84 lines
2.8 KiB
JavaScript
84 lines
2.8 KiB
JavaScript
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var Packet = require('./packets/packet');
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// as this is very low level parser, EventEmitter is not used
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// onPayload(sequenceId, payload) is called for each mysql packet
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function PacketParser(onPacket)
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{
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// array of last payload chunks
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// only used when corrent payload is not complete
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this.buffer = [];
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// total length of chunks on buffer
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this.bufferLength = 0;
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this.headerLen = 0;
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this.headerBuff = Buffer(4);
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this.state = 'head0';
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// expected payload length
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this.length = 0;
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this.sequenceId = 0;
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this.onPacket = onPacket;
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}
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PacketParser.prototype.execute = function(chunk, start, end) {
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// node 0.11 has different ondata signature
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if (!start && !end) {
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start = 0;
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end = chunk.length;
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}
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while (start < chunk.length) {
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if (this.state == 'head0' && (end - start) > 3) {
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this.length = chunk[start] + (chunk[start+1] << 8) + (chunk[start+2] << 16);
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this.sequenceId = chunk[start+3];
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var packetLength = this.length + 4;
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if (end - start > packetLength) { // more than one packet in chunk
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this.onPacket(new Packet(this.sequenceId, chunk, start + 4, start + packetLength));
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start += packetLength;
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} else if (end - start == packetLength) {
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return this.onPacket(new Packet(this.sequenceId, chunk, start + 4, start + packetLength));
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} else { // payload is incomplete
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this.buffer = [chunk.slice(start + 4, end)];
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this.bufferLength = end - start - 4;
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this.state = 'payload';
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return;
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}
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} else if (this.state == 'payload') {
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var remainingPayload = this.length - this.bufferLength;
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if (end - start >= remainingPayload) { // last chunk for payload
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var payload = new Buffer(this.length);
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var offset = 0;
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for (var i=0; i < this.buffer.length; ++i) {
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this.buffer[i].copy(payload, offset);
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offset += this.buffer[i].length;
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}
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chunk.copy(payload, offset, start, start + remainingPayload);
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this.onPacket(new Packet(this.sequenceId, payload, 0, this.length));
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this.buffer = [];
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this.bufferLength = 0;
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start += remainingPayload;
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this.state = 'head0';
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} else {
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this.buffer.push(chunk.slice(start, end));
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this.bufferLength += end - start;
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return;
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}
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} else { // length < 4 or state != header0
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if (end - start + this.headerLen < 4) {
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chunk.copy(this.headerBuff, this.headerLen, start, end);
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this.headerLen += end - start;
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this.state = 'head_';
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return;
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}
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chunk.copy(this.headerBuff, this.headerLen, start, start + 4 - this.headerLen);
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start += 4 - this.headerLen;
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this.length = this.headerBuff[0] + (this.headerBuff[1] << 8) + (this.headerBuff[2] << 16);
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this.headerLen = 0;
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this.state = 'payload';
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}
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}
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};
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module.exports = PacketParser;
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