_ Git - rust-lightning/blob - lightning/src/ln/features.rs

   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.
   3
   4 use std::{cmp, fmt};
   5 use std::result::Result;
   6 use std::marker::PhantomData;
   7
   8 use ln::msgs::DecodeError;
   9 use util::ser::{Readable, Writeable, Writer};
  10
  11 mod sealed { // You should just use the type aliases instead.
  12         pub struct InitContext {}
  13         pub struct NodeContext {}
  14         pub struct ChannelContext {}
  15
  16         /// An internal trait capturing the various feature context types
  17         pub trait Context {}
  18         impl Context for InitContext {}
  19         impl Context for NodeContext {}
  20         impl Context for ChannelContext {}
  21
  22         pub trait DataLossProtect: Context {}
  23         impl DataLossProtect for InitContext {}
  24         impl DataLossProtect for NodeContext {}
  25
  26         pub trait InitialRoutingSync: Context {}
  27         impl InitialRoutingSync for InitContext {}
  28
  29         pub trait UpfrontShutdownScript: Context {}
  30         impl UpfrontShutdownScript for InitContext {}
  31         impl UpfrontShutdownScript for NodeContext {}
  32
  33         pub trait VariableLengthOnion: Context {}
  34         impl VariableLengthOnion for InitContext {}
  35         impl VariableLengthOnion for NodeContext {}
  36
  37         pub trait PaymentSecret: Context {}
  38         impl PaymentSecret for InitContext {}
  39         impl PaymentSecret for NodeContext {}
  40
  41         pub trait BasicMPP: Context {}
  42         impl BasicMPP for InitContext {}
  43         impl BasicMPP for NodeContext {}
  44 }
  45
  46 /// Tracks the set of features which a node implements, templated by the context in which it
  47 /// appears.
  48 pub struct Features<T: sealed::Context> {
  49         /// Note that, for convinience, flags is LITTLE endian (despite being big-endian on the wire)
  50         flags: Vec<u8>,
  51         mark: PhantomData<T>,
  52 }
  53
  54 impl<T: sealed::Context> Clone for Features<T> {
  55         fn clone(&self) -> Self {
  56                 Self {
  57                         flags: self.flags.clone(),
  58                         mark: PhantomData,
  59                 }
  60         }
  61 }
  62 impl<T: sealed::Context> PartialEq for Features<T> {
  63         fn eq(&self, o: &Self) -> bool {
  64                 self.flags.eq(&o.flags)
  65         }
  66 }
  67 impl<T: sealed::Context> fmt::Debug for Features<T> {
  68         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
  69                 self.flags.fmt(fmt)
  70         }
  71 }
  72
  73 /// A feature message as it appears in an init message
  74 pub type InitFeatures = Features<sealed::InitContext>;
  75 /// A feature message as it appears in a node_announcement message
  76 pub type NodeFeatures = Features<sealed::NodeContext>;
  77 /// A feature message as it appears in a channel_announcement message
  78 pub type ChannelFeatures = Features<sealed::ChannelContext>;
  79
  80 impl InitFeatures {
  81         /// Create a Features with the features we support
  82         pub fn supported() -> InitFeatures {
  83                 InitFeatures {
  84                         flags: vec![2 | 1 << 5, 1 << (9-8) | 1 << (15 - 8), 1 << (17 - 8*2)],
  85                         mark: PhantomData,
  86                 }
  87         }
  88
  89         /// Writes all features present up to, and including, 13.
  90         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
  91                 let len = cmp::min(2, self.flags.len());
  92                 w.size_hint(len + 2);
  93                 (len as u16).write(w)?;
  94                 for i in (0..len).rev() {
  95                         if i == 0 {
  96                                 self.flags[i].write(w)?;
  97                         } else {
  98                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
  99                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 100                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 101                         }
 102                 }
 103                 Ok(())
 104         }
 105
 106         /// or's another InitFeatures into this one.
 107         pub(crate) fn or(mut self, o: InitFeatures) -> InitFeatures {
 108                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 109                 self.flags.resize(total_feature_len, 0u8);
 110                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
 111                         *byte |= *o_byte;
 112                 }
 113                 self
 114         }
 115 }
 116
 117 impl ChannelFeatures {
 118         /// Create a Features with the features we support
 119         #[cfg(not(feature = "fuzztarget"))]
 120         pub(crate) fn supported() -> ChannelFeatures {
 121                 ChannelFeatures {
 122                         flags: Vec::new(),
 123                         mark: PhantomData,
 124                 }
 125         }
 126         #[cfg(feature = "fuzztarget")]
 127         pub fn supported() -> ChannelFeatures {
 128                 ChannelFeatures {
 129                         flags: Vec::new(),
 130                         mark: PhantomData,
 131                 }
 132         }
 133
 134         /// Takes the flags that we know how to interpret in an init-context features that are also
 135         /// relevant in a channel-context features and creates a channel-context features from them.
