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message parsing code in one file.

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git-svn-id: file:///svn/unbound/trunk@245 be551aaa-1e26-0410-a405-d3ace91eadb9
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Wouter Wijngaards 2007-04-17 11:56:48 +00:00
parent 200993b89f
commit 8bda1b6893
4 changed files with 563 additions and 478 deletions
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doc/Changelog
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@ -2,6 +2,7 @@
- copy and decompress dnames.
- store calculated hash value too.
- routine to create message out of stored information.
- util/data/msgparse.c for message parsing code.
16 April 2007: Wouter
- following a small change in LDNS, parsing code calculates the

407
util/data/msgparse.c Normal file
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@ -0,0 +1,407 @@
/*
* 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 REGENTS 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.
*/
#include "config.h"
#include "util/data/msgparse.h"
#include "util/net_help.h"
#include "util/data/dname.h"
#include "util/data/packed_rrset.h"
#include "util/storage/lookup3.h"
#include "util/region-allocator.h"
/** smart comparison of (compressed, valid) dnames from packet. */
static int
smart_compare(ldns_buffer* pkt, uint8_t* dnow,
uint8_t *dprfirst, uint8_t* dprlast)
{
if( (*dnow & 0xc0) == 0xc0) {
/* ptr points to a previous dname */
uint8_t* p = ldns_buffer_at(pkt, (dnow[0]&0x3f)<<8 | dnow[1]);
if( p == dprfirst || p == dprlast )
return 0;
/* prev dname is also a ptr, both ptrs are the same. */
/* if( (*dprfirst & 0xc0) == 0xc0 &&
dprfirst[0] == dnow[0] && dprfirst[1] == dnow[1])
return 0; */
if( (*dprlast & 0xc0) == 0xc0 &&
dprlast[0] == dnow[0] && dprlast[1] == dnow[1])
return 0;
/* checks for prev dnames pointing forwards in the packet
} else {
if( (*dprfirst & 0xc0) == 0xc0 ) {
if(ldns_buffer_at(pkt, (dprfirst[0]&0x3f)<<8 |
dprfirst[1]) == dnow)
return 0;
}
if( (*dprlast & 0xc0) == 0xc0 ) {
if(ldns_buffer_at(pkt, (dprlast[0]&0x3f)<<8 |
dprlast[1]) == dnow)
return 0;
}
*/
}
return dname_pkt_compare(pkt, dnow, dprlast);
}
/** See if next rrset is nsec at zone apex. */
static int
nsec_at_apex(ldns_buffer* pkt)
{
/* we are at ttl position in packet. */
size_t pos = ldns_buffer_position(pkt);
uint16_t rdatalen;
if(ldns_buffer_remaining(pkt) < 7) /* ttl+len+root */
return 0; /* eek! */
ldns_buffer_skip(pkt, 4); /* ttl */;
rdatalen = ldns_buffer_read_u16(pkt);
if(ldns_buffer_remaining(pkt) < rdatalen) {
ldns_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) {
ldns_buffer_set_position(pkt, pos);
return 0; /* parse error */
}
/* see if SOA bit is set. */
if(ldns_buffer_position(pkt) < pos+rdatalen) {
/* nsec type bitmap contains items */
uint8_t win, blen, bits;
/* need: windownum, bitmap len, firstbyte */
if(ldns_buffer_position(pkt)+3 <= pos+rdatalen) {
ldns_buffer_set_position(pkt, pos);
return 0; /* malformed nsec */
}
win = ldns_buffer_read_u8(pkt);
blen = ldns_buffer_read_u8(pkt);
bits = ldns_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)) {
ldns_buffer_set_position(pkt, pos);
return 1;
}
}
ldns_buffer_set_position(pkt, pos);
return 0;
}
/** Calculate hash value for rrset in packet. */
static hashvalue_t
pkt_hash_rrset(struct msg_parse* msg, ldns_buffer* pkt, uint8_t* dname,
uint16_t type, uint16_t dclass, uint32_t* rrset_flags)
{
hashvalue_t h = 0xab;
if(msg->flags & BIT_CD)
*rrset_flags = PACKED_RRSET_CD;
else *rrset_flags = 0;
if(type == htons(LDNS_RR_TYPE_NSEC) && nsec_at_apex(pkt))
*rrset_flags |= PACKED_RRSET_NSEC_AT_APEX;
h = hashlittle(&type, sizeof(type), h);
h = hashlittle(&dclass, sizeof(dclass), h);
h = hashlittle(rrset_flags, sizeof(uint32_t), h);
h = dname_pkt_hash(pkt, dname, h);
return h;
}
/** compare rrset_parse with data. */
static int
rrset_parse_equals(struct rrset_parse* p, ldns_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;
}
/**
* Lookup in msg hashtable to find a rrset
*/
static struct rrset_parse*
hashtable_lookup(struct msg_parse* msg, ldns_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;
}
/** 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.
