ethernet/dist/ethernet.js

Decodes Ethernet headers

"use strict";
// Reference: https://en.wikipedia.org/wiki/IEEE_802.1Q
const TPID_8021Q = 0x8100;
const TPID_8021ad = 0x88a8;
const TPID_QinQ = 0x9100;
const decodeTCI = (tci) => {
    return {
        pcp: (tci >> 13) & 0x7,
        dei: (tci >> 11) & 0x1,
        vid: tci & 0xfff,
    };
};
const decodeTag = (data) => {
    return {
        tpid: parseInt(data.substr(0, 4), 16),
        tci: decodeTCI(parseInt(data.substr(4, 4), 16)),
    };
};
const decode = (data) => {
    if (data.length < 14 * 2) {
        throw new Error("Frame header must be at least 14 bytes");
    }
    let result = {
        destination: data.substr(0, 12),
        source: data.substr(12, 12),
        ethertype: parseInt(data.substr(24, 4), 16),
        payload: data.substring(28),
    };
    if (result.ethertype === TPID_8021Q) {
        result.tag = decodeTag(data.substr(24, 8));
        result.ethertype = parseInt(data.substr(32, 4), 16);
        result.payload = data.substring(36);
    }
    else if (result.ethertype === TPID_8021ad || result.ethertype === TPID_QinQ) {
        result.stag = decodeTag(data.substr(24, 8));
        result.ctag = decodeTag(data.substr(32, 8));
        result.ethertype = parseInt(data.substr(40, 4), 16);
        result.payload = data.substring(44);
    }
    return result;
};
/**
 * Decode an Ethernet frame
 * @param {string | Buffer} frame The raw frame data as a hex string or Node.js Buffer
 * @returns {EthernetHeader}
 */
const ethernet = (frame) => {
    if (typeof frame === "string") {
        if (!/^([A-Fa-f0-9]{2})+$/.test(frame)) {
            throw new TypeError("Frame must be hex string or Buffer");
        }
        return decode(frame);
    }
    else if (typeof Buffer !== undefined && Buffer.isBuffer(frame)) {
        return decode(frame.toString("hex"));
    }
    else {
        throw new TypeError("Frame must be hex string or Buffer");
    }
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.default = ethernet;
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