 136         pub(crate) fn with_known_relevant_init_flags(_init_ctx: &InitFeatures) -> Self {
 137                 // There are currently no channel flags defined that we understand.
 138                 Self { flags: Vec::new(), mark: PhantomData, }
 139         }
 140 }
 141
 142 impl NodeFeatures {
 143         /// Create a Features with the features we support
 144         #[cfg(not(feature = "fuzztarget"))]
 145         pub(crate) fn supported() -> NodeFeatures {
 146                 NodeFeatures {
 147                         flags: vec![2 | 1 << 5, 1 << (9-8) | 1 << (15 - 8), 1 << (17 - 8*2)],
 148                         mark: PhantomData,
 149                 }
 150         }
 151         #[cfg(feature = "fuzztarget")]
 152         pub fn supported() -> NodeFeatures {
 153                 NodeFeatures {
 154                         flags: vec![2 | 1 << 5, 1 << (9-8) | 1 << (15 - 8), 1 << (17 - 8*2)],
 155                         mark: PhantomData,
 156                 }
 157         }
 158
 159         /// Takes the flags that we know how to interpret in an init-context features that are also
 160         /// relevant in a node-context features and creates a node-context features from them.
 161         pub(crate) fn with_known_relevant_init_flags(init_ctx: &InitFeatures) -> Self {
 162                 let mut flags = Vec::new();
 163                 if init_ctx.flags.len() > 0 {
 164                         // Pull out data_loss_protect and upfront_shutdown_script (bits 0, 1, 4, and 5)
 165                         flags.push(init_ctx.flags.last().unwrap() & 0b00110011);
 166                 }
 167                 Self { flags, mark: PhantomData, }
 168         }
 169 }
 170
 171 impl<T: sealed::Context> Features<T> {
 172         /// Create a blank Features with no features set
 173         pub fn empty() -> Features<T> {
 174                 Features {
 175                         flags: Vec::new(),
 176                         mark: PhantomData,
 177                 }
 178         }
 179
 180         #[cfg(test)]
 181         /// Create a Features given a set of flags, in LE.
 182         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 183                 Features {
 184                         flags,
 185                         mark: PhantomData,
 186                 }
 187         }
 188
 189         #[cfg(test)]
 190         /// Gets the underlying flags set, in LE.
 191         pub fn le_flags(&self) -> &Vec<u8> {
 192                 &self.flags
 193         }
 194
 195         pub(crate) fn requires_unknown_bits(&self) -> bool {
 196                 self.flags.iter().enumerate().any(|(idx, &byte)| {
 197                         (match idx {
 198                                 0 => (byte & 0b01000100),
 199                                 1 => (byte & 0b00010100),
 200                                 2 => (byte & 0b01010100),
 201                                 _ => (byte & 0b01010101),
 202                         }) != 0
 203                 })
 204         }
 205
 206         pub(crate) fn supports_unknown_bits(&self) -> bool {
 207                 self.flags.iter().enumerate().any(|(idx, &byte)| {
 208                         (match idx {
 209                                 0 => (byte & 0b11000100),
 210                                 1 => (byte & 0b00111100),
 211                                 2 => (byte & 0b11111100),
 212                                 _ => byte,
 213                         }) != 0
 214                 })
 215         }
 216
 217         /// The number of bytes required to represent the feature flags present. This does not include
 218         /// the length bytes which are included in the serialized form.