* @return the rrset if found, or null if no matching rrset exists.
*/
static struct rrset_parse*
find_rrset(struct msg_parse* msg, ldns_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)
{
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) {
/* same as previous */
*prev_dname_last = dname;
return *rrset_prev;
}
}
/* find by hashing and lookup in hashtable */
*hash = pkt_hash_rrset(msg, pkt, dname, type, dclass, rrset_flags);
*rrset_prev = 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 *rrset_prev;
}
/**
* 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(ldns_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(ldns_buffer_remaining(pkt) <= 0)
return LDNS_RCODE_FORMERR;
msg->qname = ldns_buffer_current(pkt);
if((msg->qname_len = query_dname_len(pkt)) == 0)
return LDNS_RCODE_FORMERR;
if(ldns_buffer_remaining(pkt) < sizeof(uint16_t)*2)
return LDNS_RCODE_FORMERR;
msg->qtype = ldns_buffer_read_u16(pkt);
msg->qclass = ldns_buffer_read_u16(pkt);
return 0;
}
/**
* 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, ldns_pkt_section section, region_type* region)
{
struct rrset_parse* p = region_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->rr_first = 0;
p->rr_last = 0;
return p;
}
/** Add rr (from packet here) to rrset, skips rr */
static int
add_rr_to_rrset(struct rrset_parse* rrset, ldns_buffer* pkt,
region_type* region, ldns_pkt_section section)
{
uint16_t rdatalen;
/* check section of rrset. */
if(rrset->section != section) {
/* silently drop it */
verbose(VERB_DETAIL, "Packet contains rrset data in "
"multiple sections, dropped last part.");
} else {
/* create rr */
struct rr_parse* rr = region_alloc(region, sizeof(*rr));
if(!rr) return LDNS_RCODE_SERVFAIL;
rr->ttl_data = ldns_buffer_current(pkt);
rr->next = 0;
if(rrset->rr_last)
rrset->rr_last->next = rr;
else rrset->rr_first = rr;
rrset->rr_last = rr;
rrset->rr_count++;
}
/* forwards */
if(ldns_buffer_remaining(pkt) < 6) /* ttl + rdatalen */
return LDNS_RCODE_FORMERR;
ldns_buffer_skip(pkt, 4); /* ttl */
rdatalen = ldns_buffer_read_u16(pkt);
if(ldns_buffer_remaining(pkt) < rdatalen)
return LDNS_RCODE_FORMERR;
ldns_buffer_skip(pkt, (ssize_t)rdatalen);
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(ldns_buffer* pkt, struct msg_parse* msg, region_type* region,
ldns_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, *rrset_prev = NULL;
int r;
if(num_rrs == 0)
return 0;
if(ldns_buffer_remaining(pkt) <= 0)
return LDNS_RCODE_FORMERR;
for(i=0; i<num_rrs; i++) {
/* parse this RR. */
dname = ldns_buffer_current(pkt);
if((dnamelen = pkt_dname_len(pkt)) == 0)
return LDNS_RCODE_FORMERR;
if(ldns_buffer_remaining(pkt) < 10) /* type, class, ttl, len */
return LDNS_RCODE_FORMERR;
ldns_buffer_read(pkt, &type, sizeof(type));
ldns_buffer_read(pkt, &dclass, sizeof(dclass));
/* see if it is part of an existing RR set */
if((rrset = find_rrset(msg, pkt, dname, dnamelen, type, dclass,
&hash, &rrset_flags, &prev_dname_f, &prev_dname_l,
&prev_dnamelen, &prev_type, &prev_dclass,
&rrset_prev)) != 0) {
/* check if it fits the existing rrset */
/* add to rrset. */
} else {
/* 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;
rrset_prev = rrset;
}
if((r=add_rr_to_rrset(rrset, pkt, region, section)))
return r;
}
return 0;
}
int
parse_packet(ldns_buffer* pkt, struct msg_parse* msg, region_type* region)
{
int ret;
if(ldns_buffer_remaining(pkt) < LDNS_HEADER_SIZE)
return LDNS_RCODE_FORMERR;
/* read the header */
ldns_buffer_read(pkt, &msg->id, sizeof(uint16_t));
msg->flags = ldns_buffer_read_u16(pkt);
