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//! Support for TSIG.
//!
//! This module provides high-level support for signing message exchanges with
//! TSIG as defined in [RFC 2845].
//!
//! TSIG is intended to provide authentication for message exchanges. Messages
//! are signed using a secret key shared between the two participants. The
//! party sending the request – the client – generates a signature over the
//! message it is about to send using that key and adds it in a special record
//! of record type [TSIG] to the additional section of the message. The
//! receiver of the request – the server – verifies the signature using the
//! same key. When creating an answer, it too generates a signature. It
//! includes the request’s signture in this process in order to bind request
//! and answer together. This signature ends up in a TSIG record in the
//! additional section as well and can be verified by the client.
//!
//! TSIG supports a number of algorithms for boths signature generation; it
//! even allows for private algorithms. The specification requires to support
//! at least HMAC-MD5 defined in [RFC 2104]. Since MD5 is widely regarded as
//! unsafe now, we don’t follow that rule and only support the SHA-based
//! algorithms from [RFC 4653]. You can choose the algorithm to use for your
//! keys via the [`Algorithm`] enum.
//!
//! Keys are managed via the [`Key`] type. While technically the actual
//! octets of the key can be used with any algorithm, we tie together a key
//! and the algorithm to use it for. In additiona, each key also has a name,
//! which is in fact a domain name. [`Key`] values also manage the signature
//! truncation that is allowed in a future version of the specification.
//!
//! Finally, there are four types for dealing with message exchanges secured
//! with TSIG. For regular transactions that consist of a request and a
//! single message, the types [`ClientTransaction`] and [`ServerTransaction`]
//! implement the client and server role, respectively. If the answer can
//! consist of a sequence of messages, such as in AXFR, [`ClientSequence`]
//! and [`ServerSequence`] can be used instead.
//!
//! For the server transaction and sequence, there is one more thing you need:
//! a [`KeyStore`], which tries to find the key used by the client. As this
//! is a trait, you may need to implement that your particular use case. There
//! is implementations for a hash map as well as a single key (the latter
//! mostly for testing).
//!
//! [RFC 2104]: https://tools.ietf.org/html/rfc2104
//! [RFC 2845]: https://tools.ietf.org/html/rfc2845
//! [RFC 4635]: https://tools.ietf.org/html/rfc4653
//! [TSIG]: ../rdata/rfc2845/struct.Tsig.html
//! [`Algorithm`]: enum.Algorithm.html
//! [`Key`]: enum.Key.html
//! [`KeyStore`]: trait.KeyStore.html
//! [`ClientTransaction`]: struct.ClientTransaction.html
//! [`ServerTransaction`]: struct.ServerTransaction.html
//! [`ClientSequence`]: struct.ClientSequence.html
//! [`ServerSequence`]: struct.ServerSequence.html
#![cfg(feature = "tsig")]
#![cfg_attr(docsrs, doc(cfg(feature = "tsig")))]
mod interop;
use crate::base::header::HeaderSection;
use crate::base::iana::{Class, Rcode, TsigRcode};
use crate::base::message::Message;
use crate::base::message_builder::{AdditionalBuilder, MessageBuilder};
use crate::base::name::{Dname, Label, ParsedDname, ToDname, ToLabelIter};
use crate::base::octets::{
OctetsBuilder, OctetsRef, OctetsVec, ParseError, ShortBuf,
};
use crate::base::record::Record;
use crate::rdata::rfc2845::{Time48, Tsig};
use bytes::{Bytes, BytesMut};
use ring::{constant_time, hkdf::KeyType, hmac, rand};
use std::collections::HashMap;
use std::{cmp, error, fmt, hash, mem, str};
//------------ Key -----------------------------------------------------------
/// A key for creating and validating TSIG signatures.
///
/// For the algorithms included in this implementation, keys are octet strings
/// of any size that are converted into the algorithm’s native key length
/// through a well defined method. The type provides means both for creating
/// new random keys via the [`create´] function and for loading them from
/// the octets via [`new`].
///
/// Keys are identified in TSIG through a name that is encoded as a domain
/// name. While the TSIG specification allows a key to be used with any
/// algorithm, we tie them together, so each `Key` value also knows which
/// algorithm it can be used for.
///
/// Finally, TSIG allows for the use of truncated signatures. There is hard
/// rules of the minimum signature length which can be limited further by
/// local policy. This policy is kept as part of the key. The [`min_mac_len`]
/// field defines the minimum length a received signature has to have in order
/// to be accepted. Conversely, [`signing_len`] is the length of a signature
/// created with this key.
///
/// [`create`]: #method.create
/// [`new`]: #method.new
/// [`min_mac_len`]: #method.min_mac_len
/// [`signing_len`]: #method.signing_len
#[derive(Debug)]
pub struct Key {
/// The key’s bits and algorithm.
key: hmac::Key,
/// The name of the key as a domain name.
name: Dname<OctetsVec>,
/// Minimum length of received signatures.
///
/// This is guaranteed to be within the bounds specified by the standard:
/// at least 10 and at least half the algorithm’s native signature length.
/// It will also be no larger than the native signature length.
min_mac_len: usize,
/// The length of a signature created with this key.
///
/// This has the same bounds as `min_mac_len`.
signing_len: usize,
}
/// # Creating Keys
///
impl Key {
/// Creates a new key from its components.
///
/// This function can be used to import a key from some kind of serialized
/// form. The algorithm, key bits, and name are necessary. By default the
/// key will not allow any truncation.
///
/// If `min_mac_len` is not `None`, the key will accept received
/// signatures trucated to the given length. This length must not be less
/// than 10, it must not be less than half the algorithm’s native
/// signature length as returned by [`Algorithm::native_len`], and it must
/// not be larger than the full native length. The function will return an
/// error if that happens.
///
/// If `signing_len` is not `None`, the signatures produces with this key
/// will be truncated to the given length. The limits for `min_mac_len`
/// apply here as well.
///
/// [`Algorithm::native_len`]: struct.Algorithm.html#method.native_len
pub fn new(
algorithm: Algorithm,
key: &[u8],
name: Dname<OctetsVec>,
min_mac_len: Option<usize>,
signing_len: Option<usize>,
) -> Result<Self, NewKeyError> {
let (min_mac_len, signing_len) =
Self::calculate_bounds(algorithm, min_mac_len, signing_len)?;
Ok(Key {
key: hmac::Key::new(algorithm.into_hmac_algorithm(), key),
name,
min_mac_len,
signing_len,
})
}
/// Generates a new signing key.
///
/// This is similar to [`new`] but generates the bits for the key from the
/// given `rng`. It returns both the key and bits for serialization and
/// exporting.
