bitmessage-js/lib/user-agent.js

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/**
* Working with Bitmessage user agents.
* @see {@link https://bitmessage.org/wiki/User_Agent}
* @module bitmessage/user-agent
*/
"use strict";
var var_str = require("./structs").var_str;
var BM_NAME = require("../package.json").name;
var BM_VERSION = require("../package.json").version;
/**
* Decode user agent stack.
* NOTE: Decoding is rather loose and non-strict, it won't fail on bad
* user agent format because it's not that important.
* Also note that `rest` references input buffer.
* @param {Buffer} buf - A buffer that starts with encoded user agent
* @return {{software: Object[], length: number, rest: Buffer}}
* Decoded user agent structure.
*/
exports.decode = function(buf) {
var decoded = var_str.decode(buf);
var software = [];
if (decoded.str) {
software = decoded.str.slice(1, -1).split("/");
software = software.map(function(str) {
// That's more readable than /([^:]*)(?::([^(]*)(?:\(([^)]*))?)?/
var soft = {name: str};
var semicolon = soft.name.indexOf(":");
if (semicolon !== -1) {
soft.version = soft.name.slice(semicolon + 1);
soft.name = soft.name.slice(0, semicolon);
var obracket = soft.version.indexOf("(");
if (obracket !== -1) {
soft.comments = soft.version.slice(obracket + 1);
soft.version = soft.version.slice(0, obracket);
var cbracket = soft.comments.indexOf(")");
if (cbracket !== -1) {
soft.comments = soft.comments.slice(0, cbracket);
}
}
}
return soft;
});
}
return {software: software, length: decoded.length, rest: decoded.rest};
};
/**
* Encode user agent. Most underlying software comes first.
* @param {Object[]} software - List of software to encode
* @return {Buffer} Encoded user agent.
*/
var encode = exports.encode = function(software) {
var ua = software.map(function(soft) {
var version = soft.version || "0.0.0";
var str = soft.name + ":" + version;
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if (soft.comments) {
str += "(" + soft.comments + ")";
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}
return str;
}).join("/");
return var_str.encode("/" + ua + "/");
};
/**
* Encode bitmessage's user agent.
* @return {Buffer} Encoded user agent.
*/
exports.encodeSelf = function() {
return encode([{name: BM_NAME, version: BM_VERSION}]);
};
/**
* Encode user agent with bitmessage's user agent underneath. Most
* underlying software comes first.
* @param {Object[]} software - List of software to encode
* @return {Buffer} Encoded user agent.
*/
exports.encodeSelfWith = function(software) {
software = [{name: BM_NAME, version: BM_VERSION}].concat(software);
return encode(software);
};