msg->qdcount = ldns_buffer_read_u16(pkt);
msg->ancount = ldns_buffer_read_u16(pkt);
msg->nscount = ldns_buffer_read_u16(pkt);
msg->arcount = ldns_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((ret = parse_section(pkt, msg, region, LDNS_SECTION_ADDITIONAL,
msg->arcount, &msg->ar_rrsets)) != 0)
return ret;
if(ldns_buffer_remaining(pkt) > 0) {
/* spurious data at end of packet. ignore */
verbose(VERB_DETAIL, "spurious data at end of packet ignored");
}
return 0;
}

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util/data/msgparse.h Normal file
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@ -0,0 +1,154 @@
/*
* util/data/msgparse.h - 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 REGENTS 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.
*/
#ifndef UTIL_DATA_MSGPARSE_H
#define UTIL_DATA_MSGPARSE_H
#include "util/storage/lruhash.h"
struct rrset_parse;
struct rr_parse;
struct region;
/** number of buckets in parse rrset hash table. Must be power of 2. */
#define PARSE_TABLE_SIZE 1024
/** Maximum TTL that is allowed. */
#define MAX_TTL 3600*24*365*10 /* ten years */
/**
* Data stored in scratch pad memory during parsing.
* Stores the data that will enter into the msgreply and packet result.
*/
struct msg_parse {
/** id from message, network format. */
uint16_t id;
/** flags from message, host format. */
uint16_t flags;
/** count of RRs, host format */
uint16_t qdcount;
/** count of RRs, host format */
uint16_t ancount;
/** count of RRs, host format */
uint16_t nscount;
/** count of RRs, host format */
uint16_t arcount;
/** count of RRsets per section. */
size_t an_rrsets;
/** count of RRsets per section. */
size_t ns_rrsets;
/** count of RRsets per section. */
size_t ar_rrsets;
/** total number of rrsets found. */
size_t rrset_count;
/** query dname (pointer to start location in packet, NULL if none */
uint8_t* qname;
/** length of query dname in octets, 0 if none */
size_t qname_len;
/** query type, network order. 0 if qdcount=0 */
uint16_t qtype;
/** query class, network order. 0 if qdcount=0 */
uint16_t qclass;
/**
* Hash table array used during parsing to lookup rrset types.
* Based on name, type, class. Same hash value as in rrset cache.
*/
struct rrset_parse* hashtable[PARSE_TABLE_SIZE];
/** linked list of rrsets that have been found (in order). */
struct rrset_parse* rrset_first;
/** last element of rrset list. */
struct rrset_parse* rrset_last;
};
/**
* Data stored for an rrset during parsing.
*/
struct rrset_parse {
/** next in hash bucket */
struct rrset_parse* rrset_bucket_next;
/** next in list of all rrsets */
struct rrset_parse* rrset_all_next;
/** hash value of rrset */
hashvalue_t hash;
/** which section was it found in: one of
* LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL
*/
ldns_pkt_section section;
/** start of (possibly compressed) dname in packet */
uint8_t* dname;
/** length of the dname uncompressed wireformat */
size_t dname_len;
/** type, network order. */
uint16_t type;
/** class, network order. name so that it is not a c++ keyword. */
uint16_t rrset_class;
/** the flags for the rrset, like for packedrrset */
uint32_t flags;
/** number of RRs in the rr list */
size_t rr_count;
/** linked list of RRs in this rrset. */
struct rr_parse* rr_first;
/** last in list of RRs in this rrset. */
struct rr_parse* rr_last;
};
/**
* Data stored for an RR during parsing.
*/
struct rr_parse {
/**
* Pointer to the RR. Points to start of TTL value in the packet.
* Rdata length and rdata follow it.
