_ 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 }
  83
  84 struct FullUpdateValueHistograms {
  85         cltv_expiry_delta: HashMap<u16, usize>,
  86         htlc_minimum_msat: HashMap<u64, usize>,
  87         fee_base_msat: HashMap<u32, usize>,
  88         fee_proportional_millionths: HashMap<u32, usize>,
  89         htlc_maximum_msat: HashMap<u64, usize>,
  90 }
  91
  92 pub(super) fn serialize_delta_set(delta_set: DeltaSet, last_sync_timestamp: u32) -> SerializationSet {
  93         let mut serialization_set = SerializationSet {
  94                 announcements: vec![],
  95                 updates: vec![],
  96                 full_update_defaults: Default::default(),
  97                 chain_hash: BlockHash::all_zeros(),
  98                 latest_seen: 0,
  99         };
 100
 101         let mut chain_hash_set = false;
 102
 103         let mut full_update_histograms = FullUpdateValueHistograms {
 104                 cltv_expiry_delta: Default::default(),
 105                 htlc_minimum_msat: Default::default(),
 106                 fee_base_msat: Default::default(),
 107                 fee_proportional_millionths: Default::default(),
 108                 htlc_maximum_msat: Default::default(),
 109         };
 110
 111         let mut record_full_update_in_histograms = |full_update: &UnsignedChannelUpdate| {
 112                 *full_update_histograms.cltv_expiry_delta.entry(full_update.cltv_expiry_delta).or_insert(0) += 1;
 113                 *full_update_histograms.htlc_minimum_msat.entry(full_update.htlc_minimum_msat).or_insert(0) += 1;
 114                 *full_update_histograms.fee_base_msat.entry(full_update.fee_base_msat).or_insert(0) += 1;
 115                 *full_update_histograms.fee_proportional_millionths.entry(full_update.fee_proportional_millionths).or_insert(0) += 1;
 116                 *full_update_histograms.htlc_maximum_msat.entry(full_update.htlc_maximum_msat).or_insert(0) += 1;
 117         };
 118
 119         for (_scid, channel_delta) in delta_set.into_iter() {
 120
 121                 // any announcement chain hash is gonna be the same value. Just set it from the first one.
 122                 let channel_announcement_delta = channel_delta.announcement.as_ref().unwrap();
 123                 if !chain_hash_set {
 124                         chain_hash_set = true;
 125                         serialization_set.chain_hash = channel_announcement_delta.announcement.chain_hash.clone();
 126                 }
 127
 128                 let current_announcement_seen = channel_announcement_delta.seen;
 129                 let is_new_announcement = current_announcement_seen >= last_sync_timestamp;
 130                 let is_newly_updated_announcement = if let Some(first_update_seen) = channel_delta.first_update_seen {
 131                         first_update_seen >= last_sync_timestamp
 132                 } else {
 133                         false
 134                 };
 135                 let send_announcement = is_new_announcement || is_newly_updated_announcement;
 136                 if send_announcement {
 137                         serialization_set.latest_seen = max(serialization_set.latest_seen, current_announcement_seen);
 138                         serialization_set.announcements.push(channel_delta.announcement.unwrap().announcement);
 139                 }
 140
 141                 let direction_a_updates = channel_delta.updates.0;
 142                 let direction_b_updates = channel_delta.updates.1;
 143
 144                 let mut categorize_directed_update_serialization = |directed_updates: Option<DirectedUpdateDelta>| {
 145                         if let Some(updates) = directed_updates {
 146                                 if let Some(latest_update_delta) = updates.latest_update_after_seen {
 147                                         let latest_update = latest_update_delta.update;
 148
 149                                         // the returned seen timestamp should be the latest of all the returned
 150                                         // announcements and latest updates
 151                                         serialization_set.latest_seen = max(serialization_set.latest_seen, latest_update_delta.seen);
 152
 153                                         if updates.last_update_before_seen.is_some() {
 154                                                 let mutated_properties = updates.mutated_properties;
 155                                                 if mutated_properties.len() == 5 {
 156                                                         // all five values have changed, it makes more sense to just
