1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
// Copyright 2015-2019 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

//! Dynamic Delegation Discovery System

use crate::error::*;
use crate::rr::domain::Name;
use crate::serialize::binary::*;

/// [RFC 3403 DDDS DNS Database, October 2002](https://tools.ietf.org/html/rfc3403#section-4)
///
/// ```text
/// 4.1 Packet Format
///
///   The packet format of the NAPTR RR is given below.  The DNS type code
///   for NAPTR is 35.
///
///      The packet format for the NAPTR record is as follows
///                                       1  1  1  1  1  1
///         0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///       |                     ORDER                     |
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///       |                   PREFERENCE                  |
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///       /                     FLAGS                     /
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///       /                   SERVICES                    /
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///       /                    REGEXP                     /
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///       /                  REPLACEMENT                  /
///       /                                               /
///       +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///
///   <character-string> and <domain-name> as used here are defined in RFC
///   1035 [7].
/// ```
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub struct NAPTR {
    order: u16,
    preference: u16,
    flags: Box<[u8]>,
    services: Box<[u8]>,
    regexp: Box<[u8]>,
    replacement: Name,
}

impl NAPTR {
    /// Constructs a new NAPTR record
    ///
    /// # Arguments
    ///
    /// * `order` - the order in which the NAPTR records MUST be processed in order to accurately represent the ordered list of Rules.
    /// * `preference` - this field is equivalent to the Priority value in the DDDS Algorithm.
    /// * `flags` - flags to control aspects of the rewriting and interpretation of the fields in the record.  Flags are single characters from the set A-Z and 0-9.
    /// * `services` - the Service Parameters applicable to this this delegation path.
    /// * `regexp` - substitution expression that is applied to the original string held by the client in order to construct the next domain name to lookup.
    /// * `replacement` - the next domain-name to query for depending on the potential values found in the flags field.
    pub fn new(
        order: u16,
        preference: u16,
        flags: Box<[u8]>,
        services: Box<[u8]>,
        regexp: Box<[u8]>,
        replacement: Name,
    ) -> Self {
        Self {
            order,
            preference,
            flags,
            services,
            regexp,
            replacement,
        }
    }

    /// ```text
    ///   ORDER
    ///      A 16-bit unsigned integer specifying the order in which the NAPTR
    ///      records MUST be processed in order to accurately represent the
    ///      ordered list of Rules.  The ordering is from lowest to highest.
    ///      If two records have the same order value then they are considered
    ///      to be the same rule and should be selected based on the
    ///      combination of the Preference values and Services offered.
    /// ```
    pub fn order(&self) -> u16 {
        self.order
    }

    /// ```text
    ///   PREFERENCE
    ///      Although it is called "preference" in deference to DNS
    ///      terminology, this field is equivalent to the Priority value in the
    ///      DDDS Algorithm.  It is a 16-bit unsigned integer that specifies
    ///      the order in which NAPTR records with equal Order values SHOULD be
    ///      processed, low numbers being processed before high numbers.  This
    ///      is similar to the preference field in an MX record, and is used so
    ///      domain administrators can direct clients towards more capable
    ///      hosts or lighter weight protocols.  A client MAY look at records
    ///      with higher preference values if it has a good reason to do so
    ///      such as not supporting some protocol or service very well.
    ///
    ///      The important difference between Order and Preference is that once
    ///      a match is found the client MUST NOT consider records with a
    ///      different Order but they MAY process records with the same Order
    ///      but different Preferences.  The only exception to this is noted in
    ///      the second important Note in the DDDS algorithm specification
    ///      concerning allowing clients to use more complex Service
    ///      determination between steps 3 and 4 in the algorithm.  Preference
    ///      is used to give communicate a higher quality of service to rules
    ///      that are considered the same from an authority standpoint but not
    ///      from a simple load balancing standpoint.
    ///
    ///      It is important to note that DNS contains several load balancing
    ///      mechanisms and if load balancing among otherwise equal services
    ///      should be needed then methods such as SRV records or multiple A
    ///      records should be utilized to accomplish load balancing.
    /// ```
    pub fn preference(&self) -> u16 {
        self.preference
    }

    /// ```text
    ///   FLAGS
    ///      A <character-string> containing flags to control aspects of the
    ///      rewriting and interpretation of the fields in the record.  Flags
    ///      are single characters from the set A-Z and 0-9.  The case of the
    ///      alphabetic characters is not significant.  The field can be empty.
    ///
    ///      It is up to the Application specifying how it is using this
    ///      Database to define the Flags in this field.  It must define which
    ///      ones are terminal and which ones are not.
    /// ```
    pub fn flags(&self) -> &[u8] {
        &self.flags
    }

