_ Git - rapid-gossip-sync-server/blob - src/serialization.rs

   1 use std::cmp::max;
   2 use std::collections::HashMap;
   3
   4 use bitcoin::BlockHash;
   5 use bitcoin::hashes::Hash;
   6 use lightning::ln::msgs::{UnsignedChannelAnnouncement, UnsignedChannelUpdate};
   7 use lightning::util::ser::{BigSize, Writeable};
   8
   9 use crate::lookup::{DeltaSet, DirectedUpdateDelta};
  10
  11 pub(super) struct SerializationSet {
  12         pub(super) announcements: Vec<UnsignedChannelAnnouncement>,
  13         pub(super) updates: Vec<UpdateSerialization>,
  14         pub(super) full_update_defaults: DefaultUpdateValues,
  15         pub(super) latest_seen: u32,
  16         pub(super) chain_hash: BlockHash,
  17 }
  18
  19 pub(super) struct DefaultUpdateValues {
  20         pub(super) cltv_expiry_delta: u16,
  21         pub(super) htlc_minimum_msat: u64,
  22         pub(super) fee_base_msat: u32,
  23         pub(super) fee_proportional_millionths: u32,
  24         pub(super) htlc_maximum_msat: u64,
  25 }
  26
  27 impl Default for DefaultUpdateValues {
  28         fn default() -> Self {
  29                 Self {
  30                         cltv_expiry_delta: 0,
  31                         htlc_minimum_msat: 0,
  32                         fee_base_msat: 0,
  33                         fee_proportional_millionths: 0,
  34                         htlc_maximum_msat: 0,
  35                 }
  36         }
  37 }
  38
  39 pub(super) struct MutatedProperties {
  40         pub(super) flags: bool,
  41         pub(super) cltv_expiry_delta: bool,
  42         pub(super) htlc_minimum_msat: bool,
  43         pub(super) fee_base_msat: bool,
  44         pub(super) fee_proportional_millionths: bool,
  45         pub(super) htlc_maximum_msat: bool,
  46 }
  47
  48 impl Default for MutatedProperties {
  49         fn default() -> Self {
  50                 Self {
  51                         flags: false,
  52                         cltv_expiry_delta: false,
  53                         htlc_minimum_msat: false,
  54                         fee_base_msat: false,
  55                         fee_proportional_millionths: false,
  56                         htlc_maximum_msat: false,
  57                 }
  58         }
  59 }
  60
  61 pub(super) struct UpdateSerialization {
  62         pub(super) update: UnsignedChannelUpdate,
  63         pub(super) mechanism: UpdateSerializationMechanism,
  64 }
  65
  66 impl MutatedProperties {
  67         /// Does not include flags because the flag byte is always sent in full
  68         fn len(&self) -> u8 {
  69                 let mut mutations = 0;
  70                 if self.cltv_expiry_delta { mutations += 1; };
  71                 if self.htlc_minimum_msat { mutations += 1; };
  72                 if self.fee_base_msat { mutations += 1; };
  73                 if self.fee_proportional_millionths { mutations += 1; };
  74                 if self.htlc_maximum_msat { mutations += 1; };
  75                 mutations
  76         }
  77 }
  78
  79 pub(super) enum UpdateSerializationMechanism {
  80         Full,
  81         Incremental(MutatedProperties),
  82         Reminder,
  83 }
  84
  85 struct FullUpdateValueHistograms {
  86         cltv_expiry_delta: HashMap<u16, usize>,
  87         htlc_minimum_msat: HashMap<u64, usize>,
  88         fee_base_msat: HashMap<u32, usize>,
  89         fee_proportional_millionths: HashMap<u32, usize>,
  90         htlc_maximum_msat: HashMap<u64, usize>,
  91 }
  92
  93 pub(super) fn serialize_delta_set(delta_set: DeltaSet, last_sync_timestamp: u32) -> SerializationSet {
  94         let mut serialization_set = SerializationSet {
  95                 announcements: vec![],
  96                 updates: vec![],
  97                 full_update_defaults: Default::default(),
  98                 chain_hash: BlockHash::all_zeros(),
  99                 latest_seen: 0,
 100         };
 101
 102         let mut chain_hash_set = false;
 103
 104         let mut full_update_histograms = FullUpdateValueHistograms {
 105                 cltv_expiry_delta: Default::default(),
 106                 htlc_minimum_msat: Default::default(),
 107                 fee_base_msat: Default::default(),
 108                 fee_proportional_millionths: Default::default(),
 109                 htlc_maximum_msat: Default::default(),
 110         };
 111
 112         let mut record_full_update_in_histograms = |full_update: &UnsignedChannelUpdate| {
 113                 *full_update_histograms.cltv_expiry_delta.entry(full_update.cltv_expiry_delta).or_insert(0) += 1;
 114                 *full_update_histograms.htlc_minimum_msat.entry(full_update.htlc_minimum_msat).or_insert(0) += 1;