///
/// [`new`]: #method.new
pub fn generate(
algorithm: Algorithm,
rng: &dyn rand::SecureRandom,
name: Dname<OctetsVec>,
min_mac_len: Option<usize>,
signing_len: Option<usize>,
) -> Result<(Self, Bytes), GenerateKeyError> {
let (min_mac_len, signing_len) =
Self::calculate_bounds(algorithm, min_mac_len, signing_len)?;
let algorithm = algorithm.into_hmac_algorithm();
let key_len = algorithm.len();
let mut bytes = BytesMut::with_capacity(key_len);
bytes.resize(key_len, 0);
rng.fill(&mut bytes)?;
let key = Key {
key: hmac::Key::new(algorithm, &bytes),
name,
min_mac_len,
signing_len,
};
Ok((key, bytes.freeze()))
}
/// Calculates the bounds to use in the key.
///
/// Returns the actual bounds for `min_mac_len` and `signing_len` or an
/// error if the input is out of bounds.
fn calculate_bounds(
algorithm: Algorithm,
min_mac_len: Option<usize>,
signing_len: Option<usize>,
) -> Result<(usize, usize), NewKeyError> {
let min_mac_len = match min_mac_len {
Some(len) => {
if !algorithm.within_len_bounds(len) {
return Err(NewKeyError::BadMinMacLen);
}
len
}
None => algorithm.native_len(),
};
let signing_len = match signing_len {
Some(len) => {
if !algorithm.within_len_bounds(len) {
return Err(NewKeyError::BadSigningLen);
}
len
}
None => algorithm.native_len(),
};
Ok((min_mac_len, signing_len))
}
/// Creates a signing context for this key.
fn signing_context(&self) -> hmac::Context {
hmac::Context::with_key(&self.key)
}
/// Returns a the possibly truncated slice of the signature.
fn signature_slice<'a>(&self, signature: &'a hmac::Tag) -> &'a [u8] {
&signature.as_ref()[..self.signing_len]
}
}
/// # Access to Properties
///
impl Key {
/// Returns the algorithm of this key.
pub fn algorithm(&self) -> Algorithm {
Algorithm::from_hmac_algorithm(self.key.algorithm())
}
/// Returns a reference to the name of this key.
pub fn name(&self) -> &Dname<OctetsVec> {
&self.name
}
/// Returns the native length of the signature from this key.
pub fn native_len(&self) -> usize {
self.key.algorithm().len()
}
/// Returns the minimum acceptable length of a received signature.
pub fn min_mac_len(&self) -> usize {
self.min_mac_len
}
/// Returns the length of a signature generated by this key.
pub fn signing_len(&self) -> usize {
self.signing_len
}
/// Checks whether the key in the record is this key.
fn check_tsig<Octets>(
&self,
tsig: &MessageTsig<Octets>,
) -> Result<(), ValidationError>
where
for<'o> &'o Octets: OctetsRef,
{
if *tsig.owner() != self.name
|| *tsig.data().algorithm() != self.algorithm().to_dname()
{
Err(ValidationError::BadKey)
} else {
Ok(())
}
}
/// Compares two signatures.
///
/// The first signature is the expected value, the second the provided
/// one. This considers signature truncation limited to whatever is
/// acceptable by this key.
fn compare_signatures(
&self,
expected: &hmac::Tag,
provided: &[u8],
) -> Result<(), ValidationError> {
if provided.len() < self.min_mac_len {
return Err(ValidationError::BadTrunc);
}
let expected = if provided.len() < expected.as_ref().len() {
&expected.as_ref()[..provided.len()]
} else {
expected.as_ref()
};
constant_time::verify_slices_are_equal(expected, provided)
.map_err(|_| ValidationError::BadSig)
}
/// Completes a message by adding a TSIG record.
///
/// A TSIG record will be added to the additional section. It will be
/// constructed from the information obtained from this key, the
/// `variables` and `mac`. Note that the MAC already has to be truncated
/// if that is required.
///
/// The method fails if the TSIG record doesn’t fit into the message
/// anymore, in which case the builder is returned unharmed.
fn complete_message<Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>>(
&self,
message: &mut AdditionalBuilder<Target>,
variables: &Variables,
mac: &[u8],
) -> Result<(), ShortBuf> {
let id = message.header().id();
variables.push_tsig(self, mac, id, message)
}
}
//--- AsRef
impl AsRef<Key> for Key {
fn as_ref(&self) -> &Self {
self
}
}
//------------ KeyStore ------------------------------------------------------
/// A type that stores TSIG secret keys.
///
/// This trait is used by [`ServerTransaction`] and [`ServerSequence`] to
/// determine whether a key of a TSIG signed message is known to this server.
///
/// In order to allow sharing of keys, the trait allows the implementing type
/// to pick its representation via the `Key` associated type. The `get_key`
/// method tries to return a key for a given pair of name and algorithm.
///
/// Implementations are provided for a `HashMap` mapping those pairs of name
/// and algorithm to an as-ref of a key (such as an arc) as well as for
/// as-refs of a single key. The latter is useful if you know the key to use
/// already.
///
/// If you need to limit the keys available based on properties of the
/// received message, you may need to implement your key store type that
/// wraps a more general store and limits its available keys.
pub trait KeyStore {
/// The representation of the key returned by the store.
type Key: AsRef<Key>;
/// Tries to find a key in the store.
///
/// The method looks up a key based on a pair of name and algorithm. If
/// the key can be found, it is returned. Otherwise, `None` is returned.
fn get_key<N: ToDname>(
&self,
name: &N,
algorithm: Algorithm,
) -> Option<Self::Key>;
}
impl<K: AsRef<Key> + Clone> KeyStore for K {
type Key = Self;
fn get_key<N: ToDname>(
&self,
name: &N,
algorithm: Algorithm,
) -> Option<Self::Key> {
if self.as_ref().name() == name
&& self.as_ref().algorithm() == algorithm
{
Some(self.clone())
} else {
None
}
}
}
impl<K, S> KeyStore for HashMap<(Dname<OctetsVec>, Algorithm), K, S>
where
K: AsRef<Key> + Clone,
S: hash::BuildHasher,
{
type Key = K;
fn get_key<N: ToDname>(
&self,
name: &N,
algorithm: Algorithm,
) -> Option<Self::Key> {
// XXX This seems a bit wasteful.
let name = name.to_dname::<OctetsVec>().unwrap();
self.get(&(name, algorithm)).cloned()
}
}
//------------ ClientTransaction ---------------------------------------------
/// TSIG Client Transaction State.
///
/// This types allows signing a DNS request with a given key and validate an
/// answer received for it.
///
/// You create both a signed message and a client transaction by calling the
/// [`request`] function. You can then send out the signed message and wait
/// for answers. If an answer is received, you pass it into the [`answer`]
/// method. This method will remove a TSIG record if it is present directly
/// in the message and then verify that this record is correctly signing the
/// transaction. If the message doesn’t, you can drop it and try with the next
/// answer received. The transaction will remain valid.
