mmdb-lib/lib/metadata.js

Maxmind DB (MMDB) Library

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.isLegacyFormat = exports.parseMetadata = void 0;
const decoder_1 = __importDefault(require("./decoder"));
const utils_1 = __importDefault(require("./utils"));
const METADATA_START_MARKER = Buffer.from('ABCDEF4D61784D696E642E636F6D', 'hex');
const parseMetadata = (db) => {
    const offset = findStart(db);
    const decoder = new decoder_1.default(db, offset);
    const metadata = decoder.decode(offset).value;
    if (!metadata) {
        throw new Error((0, exports.isLegacyFormat)(db)
            ? utils_1.default.legacyErrorMessage
            : 'Cannot parse binary database');
    }
    utils_1.default.assert([24, 28, 32].indexOf(metadata.record_size) > -1, 'Unsupported record size');
    return {
        binaryFormatMajorVersion: metadata.binary_format_major_version,
        binaryFormatMinorVersion: metadata.binary_format_minor_version,
        buildEpoch: new Date(Number(metadata.build_epoch) * 1000),
        databaseType: metadata.database_type,
        description: metadata.description,
        ipVersion: metadata.ip_version,
        languages: metadata.languages,
        nodeByteSize: metadata.record_size / 4,
        nodeCount: metadata.node_count,
        recordSize: metadata.record_size,
        searchTreeSize: (metadata.node_count * metadata.record_size) / 4,
        // Depth depends on the IP version, it's 32 for IPv4 and 128 for IPv6.
        treeDepth: Math.pow(2, metadata.ip_version + 1),
    };
};
exports.parseMetadata = parseMetadata;
const findStart = (db) => {
    let found = 0;
    let fsize = db.length - 1;
    const mlen = METADATA_START_MARKER.length - 1;
    while (found <= mlen && fsize-- > 0) {
        found += db[fsize] === METADATA_START_MARKER[mlen - found] ? 1 : -found;
    }
    return fsize + found;
};
const isLegacyFormat = (db) => {
    const structureInfoMaxSize = 20;
    for (let i = 0; i < structureInfoMaxSize; i++) {
        const delim = db.slice(db.length - 3 - i, db.length - i);
        // Look for [0xff, 0xff, 0xff] metadata delimiter
        if (delim[0] === 255 && delim[1] === 255 && delim[2] === 255) {
            return true;
        }
    }
    return false;
};
exports.isLegacyFormat = isLegacyFormat;