zigbee-OTA/lib/ota.js

const assert = require('assert');
const upgradeFileIdentifier = Buffer.from([0x1E, 0xF1, 0xEE, 0x0B]);

function parseSubElement(buffer, position) {
    const tagID = buffer.readUInt16LE(position);
    const length = buffer.readUInt32LE(position + 2);
    const data = buffer.slice(position + 6, position + 6 + length);
    return {tagID, length, data};
}

function parseImage(buffer) {
    const header = {
        otaUpgradeFileIdentifier: buffer.subarray(0, 4),
        otaHeaderVersion: buffer.readUInt16LE(4),
        otaHeaderLength: buffer.readUInt16LE(6),
        otaHeaderFieldControl: buffer.readUInt16LE(8),
        manufacturerCode: buffer.readUInt16LE(10),
        imageType: buffer.readUInt16LE(12),
        fileVersion: buffer.readUInt32LE(14),
        zigbeeStackVersion: buffer.readUInt16LE(18),
        otaHeaderString: buffer.toString('utf8', 20, 52),
        totalImageSize: buffer.readUInt32LE(52),
    };
    let headerPos = 56;
    if (header.otaHeaderFieldControl & 1) {
        header.securityCredentialVersion = buffer.readUInt8(headerPos);
        headerPos += 1;
    }
    if (header.otaHeaderFieldControl & 2) {
        header.upgradeFileDestination = buffer.subarray(headerPos, headerPos + 8);
        headerPos += 8;
    }
    if (header.otaHeaderFieldControl & 4) {
        header.minimumHardwareVersion = buffer.readUInt16LE(headerPos);
        headerPos += 2;
        header.maximumHardwareVersion = buffer.readUInt16LE(headerPos);
        headerPos += 2;
    }

    const raw = buffer.slice(0, header.totalImageSize);

    assert(Buffer.compare(header.otaUpgradeFileIdentifier, upgradeFileIdentifier) === 0, 'Not an OTA file');

    let position = header.otaHeaderLength;
    const elements = [];
    while (position < header.totalImageSize) {
        const element = parseSubElement(buffer, position);
        elements.push(element);
        position += element.data.length + 6;
    }

    assert(position === header.totalImageSize, 'Size mismatch');
    return {header, elements, raw};
}

module.exports = {
    parseImage
};