494 lines
15 KiB
JavaScript
494 lines
15 KiB
JavaScript
/**
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* Implements common structures.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Common_structures}
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* @module bitmessage/structs
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*/
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"use strict";
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var objectAssign = Object.assign || require("object-assign");
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var bufferEqual = require("buffer-equal");
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var assert = require("./util").assert;
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var bmcrypto = require("./crypto");
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function isAscii(str) {
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for (var i = 0; i < str.length; i++) {
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if (str.charCodeAt(i) > 127) {
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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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function getchecksum(data) {
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return bmcrypto.sha512(data).slice(0, 4);
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}
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/**
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* Message structure.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Message_structure}
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* @namespace
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* @static
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*/
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var message = exports.message = {
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/** Bitmessage magic value. */
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MAGIC: 0xE9BEB4D9,
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/**
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* Decode message structure.
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* @param {Buffer} buf - Buffer that starts with encoded message
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* structure
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* @return {{command: string, payload: Buffer, length: number, rest: Buffer}}
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* Decoded message structure.
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*/
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decode: function(buf) {
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assert(buf.length >= 24, "Buffer is too small");
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assert(buf.readUInt32BE(0, true) === message.MAGIC, "Wrong magic");
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var command = buf.slice(4, 16);
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var firstNonNull;
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for (var i = 11; i >=0; i--) {
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assert(command[i] <= 127, "Non-ASCII characters in command");
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if (firstNonNull === undefined && command[i] !== 0) {
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firstNonNull = i;
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}
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}
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command = command.slice(0, firstNonNull + 1).toString("ascii");
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var payloadLength = buf.readUInt32BE(16, true);
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assert(payloadLength <= 262144, "Payload is too big");
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var checksum = buf.slice(20, 24);
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var length = 24 + payloadLength;
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var payload = buf.slice(24, length);
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assert(bufferEqual(checksum, getchecksum(payload)), "Bad checkum");
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var rest = buf.slice(length);
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return {command: command, payload: payload, length: length, rest: rest};
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},
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/**
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* Encode message structure.
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* @param {string} command - ASCII string identifying the packet
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* content
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* @param {Buffer} payload - The actual data, a message or an object
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* @return {Buffer} Encoded message structure.
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*/
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encode: function(command, payload) {
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assert(command.length <= 12, "Command is too long");
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assert(isAscii(command), "Non-ASCII characters in command");
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assert(payload.length <= 262144, "Payload is too big");
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var buf = new Buffer(24 + payload.length);
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buf.fill(0);
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buf.writeUInt32BE(message.MAGIC, 0, true);
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buf.write(command, 4);
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buf.writeUInt32BE(payload.length, 16, true);
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getchecksum(payload).copy(buf, 20);
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payload.copy(buf, 24);
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return buf;
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},
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};
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/**
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* Variable length integer.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Variable_length_integer}
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* @namespace
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* @static
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*/
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var var_int = exports.var_int = {
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/**
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* Decode `var_int`.
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* @param {Buffer} buf - A buffer that starts with encoded `var_int`
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* @return {{value: number, length: number, rest: Buffer}}
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* Decoded `var_int` structure.
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*/
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decode: function(buf) {
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var value, length;
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assert(buf.length > 0, "Empty buffer");
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switch (buf[0]) {
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case 253:
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value = buf.readUInt16BE(1);
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assert(value >= 253, "Impractical var_int");
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length = 3;
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break;
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case 254:
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value = buf.readUInt32BE(1);
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assert(value >= 65536, "Impractical var_int");
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length = 5;
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break;
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case 255:
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var hi = buf.readUInt32BE(1);
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assert(hi !== 0, "Impractical var_int");
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// Max safe number = 2^53 - 1 =
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// 0b0000000000011111111111111111111111111111111111111111111111111111
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// = 2097151*(2^32) + (2^32 - 1).
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// So it's safe until hi <= 2097151. See
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// <http://mdn.io/issafeinteger>,
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// <https://stackoverflow.com/q/307179> for details.
