// Parse resource record:
// - variable length name
// - 16-bit RR type
// - 16-bit RR class
// - 32-bit TTL
// - 16-bit resource data length in bytes
// - variable length resource data
function unpackResourceRecord(buf, offset) {
var bytes = 0;
// - variable length name
var nbname = NBName.fromBuffer(buf, offset + bytes);
if (nbname.error) {
return {error: nbname.error};
}
bytes += nbname.bytesRead;
var record = {};
record.nbname = nbname;
// - 16-bit RR type
var t = buf.readUInt16BE(offset + bytes);
bytes += 2;
record.type = con.RR_TYPE_TO_STRING[t];
if (record.type === undefined) {
return {
error: new Error('Illegal resource record type [' + t + '] for name [' +
nbname + ']')
};
}
var rdataParser = RR_TYPE_TO_PARSER[record.type];
// - 16-bit RR class
var clazz = buf.readUInt16BE(offset + bytes);
bytes += 2;
if (clazz !== con.CLASS_IN) {
return {
error: new Error('Unexpected resource record class [' + clazz +
'] for name [' + record.nbname + ']; expected class [' +
con.CLASS_IN + '].')
};
}
// - 32-bit TTL
record.ttl = buf.readUInt32BE(offset + bytes);
bytes += 4;
// - 16-bit resource data length in bytes
var dataLen = buf.readUInt16BE(offset + bytes);
bytes += 2;
// - variable length resource data
var res = rdataParser(buf, offset + bytes, dataLen, record);
if (res.error) {
return {error: res.error};
}
bytes += res.bytesRead;
return {bytesRead: bytes, record: record};
}
// Parse question section
// - variable length compressed question name
// - 16-bit question type
// - 16-bit question class
function unpackQuestion(buf, offset) {
var bytes = 0;
var question = {};
// - variable length compressed question name
var nbname = NBName.fromBuffer(buf, offset + bytes);
if (nbname.error) {
return {error: nbname.error};
}
question.nbname = nbname;
bytes += nbname.bytesRead;
// Ensure we have enough space left before proceeding to avoid throwing
if (offset + bytes + 4 > buf.length) {
return {
error: new Error('Question section is too large to fit in remaining ' +
'packet bytes.')
};
}
// - 16-bit question type
var t = buf.readUInt16BE(offset + bytes);
bytes += 2;
question.type = con.QUESTION_TYPE_TO_STRING[t];
if (question.type === undefined) {
return {
error: new Error('Unexpected question type [' + t + '] for name [' +
question.nbname + ']; should be either [nb] or ' +
'[nbstat]')
};
}
// - 16-bit question class
var clazz = buf.readUInt16BE(offset + bytes);
bytes += 2;
if (clazz !== con.CLASS_IN) {
return {
error: new Error('Unexpected question class [' + clazz +
'] for name [' + question.nbname + ']; should be [' +
CLASS_IN + ']')
};
}
return {bytesRead: bytes, record: question};
}
function nsRDataParser(buf, offset, length, record) {
var bytes = 0;
var nbname = NBName.fromBuffer(buf, offset + bytes);
if (nbname.error) {
return {error: nbname.error};
} else if (length !== nbname.bytesRead) {
return {
error: new Expect('Unexpected NS record name length for record [' +
record.nbname + '].')
};
}
bytes += nbname.bytesRead;
record.ns = {
nbname: nbname,
};
return {bytesRead: bytes};
}