 115                 *full_update_histograms.fee_base_msat.entry(full_update.fee_base_msat).or_insert(0) += 1;
 116                 *full_update_histograms.fee_proportional_millionths.entry(full_update.fee_proportional_millionths).or_insert(0) += 1;
 117                 *full_update_histograms.htlc_maximum_msat.entry(full_update.htlc_maximum_msat).or_insert(0) += 1;
 118         };
 119
 120         for (_scid, channel_delta) in delta_set.into_iter() {
 121
 122                 // any announcement chain hash is gonna be the same value. Just set it from the first one.
 123                 let channel_announcement_delta = channel_delta.announcement.as_ref().unwrap();
 124                 if !chain_hash_set {
 125                         chain_hash_set = true;
 126                         serialization_set.chain_hash = channel_announcement_delta.announcement.chain_hash.clone();
 127                 }
 128
 129                 let current_announcement_seen = channel_announcement_delta.seen;
 130                 let is_new_announcement = current_announcement_seen >= last_sync_timestamp;
 131                 let is_newly_updated_announcement = if let Some(first_update_seen) = channel_delta.first_bidirectional_updates_seen {
 132                         first_update_seen >= last_sync_timestamp
 133                 } else {
 134                         false
 135                 };
 136                 let send_announcement = is_new_announcement || is_newly_updated_announcement;
 137                 if send_announcement {
 138                         serialization_set.latest_seen = max(serialization_set.latest_seen, current_announcement_seen);
 139                         serialization_set.announcements.push(channel_delta.announcement.unwrap().announcement);
 140                 }
 141
 142                 let direction_a_updates = channel_delta.updates.0;
 143                 let direction_b_updates = channel_delta.updates.1;
 144
 145                 let mut categorize_directed_update_serialization = |directed_updates: Option<DirectedUpdateDelta>| {
 146                         if let Some(updates) = directed_updates {
 147                                 if let Some(latest_update_delta) = updates.latest_update_after_seen {
 148                                         let latest_update = latest_update_delta.update;
 149
 150                                         // the returned seen timestamp should be the latest of all the returned
 151                                         // announcements and latest updates
 152                                         serialization_set.latest_seen = max(serialization_set.latest_seen, latest_update_delta.seen);
 153
 154                                         if updates.last_update_before_seen.is_some() {
 155                                                 let mutated_properties = updates.mutated_properties;
 156                                                 if mutated_properties.len() == 5 {
 157                                                         // all five values have changed, it makes more sense to just
 158                                                         // serialize the update as a full update instead of as a change
 159                                                         // this way, the default values can be computed more efficiently
 160                                                         record_full_update_in_histograms(&latest_update);
 161                                                         serialization_set.updates.push(UpdateSerialization {
 162                                                                 update: latest_update,
 163                                                                 mechanism: UpdateSerializationMechanism::Full,
 164                                                         });
 165                                                 } else if mutated_properties.len() > 0 || mutated_properties.flags {
 166                                                         // we don't count flags as mutated properties
 167                                                         serialization_set.updates.push(UpdateSerialization {
 168                                                                 update: latest_update,
 169                                                                 mechanism: UpdateSerializationMechanism::Incremental(mutated_properties),
 170                                                         });
 171                                                 }
 172                                         } else {
