unbound/util/data/msgreply.c

/*
 * util/data/msgreply.c - store message and reply data. 
 *
 * 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.
 */

/**
 * \file
 *
 * This file contains a data structure to store a message and its reply.
 */

#include "config.h"
#include "util/data/msgreply.h"
#include "util/storage/lookup3.h"
#include "util/log.h"
#include "util/netevent.h"
#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. */
#define PARSE_TABLE_SIZE 1024

/**
 * 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;
	/** 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;
	/** 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)
{
	uint8_t* p;
	if( (*dnow & 0xc0) == 0xc0) {
		/* 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;
		/* ptr points to a previous dname */
		p = ldns_buffer_at(pkt, (dnow[0]&0x3f)<<8 | dnow[1]);
		if( p == dprfirst || p == dprlast )
			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);
}

/** 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 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, 
	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 */
	return NULL;
}

/**
 * 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;
}

/**
 * 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;
	hashvalue_t hash;
	struct rrset_parse* rrset, *rrset_prev = NULL;

	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, &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 already calculated. */
		}
	}
	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, ign.");
	}
	return 0;
}


int reply_info_parse(ldns_buffer* pkt, struct alloc_cache* alloc,
        struct query_info* qinf, struct reply_info** rep)
{
	/* use scratch pad region-allocator during parsing. */
	region_type* region = region_create(malloc, free);
	struct msg_parse* msg;
	int ret;
	
	*rep = NULL;
	msg = region_alloc(region, sizeof(*msg));
	if(!msg)
		goto malloc_error;
	memset(msg, 0, sizeof(*msg));
	
	log_assert(ldns_buffer_position(pkt) == 0);
	if((ret = parse_packet(pkt, msg, region)) != 0) {
		region_free_all(region);
		region_destroy(region);
		return ret;
	}
	/* parse OK, allocate return structures */

	/* exit and cleanup */
	region_free_all(region);
	region_destroy(region);
	return 0;
malloc_error:
	region_free_all(region);
	region_destroy(region);
	return LDNS_RCODE_SERVFAIL;
}

void 
reply_info_parsedelete(struct reply_info* rep, struct alloc_cache* alloc)
{
	size_t i;
	if(!rep) 
		return;
	/* no need to lock, since not shared in hashtables. */
	for(i=0; i<rep->rrset_count; i++) {
		ub_packed_rrset_parsedelete(rep->rrsets[i], alloc);
	}
	free(rep);
}

int 
query_info_parse(struct query_info* m, ldns_buffer* query)
{
	uint8_t* q = ldns_buffer_begin(query);
	/* minimum size: header + \0 + qtype + qclass */
	if(ldns_buffer_limit(query) < LDNS_HEADER_SIZE + 5)
		return 0;
	log_assert(!LDNS_QR_WIRE(q));
	log_assert(LDNS_OPCODE_WIRE(q) == LDNS_PACKET_QUERY);
	log_assert(LDNS_QDCOUNT(q) == 1);
	log_assert(ldns_buffer_position(query) == 0);
	m->has_cd = (int)LDNS_CD_WIRE(q);
	ldns_buffer_skip(query, LDNS_HEADER_SIZE);
	m->qname = ldns_buffer_current(query);
	if((m->qnamesize = query_dname_len(query)) == 0)
		return 0; /* parse error */
	if(ldns_buffer_remaining(query) < 4)
		return 0; /* need qtype, qclass */
	m->qtype = ldns_buffer_read_u16(query);
	m->qclass = ldns_buffer_read_u16(query);
	return 1;
}

int 
query_info_allocqname(struct query_info* m)
{
	uint8_t* q = m->qname;
	if(!(m->qname = (uint8_t*)malloc(m->qnamesize))) {
		log_err("query_info_allocqname: out of memory");
		return 0; /* out of memory */
	}
	memcpy(m->qname, q, m->qnamesize);
	return 1;
}

