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/*
 * Copyright (C) 2015 Benjamin Fry <benjaminfry@me.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//! negative cache proof for non-existence

use ::serialize::binary::*;
use ::error::*;
use ::rr::{Name, RecordType};
use ::rr::rdata::nsec3;

/// [RFC 4034, DNSSEC Resource Records, March 2005](https://tools.ietf.org/html/rfc4034#section-4)
///
/// ```text
/// 4.1.  NSEC RDATA Wire Format
///
///    The RDATA of the NSEC RR is as shown below:
///
///                         1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
///     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
///    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
///    /                      Next Domain Name                         /
///    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
///    /                       Type Bit Maps                           /
///    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
///
/// 4.1.3.  Inclusion of Wildcard Names in NSEC RDATA
///
///    If a wildcard owner name appears in a zone, the wildcard label ("*")
///    is treated as a literal symbol and is treated the same as any other
///    owner name for the purposes of generating NSEC RRs.  Wildcard owner
///    names appear in the Next Domain Name field without any wildcard
///    expansion.  [RFC4035] describes the impact of wildcards on
///    authenticated denial of existence.
/// ```
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub struct NSEC { next_domain_name: Name, type_bit_maps: Vec<RecordType> }

impl NSEC {
  pub fn new(next_domain_name: Name, type_bit_maps: Vec<RecordType>) -> NSEC {
    NSEC { next_domain_name: next_domain_name, type_bit_maps: type_bit_maps }
  }

  /// [RFC 4034, DNSSEC Resource Records, March 2005](https://tools.ietf.org/html/rfc4034#section-4.1.1)
  ///
  /// ```text
  /// 4.1.1.  The Next Domain Name Field
  ///
  ///    The Next Domain field contains the next owner name (in the canonical
  ///    ordering of the zone) that has authoritative data or contains a
  ///    delegation point NS RRset; see Section 6.1 for an explanation of
  ///    canonical ordering.  The value of the Next Domain Name field in the
  ///    last NSEC record in the zone is the name of the zone apex (the owner
  ///    name of the zone's SOA RR).  This indicates that the owner name of
  ///    the NSEC RR is the last name in the canonical ordering of the zone.
  ///
  ///    A sender MUST NOT use DNS name compression on the Next Domain Name
  ///    field when transmitting an NSEC RR.
  ///
  ///    Owner names of RRsets for which the given zone is not authoritative
  ///    (such as glue records) MUST NOT be listed in the Next Domain Name
  ///    unless at least one authoritative RRset exists at the same owner
  ///    name.
  /// ```
  pub fn get_next_domain_name(&self) -> &Name { &self.next_domain_name }

  /// [RFC 4034, DNSSEC Resource Records, March 2005](https://tools.ietf.org/html/rfc4034#section-4.1.2)
  ///
  /// ```text
  /// 4.1.2.  The Type Bit Maps Field
  ///
  ///    The Type Bit Maps field identifies the RRset types that exist at the
  ///    NSEC RR's owner name.
  ///
  ///    A zone MUST NOT include an NSEC RR for any domain name that only
  ///    holds glue records.
  /// ```
  pub fn get_type_bit_maps(&self) -> &[RecordType] { &self.type_bit_maps }
}

pub fn read(decoder: &mut BinDecoder, rdata_length: u16) -> DecodeResult<NSEC> {
  let start_idx = decoder.index();

  let next_domain_name = try!(Name::read(decoder));

  let bit_map_len = rdata_length as usize - (decoder.index() - start_idx);
  let record_types = try!(nsec3::decode_type_bit_maps(decoder, bit_map_len));

  Ok(NSEC::new(next_domain_name, record_types))
}

pub fn emit(encoder: &mut BinEncoder, rdata: &NSEC) -> EncodeResult {
  let is_canonical_names = encoder.is_canonical_names();
  encoder.set_canonical_names(true);
  try!(rdata.get_next_domain_name().emit(encoder));
  try!(nsec3::encode_bit_maps(encoder, rdata.get_type_bit_maps()));
  encoder.set_canonical_names(is_canonical_names);

  Ok(())
}

#[test]
pub fn test() {
  use ::rr::RecordType;

  let rdata = NSEC::new(Name::new().label("www").label("example").label("com"),
                        vec![RecordType::A, RecordType::AAAA, RecordType::DS, RecordType::RRSIG]);

  let mut bytes = Vec::new();
  let mut encoder: BinEncoder = BinEncoder::new(&mut bytes);
  assert!(emit(&mut encoder, &rdata).is_ok());
  let bytes = encoder.as_bytes();

  println!("bytes: {:?}", bytes);

  let mut decoder: BinDecoder = BinDecoder::new(bytes);
  let read_rdata = read(&mut decoder, bytes.len() as u16);
  assert!(read_rdata.is_ok(), format!("error decoding: {:?}", read_rdata.unwrap_err()));
  assert_eq!(rdata, read_rdata.unwrap());
}