 173                                                 // serialize the full update
 174                                                 record_full_update_in_histograms(&latest_update);
 175                                                 serialization_set.updates.push(UpdateSerialization {
 176                                                         update: latest_update,
 177                                                         mechanism: UpdateSerializationMechanism::Full,
 178                                                 });
 179                                         }
 180                                 } else if let Some(flags) = updates.serialization_update_flags {
 181                                         // we need to insert a fake channel update where the only information
 182                                         let fake_update = UnsignedChannelUpdate {
 183                                                 flags,
 184                                                 chain_hash: BlockHash::all_zeros(),
 185                                                 short_channel_id: 0,
 186                                                 cltv_expiry_delta: 0,
 187                                                 fee_base_msat: 0,
 188                                                 fee_proportional_millionths: 0,
 189                                                 htlc_maximum_msat: 0,
 190                                                 htlc_minimum_msat: 0,
 191                                                 timestamp: 0,
 192                                                 excess_data: Vec::with_capacity(0),
 193                                         };
 194                                         serialization_set.updates.push(UpdateSerialization {
 195                                                 update: fake_update,
 196                                                 mechanism: UpdateSerializationMechanism::Reminder
 197                                         })
 198                                 }
 199                         }
 200                 };
 201
 202                 categorize_directed_update_serialization(direction_a_updates);
 203                 categorize_directed_update_serialization(direction_b_updates);
 204         }
 205
 206         let default_update_values = DefaultUpdateValues {
 207                 cltv_expiry_delta: find_most_common_histogram_entry_with_default(full_update_histograms.cltv_expiry_delta, 0),
 208                 htlc_minimum_msat: find_most_common_histogram_entry_with_default(full_update_histograms.htlc_minimum_msat, 0),
 209                 fee_base_msat: find_most_common_histogram_entry_with_default(full_update_histograms.fee_base_msat, 0),
 210                 fee_proportional_millionths: find_most_common_histogram_entry_with_default(full_update_histograms.fee_proportional_millionths, 0),
 211                 htlc_maximum_msat: find_most_common_histogram_entry_with_default(full_update_histograms.htlc_maximum_msat, 0),
 212         };
 213
 214         serialization_set.full_update_defaults = default_update_values;
 215         serialization_set
 216 }
 217
 218 pub fn serialize_stripped_channel_announcement(announcement: &UnsignedChannelAnnouncement, node_id_a_index: usize, node_id_b_index: usize, previous_scid: u64) -> Vec<u8> {
 219         let mut stripped_announcement = vec![];
 220
 221         announcement.features.write(&mut stripped_announcement).unwrap();
 222
 223         if previous_scid > announcement.short_channel_id {
 224                 panic!("unsorted scids!");
 225         }
 226         let scid_delta = BigSize(announcement.short_channel_id - previous_scid);
 227         scid_delta.write(&mut stripped_announcement).unwrap();
 228
 229         // write indices of node ids rather than the node IDs themselves
 230         BigSize(node_id_a_index as u64).write(&mut stripped_announcement).unwrap();
 231         BigSize(node_id_b_index as u64).write(&mut stripped_announcement).unwrap();
 232
 233         // println!("serialized CA: {}, \n{:?}\n{:?}\n", announcement.short_channel_id, announcement.node_id_1, announcement.node_id_2);
 234         stripped_announcement
 235 }
 236
 237 pub(super) fn serialize_stripped_channel_update(update: &UpdateSerialization, default_values: &DefaultUpdateValues, previous_scid: u64) -> Vec<u8> {
 238         let latest_update = &update.update;
 239         let mut serialized_flags = latest_update.flags;
 240
 241         if previous_scid > latest_update.short_channel_id {
 242                 panic!("unsorted scids!");
 243         }
 244
 245         let mut delta_serialization = Vec::new();
