_ Git - dnssec-prover/blob - src/query.rs

   1 //! This module exposes utilities for building DNSSEC proofs by directly querying a recursive
   2 //! resolver.
   3
   4 use std::cmp;
   5 use std::net::{SocketAddr, TcpStream};
   6 use std::io::{Read, Write, Error, ErrorKind};
   7
   8 #[cfg(feature = "tokio")]
   9 use tokio_crate::net::TcpStream as TokioTcpStream;
  10 #[cfg(feature = "tokio")]
  11 use tokio_crate::io::{AsyncReadExt, AsyncWriteExt};
  12
  13 use crate::rr::*;
  14 use crate::ser::*;
  15
  16 // We don't care about transaction IDs as we're only going to accept signed data. Thus, we use
  17 // this constant instead of a random value.
  18 const TXID: u16 = 0x4242;
  19
  20 fn build_query(domain: &Name, ty: u16) -> Vec<u8> {
  21         // TODO: Move to not allocating for the query
  22         let mut query = Vec::with_capacity(1024);
  23         let query_msg_len: u16 = 2 + 2 + 8 + 2 + 2 + name_len(domain) + 11;
  24         query.extend_from_slice(&query_msg_len.to_be_bytes());
  25         query.extend_from_slice(&TXID.to_be_bytes());
  26         query.extend_from_slice(&[0x01, 0x20]); // Flags: Recursive, Authenticated Data
  27         query.extend_from_slice(&[0, 1, 0, 0, 0, 0, 0, 1]); // One question, One additional
  28         write_name(&mut query, domain);
  29         query.extend_from_slice(&ty.to_be_bytes());
  30         query.extend_from_slice(&1u16.to_be_bytes()); // INternet class
  31         query.extend_from_slice(&[0, 0, 0x29]); // . OPT
  32         query.extend_from_slice(&0u16.to_be_bytes()); // 0 UDP payload size
  33         query.extend_from_slice(&[0, 0]); // EDNS version 0
  34         query.extend_from_slice(&0x8000u16.to_be_bytes()); // Accept DNSSEC RRs
  35         query.extend_from_slice(&0u16.to_be_bytes()); // No additional data
  36         query
  37 }
  38
  39 #[cfg(fuzzing)]
  40 /// Read some input and parse it as if it came from a server, for fuzzing.
  41 pub fn fuzz_response(response: &[u8]) {
  42         let (mut proof, mut names) = (Vec::new(), Vec::new());
  43         let _ = handle_response(response, &mut proof, &mut names);
  44 }
  45
  46 fn handle_response(resp: &[u8], proof: &mut Vec<u8>, rrsig_key_names: &mut Vec<Name>) -> Result<u32, ()> {
  47         let mut read: &[u8] = resp;
  48         if read_u16(&mut read)? != TXID { return Err(()); }
  49         // 2 byte transaction ID
  50         let flags = read_u16(&mut read)?;
  51         if flags & 0b1000_0000_0000_0000 == 0 {
  52                 return Err(());
  53         }
  54         if flags & 0b0111_1010_0000_0111 != 0 {
  55                 return Err(());
  56         }
  57         if flags & 0b10_0000 == 0 {
  58                 return Err(());
  59         }
  60         let questions = read_u16(&mut read)?;
  61         if questions != 1 { return Err(()); }
  62         let answers = read_u16(&mut read)?;
  63         if answers == 0 { return Err(()); }
  64         let _authorities = read_u16(&mut read)?;
  65         let _additional = read_u16(&mut read)?;
  66
  67         for _ in 0..questions {
  68                 read_wire_packet_name(&mut read, resp)?;
  69                 read_u16(&mut read)?; // type
  70                 read_u16(&mut read)?; // class
  71         }
  72
  73         // Only read the answers (skip authorities and additional) as that's all we care about.
  74         let mut min_ttl = u32::MAX;
  75         for _ in 0..answers {
  76                 let (rr, ttl) = parse_wire_packet_rr(&mut read, &resp)?;
  77                 write_rr(&rr, ttl, proof);
  78                 min_ttl = cmp::min(min_ttl, ttl);
  79                 if let RR::RRSig(rrsig) = rr { rrsig_key_names.push(rrsig.key_name); }
  80         }
  81         Ok(min_ttl)
  82 }
  83
  84 const MAX_REQUESTS: usize = 10;
  85 /// A simple state machine which will generate a series of queries and process the responses until
  86 /// it has built a DNSSEC proof.