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// TODO(Kagami): We may want to return raw Buffer for
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// 2^53 <= value <= 2^64 - 1 range. Possibly using the optional
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// argument because most of the code expect to get a number when
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// calling `var_int.decode`.
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assert(hi <= 2097151, "Unsafe integer");
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var lo = buf.readUInt32BE(5);
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value = hi * 4294967296 + lo;
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length = 9;
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break;
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default:
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value = buf[0];
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length = 1;
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}
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var rest = buf.slice(length);
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return {value: value, length: length, rest: rest};
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},
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/**
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* Encode number into `var_int`.
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* @param {(number|Buffer)} value - Input number
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* @return {Buffer} Encoded `var_int`.
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*/
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encode: function(value) {
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var buf, targetStart;
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if (typeof value === "number") {
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assert(value >= 0, "Value cannot be less than zero");
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if (value < 253) {
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buf = new Buffer([value]);
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} else if (value < 65536) {
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buf = new Buffer(3);
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buf[0] = 253;
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buf.writeUInt16BE(value, 1, true);
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} else if (value < 4294967296) {
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buf = new Buffer(5);
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buf[0] = 254;
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buf.writeUInt32BE(value, 1, true);
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} else {
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assert(value <= 9007199254740991, "Unsafe integer");
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buf = new Buffer(9);
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buf[0] = 255;
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buf.writeUInt32BE(Math.floor(value / 4294967296), 1, true); // high32
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buf.writeUInt32BE(value % 4294967296, 5, true); // low32
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}
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} else if (Buffer.isBuffer(value)) {
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assert(value.length <= 8, "Buffer is too big");
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buf = new Buffer(9);
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buf.fill(0);
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buf[0] = 255;
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targetStart = 1 + (8 - value.length);
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value.copy(buf, targetStart);
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} else {
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throw new Error("Value encode error");
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}
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return buf;
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},
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};
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/**
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* Variable length string.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Variable_length_string}
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* @namespace
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*/
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exports.var_str = {
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/**
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* Decode `var_str`.
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* @param {Buffer} buf - A buffer that starts with encoded `var_str`
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* @return {{str: string, length: number, rest: Buffer}}
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* Decoded `var_str` structure.
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*/
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decode: function(buf) {
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var decoded = var_int.decode(buf);
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var strLength = decoded.value;
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// XXX(Kagami): Spec doesn't mention encoding, using UTF-8.
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var str = decoded.rest.slice(0, strLength).toString();
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var rest = decoded.rest.slice(strLength);
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return {str: str, length: decoded.length + strLength, rest: rest};
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},
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/**
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* Encode string into `var_str`.
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* @param {string} str - A string
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* @return {Buffer} Encoded `var_str`.
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*/
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encode: function(str) {
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// XXX(Kagami): Spec doesn't mention encoding, using UTF-8.
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var strBuf = new Buffer(str);
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return Buffer.concat([var_int.encode(strBuf.length), strBuf]);
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},
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};
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/**
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* Variable length list of integers.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Variable_length_list_of_integers}
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* @namespace
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*/
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exports.var_int_list = {
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/**
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* Decode `var_int_list`.
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* @param {Buffer} buf - A buffer that starts with encoded
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* `var_int_list`
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* @return {{list: number[], length: number, rest: Buffer}}
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* Decoded `var_int_list` structure.
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*/
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decode: function(buf) {
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var decoded = var_int.decode(buf);
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var listLength = decoded.value;
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var list = new Array(listLength);
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var rest = decoded.rest;
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var sumLength = decoded.length;
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for (var i = 0; i < listLength; i++) {
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decoded = var_int.decode(rest);
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list[i] = decoded.value;
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rest = decoded.rest;
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sumLength += decoded.length;
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}
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return {list: list, length: sumLength, rest: rest};
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},
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/**
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* Encode list of numbers into `var_int_list`.
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* @param {number[]} list - A number list
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* @return {Buffer} Encoded `var_int_list`.
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*/
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encode: function(list) {
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var listBuf = Buffer.concat(list.map(var_int.encode));
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return Buffer.concat([var_int.encode(list.length), listBuf]);
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},
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};
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// See https://en.wikipedia.org/wiki/IPv6#IPv4-mapped_IPv6_addresses
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var IPv4_MAPPING = new Buffer([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255]);
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// Very simple inet_ntop(3) equivalent.
