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107 lines
2.9 KiB
JavaScript
107 lines
2.9 KiB
JavaScript
/*jshint bitwise: false*/
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/*
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This file is part of web3.js.
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web3.js is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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web3.js is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with web3.js. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file bloom.js
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* @author Bas van Kervel <bas@ethereum.org>
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* @date 2017
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*/
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/**
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* Ethereum bloom filter support.
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*
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* @module bloom
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* @class [bloom] bloom
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*/
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var utils = require("./utils.js");
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var sha3 = require("./sha3.js");
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function codePointToInt(codePoint) {
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if (codePoint >= 48 && codePoint <= 57) { /*['0'..'9'] -> [0..9]*/
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return codePoint-48;
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}
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if (codePoint >= 65 && codePoint <= 70) { /*['A'..'F'] -> [10..15]*/
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return codePoint-55;
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}
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if (codePoint >= 97 && codePoint <= 102) { /*['a'..'f'] -> [10..15]*/
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return codePoint-87;
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}
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throw "invalid bloom";
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}
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function testBytes(bloom, bytes) {
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var hash = sha3(bytes, {encoding: "hex"});
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for (var i=0; i < 12; i+=4) {
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// calculate bit position in bloom fiter that must be active
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var bitpos = ((parseInt(hash.substr(i, 2), 16) << 8) + parseInt(hash.substr((i+2), 2), 16)) & 2047;
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// test if bitpos in bloom is active
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var code = codePointToInt(bloom.charCodeAt(bloom.length-1-Math.floor(bitpos/4)));
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var offset = 1 << (bitpos % 4);
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if ((code&offset) !== offset) {
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return false;
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}
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}
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return true;
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}
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/**
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* Returns true if address is part of the given bloom.
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* note: false positives are possible.
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*
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* @method testAddress
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* @param {String} hex encoded bloom
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* @param {String} address in hex notation
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* @returns {Boolean} topic is (probably) part of the block
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*/
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var testAddress = function(bloom, address) {
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if (!utils.isBloom(bloom)) throw "invalid bloom";
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if (!utils.isAddress(address)) throw "invalid address";
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return testBytes(bloom, address);
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};
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/**
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* Returns true if the topic is part of the given bloom.
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* note: false positives are possible.
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*
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* @method hasTopic
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* @param {String} hex encoded bloom
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* @param {String} address in hex notation
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* @returns {Boolean} topic is (probably) part of the block
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*/
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var testTopic = function(bloom, topic) {
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if (!utils.isBloom(bloom)) throw "invalid bloom";
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if (!utils.isTopic(topic)) throw "invalid topic";
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return testBytes(bloom, topic);
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};
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module.exports = {
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testAddress: testAddress,
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testTopic: testTopic,
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};
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