  87 ///
  88 /// A [`ProofBuilder`] driver starts with [`ProofBuilder::new`], fetching the state machine and
  89 /// initial query. As long as [`ProofBuilder::awaiting_responses`] returns true, responses should
  90 /// be read from the resolver. For each query response read from the DNS resolver,
  91 /// [`ProofBuilder::process_response`] should be called, and each fresh query returned should be
  92 /// sent to the resolver. Once [`ProofBuilder::awaiting_responses`] returns false,
  93 /// [`ProofBuilder::finish_proof`] should be called to fetch the resulting proof.
  94 pub struct ProofBuilder {
  95         proof: Vec<u8>,
  96         min_ttl: u32,
  97         dnskeys_requested: Vec<Name>,
  98         pending_queries: usize,
  99         queries_made: usize,
 100 }
 101
 102 impl ProofBuilder {
 103         /// Constructs a new [`ProofBuilder`] and an initial query to send to the recursive resolver to
 104         /// begin the proof building process.
 105         ///
 106         /// Given a correctly-functioning resolver the proof will ultimately be able to prove the
 107         /// contents of any records with the given `ty`pe at the given `name` (as long as the given
 108         /// `ty`pe is supported by this library).
 109         ///
 110         /// You can find constants for supported standard types in the [`crate::rr`] module.
 111         pub fn new(name: &Name, ty: u16) -> (ProofBuilder, Vec<u8>) {
 112                 let initial_query = build_query(name, ty);
 113                 (ProofBuilder {
 114                         proof: Vec::new(),
 115                         min_ttl: u32::MAX,
 116                         dnskeys_requested: Vec::with_capacity(MAX_REQUESTS),
 117                         pending_queries: 1,
 118                         queries_made: 1,
 119                 }, initial_query)
 120         }
 121
 122         /// Returns true as long as further responses are expected from the resolver.
 123         ///
 124         /// As long as this returns true, responses should be read from the resolver and passed to
 125         /// [`Self::process_response`]. Once this returns false, [`Self::finish_proof`] should be used
 126         /// to (possibly) get the final proof.
 127         pub fn awaiting_responses(&self) -> bool {
 128                 self.pending_queries > 0 && self.queries_made <= MAX_REQUESTS
 129         }
 130
 131         /// Processes a query response from the recursive resolver, returning a list of new queries to
 132         /// send to the resolver.
 133         pub fn process_response(&mut self, resp: &[u8]) -> Result<Vec<Vec<u8>>, ()> {
 134                 if self.pending_queries == 0 { return Err(()); }
 135
 136                 let mut rrsig_key_names = Vec::new();
 137                 let min_ttl = handle_response(&resp, &mut self.proof, &mut rrsig_key_names)?;
 138                 self.min_ttl = cmp::min(self.min_ttl, min_ttl);
 139                 self.pending_queries -= 1;
 140
 141                 rrsig_key_names.sort_unstable();
 142                 rrsig_key_names.dedup();
 143
 144                 let mut new_queries = Vec::with_capacity(2);
 145                 for key_name in rrsig_key_names.drain(..) {
 146                         if !self.dnskeys_requested.contains(&key_name) {
 147                                 new_queries.push(build_query(&key_name, DnsKey::TYPE));
 148                                 self.pending_queries += 1;
 149                                 self.queries_made += 1;
 150                                 self.dnskeys_requested.push(key_name.clone());
 151
 152                                 if key_name.as_str() != "." {
 153                                         new_queries.push(build_query(&key_name, DS::TYPE));
 154                                         self.pending_queries += 1;
 155                                         self.queries_made += 1;
 156                                 }
 157                         }
 158                 }
 159                 if self.queries_made <= MAX_REQUESTS {
 160                         Ok(new_queries)
 161                 } else {
 162                         Ok(Vec::new())
 163                 }
 164         }
 165
 166         /// Finalizes the proof, if one is available, and returns it as well as the TTL that should be
 167         /// used to cache the proof (i.e. the lowest TTL of all records which were used to build the
 168         /// proof).