///
/// [`request`]: #method.request
/// [`answer`]: #method.answer
#[derive(Clone, Debug)]
pub struct ClientTransaction<K> {
context: SigningContext<K>,
}
impl<K: AsRef<Key>> ClientTransaction<K> {
/// Creates a transaction for a request.
///
/// The method takes a complete message in the form of an additional
/// builder and a key. It signs the message with the key and adds the
/// signature as a TSIG record to the message’s additional section. It
/// also creates a transaction value that can later be used to validate
/// the response. It returns both the message and the transaction.
///
/// The function can fail if the TSIG record doesn’t actually fit into
/// the message anymore. In this case, the function returns an error and
/// the untouched message.
///
/// Unlike [`request_with_fudge`], this function uses the
/// recommended default value for _fudge:_ 300 seconds.
///
/// [`request_with_fudge`]: #method.request_with_fudge
pub fn request<Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>>(
key: K,
message: &mut AdditionalBuilder<Target>,
) -> Result<Self, ShortBuf> {
Self::request_with_fudge(key, message, 300)
}
/// Creates a transaction for a request with provided fudge.
///
/// The method takes a complete message in the form of an additional
/// builder and a key. It signs the message with the key and adds the
/// signature as a TSIG record to the message’s additional section. It
/// also creates a transaction value that can later be used to validate
/// the response. It returns both the message and the transaction.
///
/// The `fudge` argument provides the number of seconds that the
/// receiver’s clock may be off from this system’s current time when it
/// receives the message. The specification recommends a value of 300
/// seconds. Unless there is good reason to not use this recommendation,
/// you can simply use [`request`] instead.
///
/// The function can fail if the TSIG record doesn’t actually fit into
/// the message anymore. In this case, the function returns an error and
/// the untouched message.
///
/// [`request`]: #method.request
pub fn request_with_fudge<Target>(
key: K,
message: &mut AdditionalBuilder<Target>,
fudge: u16,
) -> Result<Self, ShortBuf>
where
Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>,
{
let variables =
Variables::new(Time48::now(), fudge, TsigRcode::NoError, None);
let (mut context, mac) = SigningContext::request(
key,
message.as_slice(),
None,
&variables,
);
let mac = context.key().signature_slice(&mac);
context.apply_signature(mac);
context.key().complete_message(message, &variables, mac)?;
Ok(ClientTransaction { context })
}
/// Validates an answer.
///
/// Takes a message and checks whether it is a correctly signed answer
/// for this transaction.
///
/// First, if the last record in the message’s additional section is the
/// only TSIG record in the message, it takes it out. It then checks
/// whether this record is a correct record for this transaction and if
/// it correctly signs the answer for this transaction. If any of this
/// fails, returns an error.
pub fn answer<Octets>(
&self,
message: &mut Message<Octets>,
) -> Result<(), ValidationError>
where
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'a> &'a Octets: OctetsRef,
{
let tsig = match self.context.get_answer_tsig(message)? {
Some(some) => some,
None => return Err(ValidationError::ServerUnsigned),
};
let mut header = message.header_section();
header.header_mut().set_id(tsig.data().original_id());
header.counts_mut().dec_arcount();
let signature = self.context.answer(
header.as_slice(),
Some(
&message.as_slice()
[mem::size_of::<HeaderSection>()..tsig.start],
),
&tsig.variables(),
);
self.context
.key()
.compare_signatures(&signature, tsig.data().mac().as_ref())?;
self.context.check_answer_time(message, &tsig)?;
remove_tsig(tsig.into_original_id(), message);
Ok(())
}
/// Returns a reference to the transaction’s key.
pub fn key(&self) -> &Key {
self.context.key()
}
}
//------------ ServerTransaction ---------------------------------------------
/// TSIG Server Transaction State.
///
/// This type allows checking a received request and sign an answer to it
/// before sending it out.
///
/// A received request is given to [`request`][Self::request] together with
/// a set of acceptable keys via a key store which will produce a server
/// transaction value if the message was signed. Once an answer is ready, it
/// can be given to that transaction value to sign it, thereby producing a
/// message that can be returned to the client.
#[derive(Clone, Debug)]
pub struct ServerTransaction<K> {
context: SigningContext<K>,
}
impl<K: AsRef<Key>> ServerTransaction<K> {
/// Creates a transaction for a request.
///
/// The function checks whether the message carries exactly one TSIG
/// record as the last record of the additional section. If this is the
/// case, it removes the record form the message and checks whether it
/// is correctly signing the request with any of the keys provided by
/// the `store`. If that is the case, too, returns a server transaction.
///
/// If the message did not have a TSIG record, returns `Ok(None)`
/// indicating the lack of signing.
///
/// If anything is wrong with the message with regards to TSIG, the
/// function returns the error message that should be returned to the
/// client as the error case of the result.
pub fn request<Store, Octets>(
store: &Store,
message: &mut Message<Octets>,
) -> Result<Option<Self>, ServerError<K>>
where
Store: KeyStore<Key = K>,
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'o> &'o Octets: OctetsRef,
{
SigningContext::server_request(store, message).map(|context| {
context.map(|context| ServerTransaction { context })
})
}
/// Produces a signed answer.
///
/// The method takes a message builder that has been processed to the
/// additional stage already. It will then produce a signature for this
/// message using the key and additional information derived from the
/// original request. It tries to add this signature to the message as
/// a TSIG record. If this succeeds, it freezes the message since the
/// TSIG record must be the last record and returns it.
///
/// If appending the TSIG record fails, which can only happen if there
/// isn’t enough space left, it returns the builder unchanged as the
/// error case.
pub fn answer<Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>>(
self,
message: &mut AdditionalBuilder<Target>,
) -> Result<(), ShortBuf> {
self.answer_with_fudge(message, 300)
}
/// Produces a signed answer with a given fudge.
///
/// This method is similar to [`answer`] but lets you explicitely state
/// the `fudge`, i.e., the number of seconds the recipient’s clock is
/// allowed to differ from your current time when checking the signature.
/// The default, suggested by the RFC, is 300.
///
/// [`answer`]: #method.answer
pub fn answer_with_fudge<Target>(
self,
message: &mut AdditionalBuilder<Target>,
fudge: u16,
) -> Result<(), ShortBuf>
where
Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>,
{
let variables =
Variables::new(Time48::now(), fudge, TsigRcode::NoError, None);
let (mac, key) =
self.context
.final_answer(message.as_slice(), None, &variables);
let mac = key.as_ref().signature_slice(&mac);
key.as_ref().complete_message(message, &variables, mac)
}
/// Returns a reference to the transaction’s key.
pub fn key(&self) -> &Key {
self.context.key()
}
}
//------------ ClientSequence ------------------------------------------------
/// TSIG client sequence state.
