6)
return 0;
sldns_buffer_skip(pkt, 4); /* ttl */
rlen = sldns_buffer_read_u16(pkt);
if(sldns_buffer_remaining(pkt) < rlen) {
sldns_buffer_set_position(pkt, pos);
return 0;
}
sldns_buffer_set_position(pkt, pos);
sig = rrset->rrsig_first;
while(sig) {
/* check if rdatalen is same */
memmove(&siglen, sig->ttl_data+4, sizeof(siglen));
siglen = ntohs(siglen);
/* checks if data in packet is exactly the same, this means
* also dname in rdata is the same, but rrsig is not allowed
* to have compressed dnames anyway. If it is compressed anyway
* it will lead to duplicate rrs for qtype=RRSIG. (or ANY).
*
* Cannot use sig->size because size of the other one is not
* calculated yet.
*/
if(siglen == rlen) {
if(siglen>0 && memcmp(sig->ttl_data+6, ttldata+6,
siglen) == 0) {
/* same! */
return 1;
}
}
sig = sig->next;
}
return 0;
}
/** Add rr (from packet here) to rrset, skips rr */
static int
add_rr_to_rrset(struct rrset_parse* rrset, sldns_buffer* pkt,
struct msg_parse* msg, struct regional* region,
sldns_pkt_section section, uint16_t type)
{
struct rr_parse* rr;
/* check section of rrset. */
if(rrset->section != section && type != LDNS_RR_TYPE_RRSIG &&
rrset->type != LDNS_RR_TYPE_RRSIG) {
/* silently drop it - we drop the last part, since
* trust in rr data depends on the section it is in.
* the less trustworthy part is discarded.
* also the last part is more likely to be incomplete.
* RFC 2181: must put RRset only once in response. */
/*
verbose(VERB_QUERY, "Packet contains rrset data in "
"multiple sections, dropped last part.");
log_buf(VERB_QUERY, "packet was", pkt);
*/
/* forwards */
if(!skip_ttl_rdata(pkt))
return LDNS_RCODE_FORMERR;
return 0;
}
if( (msg->qtype == LDNS_RR_TYPE_RRSIG ||
msg->qtype == LDNS_RR_TYPE_ANY)
&& sig_is_double(pkt, rrset, sldns_buffer_current(pkt))) {
if(!skip_ttl_rdata(pkt))
return LDNS_RCODE_FORMERR;
return 0;
}
/* create rr */
if(!(rr = (struct rr_parse*)regional_alloc(region, sizeof(*rr))))
return LDNS_RCODE_SERVFAIL;
rr->outside_packet = 0;
rr->ttl_data = sldns_buffer_current(pkt);
rr->next = 0;
if(type == LDNS_RR_TYPE_RRSIG && rrset->type != LDNS_RR_TYPE_RRSIG) {
if(rrset->rrsig_last)
rrset->rrsig_last->next = rr;
else rrset->rrsig_first = rr;
rrset->rrsig_last = rr;
rrset->rrsig_count++;
} else {
if(rrset->rr_last)
rrset->rr_last->next = rr;
else rrset->rr_first = rr;
rrset->rr_last = rr;
rrset->rr_count++;
}
/* calc decompressed size */
if(!calc_size(pkt, type, rr))
return LDNS_RCODE_FORMERR;
rrset->size += rr->size;
return 0;
}
/**
* Parse packet RR section, for answer, authority and additional sections.
* @param pkt: packet, position at call must be at start of section.
* at end position is after section.
* @param msg: store results here.
* @param region: how to alloc results.
* @param section: section enum.
* @param num_rrs: how many rrs are in the section.
* @param num_rrsets: returns number of rrsets in the section.
* @return: 0 if OK, or rcode on error.
