/src/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/config_file.h"
#include "util/data/msgparse.h"
#include "util/data/msgreply.h"
#include "util/data/dname.h"
#include "util/data/packed_rrset.h"
#include "util/netevent.h"
#include "util/storage/lookup3.h"
#include "util/regional.h"
#include "sldns/rrdef.h"
#include "sldns/sbuffer.h"
#include "sldns/parseutil.h"
#include "sldns/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;
    if((size_t)PTR_OFFSET(dnow[0], dnow[1])
      >= sldns_buffer_limit(pkt))
      return -1;
    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_type 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_type
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_type 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_type
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_type h = 0xab;
  h = dname_pkt_hash(pkt, dname, h);
  return h;
}

/** create a rrset hash from a partial dname hash */
static hashvalue_type
pkt_hash_rrset_rest(hashvalue_type 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_type 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_type 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_type 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_type 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_type* 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_type 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_type 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;
}

static int
edns_opt_list_append_keepalive(struct edns_option** list, int msec,
    struct regional* region)
{
  uint8_t data[2]; /* For keepalive value */
  data[0] = (uint8_t)((msec >> 8) & 0xff);
  data[1] = (uint8_t)(msec & 0xff);
  return edns_opt_list_append(list, LDNS_EDNS_KEEPALIVE, sizeof(data),
      data, region);
}

/** parse EDNS options from EDNS wireformat rdata */
static int
parse_edns_options_from_query(uint8_t* rdata_ptr, size_t rdata_len,
  struct edns_data* edns, struct config_file* cfg, struct comm_point* c,
  struct regional* region)
{
  /* To respond with a Keepalive option, the client connection must have
   * received one message with a TCP Keepalive EDNS option, and that
   * option must have 0 length data. Subsequent messages sent on that
   * connection will have a TCP Keepalive option.
   *
   * In the if-statement below, the option is added unsolicited. This
   * means that the client has sent an KEEPALIVE option earlier. We know
   * here this is true, because c->tcp_keepalive is set.
   */
  if (cfg && cfg->do_tcp_keepalive && c && c->type != comm_udp && c->tcp_keepalive) {
    if(!edns_opt_list_append_keepalive(&edns->opt_list_out,
          c->tcp_timeout_msec / 100, region)) {
      log_err("out of memory");
      return LDNS_RCODE_SERVFAIL;
    }
  }

  /* while still more options, and have code+len to read */
  /* ignores partial content (i.e. rdata len 3) */
  while(rdata_len >= 4) {
    uint16_t opt_code = sldns_read_uint16(rdata_ptr);
    uint16_t opt_len = sldns_read_uint16(rdata_ptr+2);
    rdata_ptr += 4;
    rdata_len -= 4;
    if(opt_len > rdata_len)
      break; /* option code partial */

    /* handle parse time edns options here */
    switch(opt_code) {
    case LDNS_EDNS_NSID:
      if (!cfg || !cfg->nsid)
        break;
      if(!edns_opt_list_append(&edns->opt_list_out,
            LDNS_EDNS_NSID, cfg->nsid_len,
            cfg->nsid, region)) {
        log_err("out of memory");
        return LDNS_RCODE_SERVFAIL;
      }
      break;

    case LDNS_EDNS_KEEPALIVE:
      /* To respond with a Keepalive option, the client
       * connection must have received one message with a TCP
       * Keepalive EDNS option, and that option must have 0
       * length data. Subsequent messages sent on that
       * connection will have a TCP Keepalive option.
       *
       * This should be the first time the client sends this
       * option, so c->tcp_keepalive is not set.
       * Besides adding the reply KEEPALIVE option, 
       * c->tcp_keepalive will be set so that the
       * option will be added unsolicited in subsequent
       * responses (see the comment above the if-statement
       * at the start of this function).
       */
      if (!cfg || !cfg->do_tcp_keepalive || !c ||
          c->type == comm_udp || c->tcp_keepalive)
        break;
      if(opt_len) {
        verbose(VERB_ALGO, "query with bad edns keepalive.");
        return LDNS_RCODE_FORMERR;
      }
      if(!edns_opt_list_append_keepalive(&edns->opt_list_out,
            c->tcp_timeout_msec / 100,
            region)) {
        log_err("out of memory");
        return LDNS_RCODE_SERVFAIL;
      }
      c->tcp_keepalive = 1;
      break;

    case LDNS_EDNS_PADDING:
      if(!cfg || !cfg->pad_responses ||
          !c || c->type != comm_tcp ||!c->ssl)
        break;
      if(!edns_opt_list_append(&edns->opt_list_out,
            LDNS_EDNS_PADDING,
            0, NULL, region)) {
        log_err("out of memory");
        return LDNS_RCODE_SERVFAIL;
      }
      edns->padding_block_size = cfg->pad_responses_block_size;
      break;

