X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Ffeatures.rs;h=32ba9de758632036942318c756f64708793e1b1a;hb=22398853c97966f42c709669fff3c63486d82993;hp=d1f6b89db4f87e968e3624289331c00c476875fe;hpb=35573bb3d7bf8c7f7b9d8759afa555aec2735a44;p=rust-lightning diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs index d1f6b89d..32ba9de7 100644 --- a/lightning/src/ln/features.rs +++ b/lightning/src/ln/features.rs @@ -22,7 +22,7 @@ //! [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}; @@ -194,6 +194,30 @@ mod sealed { 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. @@ -325,7 +349,7 @@ mod sealed { 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], @@ -388,11 +412,22 @@ pub type ChannelFeatures = Features; /// Features used within an invoice. pub type InvoiceFeatures = Features; +/// 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; + impl InitFeatures { /// Writes all features present up to, and including, 13. pub(crate) fn write_up_to_13(&self, w: &mut W) -> Result<(), io::Error> { let len = cmp::min(2, self.flags.len()); - w.size_hint(len + 2); (len as u16).write(w)?; for i in (0..len).rev() { if i == 0 { @@ -433,16 +468,38 @@ impl InvoiceFeatures { /// Getting a route for a keysend payment to a private node requires providing the payee's /// features (since they were not announced in a node announcement). However, keysend payments /// don't have an invoice to pull the payee's features from, so this method is provided for use in - /// [`get_keysend_route`], thus omitting the need for payers to manually construct an - /// `InvoiceFeatures` for [`get_route`]. + /// [`Payee::for_keysend`], thus omitting the need for payers to manually construct an + /// `InvoiceFeatures` for [`find_route`]. /// - /// [`get_keysend_route`]: crate::routing::router::get_keysend_route - /// [`get_route`]: crate::routing::router::get_route + /// [`Payee::for_keysend`]: crate::routing::router::Payee::for_keysend + /// [`find_route`]: crate::routing::router::find_route pub(crate) fn for_keysend() -> InvoiceFeatures { InvoiceFeatures::empty().set_variable_length_onion_optional() } } +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(); + ::set_required_bit(&mut ret.flags); + ret + } +} + impl ToBase32 for InvoiceFeatures { fn write_base32(&self, writer: &mut W) -> Result<(), ::Err> { // Explanation for the "4": the normal way to round up when dividing is to add the divisor @@ -554,6 +611,25 @@ impl Features { &self.flags } + fn write_be(&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) -> Features { + 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 { @@ -584,12 +660,6 @@ impl Features { (byte & unknown_features) != 0 }) } - - /// The number of bytes required to represent the feature flags present. This does not include - /// the length bytes which are included in the serialized form. - pub(crate) fn byte_count(&self) -> usize { - self.flags.len() - } } impl Features { @@ -699,32 +769,44 @@ impl Features { self } } - -impl Writeable for Features { - fn write(&self, w: &mut W) -> Result<(), io::Error> { - w.size_hint(self.flags.len() + 2); - (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(&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: &mut R) -> Result { + Ok(Self::from_be_bytes(Vec::::read(r)?)) + } } - Ok(()) } } - -impl Readable for Features { +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(&self, w: &mut W) -> Result<(), io::Error> { + self.write_be(w) + } +} +impl Readable for ChannelTypeFeatures { fn read(r: &mut R) -> Result { - let mut flags: Vec = 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] @@ -835,7 +917,7 @@ mod tests { #[test] fn convert_to_context_with_unknown_flags() { // Ensure the `from` context has fewer known feature bytes than the `to` context. - assert!(InvoiceFeatures::known().byte_count() < NodeFeatures::known().byte_count()); + assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len()); let invoice_features = InvoiceFeatures::known().set_unknown_feature_optional(); assert!(invoice_features.supports_unknown_bits()); let node_features: NodeFeatures = invoice_features.to_context(); @@ -883,4 +965,15 @@ mod tests { 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()); + } }