*/
static int
parse_section(sldns_buffer* pkt, struct msg_parse* msg,
struct regional* region, sldns_pkt_section section,
uint16_t num_rrs, size_t* num_rrsets)
{
uint16_t i;
uint8_t* dname, *prev_dname_f = NULL, *prev_dname_l = NULL;
size_t dnamelen, prev_dnamelen = 0;
uint16_t type, prev_type = 0;
uint16_t dclass, prev_dclass = 0;
uint32_t rrset_flags = 0;
hashvalue_t hash = 0;
struct rrset_parse* rrset = NULL;
int r;
if(num_rrs == 0)
return 0;
if(sldns_buffer_remaining(pkt) <= 0)
return LDNS_RCODE_FORMERR;
for(i=0; i<num_rrs; i++) {
/* parse this RR. */
dname = sldns_buffer_current(pkt);
if((dnamelen = pkt_dname_len(pkt)) == 0)
return LDNS_RCODE_FORMERR;
if(sldns_buffer_remaining(pkt) < 10) /* type, class, ttl, len */
return LDNS_RCODE_FORMERR;
type = sldns_buffer_read_u16(pkt);
sldns_buffer_read(pkt, &dclass, sizeof(dclass));
if(0) { /* debug show what is being parsed. */
if(type == LDNS_RR_TYPE_RRSIG) {
uint16_t t;
if(pkt_rrsig_covered(pkt,
sldns_buffer_current(pkt), &t))
fprintf(stderr, "parse of %s(%d) [%s(%d)]",
sldns_rr_descript(type)?
sldns_rr_descript(type)->_name: "??",
(int)type,
sldns_rr_descript(t)?
sldns_rr_descript(t)->_name: "??",
(int)t);
} else
fprintf(stderr, "parse of %s(%d)",
sldns_rr_descript(type)?
sldns_rr_descript(type)->_name: "??",
(int)type);
fprintf(stderr, " %s(%d) ",
sldns_lookup_by_id(sldns_rr_classes,
(int)ntohs(dclass))?sldns_lookup_by_id(
sldns_rr_classes, (int)ntohs(dclass))->name:
"??", (int)ntohs(dclass));
dname_print(stderr, pkt, dname);
fprintf(stderr, "\n");
}
/* see if it is part of an existing RR set */
if(!find_rrset(msg, pkt, dname, dnamelen, type, dclass, &hash,
&rrset_flags, &prev_dname_f, &prev_dname_l,
&prev_dnamelen, &prev_type, &prev_dclass, &rrset,
section, region))
return LDNS_RCODE_SERVFAIL;
if(!rrset) {
/* it is a new RR set. hash&flags already calculated.*/
(*num_rrsets)++;
rrset = new_rrset(msg, dname, dnamelen, type, dclass,
hash, rrset_flags, section, region);
if(!rrset)
return LDNS_RCODE_SERVFAIL;
}
else if(0) {
fprintf(stderr, "is part of existing: ");
dname_print(stderr, pkt, rrset->dname);
fprintf(stderr, " type %s(%d)\n",
sldns_rr_descript(rrset->type)?
sldns_rr_descript(rrset->type)->_name: "??",
(int)rrset->type);
}
/* add to rrset. */
if((r=add_rr_to_rrset(rrset, pkt, msg, region, section,
type)) != 0)
return r;
}
return 0;
}
int
parse_packet(sldns_buffer* pkt, struct msg_parse* msg, struct regional* region)
{
int ret;
if(sldns_buffer_remaining(pkt) < LDNS_HEADER_SIZE)
return LDNS_RCODE_FORMERR;
/* read the header */
sldns_buffer_read(pkt, &msg->id, sizeof(uint16_t));
msg->flags = sldns_buffer_read_u16(pkt);
msg->qdcount = sldns_buffer_read_u16(pkt);
msg->ancount = sldns_buffer_read_u16(pkt);
msg->nscount = sldns_buffer_read_u16(pkt);
msg->arcount = sldns_buffer_read_u16(pkt);
if(msg->qdcount > 1)
return LDNS_RCODE_FORMERR;
if((ret = parse_query_section(pkt, msg)) != 0)
return ret;
if((ret = parse_section(pkt, msg, region, LDNS_SECTION_ANSWER,
msg->ancount, &msg->an_rrsets)) != 0)
return ret;
if((ret = parse_section(pkt, msg, region, LDNS_SECTION_AUTHORITY,
msg->nscount, &msg->ns_rrsets)) != 0)
return ret;
if(sldns_buffer_remaining(pkt) == 0 && msg->arcount == 1) {
/* BIND accepts leniently that an EDNS record is missing.