 246         let mut prefixed_serialization = Vec::new();
 247
 248         match &update.mechanism {
 249                 UpdateSerializationMechanism::Full => {
 250                         if latest_update.cltv_expiry_delta != default_values.cltv_expiry_delta {
 251                                 serialized_flags |= 0b_0100_0000;
 252                                 latest_update.cltv_expiry_delta.write(&mut delta_serialization).unwrap();
 253                         }
 254
 255                         if latest_update.htlc_minimum_msat != default_values.htlc_minimum_msat {
 256                                 serialized_flags |= 0b_0010_0000;
 257                                 latest_update.htlc_minimum_msat.write(&mut delta_serialization).unwrap();
 258                         }
 259
 260                         if latest_update.fee_base_msat != default_values.fee_base_msat {
 261                                 serialized_flags |= 0b_0001_0000;
 262                                 latest_update.fee_base_msat.write(&mut delta_serialization).unwrap();
 263                         }
 264
 265                         if latest_update.fee_proportional_millionths != default_values.fee_proportional_millionths {
 266                                 serialized_flags |= 0b_0000_1000;
 267                                 latest_update.fee_proportional_millionths.write(&mut delta_serialization).unwrap();
 268                         }
 269
 270                         if latest_update.htlc_maximum_msat != default_values.htlc_maximum_msat {
 271                                 serialized_flags |= 0b_0000_0100;
 272                                 latest_update.htlc_maximum_msat.write(&mut delta_serialization).unwrap();
 273                         }
 274                 }
 275
 276                 UpdateSerializationMechanism::Incremental(mutated_properties) => {
 277                         // indicate that this update is incremental
 278                         serialized_flags |= 0b_1000_0000;
 279
 280                         if mutated_properties.cltv_expiry_delta {
 281                                 serialized_flags |= 0b_0100_0000;
 282                                 latest_update.cltv_expiry_delta.write(&mut delta_serialization).unwrap();
 283                         }
 284
 285                         if mutated_properties.htlc_minimum_msat {
 286                                 serialized_flags |= 0b_0010_0000;
 287                                 latest_update.htlc_minimum_msat.write(&mut delta_serialization).unwrap();
 288                         }
 289
 290                         if mutated_properties.fee_base_msat {
 291                                 serialized_flags |= 0b_0001_0000;
 292                                 latest_update.fee_base_msat.write(&mut delta_serialization).unwrap();
 293                         }
 294
 295                         if mutated_properties.fee_proportional_millionths {
 296                                 serialized_flags |= 0b_0000_1000;
 297                                 latest_update.fee_proportional_millionths.write(&mut delta_serialization).unwrap();
 298                         }
 299
 300                         if mutated_properties.htlc_maximum_msat {
 301                                 serialized_flags |= 0b_0000_0100;
 302                                 latest_update.htlc_maximum_msat.write(&mut delta_serialization).unwrap();
 303                         }
 304                 },
 305
 306                 UpdateSerializationMechanism::Reminder => {
 307                         // indicate that this update is incremental
 308                         serialized_flags |= 0b_1000_0000;
 309                 }
 310         }
 311         let scid_delta = BigSize(latest_update.short_channel_id - previous_scid);
 312         scid_delta.write(&mut prefixed_serialization).unwrap();
 313
 314         serialized_flags.write(&mut prefixed_serialization).unwrap();
 315         prefixed_serialization.append(&mut delta_serialization);
 316
 317         prefixed_serialization
 318 }
 319
 320 pub(super) fn find_most_common_histogram_entry_with_default<T: Copy>(histogram: HashMap<T, usize>, default: T) -> T {
 321         let most_frequent_entry = histogram.iter().max_by(|a, b| a.1.cmp(&b.1));
 322         if let Some(entry_details) = most_frequent_entry {
 323                 // .0 is the value
 324                 // .1 is the frequency
 325                 return entry_details.0.to_owned();
 326         }
 327         // the default should pretty much always be a 0 as T
 328         // though for htlc maximum msat it could be a u64::max
 329         default
 330 }