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function inet_ntop(buf) {
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assert(buf.length === 16, "Bad buffer size");
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// IPv4 mapped to IPv6.
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if (bufferEqual(buf.slice(0, 12), IPv4_MAPPING)) {
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return Array.prototype.join.call(buf.slice(12), ".");
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// IPv6.
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} else {
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var groups = [];
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for (var i = 0; i < 8; i++) {
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groups.push(buf.readUInt16BE(i * 2, true).toString(16));
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}
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return groups.join(":");
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}
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}
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// Very simple inet_pton(3) equivalent.
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function inet_pton(str) {
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var buf = new Buffer(16);
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buf.fill(0);
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// IPv4.
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if (str.indexOf(":") === -1) {
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IPv4_MAPPING.copy(buf);
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var octets = str.split(/\./g).map(function(s) {return parseInt(s, 10);});
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// Support short form from inet_aton(3) man page.
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if (octets.length === 1) {
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buf.writeUInt32BE(octets[0], 12);
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} else {
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// Check against 1000.bad.addr
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octets.forEach(function(octet) {
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assert(octet >= 0, "Bad IPv4 address");
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assert(octet <= 255, "Bad IPv4 address");
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});
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if (octets.length === 2) {
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buf[12] = octets[0];
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buf[15] = octets[1];
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} else if (octets.length === 3) {
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buf[12] = octets[0];
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buf[13] = octets[1];
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buf[15] = octets[2];
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} else if (octets.length === 4) {
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buf[12] = octets[0];
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buf[13] = octets[1];
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buf[14] = octets[2];
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buf[15] = octets[3];
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} else {
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throw new Error("Bad IPv4 address");
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}
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}
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// IPv6.
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} else {
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var dgroups = str.split(/::/g);
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// Check against 1::1::1
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assert(dgroups.length <= 2, "Bad IPv6 address");
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var groups = [];
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var i;
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if (dgroups[0]) {
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groups.push.apply(groups, dgroups[0].split(/:/g));
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}
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if (dgroups.length === 2) {
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if (dgroups[1]) {
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var splitted = dgroups[1].split(/:/g);
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var fill = 8 - (groups.length + splitted.length);
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// Check against 1:1:1:1::1:1:1:1
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assert(fill > 0, "Bad IPv6 address");
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for (i = 0; i < fill; i++) {
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groups.push(0);
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}
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groups.push.apply(groups, splitted);
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} else {
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// Check against 1:1:1:1:1:1:1:1::
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assert(groups.length <= 7, "Bad IPv6 address");
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}
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} else {
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// Check against 1:1:1
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assert(groups.length === 8, "Bad IPv6 address");
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}
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for (i = 0; i < Math.min(groups.length, 8); i++) {
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buf.writeUInt16BE(parseInt(groups[i], 16), i * 2);
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}
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}
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return buf;
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}
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/**
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* Network address.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Network_address}
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* @namespace
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*/
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exports.net_addr = {
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/**
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* Decode `net_addr`.
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* @param {Buffer} buf - A buffer that contains encoded `net_addr`
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* @param {?Object} opts - Decode options; use `short` option to
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* decode `net_addr` used in version message
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* @return {Object} Decoded `net_addr` structure.
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*/
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decode: function(buf, opts) {
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var short = !!(opts || {}).short;
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var res = {};
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if (short) {
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assert(buf.length === 26, "Bad buffer size");
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} else {
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assert(buf.length === 38, "Bad buffer size");
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var timeHi = buf.readUInt32BE(0, true);
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var timeLo = buf.readUInt32BE(4, true);
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// JavaScript's Date object can't work with timestamps higher than
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// 8640000000000 (~2^43, ~275760 year). Hope JavaScript will
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// support 64-bit numbers up to this date.
