@node-lightning/wire/lib/messages/NodeAnnouncementMessage.ts

Lightning Network Wire Protocol

import { BufferReader, BufferWriter } from "@node-lightning/bufio";
import { BitField } from "@node-lightning/core";
import * as crypto from "@node-lightning/crypto";
import { deserializeAddress } from "../deserialize/address/deserializeAddress";
import { Address } from "../domain/Address";
import { NodeFeatureFlags } from "../flags/NodeFeatureFlags";
import { MessageType } from "../MessageType";
import { serializeAddress } from "../serialize/address/serializeAddress";
import { IWireMessage } from "./IWireMessage";

/**
 * This gossip message allows a node to indicate extra data associated with it,
 * in addition to its public key. To avoid trivial denial of service attacks,
 * nodes not associated with an already known channel are ignored.
 */
export class NodeAnnouncementMessage implements IWireMessage {
    public static deserialize(payload: Buffer) {
        const instance = new NodeAnnouncementMessage();
        const reader = new BufferReader(payload);
        reader.readUInt16BE(); // read off type

        instance.signature = reader.readBytes(64);

        const flen = reader.readUInt16BE();
        instance.features = BitField.fromBuffer(reader.readBytes(flen));

        instance.timestamp = reader.readUInt32BE();
        instance.nodeId = reader.readBytes(33);
        instance.rgbColor = reader.readBytes(3);
        instance.alias = reader.readBytes(32);
        instance.addresses = [];

        const addrlen = reader.readUInt16BE(); // number of bytes
        const startPos = reader.position;
        while (reader.position < startPos + addrlen) {
            const type = reader.readUInt8();
            const address = deserializeAddress(type, reader);
            instance.addresses.push(address);
        }

        return instance;
    }

    /**
     * Message hashing is after the first 66 bytes of the message
     * and excludes the type and signature. It performs a double
     * sha-256 hash of the remaining bytes.
     */
    public static hash(msg: NodeAnnouncementMessage): Buffer {
        const bytes = msg.serialize().slice(66); // type + signature
        return crypto.hash256(bytes);
    }

    /**
     * Verifies the message signature
     */
    public static verifySignatures(msg: NodeAnnouncementMessage): boolean {
        const hash = NodeAnnouncementMessage.hash(msg);
        return crypto.verifySig(hash, msg.signature, msg.nodeId);
    }

    /**
     * Type 257
     */
    public type: MessageType = MessageType.NodeAnnouncement;

    /**
     * Signature of the announcement message by the node's public key
     * returned as a 64-byte Buffer.
     */
    public signature: Buffer;

    public features: BitField<NodeFeatureFlags>;

    public timestamp: number;

    /**
     * Compressed public key of the node that is a 33-byte
     * buffer.
     */
    public nodeId: Buffer;

    /**
     * Color of the node returned as a 3-byte Buffer.
     */
    public rgbColor: Buffer;

    /**
     * Alias of the node returned as a 32-byte Buffer.
     */
    public alias: Buffer;

    /**
     * Addresses that the node allow public network connections
     * on. The type indicates how the address is encoded. Addresses
     * are in order of connectivity preference. Currently
     * supported addresses formats are IPv4, IPv6, Tor2 and Tor3
     */
    public addresses: Address[] = [];

    public serialize() {
        const featuresBuffer = this.features.toBuffer();
        const featuresLen = featuresBuffer.length;

        // serialize addresses into buffers so we can obtain the length
        const addressBuffers = [];
        for (const address of this.addresses) {
            addressBuffers.push(serializeAddress(address));
        }

        // obtain total address length
        // eslint-disable-next-line
        const addressBytes: number = addressBuffers.map(b => b.length).reduce((sum, val) => sum + val, 0); // prettier-ignore

        const len =
            2 + // type
            64 + // signature
            2 + // flen
            featuresLen + // features length
            4 + // timestamp
            33 + // node_id
            3 + // rgb_color
            32 + // alias
            2 + // addresses
            addressBytes; // cumulative addr bytes
        const writer = new BufferWriter(Buffer.alloc(len));

        writer.writeUInt16BE(this.type);
        writer.writeBytes(this.signature);
        writer.writeUInt16BE(featuresLen);
        if (featuresLen > 0) writer.writeBytes(featuresBuffer);
        writer.writeUInt32BE(this.timestamp);
        writer.writeBytes(this.nodeId);
        writer.writeBytes(this.rgbColor);
        writer.writeBytes(this.alias);
        writer.writeUInt16BE(addressBytes);
        for (const addressBuffer of addressBuffers) {
            writer.writeBytes(addressBuffer);
        }

        return writer.toBuffer();
    }
}