///
/// This type allows a client to create a signed request and later check a
/// series of answers for being signed accordingly. It is necessary because
/// the signatures in the second and later answers in the sequence are
/// generated in a different way than the first one.
///
/// Much like with [`ClientTransaction`], you can sign a request via the
/// [`request`] method provding the signing key and receiving the signed
/// version of the message and a client transaction value. You can then use
/// this value to validate a sequence of answers as they are received by
/// giving them to the [`answer`] method.
///
/// Once you have received the last answer, you call the [`done`] method to
/// check whether the sequence was allowed to end. This is necessary because
/// TSIG allows intermediary messages to be unsigned but demands the last
/// message to be signed.
///
/// [`ClientTransaction`]: struct.ClientTransaction.html
/// [`request`]: #method.request
/// [`answer`]: #method.answer
/// [`done`]: #method.done
#[derive(Clone, Debug)]
pub struct ClientSequence<K> {
/// A signing context to be used for the next signed answer.
context: SigningContext<K>,
/// Are we still waiting for the first answer?
first: bool,
/// How many unsigned answers have we seen since the last signed answer?
unsigned: usize,
}
impl<K: AsRef<Key>> ClientSequence<K> {
/// Creates a sequence for a request.
///
/// The function will sign the message as it has been built so far using
/// the given key and add a corresponding TSIG record to it. If this
/// fails because there wasn’t enough space left in the message builder,
/// returns the builder untouched as the error case. Otherwise, it will
/// freeze the message and return both it and a new value of a client
/// sequence.
pub fn request<Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>>(
key: K,
message: &mut AdditionalBuilder<Target>,
) -> Result<Self, ShortBuf> {
Self::request_with_fudge(key, message, 300)
}
/// Creates a sequence for a request with a specific fudge.
///
/// This is almost identical to [`request`] but allows you to explicitely
/// specify a value of fudge which describes the number of seconds the
/// recipients clock may differ from this system’s current time when
/// checking the request. The default value used by [`request`] is 300
/// seconds.
///
/// [`request`]: #method.request
pub fn request_with_fudge<Target>(
key: K,
message: &mut AdditionalBuilder<Target>,
fudge: u16,
) -> Result<Self, ShortBuf>
where
Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>,
{
let variables =
Variables::new(Time48::now(), fudge, TsigRcode::NoError, None);
let (mut context, mac) = SigningContext::request(
key,
message.as_slice(),
None,
&variables,
);
let mac = context.key().signature_slice(&mac);
context.apply_signature(mac);
context.key().complete_message(message, &variables, mac)?;
Ok(ClientSequence {
context,
first: true,
unsigned: 0,
})
}
/// Validates an answer.
///
/// If the answer contains exactly one TSIG record as its last record,
/// removes this record and checks that it correctly signs this message
/// as part of the sequence.
///
/// If it doesn’t or if there had been more than 99 unsigned messages in
/// the sequence since the last signed one, returns an error.
pub fn answer<Octets>(
&mut self,
message: &mut Message<Octets>,
) -> Result<(), ValidationError>
where
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'a> &'a Octets: OctetsRef,
{
if self.first {
self.answer_first(message)
} else {
self.answer_subsequent(message)
}
}
/// Validates the end of the sequence.
///
/// Specifically, this checks that the last message given to [`answer`]
/// had been signed.
///
/// [`answer`]: #method.answer
pub fn done(self) -> Result<(), ValidationError> {
// The last message must be signed, so the counter must be 0 here.
if self.unsigned != 0 {
Err(ValidationError::TooManyUnsigned)
} else {
Ok(())
}
}
/// Checks the first answer in the sequence.
fn answer_first<Octets>(
&mut self,
message: &mut Message<Octets>,
) -> Result<(), ValidationError>
where
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'a> &'a Octets: OctetsRef,
{
let tsig = match self.context.get_answer_tsig(message)? {
Some(some) => some,
None => return Err(ValidationError::ServerUnsigned),
};
let mut header = message.header_section();
header.header_mut().set_id(tsig.data().original_id());
header.counts_mut().dec_arcount();
let signature = self.context.first_answer(
header.as_slice(),
Some(
&message.as_slice()
[mem::size_of::<HeaderSection>()..tsig.start],
),
&tsig.variables(),
);
self.context
.key()
.compare_signatures(&signature, tsig.data().mac().as_ref())?;
self.context.apply_signature(tsig.data().mac().as_ref());
self.context.check_answer_time(message, &tsig)?;
self.first = false;
remove_tsig(tsig.into_original_id(), message);
Ok(())
}
/// Checks any subsequent answer in the sequence.
fn answer_subsequent<Octets>(
&mut self,
message: &mut Message<Octets>,
) -> Result<(), ValidationError>
where
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'a> &'a Octets: OctetsRef,
{
let tsig = match self.context.get_answer_tsig(message)? {
Some(tsig) => tsig,
None => {
if self.unsigned < 99 {
self.context.unsigned_subsequent(message.as_slice());
self.unsigned += 1;
return Ok(());
} else {
return Err(ValidationError::TooManyUnsigned);
}
}
};
// Check the MAC.
let mut header = message.header_section();
header.header_mut().set_id(tsig.data().original_id());
header.counts_mut().dec_arcount();
let signature = self.context.signed_subsequent(
header.as_slice(),
Some(
&message.as_slice()
[mem::size_of::<HeaderSection>()..tsig.start],
),
&tsig.variables(),
);
self.context
.key()
.compare_signatures(&signature, tsig.data().mac().as_ref())?;
self.context.apply_signature(tsig.data().mac().as_ref());
self.context.check_answer_time(message, &tsig)?;
self.unsigned = 0;
remove_tsig(tsig.into_original_id(), message);
Ok(())
}
/// Returns a reference to the transaction’s key.
pub fn key(&self) -> &Key {
self.context.key()
}
}
//------------ ServerSequence ------------------------------------------------
/// TSIG server sequence state.
///
/// This type allows to verify that a request has been correctly signed with
/// a known key and produce a sequence of answers to this request.
///
/// A sequence is created by giving a received message and a set of
/// acceptable keys to the [`request`][Self::request] function. It will
/// produce a server sequence value if the message was correctly signed with
/// any of keys. Each answer message is then given to
/// [`answer`][Self::answer] to finalize it into a signed message.
///
/// Note that while the original [RFC 2845] allows a sequence of up to 99
/// intermediary messages not to be signed, this is in the process of being
/// deprecated. This implementation therefore signs each and every answer.
