1 //! Lightning exposes sets of supported operations through "feature flags". This module includes
2 //! types to store those feature flags and query for specific flags.
5 use std::result::Result;
6 use std::marker::PhantomData;
8 use ln::msgs::DecodeError;
9 use util::ser::{Readable, Writeable, Writer};
11 mod sealed { // You should just use the type aliases instead.
12 pub struct InitContext {}
13 pub struct NodeContext {}
14 pub struct ChannelContext {}
16 /// An internal trait capturing the various feature context types
18 impl Context for InitContext {}
19 impl Context for NodeContext {}
20 impl Context for ChannelContext {}
22 pub trait DataLossProtect: Context {}
23 impl DataLossProtect for InitContext {}
24 impl DataLossProtect for NodeContext {}
26 pub trait InitialRoutingSync: Context {}
27 impl InitialRoutingSync for InitContext {}
29 pub trait UpfrontShutdownScript: Context {}
30 impl UpfrontShutdownScript for InitContext {}
31 impl UpfrontShutdownScript for NodeContext {}
34 /// Tracks the set of features which a node implements, templated by the context in which it
36 pub struct Features<T: sealed::Context> {
37 /// Note that, for convinience, flags is LITTLE endian (despite being big-endian on the wire)
42 impl<T: sealed::Context> Clone for Features<T> {
43 fn clone(&self) -> Self {
45 flags: self.flags.clone(),
50 impl<T: sealed::Context> PartialEq for Features<T> {
51 fn eq(&self, o: &Self) -> bool {
52 self.flags.eq(&o.flags)
55 impl<T: sealed::Context> fmt::Debug for Features<T> {
56 fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
61 /// A feature message as it appears in an init message
62 pub type InitFeatures = Features<sealed::InitContext>;
63 /// A feature message as it appears in a node_announcement message
64 pub type NodeFeatures = Features<sealed::NodeContext>;
65 /// A feature message as it appears in a channel_announcement message
66 pub type ChannelFeatures = Features<sealed::ChannelContext>;
69 /// Create a Features with the features we support
70 #[cfg(not(feature = "fuzztarget"))]
71 pub(crate) fn supported() -> InitFeatures {
73 flags: vec![2 | 1 << 5],
77 #[cfg(feature = "fuzztarget")]
78 pub fn supported() -> InitFeatures {
80 flags: vec![2 | 1 << 5],
85 /// Writes all features present up to, and including, 13.
86 pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
87 let len = cmp::min(2, self.flags.len());
89 (len as u16).write(w)?;
90 for i in (0..len).rev() {
92 self.flags[i].write(w)?;
94 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
95 // up-to-and-including-bit-5, 0-indexed, on this byte:
96 (self.flags[i] & 0b00_11_11_11).write(w)?;
102 /// or's another InitFeatures into this one.
103 pub(crate) fn or(mut self, o: InitFeatures) -> InitFeatures {
104 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
105 self.flags.resize(total_feature_len, 0u8);
106 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
113 impl ChannelFeatures {
114 /// Create a Features with the features we support
115 #[cfg(not(feature = "fuzztarget"))]
116 pub(crate) fn supported() -> ChannelFeatures {
122 #[cfg(feature = "fuzztarget")]
123 pub fn supported() -> ChannelFeatures {
132 /// Create a Features with the features we support
133 #[cfg(not(feature = "fuzztarget"))]
134 pub(crate) fn supported() -> NodeFeatures {
136 flags: vec![2 | 1 << 5],
140 #[cfg(feature = "fuzztarget")]
141 pub fn supported() -> NodeFeatures {
143 flags: vec![2 | 1 << 5],
149 impl<T: sealed::Context> Features<T> {
150 /// Create a blank Features with no features set
151 pub fn empty() -> Features<T> {
159 /// Create a Features given a set of flags, in LE.
160 pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
168 /// Gets the underlying flags set, in LE.
169 pub fn le_flags(&self) -> &Vec<u8> {
173 pub(crate) fn requires_unknown_bits(&self) -> bool {
174 self.flags.iter().enumerate().any(|(idx, &byte)| {
175 ( idx != 0 && (byte & 0x55) != 0 ) || ( idx == 0 && (byte & 0x14) != 0 )
179 pub(crate) fn supports_unknown_bits(&self) -> bool {
180 self.flags.iter().enumerate().any(|(idx, &byte)| {
181 ( idx != 0 && byte != 0 ) || ( idx == 0 && (byte & 0xc4) != 0 )
185 /// The number of bytes required to represent the feature flags present. This does not include
186 /// the length bytes which are included in the serialized form.
187 pub(crate) fn byte_count(&self) -> usize {
192 pub(crate) fn set_require_unknown_bits(&mut self) {
193 let newlen = cmp::max(2, self.flags.len());
194 self.flags.resize(newlen, 0u8);
195 self.flags[1] |= 0x40;
199 pub(crate) fn clear_require_unknown_bits(&mut self) {
200 let newlen = cmp::max(2, self.flags.len());
201 self.flags.resize(newlen, 0u8);
202 self.flags[1] &= !0x40;
203 if self.flags.len() == 2 && self.flags[1] == 0 {
204 self.flags.resize(1, 0u8);
209 impl<T: sealed::DataLossProtect> Features<T> {
210 pub(crate) fn supports_data_loss_protect(&self) -> bool {
211 self.flags.len() > 0 && (self.flags[0] & 3) != 0
215 impl<T: sealed::UpfrontShutdownScript> Features<T> {
216 pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
217 self.flags.len() > 0 && (self.flags[0] & (3 << 4)) != 0
220 pub(crate) fn unset_upfront_shutdown_script(&mut self) {
221 self.flags[0] ^= 1 << 5;
225 impl<T: sealed::InitialRoutingSync> Features<T> {
226 pub(crate) fn initial_routing_sync(&self) -> bool {
227 self.flags.len() > 0 && (self.flags[0] & (1 << 3)) != 0
229 pub(crate) fn set_initial_routing_sync(&mut self) {
230 if self.flags.len() == 0 {
231 self.flags.resize(1, 1 << 3);
233 self.flags[0] |= 1 << 3;
238 impl<T: sealed::Context> Writeable for Features<T> {
239 fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
240 w.size_hint(self.flags.len() + 2);
241 (self.flags.len() as u16).write(w)?;
242 for f in self.flags.iter().rev() { // Swap back to big-endian
249 impl<R: ::std::io::Read, T: sealed::Context> Readable<R> for Features<T> {
250 fn read(r: &mut R) -> Result<Self, DecodeError> {
251 let mut flags: Vec<u8> = Readable::read(r)?;
252 flags.reverse(); // Swap to little-endian