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assert(timeHi <= 2011, "Time is too high");
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assert(timeHi !== 2011 || timeLo <= 2820767744, "Time is too high");
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res.time = new Date((timeHi * 4294967296 + timeLo) * 1000);
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res.stream = buf.readUInt32BE(8, true);
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buf = buf.slice(12);
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}
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res.services = serviceFeatures.decode(buf.slice(0, 8));
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res.host = inet_ntop(buf.slice(8, 24));
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res.port = buf.readUInt16BE(24, true);
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return res;
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},
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/**
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* Encode `net_addr`.
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* @param {Object} opts - Encode options; use `short` option to encode
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* `net_addr` used in version message
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* @return {Buffer} Encoded `net_addr`.
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*/
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encode: function(opts) {
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// Be aware of `Buffer.slice` quirk in browserify:
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// <http://git.io/lNZF1A> (does not modify parent buffer's memory in
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// old browsers).
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var buf, shift;
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if (opts.short) {
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buf = new Buffer(26);
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shift = 0;
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} else {
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buf = new Buffer(38);
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var time = opts.time || new Date();
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time = Math.floor(time.getTime() / 1000);
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buf.writeUInt32BE(Math.floor(time / 4294967296), 0, true); // high32
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buf.writeUInt32BE(time % 4294967296, 4, true); // low32
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buf.writeUInt32BE(opts.stream, 8);
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shift = 12;
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}
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var services = opts.services || [serviceFeatures.NODE_NETWORK];
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serviceFeatures.encode(services).copy(buf, shift);
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inet_pton(opts.host).copy(buf, shift + 8);
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buf.writeUInt16BE(opts.port, shift + 24);
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return buf;
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},
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};
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/**
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* Message encodings. Extends {@link var_int} by adding known encoding type
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* constants.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Message_Encodings}
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* @namespace
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*/
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exports.messageEncodings = objectAssign(Object.create(var_int), {
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/**
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* Any data with this number may be ignored. The sending node might
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* simply be sharing its public key with you.
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*/
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IGNORE: 0,
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/**
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* UTF-8. No 'Subject' or 'Body' sections. Useful for simple strings
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* of data, like URIs or magnet links.
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*/
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TRIVIAL: 1,
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/**
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* UTF-8. Uses 'Subject' and 'Body' sections. No MIME is used.
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*/
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SIMPLE: 2,
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});
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// Creates bitfield class of the specified size.
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var bitfield = function(size) {
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var bytesize = size / 8;
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return {
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decode: function(buf) {
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assert(buf.length === bytesize, "Bad buffer size");
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var features = [];
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var index;
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for (var i = 0; i < size; i++) {
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index = bytesize - Math.floor(i / 8) - 1;
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if ((buf[index] & (1 << (i % 8))) !== 0) { // jshint ignore:line
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features.push(i);
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}
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}
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return features;
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},
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encode: function(features) {
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var buf = new Buffer(bytesize);
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buf.fill(0);
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features.forEach(function(feature) {
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assert(feature >= 0, "Bad feature");
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assert(feature <= (size - 1), "Bad feature");
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var index = bytesize - Math.floor(feature / 8) - 1;
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buf[index] |= 1 << (feature % 8); // jshint ignore:line
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});
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return buf;
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},
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};
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};
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/**
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* Service bitfield features. Implements encoding/decoding for a 8-byte
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* buffer object.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#version}
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* @namespace
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* @static
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*/
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var serviceFeatures = exports.serviceFeatures = objectAssign(bitfield(64), {
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/** This is a normal network node. */
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NODE_NETWORK: 0,
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});
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/**
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* Pubkey bitfield features. Implements encoding/decoding for a 4-byte
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* buffer object.
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* @see {@link https://bitmessage.org/wiki/Protocol_specification#Pubkey_bitfield_features}
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* @namespace
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*/
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exports.pubkeyFeatures = objectAssign(bitfield(32), {
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/**
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* Receiving node expects that the RIPE hash encoded in their address
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* preceedes the encrypted message data of msg messages bound for
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* them.
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*/
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INCLUDE_DESTINATION: 30,
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/**
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* If true, the receiving node does send acknowledgements (rather than
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* dropping them).
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*/
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DOES_ACK: 31,
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});
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