 169         pub fn finish_proof(self) -> Result<(Vec<u8>, u32), ()> {
 170                 if self.pending_queries > 0 || self.queries_made > MAX_REQUESTS {
 171                         Err(())
 172                 } else {
 173                         Ok((self.proof, self.min_ttl))
 174                 }
 175         }
 176 }
 177
 178 fn send_query(stream: &mut TcpStream, query: &[u8]) -> Result<(), Error> {
 179         stream.write_all(&query)?;
 180         Ok(())
 181 }
 182
 183 #[cfg(feature = "tokio")]
 184 async fn send_query_async(stream: &mut TokioTcpStream, query: &[u8]) -> Result<(), Error> {
 185         stream.write_all(&query).await?;
 186         Ok(())
 187 }
 188
 189 type MsgBuf = [u8; u16::MAX as usize];
 190
 191 fn read_response(stream: &mut TcpStream, response_buf: &mut MsgBuf) -> Result<u16, Error> {
 192         let mut len_bytes = [0; 2];
 193         stream.read_exact(&mut len_bytes)?;
 194         let len = u16::from_be_bytes(len_bytes);
 195         stream.read_exact(&mut response_buf[..len as usize])?;
 196         Ok(len)
 197 }
 198
 199 #[cfg(feature = "tokio")]
 200 async fn read_response_async(stream: &mut TokioTcpStream, response_buf: &mut MsgBuf) -> Result<u16, Error> {
 201         let mut len_bytes = [0; 2];
 202         stream.read_exact(&mut len_bytes).await?;
 203         let len = u16::from_be_bytes(len_bytes);
 204         stream.read_exact(&mut response_buf[..len as usize]).await?;
 205         Ok(len)
 206 }
 207
 208 macro_rules! build_proof_impl {
 209         ($stream: ident, $send_query: ident, $read_response: ident, $domain: expr, $ty: expr $(, $async_ok: tt)?) => { {
 210                 // We require the initial query to have already gone out, and assume our resolver will
 211                 // return any CNAMEs all the way to the final record in the response. From there, we just
 212                 // have to take any RRSIGs in the response and walk them up to the root. We do so
 213                 // iteratively, sending DNSKEY and DS lookups after every response, deduplicating requests
 214                 // using `dnskeys_requested`.
 215                 let (mut builder, initial_query) = ProofBuilder::new($domain, $ty);
 216                 $send_query(&mut $stream, &initial_query)
 217                         $(.await?; $async_ok)??; // Either await?; Ok(())?, or just ?
 218                 let mut response_buf = [0; u16::MAX as usize];
 219                 while builder.awaiting_responses() {
 220                         let response_len = $read_response(&mut $stream, &mut response_buf)
 221                                 $(.await?; $async_ok)??; // Either await?; Ok(())?, or just ?
 222                         let new_queries = builder.process_response(&response_buf[..response_len as usize])
 223                                 .map_err(|()| Error::new(ErrorKind::Other, "Bad response"))?;
 224                         for query in new_queries {
 225                                 $send_query(&mut $stream, &query)
 226                                         $(.await?; $async_ok)??; // Either await?; Ok(())?, or just ?
 227                         }
 228                 }
 229
 230                 builder.finish_proof()
 231                         .map_err(|()| Error::new(ErrorKind::Other, "Too many requests required"))
 232         } }
 233 }
 234
 235 fn build_proof(resolver: SocketAddr, domain: &Name, ty: u16) -> Result<(Vec<u8>, u32), Error> {
 236         let mut stream = TcpStream::connect(resolver)?;
 237         build_proof_impl!(stream, send_query, read_response, domain, ty)
 238 }
 239
 240 #[cfg(feature = "tokio")]
 241 async fn build_proof_async(resolver: SocketAddr, domain: &Name, ty: u16) -> Result<(Vec<u8>, u32), Error> {
 242         let mut stream = TokioTcpStream::connect(resolver).await?;
 243         build_proof_impl!(stream, send_query_async, read_response_async, domain, ty, { Ok::<(), Error>(()) })
 244 }
 245
 246 /// Builds a DNSSEC proof for an A record by querying a recursive resolver, returning the proof as
 247 /// well as the TTL for the proof provided by the recursive resolver.
 248 ///
 249 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 250 /// module to validate the records contained.
 251 pub fn build_a_proof(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 252         build_proof(resolver, domain, A::TYPE)
 253 }
 254
 255 /// Builds a DNSSEC proof for an AAAA record by querying a recursive resolver, returning the proof
 256 /// as well as the TTL for the proof provided by the recursive resolver.
 257 ///
 258 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 259 /// module to validate the records contained.
 260 pub fn build_aaaa_proof(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 261         build_proof(resolver, domain, AAAA::TYPE)
 262 }
 263
 264 /// Builds a DNSSEC proof for an TXT record by querying a recursive resolver, returning the proof
 265 /// as well as the TTL for the proof provided by the recursive resolver.
 266 ///
 267 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 268 /// module to validate the records contained.