///
/// [RFC 2845]: https://tools.ietf.org/html/rfc2845
#[derive(Clone, Debug)]
pub struct ServerSequence<K> {
/// A signing context to be used for the next signed answer.
///
context: SigningContext<K>,
/// Are we still waiting for the first answer?
first: bool,
}
impl<K: AsRef<Key>> ServerSequence<K> {
/// Creates a sequence from the request.
///
/// The function checks whether the message carries exactly one TSIG
/// record as the last record of the additional section. If this is the
/// case, it removes the record form the message and checks whether it
/// is correctly signing the request with any of the keys provided by
/// the `store`. If that is the case, too, returns a server transaction.
///
/// If the message did not have a TSIG record, returns `Ok(None)`
/// indicating the lack of signing.
///
/// If anything is wrong with the message with regards to TSIG, the
/// function returns the error message that should be returned to the
/// client as the error case of the result.
pub fn request<Store, Octets>(
store: &Store,
message: &mut Message<Octets>,
) -> Result<Option<Self>, ServerError<K>>
where
Store: KeyStore<Key = K>,
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'o> &'o Octets: OctetsRef,
{
SigningContext::server_request(store, message).map(|context| {
context.map(|context| ServerSequence {
context,
first: false,
})
})
}
/// Produces a signed answer.
///
/// The method takes a message builder progressed into the additional
/// section and signs it as the next answer in the sequence. To do so,
/// it attempts to add a TSIG record to the additional section, if that
/// fails because there wasn’t enough space in the builder, returns the
/// unchanged builder as an error.
pub fn answer<Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>>(
&mut self,
message: &mut AdditionalBuilder<Target>,
) -> Result<(), ShortBuf> {
self.answer_with_fudge(message, 300)
}
/// Produces a signed answer with a given fudge.
///
/// This is nearly identical to [`answer`][Self::answer] except that it
/// allows to specify the ‘fudge’ which declares the number of seconds
/// the receiver’s clock may be off from this systems current time.
pub fn answer_with_fudge<Target>(
&mut self,
message: &mut AdditionalBuilder<Target>,
fudge: u16,
) -> Result<(), ShortBuf>
where
Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>,
{
let variables =
Variables::new(Time48::now(), fudge, TsigRcode::NoError, None);
let mac = if self.first {
self.first = false;
self.context
.first_answer(message.as_slice(), None, &variables)
} else {
self.context.signed_subsequent(
message.as_slice(),
None,
&variables,
)
};
let mac = self.key().signature_slice(&mac);
self.key().complete_message(message, &variables, mac)
}
/// Returns a reference to the transaction’s key.
pub fn key(&self) -> &Key {
self.context.key()
}
}
//------------ SigningContext ------------------------------------------------
/// A TSIG signing context.
///
/// This is a thin wrapper around a ring signing context and a key providing
/// all the signing needs.
///
/// When signing answers, the signature of previous messages is being digested
/// as the first element. This type allows to do that right after having
/// generated or received the signature so that it doesn’t need to be kept
/// around.
///
/// The type is generic over a representation of a key so that you can use
/// arcs and whatnots here.
#[derive(Clone, Debug)]
struct SigningContext<K> {
/// The ring signing context.
context: hmac::Context,
/// The key.
///
/// It will be used as part of the complete TSIG variables as well as
/// for creating new signing contexts.
key: K,
}
impl<K: AsRef<Key>> SigningContext<K> {
/// Checks the a request received by a server.
///
/// This is the code that is shared by `ServerTransaction` and
/// `ServerSequence`. It checks for a TSIG record and, if it is present,
/// checks that the record signs the message with a key known to the
/// store.
///
/// Returns a signing context if there was a TSIG record and it was
/// correctly signed with a known key. Returns `Ok(None)` if there was
/// no TSIG record at all. Returns an error with a message to be returned
/// to the client otherwise.
fn server_request<Store, Octets>(
store: &Store,
message: &mut Message<Octets>,
) -> Result<Option<Self>, ServerError<Store::Key>>
where
Store: KeyStore<Key = K>,
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'a> &'a Octets: OctetsRef,
{
// 4.5 Server TSIG checks
//
// First, do we have a valid TSIG?
let tsig = match MessageTsig::from_message(message) {
Some(tsig) => tsig,
None => return Ok(None),
};
// 4.5.1. KEY check and error handling
let algorithm = match Algorithm::from_dname(tsig.data().algorithm()) {
Some(algorithm) => algorithm,
None => return Err(ServerError::unsigned(TsigRcode::BadKey)),
};
let key = match store.get_key(tsig.owner(), algorithm) {
Some(key) => key,
None => return Err(ServerError::unsigned(TsigRcode::BadKey)),
};
let variables = tsig.variables();
// 4.5.3 MAC check
//
// Contrary to RFC 2845, this must be done before the time check.
let mut header = message.header_section();
header.header_mut().set_id(tsig.data().original_id());
header.counts_mut().dec_arcount();
let (mut context, signature) = Self::request(
key,
header.as_slice(),
Some(
&message.as_slice()
[mem::size_of::<HeaderSection>()..tsig.start],
),
&variables,
);
let res = context
.key
.as_ref()
.compare_signatures(&signature, tsig.data().mac().as_ref());
if let Err(err) = res {
return Err(ServerError::unsigned(match err {
ValidationError::BadTrunc => TsigRcode::BadTrunc,
ValidationError::BadKey => TsigRcode::BadKey,
_ => TsigRcode::FormErr,
}));
}
// The signature is fine. Add it to the context for later.
context.apply_signature(tsig.data().mac().as_ref());
// 4.5.2 Time check
//
// Note that we are not doing the caching of the most recent
// time_signed because, well, that’ll require mutexes and stuff.
if !tsig.data().is_valid_now() {
return Err(ServerError::signed(
context,
Variables::new(
variables.time_signed,
variables.fudge,
TsigRcode::BadTime,
Some(Time48::now()),
),
));
}
remove_tsig(tsig.into_original_id(), message);
Ok(Some(context))
}
/// Extracts the TSIG record from an anwer.
///
/// This is the first part of the code shared by the various answer
/// functions of `ClientTransaction` and `ClientSequence`. It does
/// everything that needs to be done before actually verifying the
/// signature: Find the TSIG record, handle unsigned errors, check
/// that the key and algorithm correspond to our key and algorithm.
///
/// Since there may be unsigned messages in client sequences, returns
/// `Ok(None)` if there is no TSIG at all. Otherwise, if all steps
/// succeed, returns the TSIG variables and the TSIG record. If there
/// is an error, returns that.
