@node-dlc/wire/lib/messages/QueryShortChannelIdsMessage.ts

Lightning Network Wire Protocol

import { BufferReader, BufferWriter } from '@node-dlc/bufio';
import { BitField } from '@node-dlc/common';
import { ShortChannelId } from '@node-dlc/common';
import { shortChannelIdFromBuffer } from '@node-dlc/common';

import { QueryScidFlags } from '../flags/QueryScidFlags';
import { MessageType } from '../MessageType';
import { Encoder } from '../serialize/Encoder';
import { EncodingType } from '../serialize/EncodingType';
import { readTlvs } from '../serialize/readTlvs';
import { IWireMessage } from './IWireMessage';

export class QueryShortChannelIdsMessage implements IWireMessage {
  public static deserialize(payload: Buffer): QueryShortChannelIdsMessage {
    const instance = new QueryShortChannelIdsMessage();
    const reader = new BufferReader(payload);

    reader.readUInt16BE(); // read off type
    instance.chainHash = reader.readBytes(32); // chain_hash

    // process the encoded short channel ids by reading the length of
    // encoded data, then using the decoder to get the raw buffer after
    // using the appropriate decoding scheme
    const encodedScidLen = reader.readUInt16BE();
    const encodedScidBuffer = reader.readBytes(encodedScidLen);
    const scidBuffer = new Encoder().decode(encodedScidBuffer);

    // After we have a raw buffer of scid values (each 8 bytes) we can read
    // the data from the buffer
    const scidReader = new BufferReader(scidBuffer);
    while (!scidReader.eof) {
      const scid = shortChannelIdFromBuffer(scidReader.readBytes(8));
      instance.shortChannelIds.push(scid);
    }

    // Process all TLVs available on the reader
    readTlvs(reader, (type: bigint, valueReader: BufferReader) => {
      switch (type) {
        case BigInt(1): {
          const bytes = valueReader.readBytes();
          const flagBytes = new Encoder().decode(bytes);
          const flagReader = new BufferReader(flagBytes);
          while (!flagReader.eof) {
            const rawFlags = flagReader.readBigSize();
            const flags = new BitField<QueryScidFlags>(rawFlags);
            instance.flags.push(flags);
          }
          return true;
        }
        default:
          return false;
      }
    });

    return instance;
  }

  /**
   * Type 261
   */
  public type: MessageType = MessageType.QueryShortChannelIds;

  /**
   * 32-byte chain hash
   */
  public chainHash: Buffer;

  /**
   * List of channels to query
   */
  public shortChannelIds: ShortChannelId[] = [];

  /**
   * Optional flags that can be set when gossip_queries_ex is enabled.
   */
  public flags: Array<BitField<QueryScidFlags>> = [];

  public serialize(encoding: EncodingType = EncodingType.ZlibDeflate): Buffer {
    const rawIdsBuffer = Buffer.concat(
      this.shortChannelIds.map((p) => p.toBuffer()),
    );
    const esids = new Encoder().encode(encoding, rawIdsBuffer);

    const writer = new BufferWriter();
    writer.writeUInt16BE(this.type);
    writer.writeBytes(this.chainHash);
    writer.writeUInt16BE(esids.length);
    writer.writeBytes(esids);

    // encode TLV 1
    if (this.flags.length) {
      // combine all BitFields into buffers
      const flagBufs: Buffer[] = [];
      for (const flag of this.flags) {
        flagBufs.push(flag.toBuffer());
      }
      const flagBytes = Buffer.concat(flagBufs);

      // encode the flag bytes according to the encoding strategy
      const encodedFlagBytes = new Encoder().encode(encoding, flagBytes);

      // write TLV data
      writer.writeBigSize(1);
      writer.writeBigSize(encodedFlagBytes.length);
      writer.writeBytes(encodedFlagBytes);
    }

    return writer.toBuffer();
  }
}