bitmessage-js/lib/net/base.js

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/**
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* Networking base module. Defines base transport interface, useful for
* implementing new transports. End-users should import some transport
* instead in order to connect/accept connections to/from other nodes.
* **NOTE**: `BaseTransport` is exported as a module.
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* @example var BaseTransport = require("bitmessage/lib/net/base");
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* @module bitmessage/net/base
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*/
// TODO(Kagami): Write some sort of tutorial.
"use strict";
var inherits = require("inherits");
var EventEmitter = require("events").EventEmitter;
var bufferEqual = require("buffer-equal");
var util = require("../_util");
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var PPromise = require("../platform").Promise;
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var structs = require("../structs");
var messages = require("../messages");
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var ServicesBitfield = structs.ServicesBitfield;
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/**
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* Base transport class. Allows to use single class for both client and
* server modes (as separate instances).
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* @constructor
* @static
*/
function BaseTransport() {
BaseTransport.super_.call(this);
}
inherits(BaseTransport, EventEmitter);
/**
* Do the transport-specific bootstrap process and return promise that
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* contains discovered nodes when fulfilled (both modes).
* NOTE: Do not use nodes received by this method in `addr` messages!
* This is meaningless.
* @return {Promise.<Array>}
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* @abstract
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*/
BaseTransport.prototype.bootstrap = function() {
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return PPromise.reject(new Error("Not implemented"));
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};
/**
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* Connect to the transport-specific address. Enters client mode. Should
* emit `open` event after successful connect and `established` event
* after `verack` messages exchange.
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* @abstract
*/
BaseTransport.prototype.connect = function() {
throw new Error("Not implemented");
};
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/**
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* Listen for the transport-specific incoming connections. Enters server
* mode. Should emit `connection` event with a transport instance for
* each new connection.
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* @abstract
*/
BaseTransport.prototype.listen = function() {
throw new Error("Not implemented");
};
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/**
* Send [message]{@link module:bitmessage/structs.message} over the
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* wire (client mode only).
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* @param {(Buffer|string)} msg - Encoded message or command string
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* @param {Buffer=} payload - Message payload (used if the first
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* argument is a string)
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* @abstract
*/
BaseTransport.prototype.send = function() {
throw new Error("Not implemented");
};
/**
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* Send [message]{@link module:bitmessage/structs.message} to all
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* connected clients (server mode only).
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* @param {(Buffer|string)} msg - Encoded message or command string
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* @param {Buffer=} payload - Message payload (used if the first
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* argument is a string)
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* @abstract
*/
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BaseTransport.prototype.broadcast = function() {
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throw new Error("Not implemented");
};
/**
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* Close connection(s) and/or stop listening (both modes).
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* @abstract
*/
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BaseTransport.prototype.close = function() {
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throw new Error("Not implemented");
};
// Private helpers.
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// Make a message from variable number of arguments.
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BaseTransport._getmsg = function(args) {
if (typeof args[0] === "string") {
return structs.message.encode(args[0], args[1]);
} else {
return args[0];
}
};
// Unmap IPv4-mapped IPv6 address.
BaseTransport._unmap = function(addr) {
if (addr.slice(0, 7) === "::ffff:") {
return addr.slice(7);
} else {
return addr;
}
};
// Check whether two given arrays intersect.
// NOTE(Kagami): It has O(n*m) complexity in the worst case but:
// * Max length of stream list = 160,000
// * One of the arrays (our streams) should have reasonable length
function intersects(a, b) {
var alen = a.length;
var blen = b.length;
if (!alen || !blen) {
return false;
}
var i, j;
for (i = 0; i < alen; ++i) {
for (j = 0; j < blen; ++j) {
if (a[i] === b[j]) {
return true;
}
}
}
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return false;
}
// Decode and validate version message.
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BaseTransport.prototype._decodeVersion = function(payload, opts) {
opts = opts || {};
var version;
try {
version = messages.version.decodePayload(payload);
} catch(err) {
throw new Error("Version decode error: " + err.message);
}
if (version.version < util.PROTOCOL_VERSION) {
throw new Error("Peer uses old protocol v" + version.version);
}
// TODO(Kagami): We may want to send error message describing the time
// offset problem to this node as PyBitmessage.
var delta = (version.time.getTime() - new Date().getTime()) / 1000;
if (delta > 3600) {
throw new Error("Peer's time is too far in the future: +" + delta + "s");
}
if (delta < -3600) {
throw new Error("Peer's time is too far in the past: " + delta + "s");
}
if (bufferEqual(version.nonce, messages.version.randomNonce)) {
throw new Error("Connection to self");
}
if (!intersects(this.streams, version.streams)) {
throw new Error(
"Peer isn't interested in our streams; " +
"first 10 peer's streams: " + version.streams.slice(0, 10)
);
}
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if (opts.network && !version.services.get(ServicesBitfield.NODE_NETWORK)) {
throw new Error("Not a normal network node: " + version.services);
}
if (opts.gateway && !version.services.get(ServicesBitfield.NODE_GATEWAY)) {
throw new Error("Not a gateway node: " + version.services);
}
if (opts.mobile && !version.services.get(ServicesBitfield.NODE_MOBILE)) {
throw new Error("Not a mobile node: " + version.services);
}
return version;
};
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module.exports = BaseTransport;