    default:
      break;
    }
    if(!edns_opt_list_append(&edns->opt_list_in,
        opt_code, opt_len, rdata_ptr, region)) {
      log_err("out of memory");
      return LDNS_RCODE_SERVFAIL;
    }
    rdata_ptr += opt_len;
    rdata_len -= opt_len;
  }
  return LDNS_RCODE_NOERROR;
}

int 
parse_extract_edns_from_response_msg(struct msg_parse* msg,
  struct edns_data* edns, struct regional* region)
{
  struct rrset_parse* rrset = msg->rrset_first;
  struct rrset_parse* prev = 0;
  struct rrset_parse* found = 0;
  struct rrset_parse* found_prev = 0;
  size_t rdata_len;
  uint8_t* rdata_ptr;
  /* 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);
  edns->opt_list_in = NULL;
  edns->opt_list_out = NULL;
  edns->opt_list_inplace_cb_out = NULL;
  edns->padding_block_size = 0;

  /* take the options */
  rdata_len = found->rr_first->size-2;
  rdata_ptr = found->rr_first->ttl_data+6;

  /* while still more options, and have code+len to read */
  /* ignores partial content (i.e. rdata len 3) */
  while(rdata_len >= 4) {
    uint16_t opt_code = sldns_read_uint16(rdata_ptr);
    uint16_t opt_len = sldns_read_uint16(rdata_ptr+2);
    rdata_ptr += 4;
    rdata_len -= 4;
    if(opt_len > rdata_len)
      break; /* option code partial */

    if(!edns_opt_list_append(&edns->opt_list_in,
        opt_code, opt_len, rdata_ptr, region)) {
      log_err("out of memory");
      break;
    }
    rdata_ptr += opt_len;
    rdata_len -= opt_len;
  }
  /* ignore rrsigs */
  return LDNS_RCODE_NOERROR;
}

/** skip RR in packet */
static int
skip_pkt_rr(sldns_buffer* pkt)
{
  if(sldns_buffer_remaining(pkt) < 1) return 0;
  if(!pkt_dname_len(pkt))
    return 0;
  if(sldns_buffer_remaining(pkt) < 4) return 0;
  sldns_buffer_skip(pkt, 4); /* type and class */
  if(!skip_ttl_rdata(pkt))
    return 0;
  return 1;
}

/** skip RRs from packet */
int
skip_pkt_rrs(sldns_buffer* pkt, int num)
{
  int i;
  for(i=0; i<num; i++) {
    if(!skip_pkt_rr(pkt))
      return 0;
  }
  return 1;
}

int 
parse_edns_from_query_pkt(sldns_buffer* pkt, struct edns_data* edns,
  struct config_file* cfg, struct comm_point* c, struct regional* region)
{
  size_t rdata_len;
  uint8_t* rdata_ptr;
  log_assert(LDNS_QDCOUNT(sldns_buffer_begin(pkt)) == 1);
  memset(edns, 0, sizeof(*edns));
  if(LDNS_ANCOUNT(sldns_buffer_begin(pkt)) != 0 ||
    LDNS_NSCOUNT(sldns_buffer_begin(pkt)) != 0) {
    if(!skip_pkt_rrs(pkt, ((int)LDNS_ANCOUNT(sldns_buffer_begin(pkt)))+
      ((int)LDNS_NSCOUNT(sldns_buffer_begin(pkt)))))
      return LDNS_RCODE_FORMERR;
  }
  /* 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) {
    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);
  edns->opt_list_in = NULL;
  edns->opt_list_out = NULL;
  edns->opt_list_inplace_cb_out = NULL;
  edns->padding_block_size = 0;

  /* take the options */
  rdata_len = sldns_buffer_read_u16(pkt);
  if(sldns_buffer_remaining(pkt) < rdata_len)
    return LDNS_RCODE_FORMERR;
  rdata_ptr = sldns_buffer_current(pkt);
  /* ignore rrsigs */
  return parse_edns_options_from_query(rdata_ptr, rdata_len, edns, cfg,
      c, region);
}

void
log_edns_opt_list(enum verbosity_value level, const char* info_str,
  struct edns_option* list)
{
  if(verbosity >= level && list) {
    char str[128], *s;
    size_t slen;
    verbose(level, "%s", info_str);
    while(list) {
      s = str;
      slen = sizeof(str);
      (void)sldns_wire2str_edns_option_print(&s, &slen, list->opt_code,
        list->opt_data, list->opt_len);
      verbose(level, "  %s", str);
      list = list->next;
    }
  }
}


Coverage Report

Created: 2023-06-07 06:25