 219         pub(crate) fn byte_count(&self) -> usize {
 220                 self.flags.len()
 221         }
 222
 223         #[cfg(test)]
 224         pub(crate) fn set_require_unknown_bits(&mut self) {
 225                 let newlen = cmp::max(3, self.flags.len());
 226                 self.flags.resize(newlen, 0u8);
 227                 self.flags[2] |= 0x40;
 228         }
 229
 230         #[cfg(test)]
 231         pub(crate) fn clear_require_unknown_bits(&mut self) {
 232                 let newlen = cmp::max(3, self.flags.len());
 233                 self.flags.resize(newlen, 0u8);
 234                 self.flags[2] &= !0x40;
 235                 if self.flags.len() == 3 && self.flags[2] == 0 {
 236                         self.flags.resize(2, 0u8);
 237                 }
 238                 if self.flags.len() == 2 && self.flags[1] == 0 {
 239                         self.flags.resize(1, 0u8);
 240                 }
 241         }
 242 }
 243
 244 impl<T: sealed::DataLossProtect> Features<T> {
 245         pub(crate) fn supports_data_loss_protect(&self) -> bool {
 246                 self.flags.len() > 0 && (self.flags[0] & 3) != 0
 247         }
 248 }
 249
 250 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 251         pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
 252                 self.flags.len() > 0 && (self.flags[0] & (3 << 4)) != 0
 253         }
 254         #[cfg(test)]
 255         pub(crate) fn unset_upfront_shutdown_script(&mut self) {
 256                 self.flags[0] ^= 1 << 5;
 257         }
 258 }
 259
 260 impl<T: sealed::VariableLengthOnion> Features<T> {
 261         pub(crate) fn supports_variable_length_onion(&self) -> bool {
 262                 self.flags.len() > 1 && (self.flags[1] & 3) != 0
 263         }
 264 }
 265
 266 impl<T: sealed::InitialRoutingSync> Features<T> {
 267         pub(crate) fn initial_routing_sync(&self) -> bool {
 268                 self.flags.len() > 0 && (self.flags[0] & (1 << 3)) != 0
 269         }
 270         pub(crate) fn set_initial_routing_sync(&mut self) {
 271                 if self.flags.len() == 0 {
 272                         self.flags.resize(1, 1 << 3);
 273                 } else {
 274                         self.flags[0] |= 1 << 3;
 275                 }
 276         }
 277 }
 278
 279 impl<T: sealed::PaymentSecret> Features<T> {
 280         #[allow(dead_code)]
 281         // Note that we never need to test this since what really matters is the invoice - iff the
 282         // invoice provides a payment_secret, we assume all the way through that we can do MPP.
 283         pub(crate) fn payment_secret(&self) -> bool {
 284                 self.flags.len() > 1 && (self.flags[1] & (3 << (12-8))) != 0
 285         }
 286 }
 287
 288 impl<T: sealed::BasicMPP> Features<T> {
 289         // We currently never test for this since we don't actually *generate* multipath routes.
 290         #[allow(dead_code)]
 291         pub(crate) fn basic_mpp(&self) -> bool {
 292                 self.flags.len() > 2 && (self.flags[2] & (3 << (16-8*2))) != 0
 293         }
 294 }
 295
 296 impl<T: sealed::Context> Writeable for Features<T> {
 297         fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
 298                 w.size_hint(self.flags.len() + 2);
 299                 (self.flags.len() as u16).write(w)?;
 300                 for f in self.flags.iter().rev() { // Swap back to big-endian
 301                         f.write(w)?;
 302                 }
 303                 Ok(())
 304         }
 305 }
 306
 307 impl<R: ::std::io::Read, T: sealed::Context> Readable<R> for Features<T> {
 308         fn read(r: &mut R) -> Result<Self, DecodeError> {
 309                 let mut flags: Vec<u8> = Readable::read(r)?;
 310                 flags.reverse(); // Swap to little-endian
 311                 Ok(Self {
 312                         flags,
 313                         mark: PhantomData,
 314                 })
 315         }
 316 }
 317
 318 #[cfg(test)]
 319 mod tests {
 320         use super::{ChannelFeatures, InitFeatures, NodeFeatures};
 321
 322         #[test]
 323         fn sanity_test_our_features() {
 324                 assert!(!ChannelFeatures::supported().requires_unknown_bits());
 325                 assert!(!ChannelFeatures::supported().supports_unknown_bits());
 326                 assert!(!InitFeatures::supported().requires_unknown_bits());
 327                 assert!(!InitFeatures::supported().supports_unknown_bits());
 328                 assert!(!NodeFeatures::supported().requires_unknown_bits());
 329                 assert!(!NodeFeatures::supported().supports_unknown_bits());
 330
 331                 assert!(InitFeatures::supported().supports_upfront_shutdown_script());
 332                 assert!(NodeFeatures::supported().supports_upfront_shutdown_script());
 333
 334                 assert!(InitFeatures::supported().supports_data_loss_protect());
 335                 assert!(NodeFeatures::supported().supports_data_loss_protect());
 336
 337                 let mut init_features = InitFeatures::supported();
 338                 init_features.set_initial_routing_sync();
 339                 assert!(!init_features.requires_unknown_bits());
 340                 assert!(!init_features.supports_unknown_bits());
 341         }
 342
 343         #[test]
 344         fn sanity_test_unkown_bits_testing() {
 345                 let mut features = ChannelFeatures::supported();
 346                 features.set_require_unknown_bits();
 347                 assert!(features.requires_unknown_bits());
 348                 features.clear_require_unknown_bits();
 349                 assert!(!features.requires_unknown_bits());
 350         }
 351 }