* its dname, type and class are the same and stored for the rrset.
*/
uint8_t* ttl_data;
/** the length of the rdata if allocated (with no dname compression)*/
size_t size;
/** next in list of RRs. */
struct rr_parse* next;
};
/**
* Parse the packet.
* @param pkt: packet, position at call must be at start of packet.
* at end position is after packet.
* @param msg: where to store results.
* @param region: how to alloc results.
* @return: 0 if OK, or rcode on error.
*/
int parse_packet(ldns_buffer* pkt, struct msg_parse* msg,
struct region* region);
#endif /* UTIL_DATA_MSGPARSE_H */

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util/data/msgreply.c
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@ -48,484 +48,7 @@
#include "util/net_help.h"
#include "util/data/dname.h"
#include "util/region-allocator.h"
struct rrset_parse;
struct rr_parse;
/** number of buckets in parse rrset hash table. Must be power of 2. */
#define PARSE_TABLE_SIZE 1024
/** Maximum TTL that is allowed. */
#define MAX_TTL 3600*24*365*10 /* ten years */
/**
* Data stored in scratch pad memory during parsing.
* Stores the data that will enter into the msgreply and packet result.
*/
struct msg_parse {
/** id from message, network format. */
uint16_t id;
/** flags from message, host format. */
uint16_t flags;
/** count of RRs, host format */
uint16_t qdcount;
/** count of RRs, host format */
uint16_t ancount;
/** count of RRs, host format */
uint16_t nscount;
/** count of RRs, host format */
uint16_t arcount;
/** count of RRsets per section. */
size_t an_rrsets;
/** count of RRsets per section. */
size_t ns_rrsets;
/** count of RRsets per section. */
size_t ar_rrsets;
/** total number of rrsets found. */
size_t rrset_count;
/** query dname (pointer to start location in packet, NULL if none */
uint8_t* qname;
/** length of query dname in octets, 0 if none */
size_t qname_len;
/** query type, network order. 0 if qdcount=0 */
uint16_t qtype;
/** query class, network order. 0 if qdcount=0 */
uint16_t qclass;
/**
* Hash table array used during parsing to lookup rrset types.
* Based on name, type, class. Same hash value as in rrset cache.
*/
struct rrset_parse* hashtable[PARSE_TABLE_SIZE];
/** linked list of rrsets that have been found (in order). */
struct rrset_parse* rrset_first;
/** last element of rrset list. */
struct rrset_parse* rrset_last;
};
/**
* Data stored for an rrset during parsing.
*/
struct rrset_parse {
/** next in hash bucket */
struct rrset_parse* rrset_bucket_next;
/** next in list of all rrsets */
struct rrset_parse* rrset_all_next;
/** hash value of rrset */
hashvalue_t hash;
/** which section was it found in: one of
* LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL
*/
ldns_pkt_section section;
/** start of (possibly compressed) dname in packet */
uint8_t* dname;
/** length of the dname uncompressed wireformat */
size_t dname_len;
/** type, network order. */
uint16_t type;
/** class, network order. name so that it is not a c++ keyword. */
uint16_t rrset_class;
/** the flags for the rrset, like for packedrrset */
uint32_t flags;
/** number of RRs in the rr list */
size_t rr_count;
/** linked list of RRs in this rrset. */
struct rr_parse* rr_first;
/** last in list of RRs in this rrset. */
struct rr_parse* rr_last;
};
/**
* Data stored for an RR during parsing.
*/
struct rr_parse {
/**
* Pointer to the RR. Points to start of TTL value in the packet.
* Rdata length and rdata follow it.
* its dname, type and class are the same and stored for the rrset.
