94 lines
2.5 KiB
JavaScript
94 lines
2.5 KiB
JavaScript
'use strict';
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var bitcore = require('bitcore');
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var BufferUtil = bitcore.util.buffer;
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var Hash = bitcore.crypto.Hash;
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function Messages(options) {
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this.commands = new Messages.Commands(options);
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if (!options) {
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options = {};
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}
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// map command messages
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for (var key in this.commands) {
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this[key] = this.commands[key];
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}
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var defaultMagicNumber = bitcore.Networks.defaultNetwork.networkMagic.readUInt32LE(0);
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this.magicNumber = options.magicNumber || defaultMagicNumber;
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}
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Messages.MINIMUM_LENGTH = 20;
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Messages.PAYLOAD_START = 16;
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Messages.Message = require('./message');
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Messages.Commands = require('./commands');
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Messages.prototype.parseMessage = function(dataBuffer) {
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/* jshint maxstatements: 18 */
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if (dataBuffer.length < Messages.MINIMUM_LENGTH) {
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return;
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}
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// Search the next magic number
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if (!this.discardUntilNextMessage(dataBuffer)) return;
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var payloadLen = (dataBuffer.get(Messages.PAYLOAD_START)) +
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(dataBuffer.get(Messages.PAYLOAD_START + 1) << 8) +
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(dataBuffer.get(Messages.PAYLOAD_START + 2) << 16) +
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(dataBuffer.get(Messages.PAYLOAD_START + 3) << 24);
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var messageLength = 24 + payloadLen;
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if (dataBuffer.length < messageLength) {
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return;
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}
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var command = dataBuffer.slice(4, 16).toString('ascii').replace(/\0+$/, '');
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var payload = dataBuffer.slice(24, messageLength);
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var checksum = dataBuffer.slice(20, 24);
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var checksumConfirm = Hash.sha256sha256(payload).slice(0, 4);
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if (!BufferUtil.equals(checksumConfirm, checksum)) {
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dataBuffer.skip(messageLength);
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return;
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}
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dataBuffer.skip(messageLength);
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return this.buildFromBuffer(command, payload);
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};
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Messages.prototype.discardUntilNextMessage = function(dataBuffer) {
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var i = 0;
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for (;;) {
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// check if it's the beginning of a new message
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var packageNumber = dataBuffer.slice(0, 4).readUInt32LE(0);
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if (packageNumber === this.magicNumber) {
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dataBuffer.skip(i);
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return true;
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}
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// did we reach the end of the buffer?
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if (i > (dataBuffer.length - 4)) {
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dataBuffer.skip(i);
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return false;
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}
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i++; // continue scanning
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}
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};
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Messages.prototype.buildFromBuffer = function(command, payload) {
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if (!this.commands[command]) {
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throw new Error('Unsupported message command: ' + command);
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}
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return this.commands[command].fromBuffer(payload);
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};
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Messages.prototype.build = Messages.prototype.buildFromObject = function(command, object) {
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return this.commands[command].fromObject(object);
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};
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module.exports = Messages;
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