/** tiny subroutine for msgreply_compare */
#define COMPARE_IT(x, y) \
	if( (x) < (y) ) return -1; \
	else if( (x) > (y) ) return +1; \
	log_assert( (x) == (y) );

int 
query_info_compare(void* m1, void* m2)
{
	struct query_info* msg1 = (struct query_info*)m1;
	struct query_info* msg2 = (struct query_info*)m2;
	int mc;
	/* from most different to least different for speed */
	COMPARE_IT(msg1->qtype, msg2->qtype);
	if((mc = query_dname_compare(msg1->qname, msg2->qname)) != 0)
		return mc;
	log_assert(msg1->qnamesize == msg2->qnamesize);
	COMPARE_IT(msg1->has_cd, msg2->has_cd);
	COMPARE_IT(msg1->qclass, msg2->qclass);
	return 0;
#undef COMPARE_IT
}

void 
query_info_clear(struct query_info* m)
{
	free(m->qname);
	m->qname = NULL;
}

void 
reply_info_clear(struct reply_info* m)
{
	free(m->reply);
	m->reply = NULL;
}

size_t 
msgreply_sizefunc(void* k, void* d)
{
	struct query_info* q = (struct query_info*)k;
	struct reply_info* r = (struct reply_info*)d;
	return sizeof(struct msgreply_entry) + sizeof(struct reply_info)
		+ r->replysize + q->qnamesize;
}

void 
query_entry_delete(void *k, void* ATTR_UNUSED(arg))
{
	struct msgreply_entry* q = (struct msgreply_entry*)k;
	lock_rw_destroy(&q->entry.lock);
	query_info_clear(&q->key);
	free(q);
}

void 
reply_info_delete(void* d, void* ATTR_UNUSED(arg))
{
	struct reply_info* r = (struct reply_info*)d;
	reply_info_clear(r);
	free(r);
}

hashvalue_t 
query_info_hash(struct query_info *q)
{
	uint8_t labuf[LDNS_MAX_LABELLEN+1];
	uint8_t lablen;
	uint8_t* d;
	int i;

	hashvalue_t h = 0xab;
	h = hashlittle(&q->qtype, sizeof(q->qtype), h);
	h = hashlittle(&q->qclass, sizeof(q->qclass), h);
	h = hashlittle(&q->has_cd, sizeof(q->has_cd), h);

	/* preserve case of query, make hash label by label */
	d = q->qname;
	lablen = *d;
	while(lablen) {
		log_assert(lablen <= LDNS_MAX_LABELLEN);
		labuf[0] = lablen;
		d++;
		i=0;
		while(lablen--)
			labuf[++i] = (uint8_t)tolower((int)*d++);
		h = hashlittle(labuf, labuf[0] + 1, h);
		lablen = *d;
	}

	return h;
}

void 
reply_info_answer(struct reply_info* rep, uint16_t qflags, 
	ldns_buffer* buffer)
{
	uint16_t flags;
	ldns_buffer_clear(buffer);
	ldns_buffer_skip(buffer, 2); /* ID */
	flags = rep->flags | (qflags & BIT_RD); /* copy RD bit */
	log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
	ldns_buffer_write_u16(buffer, flags);
	ldns_buffer_write(buffer, rep->reply, rep->replysize);
	ldns_buffer_flip(buffer);
}

void 
reply_info_answer_iov(struct reply_info* rep, uint16_t qid,
        uint16_t qflags, struct comm_reply* comrep, int cached)
{
	/* [0]=reserved for tcplen, [1]=id, [2]=flags, [3]=message */
	struct iovec iov[4];

	iov[1].iov_base = (void*)&qid;
	iov[1].iov_len = sizeof(uint16_t);
	if(!cached) {
		/* original flags, copy RD bit from query. */
		qflags = rep->flags | (qflags & BIT_RD); 
	} else {
		/* remove AA bit, copy RD and CD bits from query. */
		qflags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD)); 
	}
	log_assert(qflags & BIT_QR); /* QR bit must be on in our replies */
	qflags = htons(qflags);
	iov[2].iov_base = (void*)&qflags;
	iov[2].iov_len = sizeof(uint16_t);
	iov[3].iov_base = (void*)rep->reply;
	iov[3].iov_len = rep->replysize;
	comm_point_send_reply_iov(comrep, iov, 4);
}

struct msgreply_entry* 
query_info_entrysetup(struct query_info* q, struct reply_info* r, 
	hashvalue_t h)
{
	struct msgreply_entry* e = (struct msgreply_entry*)malloc( 
		sizeof(struct msgreply_entry));
	if(!e) return NULL;
	memcpy(&e->key, q, sizeof(*q));
	e->entry.hash = h;
	e->entry.key = e;
	e->entry.data = r;
	lock_rw_init(&e->entry.lock);
	lock_protect(&e->entry.lock, &e->key, sizeof(e->key));
	lock_protect(&e->entry.lock, &e->entry.hash, sizeof(e->entry.hash) +
		sizeof(e->entry.key) + sizeof(e->entry.data));
	lock_protect(&e->entry.lock, e->key.qname, e->key.qnamesize);
	q->qname = NULL;
	return e;
}