 269 pub fn build_txt_proof(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 270         build_proof(resolver, domain, Txt::TYPE)
 271 }
 272
 273 /// Builds a DNSSEC proof for an TLSA record by querying a recursive resolver, returning the proof
 274 /// as well as the TTL for the proof provided by the recursive resolver.
 275 ///
 276 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 277 /// module to validate the records contained.
 278 pub fn build_tlsa_proof(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 279         build_proof(resolver, domain, TLSA::TYPE)
 280 }
 281
 282
 283 /// Builds a DNSSEC proof for an A record by querying a recursive resolver, returning the proof as
 284 /// well as the TTL for the proof provided by the recursive resolver.
 285 ///
 286 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 287 /// module to validate the records contained.
 288 #[cfg(feature = "tokio")]
 289 pub async fn build_a_proof_async(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 290         build_proof_async(resolver, domain, A::TYPE).await
 291 }
 292
 293 /// Builds a DNSSEC proof for an AAAA record by querying a recursive resolver, returning the proof
 294 /// as well as the TTL for the proof provided by the recursive resolver.
 295 ///
 296 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 297 /// module to validate the records contained.
 298 #[cfg(feature = "tokio")]
 299 pub async fn build_aaaa_proof_async(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 300         build_proof_async(resolver, domain, AAAA::TYPE).await
 301 }
 302
 303 /// Builds a DNSSEC proof for an TXT record by querying a recursive resolver, returning the proof
 304 /// as well as the TTL for the proof provided by the recursive resolver.
 305 ///
 306 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 307 /// module to validate the records contained.
 308 #[cfg(feature = "tokio")]
 309 pub async fn build_txt_proof_async(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 310         build_proof_async(resolver, domain, Txt::TYPE).await
 311 }
 312
 313 /// Builds a DNSSEC proof for an TLSA record by querying a recursive resolver, returning the proof
 314 /// as well as the TTL for the proof provided by the recursive resolver.
 315 ///
 316 /// Note that this proof is NOT verified in any way, you need to use the [`crate::validation`]
 317 /// module to validate the records contained.
 318 #[cfg(feature = "tokio")]
 319 pub async fn build_tlsa_proof_async(resolver: SocketAddr, domain: &Name) -> Result<(Vec<u8>, u32), Error> {
 320         build_proof_async(resolver, domain, TLSA::TYPE).await
 321 }
 322
 323 #[cfg(all(feature = "validation", test))]
 324 mod tests {
 325         use super::*;
 326         use crate::validation::*;
 327
 328         use rand::seq::SliceRandom;
 329
 330         use std::net::ToSocketAddrs;
 331         use std::time::SystemTime;
 332
 333
 334         #[test]
 335         fn test_cloudflare_txt_query() {
 336                 let sockaddr = "8.8.8.8:53".to_socket_addrs().unwrap().next().unwrap();
 337                 let query_name = "cloudflare.com.".try_into().unwrap();
 338                 let (proof, _) = build_txt_proof(sockaddr, &query_name).unwrap();
 339
 340                 let mut rrs = parse_rr_stream(&proof).unwrap();
 341                 rrs.shuffle(&mut rand::rngs::OsRng);
 342                 let verified_rrs = verify_rr_stream(&rrs).unwrap();
 343                 assert!(verified_rrs.verified_rrs.len() > 1);
 344
 345                 let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
 346                 assert!(verified_rrs.valid_from < now);
 347                 assert!(verified_rrs.expires > now);
 348         }
 349
 350         #[test]
 351         fn test_sha1_query() {
 352                 let sockaddr = "8.8.8.8:53".to_socket_addrs().unwrap().next().unwrap();
 353                 let query_name = "benthecarman.com.".try_into().unwrap();
 354                 let (proof, _) = build_a_proof(sockaddr, &query_name).unwrap();
 355
 356                 let mut rrs = parse_rr_stream(&proof).unwrap();
 357                 rrs.shuffle(&mut rand::rngs::OsRng);
 358                 let verified_rrs = verify_rr_stream(&rrs).unwrap();
 359                 assert!(verified_rrs.verified_rrs.len() >= 1);
 360
 361                 let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
 362                 assert!(verified_rrs.valid_from < now);
 363                 assert!(verified_rrs.expires > now);
 364         }
 365
 366         #[test]
 367         fn test_txt_query() {
 368                 let sockaddr = "8.8.8.8:53".to_socket_addrs().unwrap().next().unwrap();