 157                                                         // serialize the update as a full update instead of as a change
 158                                                         // this way, the default values can be computed more efficiently
 159                                                         record_full_update_in_histograms(&latest_update);
 160                                                         serialization_set.updates.push(UpdateSerialization {
 161                                                                 update: latest_update,
 162                                                                 mechanism: UpdateSerializationMechanism::Full,
 163                                                         });
 164                                                 } else if mutated_properties.len() > 0 || mutated_properties.flags {
 165                                                         // we don't count flags as mutated properties
 166                                                         serialization_set.updates.push(UpdateSerialization {
 167                                                                 update: latest_update,
 168                                                                 mechanism: UpdateSerializationMechanism::Incremental(mutated_properties),
 169                                                         });
 170                                                 }
 171                                         } else {
 172                                                 // serialize the full update
 173                                                 record_full_update_in_histograms(&latest_update);
 174                                                 serialization_set.updates.push(UpdateSerialization {
 175                                                         update: latest_update,
 176                                                         mechanism: UpdateSerializationMechanism::Full,
 177                                                 });
 178                                         }
 179                                 }
 180                         };
 181                 };
 182
 183                 categorize_directed_update_serialization(direction_a_updates);
 184                 categorize_directed_update_serialization(direction_b_updates);
 185         }
 186
 187         let default_update_values = DefaultUpdateValues {
 188                 cltv_expiry_delta: find_most_common_histogram_entry_with_default(full_update_histograms.cltv_expiry_delta, 0),
 189                 htlc_minimum_msat: find_most_common_histogram_entry_with_default(full_update_histograms.htlc_minimum_msat, 0),
 190                 fee_base_msat: find_most_common_histogram_entry_with_default(full_update_histograms.fee_base_msat, 0),
 191                 fee_proportional_millionths: find_most_common_histogram_entry_with_default(full_update_histograms.fee_proportional_millionths, 0),
 192                 htlc_maximum_msat: find_most_common_histogram_entry_with_default(full_update_histograms.htlc_maximum_msat, 0),
 193         };
 194
 195         serialization_set.full_update_defaults = default_update_values;
 196         serialization_set
 197 }
 198
 199 pub fn serialize_stripped_channel_announcement(announcement: &UnsignedChannelAnnouncement, node_id_a_index: usize, node_id_b_index: usize, previous_scid: u64) -> Vec<u8> {
 200         let mut stripped_announcement = vec![];
 201
 202         announcement.features.write(&mut stripped_announcement).unwrap();
 203
 204         if previous_scid > announcement.short_channel_id {
 205                 panic!("unsorted scids!");
 206         }
 207         let scid_delta = BigSize(announcement.short_channel_id - previous_scid);
 208         scid_delta.write(&mut stripped_announcement).unwrap();
 209
 210         // write indices of node ids rather than the node IDs themselves
 211         BigSize(node_id_a_index as u64).write(&mut stripped_announcement).unwrap();
 212         BigSize(node_id_b_index as u64).write(&mut stripped_announcement).unwrap();
 213
 214         // println!("serialized CA: {}, \n{:?}\n{:?}\n", announcement.short_channel_id, announcement.node_id_1, announcement.node_id_2);
 215         stripped_announcement
 216 }
 217
 218 pub(super) fn serialize_stripped_channel_update(update: &UpdateSerialization, default_values: &DefaultUpdateValues, previous_scid: u64) -> Vec<u8> {
 219         let latest_update = &update.update;
 220         let mut serialized_flags = latest_update.flags;
 221