///
/// Because the returned TSIG record references the message, so it will
/// later have to have the TSIG record stripped off and the ID updated.
fn get_answer_tsig<'a, Octets>(
&self,
message: &'a Message<Octets>,
) -> Result<Option<MessageTsig<'a, Octets>>, ValidationError>
where
Octets: AsRef<[u8]>,
for<'o> &'o Octets: OctetsRef,
{
// Extract TSIG or bail out.
let tsig = match MessageTsig::from_message(message) {
Some(tsig) => tsig,
None => return Ok(None),
};
// Check for unsigned errors.
if message.header().rcode() == Rcode::NotAuth {
if tsig.data().error() == TsigRcode::BadKey {
return Err(ValidationError::ServerBadKey);
}
if tsig.data().error() == TsigRcode::BadSig {
return Err(ValidationError::ServerBadSig);
}
}
// Check that the server used the correct key and algorithm.
self.key().check_tsig(&tsig)?;
Ok(Some(tsig))
}
/// Checks the timing values of an answer TSIG.
///
/// This is the second part of the code shared between the various
/// answer methods of `ClientTransaction` and `ClientSequence`. It
/// checks for timing errors reported by the server as well as the
/// time signed in the signature.
fn check_answer_time<'a, Octets>(
&self,
message: &'a Message<Octets>,
tsig: &MessageTsig<'a, Octets>,
) -> Result<(), ValidationError>
where
Octets: AsRef<[u8]>,
for<'o> &'o Octets: OctetsRef,
{
if message.header().rcode() == Rcode::NotAuth
&& tsig.data().error() == TsigRcode::BadTime
{
let server = match tsig.data().other_time() {
Some(time) => time,
None => return Err(ValidationError::FormErr),
};
return Err(ValidationError::ServerBadTime {
client: tsig.data().time_signed(),
server,
});
}
// Check the time.
if !tsig.data().is_valid_now() {
return Err(ValidationError::BadTime);
}
Ok(())
}
}
impl<K: AsRef<Key>> SigningContext<K> {
/// Creates a new signing context for the given key.
fn new(key: K) -> Self {
SigningContext {
context: key.as_ref().signing_context(),
key,
}
}
/// Returns a references to the key that was used to create the context.
fn key(&self) -> &Key {
self.key.as_ref()
}
/// Applies a signature to the signing context.
///
/// The `data` argument must be the actual signature that has already been
/// truncated if that is required.
///
/// Applies the length as a 16 bit big-endian unsigned followed by the
/// actual octets.
fn apply_signature(&mut self, data: &[u8]) {
self.context.update(&(data.len() as u16).to_be_bytes());
self.context.update(data);
}
/// Creates a signing context for a request.
///
/// Takes a key, the octets of the message with the TSIG record already
/// removed and the ID reset if necessary, and the TSIG variables from the
/// TSIG record.
///
/// Returns both a signing context and the full signature for this
/// message.
fn request(
key: K,
first: &[u8],
second: Option<&[u8]>,
variables: &Variables,
) -> (Self, hmac::Tag) {
let mut context = key.as_ref().signing_context();
context.update(first);
if let Some(second) = second {
context.update(second)
}
variables.sign(key.as_ref(), &mut context);
let signature = context.sign();
(Self::new(key), signature)
}
/// Signs an answer.
///
/// Applies the message and variables only. The request signature has to
/// have been applied already. Returns the signature for the answer.
///
/// This happens on a clone of the original signing context. The context
/// itself will _not_ change.
fn answer(
&self,
first: &[u8],
second: Option<&[u8]>,
variables: &Variables,
) -> hmac::Tag {
let mut context = self.context.clone();
context.update(first);
if let Some(second) = second {
context.update(second)
}
variables.sign(self.key.as_ref(), &mut context);
context.sign()
}
/// Signs an answer and drops the context.
///
/// This is like `answer` above but it doesn’t need to clone the context.
fn final_answer(
mut self,
first: &[u8],
second: Option<&[u8]>,
variables: &Variables,
) -> (hmac::Tag, K) {
self.context.update(first);
if let Some(second) = second {
self.context.update(second)
}
variables.sign(self.key.as_ref(), &mut self.context);
(self.context.sign(), self.key)
}
/// Signs the first answer in a sequence.
///
/// This is like `answer` but it resets the context.
fn first_answer(
&mut self,
first: &[u8],
second: Option<&[u8]>,
variables: &Variables,
) -> hmac::Tag {
// Replace current context with new context.
let mut context = self.key().signing_context();
mem::swap(&mut self.context, &mut context);
// Update the old context with message and variables, return signature
context.update(first);
if let Some(second) = second {
context.update(second)
}
variables.sign(self.key.as_ref(), &mut context);
context.sign()
}
/// Applies the content of an unsigned message to the context.
fn unsigned_subsequent(&mut self, message: &[u8]) {
self.context.update(message)
}
/// Signs a subsequent message.
///
/// Resets the context.
fn signed_subsequent(
&mut self,
first: &[u8],
second: Option<&[u8]>,
variables: &Variables,
) -> hmac::Tag {
// Replace current context with new context.
let mut context = self.key().signing_context();
mem::swap(&mut self.context, &mut context);
// Update the old context with message and timers, return signature
context.update(first);
if let Some(second) = second {
context.update(second)
}
variables.sign_timers(&mut context);
context.sign()
}
}
//------------ MessageTsig ---------------------------------------------------
/// The TSIG record of a message.
struct MessageTsig<'a, Octets>
where
for<'o> &'o Octets: OctetsRef,
{
/// The actual record.
record: Record<
ParsedDname<&'a Octets>,
Tsig<<&'a Octets as OctetsRef>::Range, ParsedDname<&'a Octets>>,
>,
/// The index of the start of the record.
start: usize,
}
impl<'a, Octets> MessageTsig<'a, Octets>
where
for<'o> &'o Octets: OctetsRef,
{
/// Get the TSIG record from a message.
///
/// Checks that there is exactly one TSIG record in the additional
/// section, that it is the last record in this section. If that is true,
/// returns the parsed TSIG records.
fn from_message(msg: &'a Message<Octets>) -> Option<Self>
where
Octets: AsRef<[u8]>,
for<'o> &'o Octets: OctetsRef,
{
let mut section = msg.additional().ok()?;
let mut start = section.pos();
let mut record = section.next()?;
loop {
record = match section.next() {
Some(record) => record,
None => break,
};
start = section.pos();
}
record
.ok()?
.into_record::<Tsig<_, _>>()
.ok()?
.map(|record| MessageTsig { record, start })
}
fn variables(&self) -> Variables {
Variables::new(
self.record.data().time_signed(),
self.record.data().fudge(),
self.record.data().error(),
self.record.data().other_time(),
)
}
fn into_original_id(self) -> u16 {
self.record.data().original_id()
}
}
impl<'a, Octets> std::ops::Deref for MessageTsig<'a, Octets>
where
for<'o> &'o Octets: OctetsRef,
{
type Target = Record<
ParsedDname<&'a Octets>,
Tsig<<&'a Octets as OctetsRef>::Range, ParsedDname<&'a Octets>>,
>;
fn deref(&self) -> &Self::Target {
&self.record
}
}
//------------ Variables -----------------------------------------------------
/// The TSIG Variables.
