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fix: add netstring encode/decode/stream library
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// adapted from 'netstring-stream', https://github.com/tlivings/netstring-stream/ | ||
import { assert } from '@agoric/assert'; | ||
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const { Transform } = require('stream'); | ||
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const COLON = 58; | ||
const COMMA = 44; | ||
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// input is a Buffer, output is a netstring-wrapped Buffer | ||
export function encode(data) { | ||
const prefix = Buffer.from(`${data.length}:`); | ||
const suffix = Buffer.from(','); | ||
return Buffer.concat([prefix, data, suffix]); | ||
} | ||
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// input is a sequence of strings, output is a byte pipe | ||
export function createWriter() { | ||
function transform(chunk, encoding, callback) { | ||
assert.equal(encoding, 'buffer'); | ||
callback(encode(chunk)); | ||
} | ||
return new Transform({ transform }); | ||
} | ||
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// Input is a Buffer containing zero or more netstrings and maybe some | ||
// leftover bytes. Output is zero or more decoded Buffers, one per netstring, | ||
// plus a Buffer of leftover bytes. | ||
// | ||
export function decode(data) { | ||
// TODO: it would be more efficient to accumulate pending data in an array, | ||
// rather than doing a concat each time | ||
let start = 0; | ||
const payloads = []; | ||
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for (;;) { | ||
const colon = data.indexOf(COLON, start); | ||
if (colon === -1) { | ||
break; // still waiting for `${LENGTH}:` | ||
} | ||
const sizeString = data.toString('utf-8', start, colon); | ||
const size = parseInt(sizeString, 10); | ||
if (!(size > -1)) { | ||
// reject NaN, all negative numbers | ||
throw Error(`unparseable size '${sizeString}', should be integer`); | ||
} | ||
if (data.length < colon + 1 + size + 1) { | ||
break; // still waiting for `${DATA}.` | ||
} | ||
if (data[colon + 1 + size] !== COMMA) { | ||
throw Error(`malformed netstring: not terminated by comma`); | ||
} | ||
payloads.push(data.subarray(colon + 1, colon + 1 + size)); | ||
start = colon + 1 + size + 1; | ||
} | ||
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const leftover = data.subarray(start); | ||
return { leftover, payloads }; | ||
} | ||
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// input is a byte pipe, output is a sequence of Buffers | ||
export function createReader() { | ||
let buffered = Buffer.from(''); | ||
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function transform(chunk, encoding, callback) { | ||
assert.equal(encoding, 'buffer'); | ||
buffered = Buffer.concat([buffered, chunk]); | ||
let res = null; | ||
try { | ||
const { leftover, payloads } = decode(buffered); | ||
buffered = leftover; | ||
for (let i = 0; i < payloads.length; i += 1) { | ||
this.push(payloads[i]); | ||
} | ||
} catch (err) { | ||
res = err; | ||
} | ||
callback(res); | ||
} | ||
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return new Transform({ transform }); | ||
} |
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import '@agoric/install-ses'; // adds 'harden' to global | ||
import test from 'ava'; | ||
import { encode, decode } from '../src/netstring'; | ||
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test('encode', t => { | ||
function eq(input, expected) { | ||
const encoded = encode(Buffer.from(input)); | ||
const expBuf = Buffer.from(expected); | ||
if (encoded.compare(expBuf) !== 0) { | ||
console.log(`got : ${encoded}`); | ||
console.log(`want: ${expBuf}`); | ||
} | ||
t.deepEqual(encoded, expBuf); | ||
} | ||
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eq('', '0:,'); | ||
eq('a', '1:a,'); | ||
eq('abc', '3:abc,'); | ||
const umlaut = 'ümlaut'; | ||
t.is(umlaut.length, 6); | ||
const umlautBuffer = Buffer.from(umlaut, 'utf-8'); | ||
t.is(umlautBuffer.length, 7); | ||
const expectedBuffer = Buffer.from(`7:${umlaut},`, 'utf-8'); | ||
eq(umlautBuffer, expectedBuffer); | ||
}); | ||
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test('decode', t => { | ||
function eq(input, expPayloads, expLeftover) { | ||
const encPayloads = expPayloads.map(Buffer.from); | ||
const encLeftover = Buffer.from(expLeftover); | ||
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const { payloads, leftover } = decode(Buffer.from(input)); | ||
t.deepEqual(payloads, encPayloads); | ||
t.deepEqual(leftover, encLeftover); | ||
} | ||
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eq('', [], ''); | ||
eq('0', [], '0'); | ||
eq('0:', [], '0:'); | ||
eq('0:,', [''], ''); | ||
eq('0:,1', [''], '1'); | ||
eq('0:,1:', [''], '1:'); | ||
eq('0:,1:a', [''], '1:a'); | ||
eq('0:,1:a,', ['', 'a'], ''); | ||
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const umlaut = 'ümlaut'; | ||
t.is(umlaut.length, 6); | ||
const umlautBuffer = Buffer.from(umlaut, 'utf-8'); | ||
t.is(umlautBuffer.length, 7); | ||
const expectedBuffer = Buffer.from(`7:${umlaut},`, 'utf-8'); | ||
eq(expectedBuffer, [umlaut], ''); | ||
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function bad(input, message) { | ||
t.throws(() => decode(Buffer.from(input)), { message }); | ||
} | ||
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// bad('a', 'non-numeric length prefix'); | ||
bad('a:', `unparseable size 'a', should be integer`); | ||
bad('1:ab', 'malformed netstring: not terminated by comma'); | ||
}); |