*/
uint8_t* ttl_data;
/** the length of the rdata if allocated (with no dname compression)*/
size_t size;
/** next in list of RRs. */
struct rr_parse* next;
};
/** smart comparison of (compressed, valid) dnames from packet. */
static int
smart_compare(ldns_buffer* pkt, uint8_t* dnow,
uint8_t *dprfirst, uint8_t* dprlast)
{
if( (*dnow & 0xc0) == 0xc0) {
/* ptr points to a previous dname */
uint8_t* p = ldns_buffer_at(pkt, (dnow[0]&0x3f)<<8 | dnow[1]);
if( p == dprfirst || p == dprlast )
return 0;
/* prev dname is also a ptr, both ptrs are the same. */
/* if( (*dprfirst & 0xc0) == 0xc0 &&
dprfirst[0] == dnow[0] && dprfirst[1] == dnow[1])
return 0; */
if( (*dprlast & 0xc0) == 0xc0 &&
dprlast[0] == dnow[0] && dprlast[1] == dnow[1])
return 0;
/* checks for prev dnames pointing forwards in the packet
} else {
if( (*dprfirst & 0xc0) == 0xc0 ) {
if(ldns_buffer_at(pkt, (dprfirst[0]&0x3f)<<8 |
dprfirst[1]) == dnow)
return 0;
}
if( (*dprlast & 0xc0) == 0xc0 ) {
if(ldns_buffer_at(pkt, (dprlast[0]&0x3f)<<8 |
dprlast[1]) == dnow)
return 0;
}
*/
}
return dname_pkt_compare(pkt, dnow, dprlast);
}
/** See if next rrset is nsec at zone apex. */
static int
nsec_at_apex(ldns_buffer* pkt)
{
/* we are at ttl position in packet. */
size_t pos = ldns_buffer_position(pkt);
uint16_t rdatalen;
if(ldns_buffer_remaining(pkt) < 7) /* ttl+len+root */
return 0; /* eek! */
ldns_buffer_skip(pkt, 4); /* ttl */;
rdatalen = ldns_buffer_read_u16(pkt);
if(ldns_buffer_remaining(pkt) < rdatalen) {
ldns_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) {
ldns_buffer_set_position(pkt, pos);
return 0; /* parse error */
}
/* see if SOA bit is set. */
if(ldns_buffer_position(pkt) < pos+rdatalen) {
/* nsec type bitmap contains items */
uint8_t win, blen, bits;
/* need: windownum, bitmap len, firstbyte */
if(ldns_buffer_position(pkt)+3 <= pos+rdatalen) {
ldns_buffer_set_position(pkt, pos);
return 0; /* malformed nsec */
}
win = ldns_buffer_read_u8(pkt);
blen = ldns_buffer_read_u8(pkt);
bits = ldns_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)) {
ldns_buffer_set_position(pkt, pos);
return 1;
}
}
ldns_buffer_set_position(pkt, pos);
return 0;
}
/** Calculate hash value for rrset in packet. */
static hashvalue_t
pkt_hash_rrset(struct msg_parse* msg, ldns_buffer* pkt, uint8_t* dname,
uint16_t type, uint16_t dclass, uint32_t* rrset_flags)
{
hashvalue_t h = 0xab;
if(msg->flags & BIT_CD)
*rrset_flags = PACKED_RRSET_CD;
else *rrset_flags = 0;
if(type == htons(LDNS_RR_TYPE_NSEC) && nsec_at_apex(pkt))
*rrset_flags |= PACKED_RRSET_NSEC_AT_APEX;
h = hashlittle(&type, sizeof(type), h);
h = hashlittle(&dclass, sizeof(dclass), h);
h = hashlittle(rrset_flags, sizeof(uint32_t), h);
h = dname_pkt_hash(pkt, dname, h);
return h;
}
/** compare rrset_parse with data. */
static int
rrset_parse_equals(struct rrset_parse* p, ldns_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;
}
/**
* Lookup in msg hashtable to find a rrset
*/
static struct rrset_parse*
hashtable_lookup(struct msg_parse* msg, ldns_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;
}
/** 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.
* @return the rrset if found, or null if no matching rrset exists.