///
/// This type keeps some of the variables that are added when calculating the
/// signature. This isn’t all the variables used, though. The remaining ones
/// are related to the key and are kept with the signing context.
#[derive(Clone, Debug)]
struct Variables {
/// The time the signature in question was created.
time_signed: Time48,
/// The infamous fudge.
fudge: u16,
/// The TSIG error code.
error: TsigRcode,
/// The content of the ‘other’ field.
///
/// According to the RFC, the only allowed value for this field is a
/// time stamp. So we keep this as an optional time value.
other: Option<Time48>,
}
impl Variables {
/// Creates a new value from the parts.
fn new(
time_signed: Time48,
fudge: u16,
error: TsigRcode,
other: Option<Time48>,
) -> Self {
Variables {
time_signed,
fudge,
error,
other,
}
}
/// Produces a TSIG record from this value and some more data.
fn push_tsig<Target: OctetsBuilder + AsMut<[u8]>>(
&self,
key: &Key,
hmac: &[u8],
original_id: u16,
builder: &mut AdditionalBuilder<Target>,
) -> Result<(), ShortBuf> {
let other = self.other.map(Time48::into_octets);
let other = match other {
Some(ref time) => time.as_ref(),
None => b"",
};
builder.push((
key.name.clone(),
Class::Any,
0,
Tsig::new(
key.algorithm().to_dname(),
self.time_signed,
self.fudge,
hmac,
original_id,
self.error,
other,
),
))
}
/// Applies the variables to a signing context.
///
/// This applies the full variables including key information.
fn sign(&self, key: &Key, context: &mut hmac::Context) {
// Key name, in canonical wire format
for label in key.name.iter_labels().map(Label::to_canonical) {
context.update(label.as_wire_slice());
}
// CLASS (Always ANY in the current specification)
context.update(&Class::Any.to_int().to_be_bytes());
// TTL (Always 0 in the current specification)
context.update(&0u32.to_be_bytes());
// Algorithm Name (in canonical wire format)
context.update(key.algorithm().into_wire_slice());
// Time Signed
context.update(&self.time_signed.into_octets());
// Fudge
context.update(&self.fudge.to_be_bytes());
// Error
context.update(&self.error.to_int().to_be_bytes());
// Other Len
if self.other.is_some() {
context.update(&6u16.to_be_bytes());
} else {
context.update(&0u16.to_be_bytes());
}
// Other
if let Some(time) = self.other {
context.update(&u64::from(time).to_be_bytes());
}
}
/// Applies only the timing values to the signing context.
fn sign_timers(&self, context: &mut hmac::Context) {
// Time Signed
context.update(&self.time_signed.into_octets());
// Fudge
context.update(&self.fudge.to_be_bytes());
}
}
//------------ Algorithm -----------------------------------------------------
/// The supported TSIG algorithms.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum Algorithm {
Sha1,
Sha256,
Sha384,
Sha512,
}
impl Algorithm {
/// Creates a value from its domain name representation.
///
/// Returns `None` if the name doesn’t represent a known algorithm.
pub fn from_dname<N: ToDname>(name: &N) -> Option<Self> {
let mut labels = name.iter_labels();
let first = match labels.next() {
Some(label) => label,
None => return None,
};
match labels.next() {
Some(label) if label.is_root() => {}
_ => return None,
}
match first.as_slice() {
b"hmac-sha1" => Some(Algorithm::Sha1),
b"hmac-sha256" => Some(Algorithm::Sha256),
b"hmac-sha384" => Some(Algorithm::Sha384),
b"hmac-sha512" => Some(Algorithm::Sha512),
_ => None,
}
}
/// Creates a value from a HMAC algorithm.
///
/// This will panic if `alg` is not one of the recognized algorithms.
fn from_hmac_algorithm(alg: hmac::Algorithm) -> Self {
if alg == hmac::HMAC_SHA1_FOR_LEGACY_USE_ONLY {
Algorithm::Sha1
} else if alg == hmac::HMAC_SHA256 {
Algorithm::Sha256
} else if alg == hmac::HMAC_SHA384 {
Algorithm::Sha384
} else if alg == hmac::HMAC_SHA512 {
Algorithm::Sha512
} else {
panic!("Unknown TSIG key algorithm.")
}
}
/// Returns the ring HMAC algorithm for this TSIG algorithm.
fn into_hmac_algorithm(self) -> hmac::Algorithm {
match self {
Algorithm::Sha1 => hmac::HMAC_SHA1_FOR_LEGACY_USE_ONLY,
Algorithm::Sha256 => hmac::HMAC_SHA256,
Algorithm::Sha384 => hmac::HMAC_SHA384,
Algorithm::Sha512 => hmac::HMAC_SHA512,
}
}
/// Returns a octet slice with the wire-format domain name for this value.
fn into_wire_slice(self) -> &'static [u8] {
match self {
Algorithm::Sha1 => b"\x09hmac-sha1\0",
Algorithm::Sha256 => b"\x0Bhmac-sha256\0",
Algorithm::Sha384 => b"\x0Bhmac-sha384\0",
Algorithm::Sha512 => b"\x0Bhmac-sha512\0",
}
}
/// Returns a domain name for this value.
pub fn to_dname(self) -> Dname<&'static [u8]> {
unsafe { Dname::from_octets_unchecked(self.into_wire_slice()) }
}
/// Returns the native length of a signature created with this algorithm.
pub fn native_len(self) -> usize {
self.into_hmac_algorithm().len()
}
/// Returns the bounds for the allowed signature size.
pub fn within_len_bounds(self, len: usize) -> bool {
len >= cmp::max(10, self.native_len() / 2) && len <= self.native_len()
}
}
//--- FromStr
impl str::FromStr for Algorithm {
type Err = AlgorithmError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s {
"hmac-sha1" => Ok(Algorithm::Sha1),
"hmac-sha256" => Ok(Algorithm::Sha256),
"hmac-sha384" => Ok(Algorithm::Sha384),
"hmac-sha512" => Ok(Algorithm::Sha512),
_ => Err(AlgorithmError),
}
}
}
//--- Display
impl fmt::Display for Algorithm {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"{}",
match *self {
Algorithm::Sha1 => "hmac-sha1",
Algorithm::Sha256 => "hmac-sha256",
Algorithm::Sha384 => "hmac-sha384",
Algorithm::Sha512 => "hmac-sha512",
}
)
}
}
//------------ Helper Functions ----------------------------------------------
fn remove_tsig<Octets>(original_id: u16, message: &mut Message<Octets>)
where
Octets: AsRef<[u8]> + AsMut<[u8]>,
for<'o> &'o Octets: OctetsRef,
{
message.header_mut().set_id(original_id);
message.remove_last_additional();
}
//============ Error Types ===================================================
//------------ ServerError ---------------------------------------------------
/// A TSIG record of a received request couldn’t be validated.
