dns-packet-typescript
Version:
An abstract-encoding compliant module for encoding / decoding DNS packets
60 lines • 2.27 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.encodingLength = exports.decode = exports.encode = void 0;
var opcodes = require("./opcodes");
var rcodes = require("./rcodes");
var QUERY_FLAG = 0;
var RESPONSE_FLAG = 1 << 15;
function encode(h, buf, offset) {
var _a, _b;
if (offset === void 0) { offset = 0; }
if (!buf)
buf = Buffer.allocUnsafe(encodingLength());
if (!offset)
offset = 0;
var flags = ((_a = h.flags) !== null && _a !== void 0 ? _a : 0) & 32767;
var type = h.type === 'response' ? RESPONSE_FLAG : QUERY_FLAG;
buf.writeUInt16BE((_b = h.id) !== null && _b !== void 0 ? _b : 0, offset);
buf.writeUInt16BE(flags | type, offset + 2);
buf.writeUInt16BE(h.questions.length, offset + 4);
buf.writeUInt16BE(h.answers.length, offset + 6);
buf.writeUInt16BE(h.authorities.length, offset + 8);
buf.writeUInt16BE(h.additionals.length, offset + 10);
return buf;
}
exports.encode = encode;
encode.bytes = 12;
function decode(buf, offset) {
if (offset === void 0) { offset = 0; }
if (!offset)
offset = 0;
if (buf.length < 12)
throw new Error('Header must be 12 bytes');
var flags = buf.readUInt16BE(offset + 2);
return {
id: buf.readUInt16BE(offset),
type: flags & RESPONSE_FLAG ? 'response' : 'query',
flags: flags & 32767,
flag_qr: ((flags >> 15) & 0x1) === 1,
opcode: opcodes.toString((flags >> 11) & 0xf),
flag_aa: ((flags >> 10) & 0x1) === 1,
flag_tc: ((flags >> 9) & 0x1) === 1,
flag_rd: ((flags >> 8) & 0x1) === 1,
flag_ra: ((flags >> 7) & 0x1) === 1,
flag_z: ((flags >> 6) & 0x1) === 1,
flag_ad: ((flags >> 5) & 0x1) === 1,
flag_cd: ((flags >> 4) & 0x1) === 1,
rcode: rcodes.toString(flags & 0xf),
questions: new Array(buf.readUInt16BE(offset + 4)),
answers: new Array(buf.readUInt16BE(offset + 6)),
authorities: new Array(buf.readUInt16BE(offset + 8)),
additionals: new Array(buf.readUInt16BE(offset + 10))
};
}
exports.decode = decode;
decode.bytes = 12;
function encodingLength() {
return 12;
}
exports.encodingLength = encodingLength;
//# sourceMappingURL=header.js.map