Implement structs.message

This commit is contained in:
Kagami Hiiragi 2015-01-04 23:22:14 +03:00
parent 3d40235e08
commit 632aa2245c
2 changed files with 93 additions and 0 deletions

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@ -7,6 +7,83 @@
"use strict"; "use strict";
var assert = require("assert"); var assert = require("assert");
var bufferEqual = require("buffer-equal");
var bmcrypto = require("./crypto");
function isAscii(str) {
for (var i = 0; i < str.length; i++) {
if (str.charCodeAt(i) > 127) {
return false;
}
}
return true;
}
function getchecksum(data) {
return bmcrypto.sha512(data).slice(0, 4);
}
/**
* Message structure.
* @see {@link https://bitmessage.org/wiki/Protocol_specification#Message_structure}
* @namespace
* @static
*/
var message = exports.message = {
/** Bitmessage magic value. */
MAGIC: 0xE9BEB4D9,
/**
* Decode message structure.
* @param {Buffer} buf - Buffer that starts with encoded message
* structure
* @return {{command: string, payload: Buffer, length: number, rest: Buffer}}
* Decoded message structure.
*/
decode: function(buf) {
assert(buf.length >= 24, "Buffer is too small");
assert(buf.readUInt32BE(0, true) === message.MAGIC, "Wrong magic");
var command = buf.slice(4, 16);
var firstNonNull;
for (var i = 11; i >=0; i--) {
assert(command[i] <= 127, "Non-ASCII characters in command");
if (firstNonNull === undefined && command[i] !== 0) {
firstNonNull = i;
}
}
command = command.slice(0, firstNonNull + 1).toString("ascii");
var payloadLength = buf.readUInt32BE(16, true);
assert(payloadLength <= 262144, "Payload is too big");
var checksum = buf.slice(20, 24);
var length = 24 + payloadLength;
var payload = buf.slice(24, length);
assert(bufferEqual(checksum, getchecksum(payload)), "Bad checkum");
var rest = buf.slice(length);
return {command: command, payload: payload, length: length, rest: rest};
},
/**
* Encode message structure.
* @param {string} command - ASCII string identifying the packet
* content
* @param {Buffer} payload - The actual data, a message or an object
* @return {Buffer} Encoded message structure.
*/
encode: function(command, payload) {
assert(command.length <= 12, "Command is too long");
assert(isAscii(command), "Non-ASCII characters in command");
assert(payload.length <= 262144, "Payload is too big");
var buf = new Buffer(24 + payload.length);
buf.fill(0);
buf.writeUInt32BE(message.MAGIC, 0, true);
buf.write(command, 4);
buf.writeUInt32BE(payload.length, 16, true);
getchecksum(payload).copy(buf, 20);
payload.copy(buf, 24);
return buf;
},
};
/** /**
* var_int. * var_int.

16
test.js
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@ -5,6 +5,7 @@ var allTests = typeof window === "undefined" ?
var bmcrypto = require("./lib/crypto"); var bmcrypto = require("./lib/crypto");
var bitmessage = require("./lib"); var bitmessage = require("./lib");
var message = bitmessage.structs.message;
var var_int = bitmessage.structs.var_int; var var_int = bitmessage.structs.var_int;
var var_str = bitmessage.structs.var_str; var var_str = bitmessage.structs.var_str;
var var_int_list = bitmessage.structs.var_int_list; var var_int_list = bitmessage.structs.var_int_list;
@ -49,6 +50,21 @@ describe("Crypto", function() {
}); });
describe("Common structures", function() { describe("Common structures", function() {
describe("message", function() {
it("should encode", function() {
expect(message.encode("test", Buffer("payload")).toString("hex")).to.equal("e9beb4d97465737400000000000000000000000770b33ce97061796c6f6164");
});
it("should decode", function() {
var res;
res = message.decode(Buffer("e9beb4d97465737400000000000000000000000770b33ce97061796c6f6164", "hex"));
expect(res.command).to.equal("test");
expect(res.payload.toString()).to.equal("payload");
expect(res.length).to.equal(31);
expect(res.rest.toString("hex")).to.equal("");
});
});
describe("var_int", function() { describe("var_int", function() {
it("should decode", function() { it("should decode", function() {
var res; var res;