//! [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
//! [messages]: crate::ln::msgs
-use io;
+use {io, io_extras};
use prelude::*;
use core::{cmp, fmt};
use core::hash::{Hash, Hasher};
BasicMPP,
],
});
+ // This isn't a "real" feature context, and is only used in the channel_type field in an
+ // `OpenChannel` message.
+ define_context!(ChannelTypeContext {
+ required_features: [
+ // Byte 0
+ ,
+ // Byte 1
+ StaticRemoteKey,
+ // Byte 2
+ ,
+ // Byte 3
+ ,
+ ],
+ optional_features: [
+ // Byte 0
+ ,
+ // Byte 1
+ ,
+ // Byte 2
+ ,
+ // Byte 3
+ ,
+ ],
+ });
/// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
/// useful for manipulating feature flags.
define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
"Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
set_variable_length_onion_required);
- define_feature!(13, StaticRemoteKey, [InitContext, NodeContext],
+ define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
"Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
set_static_remote_key_required);
define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
/// Features used within an invoice.
pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
+/// Features used within the channel_type field in an OpenChannel message.
+///
+/// A channel is always of some known "type", describing the transaction formats used and the exact
+/// semantics of our interaction with our peer.
+///
+/// Note that because a channel is a specific type which is proposed by the opener and accepted by
+/// the counterparty, only required features are allowed here.
+///
+/// This is serialized differently from other feature types - it is not prefixed by a length, and
+/// thus must only appear inside a TLV where its length is known in advance.
+pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
+
impl InitFeatures {
/// Writes all features present up to, and including, 13.
pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
}
}
+impl ChannelTypeFeatures {
+ /// Constructs the implicit channel type based on the common supported types between us and our
+ /// counterparty
+ pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
+ let mut ret = counterparty_init.to_context_internal();
+ // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
+ // optional bits and then AND out the optional ones.
+ for byte in ret.flags.iter_mut() {
+ *byte |= (*byte & 0b10_10_10_10) >> 1;
+ *byte &= 0b01_01_01_01;
+ }
+ ret
+ }
+
+ /// Constructs a ChannelTypeFeatures with only static_remotekey set
+ pub(crate) fn only_static_remote_key() -> Self {
+ let mut ret = Self::empty();
+ <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
+ ret
+ }
+}
+
impl ToBase32 for InvoiceFeatures {
fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
// Explanation for the "4": the normal way to round up when dividing is to add the divisor
&self.flags
}
+ fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ for f in self.flags.iter().rev() { // Swap back to big-endian
+ f.write(w)?;
+ }
+ Ok(())
+ }
+
+ fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
+ flags.reverse(); // Swap to little-endian
+ Self {
+ flags,
+ mark: PhantomData,
+ }
+ }
+
+ pub(crate) fn supports_any_optional_bits(&self) -> bool {
+ self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
+ }
+
/// Returns true if this `Features` object contains unknown feature flags which are set as
/// "required".
pub fn requires_unknown_bits(&self) -> bool {
self
}
}
-
-impl<T: sealed::Context> Writeable for Features<T> {
- fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.flags.len() as u16).write(w)?;
- for f in self.flags.iter().rev() { // Swap back to big-endian
- f.write(w)?;
+macro_rules! impl_feature_len_prefixed_write {
+ ($features: ident) => {
+ impl Writeable for $features {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ (self.flags.len() as u16).write(w)?;
+ self.write_be(w)
+ }
+ }
+ impl Readable for $features {
+ fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
+ Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
+ }
}
- Ok(())
}
}
-
-impl<T: sealed::Context> Readable for Features<T> {
+impl_feature_len_prefixed_write!(InitFeatures);
+impl_feature_len_prefixed_write!(ChannelFeatures);
+impl_feature_len_prefixed_write!(NodeFeatures);
+impl_feature_len_prefixed_write!(InvoiceFeatures);
+
+// Because ChannelTypeFeatures only appears inside of TLVs, it doesn't have a length prefix when
+// serialized. Thus, we can't use `impl_feature_len_prefixed_write`, above, and have to write our
+// own serialization.
+impl Writeable for ChannelTypeFeatures {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ self.write_be(w)
+ }
+}
+impl Readable for ChannelTypeFeatures {
fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
- let mut flags: Vec<u8> = Readable::read(r)?;
- flags.reverse(); // Swap to little-endian
- Ok(Self {
- flags,
- mark: PhantomData,
- })
+ let v = io_extras::read_to_end(r)?;
+ Ok(Self::from_be_bytes(v))
}
}
#[cfg(test)]
mod tests {
- use super::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
+ use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
#[test]
let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
assert_eq!(features, features_deserialized);
}
+
+ #[test]
+ fn test_channel_type_mapping() {
+ // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
+ // required-StaticRemoteKey ChannelTypeFeatures.
+ let init_features = InitFeatures::empty().set_static_remote_key_optional();
+ let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
+ assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
+ assert!(!converted_features.supports_any_optional_bits());
+ assert!(converted_features.requires_static_remote_key());
+ }
}
projects / rust-lightning / commitdiff