///
/// A value of this type carries all information necessary to produce the
/// error response to be send back to the client.
#[derive(Clone)]
pub struct ServerError<K>(ServerErrorInner<K>);
#[derive(Clone)]
enum ServerErrorInner<K> {
/// Return an unsigned error message.
///
/// To crate the actual message, we need the original message with the
/// TSIG intact as the last additional record.
Unsigned { error: TsigRcode },
/// Return a signed error message.
Signed {
context: SigningContext<K>,
variables: Variables,
},
}
impl<K> ServerError<K> {
fn unsigned(error: TsigRcode) -> Self {
ServerError(ServerErrorInner::Unsigned { error })
}
fn signed(context: SigningContext<K>, variables: Variables) -> Self {
ServerError(ServerErrorInner::Signed { context, variables })
}
pub fn error(&self) -> TsigRcode {
match self.0 {
ServerErrorInner::Unsigned { error } => error,
ServerErrorInner::Signed { ref variables, .. } => variables.error,
}
}
}
impl<K: AsRef<Key>> ServerError<K> {
pub fn build_message<Octets, Target>(
self,
msg: &Message<Octets>,
builder: MessageBuilder<Target>,
) -> Result<AdditionalBuilder<Target>, ShortBuf>
where
Octets: AsRef<[u8]>,
for<'a> &'a Octets: OctetsRef,
Target: OctetsBuilder + AsRef<[u8]> + AsMut<[u8]>,
{
let builder = builder.start_answer(msg, Rcode::NotAuth)?;
let mut builder = builder.additional();
match self.0 {
ServerErrorInner::Unsigned { error } => {
let tsig = {
MessageTsig::from_message(msg)
.expect("missing or malformed TSIG record")
};
builder.push((
tsig.owner(),
tsig.class(),
tsig.ttl(),
Tsig::new(
tsig.data().algorithm(),
tsig.data().time_signed(),
tsig.data().fudge(),
b"",
msg.header().id(),
error,
b"",
),
))?;
}
ServerErrorInner::Signed { context, variables } => {
let (mac, key) = context.final_answer(
builder.as_slice(),
None,
&variables,
);
let mac = key.as_ref().signature_slice(&mac);
key.as_ref().complete_message(
&mut builder,
&variables,
mac,
)?;
}
}
Ok(builder)
}
}
//--- Debug, Display, and Error
impl<K> fmt::Debug for ServerError<K> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("ServerError").field(&self.0).finish()
}
}
impl<K> fmt::Debug for ServerErrorInner<K> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
ServerErrorInner::Unsigned { error } => {
f.debug_struct("Unsigned").field("error", &error).finish()
}
ServerErrorInner::Signed { ref variables, .. } => f
.debug_struct("Signed")
.field("variables", variables)
.finish(),
}
}
}
impl<K> fmt::Display for ServerError<K> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.error().fmt(f)
}
}
impl<K> error::Error for ServerError<K> {}
//------------ NewKeyError ---------------------------------------------------
/// A key couldn’t be created.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum NewKeyError {
BadMinMacLen,
BadSigningLen,
}
//--- Display and Error
impl fmt::Display for NewKeyError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
NewKeyError::BadMinMacLen => {
f.write_str("minimum signature length out of bounds")
}
NewKeyError::BadSigningLen => {
f.write_str("created signature length out of bounds")
}
}
}
}
impl error::Error for NewKeyError {}
//------------ GenerateKeyError ----------------------------------------------
/// A key couldn’t be created.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum GenerateKeyError {
BadMinMacLen,
BadSigningLen,
GenerationFailed,
}
//--- From
impl From<NewKeyError> for GenerateKeyError {
fn from(err: NewKeyError) -> Self {
match err {
NewKeyError::BadMinMacLen => GenerateKeyError::BadMinMacLen,
NewKeyError::BadSigningLen => GenerateKeyError::BadSigningLen,
}
}
}
impl From<ring::error::Unspecified> for GenerateKeyError {
fn from(_: ring::error::Unspecified) -> Self {
GenerateKeyError::GenerationFailed
}
}
//--- Display and Error
impl fmt::Display for GenerateKeyError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
GenerateKeyError::BadMinMacLen => {
f.write_str("minimum signature length out of bounds")
}
GenerateKeyError::BadSigningLen => {
f.write_str("created signature length out of bounds")
}
GenerateKeyError::GenerationFailed => {
f.write_str("generating key failed")
}
}
}
}
impl error::Error for GenerateKeyError {}
//------------ AlgorithmError ------------------------------------------------
/// An invalid algorithm was provided.
#[derive(Clone, Copy, Debug)]
pub struct AlgorithmError;
//--- Display and Error
impl fmt::Display for AlgorithmError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("invalid algorithm")
}
}
impl error::Error for AlgorithmError {}
//------------ ValidationError -----------------------------------------------
/// An error happened while validating a TSIG-signed message.
#[derive(Clone, Copy, Debug)]
pub enum ValidationError {
BadAlg,
BadOther,
BadSig,
BadTrunc,
BadKey,
BadTime,
FormErr,
ServerUnsigned,
ServerBadKey,
ServerBadSig,
ServerBadTime { client: Time48, server: Time48 },
TooManyUnsigned,
}
//--- From
impl From<ParseError> for ValidationError {
fn from(_: ParseError) -> Self {
ValidationError::FormErr
}
}
//--- Display and Error
impl fmt::Display for ValidationError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
ValidationError::BadAlg => f.write_str("unknown algorithm"),
ValidationError::BadOther => {
f.write_str("bad content of 'other' field")
}
ValidationError::BadSig => f.write_str("bad signature"),
ValidationError::BadTrunc => f.write_str("short signature"),
ValidationError::BadKey => f.write_str("unknown key"),
ValidationError::BadTime => f.write_str("bad time"),
ValidationError::FormErr => f.write_str("format error"),
ValidationError::ServerUnsigned => f.write_str("unsigned answer"),
ValidationError::ServerBadKey => {
f.write_str("unknown key on server")
}
ValidationError::ServerBadSig => {
f.write_str("server failed to verify MAC")
}
ValidationError::ServerBadTime { .. } => {
f.write_str("server reported bad time")
}
ValidationError::TooManyUnsigned => {
f.write_str("too many unsigned messages")
}
}
}
}
impl error::Error for ValidationError {}