@ndn/lp/lib/packet_node.js

NDNts: NDN Link Protocol

import { NackHeader } from "@ndn/packet";
import { Encoder, EvDecoder, NNI } from "@ndn/tlv";
import { assert } from "@ndn/util";
import { TT } from "./an_node.js";
function isCritical(tt) {
    return !(tt >= 800 && tt <= 959 && tt % 4 === 0);
}
const EVD = new EvDecoder("LpPacket", TT.LpPacket)
    .add(TT.LpSeqNum, (t, { nniBig }) => t.fragSeqNum = nniBig)
    .add(TT.FragIndex, (t, { nni }) => t.fragIndex = nni)
    .add(TT.FragCount, (t, { nni }) => t.fragCount = nni)
    .add(TT.PitToken, (t, { value }) => t.pitToken = value)
    .add(TT.Nack, (t, { decoder }) => t.nack = decoder.decode(NackHeader))
    .add(TT.CongestionMark, (t, { nni }) => t.congestionMark = nni)
    .add(TT.LpPayload, (t, { value }) => t.payload = value)
    .setIsCritical(isCritical);
/** NDNLPv2 packet. */
export class LpPacket {
    static decodeFrom(decoder) {
        return EVD.decode(new LpPacket(), decoder);
    }
    fragSeqNum;
    fragIndex = 0;
    fragCount = 1;
    /**
     * L3 payload.
     *
     * @remarks
     * This field may contain either a whole L3 packet or fragment of one.
     * This is also known as *fragment* in other libraries.
     */
    payload;
    /**
     * Extract L3 fields only.
     *
     * @remarks
     * They may be copied to another LpPacket via `Object.assign()`.
     */
    get l3() {
        const t = {};
        for (const k of ["pitToken", "nack", "congestionMark"]) {
            t[k] = this[k];
        }
        return t;
    }
    /**
     * Prepend LpPacket to encoder.
     *
     * @throws Error
     * Thrown if fragmentation headers violate invariants:
     * - `.fragIndex >= .fragCount`
     * - `.fragSeqNum` is unset but `.fragCount > 1`
     */
    encodeTo(encoder) {
        encoder.prependTlv(TT.LpPacket, ...this.encodeFragHeaders(), ...this.encodeL3Headers(), [TT.LpPayload, Encoder.OmitEmpty, this.payload]);
    }
    encodeFragHeaders() {
        assert(this.fragIndex < this.fragCount);
        if (this.fragSeqNum === undefined) {
            assert(this.fragCount === 1);
            return [];
        }
        return [
            [TT.LpSeqNum, NNI(this.fragSeqNum, { len: 8 })],
            this.fragIndex > 0 && [TT.FragIndex, NNI(this.fragIndex)],
            this.fragCount > 1 && [TT.FragCount, NNI(this.fragCount)],
        ];
    }
    /**
     * Determine whether any L3 header is present.
     * @see {@link LpL3}
     */
    hasL3Headers() {
        const { congestionMark = 0 } = this;
        return !!this.pitToken || !!this.nack || congestionMark > 0;
    }
    /**
     * Encode L3 headers.
     * @see {@link LpL3}
     */
    encodeL3Headers() {
        const { congestionMark = 0 } = this;
        return [
            [TT.PitToken, Encoder.OmitEmpty, this.pitToken],
            this.nack,
            congestionMark > 0 && [TT.CongestionMark, NNI(congestionMark)],
        ];
    }
}