* so, we do too. */
} else if((ret = parse_section(pkt, msg, region,
LDNS_SECTION_ADDITIONAL, msg->arcount, &msg->ar_rrsets)) != 0)
return ret;
/* if(sldns_buffer_remaining(pkt) > 0) { */
/* there is spurious data at end of packet. ignore */
/* } */
msg->rrset_count = msg->an_rrsets + msg->ns_rrsets + msg->ar_rrsets;
return 0;
}
int
parse_extract_edns(struct msg_parse* msg, struct edns_data* edns)
{
struct rrset_parse* rrset = msg->rrset_first;
struct rrset_parse* prev = 0;
struct rrset_parse* found = 0;
struct rrset_parse* found_prev = 0;
/* since the class encodes the UDP size, we cannot use hash table to
* find the EDNS OPT record. Scan the packet. */
while(rrset) {
if(rrset->type == LDNS_RR_TYPE_OPT) {
/* only one OPT RR allowed. */
if(found) return LDNS_RCODE_FORMERR;
/* found it! */
found_prev = prev;
found = rrset;
}
prev = rrset;
rrset = rrset->rrset_all_next;
}
if(!found) {
memset(edns, 0, sizeof(*edns));
edns->udp_size = 512;
return 0;
}
/* check the found RRset */
/* most lenient check possible. ignore dname, use last opt */
if(found->section != LDNS_SECTION_ADDITIONAL)
return LDNS_RCODE_FORMERR;
if(found->rr_count == 0)
return LDNS_RCODE_FORMERR;
if(0) { /* strict checking of dname and RRcount */
if(found->dname_len != 1 || !found->dname
|| found->dname[0] != 0) return LDNS_RCODE_FORMERR;
if(found->rr_count != 1) return LDNS_RCODE_FORMERR;
}
log_assert(found->rr_first && found->rr_last);
/* remove from packet */
if(found_prev) found_prev->rrset_all_next = found->rrset_all_next;
else msg->rrset_first = found->rrset_all_next;
if(found == msg->rrset_last)
msg->rrset_last = found_prev;
msg->arcount --;
msg->ar_rrsets --;
msg->rrset_count --;
/* take the data ! */
edns->edns_present = 1;
edns->ext_rcode = found->rr_last->ttl_data[0];
edns->edns_version = found->rr_last->ttl_data[1];
edns->bits = sldns_read_uint16(&found->rr_last->ttl_data[2]);
edns->udp_size = ntohs(found->rrset_class);
/* ignore rdata and rrsigs */
return 0;
}
int
parse_edns_from_pkt(sldns_buffer* pkt, struct edns_data* edns)
{
log_assert(LDNS_QDCOUNT(sldns_buffer_begin(pkt)) == 1);
log_assert(LDNS_ANCOUNT(sldns_buffer_begin(pkt)) == 0);
log_assert(LDNS_NSCOUNT(sldns_buffer_begin(pkt)) == 0);
/* check edns section is present */
if(LDNS_ARCOUNT(sldns_buffer_begin(pkt)) > 1) {
return LDNS_RCODE_FORMERR;
}
if(LDNS_ARCOUNT(sldns_buffer_begin(pkt)) == 0) {
memset(edns, 0, sizeof(*edns));
edns->udp_size = 512;
return 0;
}
/* domain name must be the root of length 1. */
if(pkt_dname_len(pkt) != 1)
return LDNS_RCODE_FORMERR;
if(sldns_buffer_remaining(pkt) < 10) /* type, class, ttl, rdatalen */
return LDNS_RCODE_FORMERR;
if(sldns_buffer_read_u16(pkt) != LDNS_RR_TYPE_OPT)
return LDNS_RCODE_FORMERR;
edns->edns_present = 1;
edns->udp_size = sldns_buffer_read_u16(pkt); /* class is udp size */
edns->ext_rcode = sldns_buffer_read_u8(pkt); /* ttl used for bits */
edns->edns_version = sldns_buffer_read_u8(pkt);
edns->bits = sldns_buffer_read_u16(pkt);
/* ignore rdata and rrsigs */
return 0;
}
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