*/
static struct rrset_parse*
find_rrset(struct msg_parse* msg, ldns_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)
{
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) {
/* same as previous */
*prev_dname_last = dname;
return *rrset_prev;
}
}
/* find by hashing and lookup in hashtable */
*hash = pkt_hash_rrset(msg, pkt, dname, type, dclass, rrset_flags);
*rrset_prev = 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 *rrset_prev;
}
/**
* 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(ldns_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(ldns_buffer_remaining(pkt) <= 0)
return LDNS_RCODE_FORMERR;
msg->qname = ldns_buffer_current(pkt);
if((msg->qname_len = query_dname_len(pkt)) == 0)
return LDNS_RCODE_FORMERR;
if(ldns_buffer_remaining(pkt) < sizeof(uint16_t)*2)
return LDNS_RCODE_FORMERR;
msg->qtype = ldns_buffer_read_u16(pkt);
msg->qclass = ldns_buffer_read_u16(pkt);
return 0;
}
/**
* 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, ldns_pkt_section section, region_type* region)
{
struct rrset_parse* p = region_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->rr_first = 0;
p->rr_last = 0;
return p;
}
/** Add rr (from packet here) to rrset, skips rr */
static int
add_rr_to_rrset(struct rrset_parse* rrset, ldns_buffer* pkt,
region_type* region, ldns_pkt_section section)
{
uint16_t rdatalen;
/* check section of rrset. */
if(rrset->section != section) {
/* silently drop it */
verbose(VERB_DETAIL, "Packet contains rrset data in "
"multiple sections, dropped last part.");
} else {
/* create rr */
struct rr_parse* rr = region_alloc(region, sizeof(*rr));
if(!rr) return LDNS_RCODE_SERVFAIL;
rr->ttl_data = ldns_buffer_current(pkt);
rr->next = 0;
if(rrset->rr_last)
rrset->rr_last->next = rr;
else rrset->rr_first = rr;
rrset->rr_last = rr;
rrset->rr_count++;
}
/* forwards */
if(ldns_buffer_remaining(pkt) < 6) /* ttl + rdatalen */
return LDNS_RCODE_FORMERR;
ldns_buffer_skip(pkt, 4); /* ttl */
rdatalen = ldns_buffer_read_u16(pkt);
if(ldns_buffer_remaining(pkt) < rdatalen)
return LDNS_RCODE_FORMERR;
ldns_buffer_skip(pkt, (ssize_t)rdatalen);
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(ldns_buffer* pkt, struct msg_parse* msg, region_type* region,
ldns_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, *rrset_prev = NULL;
int r;
if(num_rrs == 0)
return 0;
if(ldns_buffer_remaining(pkt) <= 0)
return LDNS_RCODE_FORMERR;
for(i=0; i<num_rrs; i++) {
/* parse this RR. */
dname = ldns_buffer_current(pkt);
if((dnamelen = pkt_dname_len(pkt)) == 0)
return LDNS_RCODE_FORMERR;
if(ldns_buffer_remaining(pkt) < 10) /* type, class, ttl, len */
return LDNS_RCODE_FORMERR;
ldns_buffer_read(pkt, &type, sizeof(type));
ldns_buffer_read(pkt, &dclass, sizeof(dclass));
/* see if it is part of an existing RR set */
if((rrset = find_rrset(msg, pkt, dname, dnamelen, type, dclass,
&hash, &rrset_flags, &prev_dname_f, &prev_dname_l,
&prev_dnamelen, &prev_type, &prev_dclass,
&rrset_prev)) != 0) {
/* check if it fits the existing rrset */
/* add to rrset. */
} else {
/* 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;
rrset_prev = rrset;
}
if((r=add_rr_to_rrset(rrset, pkt, region, section)))
return r;
}
return 0;
}
/**
* Parse the packet.
* @param pkt: packet, position at call must be at start of packet.
* at end position is after packet.
* @param msg: where to store results.
* @param region: how to alloc results.
* @return: 0 if OK, or rcode on error.
*/
static int
parse_packet(ldns_buffer* pkt, struct msg_parse* msg,
region_type* region)
{
int ret;
if(ldns_buffer_remaining(pkt) < LDNS_HEADER_SIZE)
return LDNS_RCODE_FORMERR;
/* read the header */
ldns_buffer_read(pkt, &msg->id, sizeof(uint16_t));
msg->flags = ldns_buffer_read_u16(pkt);
msg->qdcount = ldns_buffer_read_u16(pkt);
msg->ancount = ldns_buffer_read_u16(pkt);
msg->nscount = ldns_buffer_read_u16(pkt);
msg->arcount = ldns_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((ret = parse_section(pkt, msg, region, LDNS_SECTION_ADDITIONAL,
msg->arcount, &msg->ar_rrsets)) != 0)
return ret;
if(ldns_buffer_remaining(pkt) > 0) {
/* spurious data at end of packet. ignore */
verbose(VERB_DETAIL, "spurious data at end of packet ignored");
}
return 0;
}
#include "util/data/msgparse.h"
/** copy and allocate an uncompressed dname. */
static uint8_t*