 369                 let query_name = "matt.user._bitcoin-payment.mattcorallo.com.".try_into().unwrap();
 370                 let (proof, _) = build_txt_proof(sockaddr, &query_name).unwrap();
 371
 372                 let mut rrs = parse_rr_stream(&proof).unwrap();
 373                 rrs.shuffle(&mut rand::rngs::OsRng);
 374                 let verified_rrs = verify_rr_stream(&rrs).unwrap();
 375                 assert_eq!(verified_rrs.verified_rrs.len(), 1);
 376
 377                 let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
 378                 assert!(verified_rrs.valid_from < now);
 379                 assert!(verified_rrs.expires > now);
 380         }
 381
 382         #[test]
 383         fn test_cname_query() {
 384                 for resolver in ["1.1.1.1:53", "8.8.8.8:53", "9.9.9.9:53"] {
 385                         let sockaddr = resolver.to_socket_addrs().unwrap().next().unwrap();
 386                         let query_name = "cname_test.matcorallo.com.".try_into().unwrap();
 387                         let (proof, _) = build_txt_proof(sockaddr, &query_name).unwrap();
 388
 389                         let mut rrs = parse_rr_stream(&proof).unwrap();
 390                         rrs.shuffle(&mut rand::rngs::OsRng);
 391                         let verified_rrs = verify_rr_stream(&rrs).unwrap();
 392                         assert_eq!(verified_rrs.verified_rrs.len(), 2);
 393
 394                         let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
 395                         assert!(verified_rrs.valid_from < now);
 396                         assert!(verified_rrs.expires > now);
 397
 398                         let resolved_rrs = verified_rrs.resolve_name(&query_name);
 399                         assert_eq!(resolved_rrs.len(), 1);
 400                         if let RR::Txt(txt) = &resolved_rrs[0] {
 401                                 assert_eq!(txt.name.as_str(), "txt_test.matcorallo.com.");
 402                                 assert_eq!(txt.data, b"dnssec_prover_test");
 403                         } else { panic!(); }
 404                 }
 405         }
 406
 407         #[cfg(feature = "tokio")]
 408         use tokio_crate as tokio;
 409
 410         #[cfg(feature = "tokio")]
 411         #[tokio::test]
 412         async fn test_txt_query_async() {
 413                 let sockaddr = "8.8.8.8:53".to_socket_addrs().unwrap().next().unwrap();
 414                 let query_name = "matt.user._bitcoin-payment.mattcorallo.com.".try_into().unwrap();
 415                 let (proof, _) = build_txt_proof_async(sockaddr, &query_name).await.unwrap();
 416
 417                 let mut rrs = parse_rr_stream(&proof).unwrap();
 418                 rrs.shuffle(&mut rand::rngs::OsRng);
 419                 let verified_rrs = verify_rr_stream(&rrs).unwrap();
 420                 assert_eq!(verified_rrs.verified_rrs.len(), 1);
 421
 422                 let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
 423                 assert!(verified_rrs.valid_from < now);
 424                 assert!(verified_rrs.expires > now);
 425         }
 426
 427         #[cfg(feature = "tokio")]
 428         #[tokio::test]
 429         async fn test_cross_domain_cname_query_async() {
 430                 for resolver in ["1.1.1.1:53", "8.8.8.8:53", "9.9.9.9:53"] {
 431                         let sockaddr = resolver.to_socket_addrs().unwrap().next().unwrap();
 432                         let query_name = "wildcard.x_domain_cname_wild.matcorallo.com.".try_into().unwrap();
 433                         let (proof, _) = build_txt_proof_async(sockaddr, &query_name).await.unwrap();
 434
 435                         let mut rrs = parse_rr_stream(&proof).unwrap();
 436                         rrs.shuffle(&mut rand::rngs::OsRng);
 437                         let verified_rrs = verify_rr_stream(&rrs).unwrap();
 438                         assert_eq!(verified_rrs.verified_rrs.len(), 2);
 439
 440                         let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
 441                         assert!(verified_rrs.valid_from < now);
 442                         assert!(verified_rrs.expires > now);
 443
 444                         let resolved_rrs = verified_rrs.resolve_name(&query_name);
 445                         assert_eq!(resolved_rrs.len(), 1);
 446                         if let RR::Txt(txt) = &resolved_rrs[0] {
 447                                 assert_eq!(txt.name.as_str(), "matt.user._bitcoin-payment.mattcorallo.com.");
 448                                 assert!(txt.data.starts_with(b"bitcoin:"));
 449                         } else { panic!(); }
 450                 }
 451         }
 452 }