 222         if previous_scid > latest_update.short_channel_id {
 223                 panic!("unsorted scids!");
 224         }
 225
 226         let mut delta_serialization = Vec::new();
 227         let mut prefixed_serialization = Vec::new();
 228
 229         match &update.mechanism {
 230                 UpdateSerializationMechanism::Full => {
 231                         if latest_update.cltv_expiry_delta != default_values.cltv_expiry_delta {
 232                                 serialized_flags |= 0b_0100_0000;
 233                                 latest_update.cltv_expiry_delta.write(&mut delta_serialization).unwrap();
 234                         }
 235
 236                         if latest_update.htlc_minimum_msat != default_values.htlc_minimum_msat {
 237                                 serialized_flags |= 0b_0010_0000;
 238                                 latest_update.htlc_minimum_msat.write(&mut delta_serialization).unwrap();
 239                         }
 240
 241                         if latest_update.fee_base_msat != default_values.fee_base_msat {
 242                                 serialized_flags |= 0b_0001_0000;
 243                                 latest_update.fee_base_msat.write(&mut delta_serialization).unwrap();
 244                         }
 245
 246                         if latest_update.fee_proportional_millionths != default_values.fee_proportional_millionths {
 247                                 serialized_flags |= 0b_0000_1000;
 248                                 latest_update.fee_proportional_millionths.write(&mut delta_serialization).unwrap();
 249                         }
 250
 251                         if latest_update.htlc_maximum_msat != default_values.htlc_maximum_msat {
 252                                 serialized_flags |= 0b_0000_0100;
 253                                 latest_update.htlc_maximum_msat.write(&mut delta_serialization).unwrap();
 254                         }
 255                 }
 256
 257                 UpdateSerializationMechanism::Incremental(mutated_properties) => {
 258                         // indicate that this update is incremental
 259                         serialized_flags |= 0b_1000_0000;
 260
 261                         if mutated_properties.cltv_expiry_delta {
 262                                 serialized_flags |= 0b_0100_0000;
 263                                 latest_update.cltv_expiry_delta.write(&mut delta_serialization).unwrap();
 264                         }
 265
 266                         if mutated_properties.htlc_minimum_msat {
 267                                 serialized_flags |= 0b_0010_0000;
 268                                 latest_update.htlc_minimum_msat.write(&mut delta_serialization).unwrap();
 269                         }
 270
 271                         if mutated_properties.fee_base_msat {
 272                                 serialized_flags |= 0b_0001_0000;
 273                                 latest_update.fee_base_msat.write(&mut delta_serialization).unwrap();
 274                         }
 275
 276                         if mutated_properties.fee_proportional_millionths {
 277                                 serialized_flags |= 0b_0000_1000;
 278                                 latest_update.fee_proportional_millionths.write(&mut delta_serialization).unwrap();
 279                         }
 280
 281                         if mutated_properties.htlc_maximum_msat {
 282                                 serialized_flags |= 0b_0000_0100;
 283                                 latest_update.htlc_maximum_msat.write(&mut delta_serialization).unwrap();
 284                         }
 285                 }
 286         }
 287         let scid_delta = BigSize(latest_update.short_channel_id - previous_scid);
 288         scid_delta.write(&mut prefixed_serialization).unwrap();
 289
 290         serialized_flags.write(&mut prefixed_serialization).unwrap();
 291         prefixed_serialization.append(&mut delta_serialization);
 292
 293         prefixed_serialization
 294 }
 295
 296 pub(super) fn find_most_common_histogram_entry_with_default<T: Copy>(histogram: HashMap<T, usize>, default: T) -> T {
 297         let most_frequent_entry = histogram.iter().max_by(|a, b| a.1.cmp(&b.1));
 298         if let Some(entry_details) = most_frequent_entry {
 299                 // .0 is the value
 300                 // .1 is the frequency
 301                 return entry_details.0.to_owned();
 302         }
 303         // the default should pretty much always be a 0 as T
 304         // though for htlc maximum msat it could be a u64::max
 305         default
 306 }