    /// ```text
    ///   SERVICES
    ///      A <character-string> that specifies the Service Parameters
    ///      applicable to this this delegation path.  It is up to the
    ///      Application Specification to specify the values found in this
    ///      field.
    /// ```
    pub fn services(&self) -> &[u8] {
        &self.services
    }

    /// ```text
    ///   REGEXP
    ///      A <character-string> containing a substitution expression that is
    ///      applied to the original string held by the client in order to
    ///      construct the next domain name to lookup.  See the DDDS Algorithm
    ///      specification for the syntax of this field.
    ///
    ///      As stated in the DDDS algorithm, The regular expressions MUST NOT
    ///      be used in a cumulative fashion, that is, they should only be
    ///      applied to the original string held by the client, never to the
    ///      domain name p  roduced by a previous NAPTR rewrite.  The latter is
    ///      tempting in some applications but experience has shown such use to
    ///      be extremely fault sensitive, very error prone, and extremely
    ///      difficult to debug.
    /// ```
    pub fn regexp(&self) -> &[u8] {
        &self.regexp
    }

    /// ```text
    ///   REPLACEMENT
    ///      A <domain-name> which is the next domain-name to query for
    ///      depending on the potential values found in the flags field.  This
    ///      field is used when the regular expression is a simple replacement
    ///      operation.  Any value in this field MUST be a fully qualified
    ///      domain-name.  Name compression is not to be used for this field.
    ///
    ///      This field and the REGEXP field together make up the Substitution
    ///      Expression in the DDDS Algorithm.  It is simply a historical
    ///      optimization specifically for DNS compression that this field
    ///      exists.  The fields are also mutually exclusive.  If a record is
    ///      returned that has values for both fields then it is considered to
    ///      be in error and SHOULD be either ignored or an error returned.
    /// ```
    pub fn replacement(&self) -> &Name {
        &self.replacement
    }
}

/// verifies that the flags are valid
pub fn verify_flags(flags: &[u8]) -> bool {
    flags.iter().all(|c| match c {
        b'0'..=b'9' => true,
        b'a'..=b'z' => true,
        b'A'..=b'Z' => true,
        _ => false,
    })
}

/// Read the RData from the given Decoder
pub fn read(decoder: &mut BinDecoder) -> ProtoResult<NAPTR> {
    Ok(NAPTR::new(
        decoder.read_u16()?.unverified(/*any u16 is valid*/),
        decoder.read_u16()?.unverified(/*any u16 is valid*/),
        // must be 0-9a-z
        decoder
            .read_character_data()?
            .verify_unwrap(|s| verify_flags(s))
            .map_err(|_e| ProtoError::from("flags are not within range [a-zA-Z0-9]"))?
            .to_vec()
            .into_boxed_slice(),
        decoder.read_character_data()?.unverified(/*any chardata*/).to_vec().into_boxed_slice(),
        decoder.read_character_data()?.unverified(/*any chardata*/).to_vec().into_boxed_slice(),
        Name::read(decoder)?,
    ))
}

/// Declares the method for emitting this type
pub fn emit(encoder: &mut BinEncoder, naptr: &NAPTR) -> ProtoResult<()> {
    naptr.order.emit(encoder)?;
    naptr.preference.emit(encoder)?;
    encoder.emit_character_data(&naptr.flags)?;
    encoder.emit_character_data(&naptr.services)?;
    encoder.emit_character_data(&naptr.regexp)?;

    encoder.with_canonical_names(|encoder| naptr.replacement.emit(encoder))?;
    Ok(())
}

#[cfg(test)]
mod tests {
    #![allow(clippy::dbg_macro, clippy::print_stdout)]

    use super::*;
    #[test]
    pub fn test() {
        use std::str::FromStr;

        let rdata = NAPTR::new(
            8,
            16,
            b"aa11AA".to_vec().into_boxed_slice(),
            b"services".to_vec().into_boxed_slice(),
            b"regexpr".to_vec().into_boxed_slice(),
            Name::from_str("naptr.example.com").unwrap(),
        );

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

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

        let mut decoder: BinDecoder = BinDecoder::new(bytes);
        let read_rdata = read(&mut decoder).expect("Decoding error");
        assert_eq!(rdata, read_rdata);
    }

    #[test]
    pub fn test_bad_data() {
        use std::str::FromStr;

        let rdata = NAPTR::new(
            8,
            16,
            b"aa11AA-".to_vec().into_boxed_slice(),
            b"services".to_vec().into_boxed_slice(),
            b"regexpr".to_vec().into_boxed_slice(),
            Name::from_str("naptr.example.com").unwrap(),
        );

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

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

        let mut decoder: BinDecoder = BinDecoder::new(bytes);
        let read_rdata = read(&mut decoder);
        assert!(
            read_rdata.is_err(),
            "should have failed decoding with bad flag data"
        );
    }
}