test and fix oops (#9)

- port tests from `pull-box-stream`
- fix anything that fails tests
  - handle stream chunks > max content length
  - max content length is (2^16 - 1), not (2^16)
  - content length is encoded as uint, not int

SPEC.md

@@ -87,7 +87,7 @@ We start with a length chunk, seen here in plaintext:
 
 The length is a 16-bits unsigned integer (encoded as big-endian).
 
-(The maximum content length is 2^16 bytes or 65,536 bytes or 65.536 Kb)
+(The maximum content length is $`2^{16} - 1`$ bytes or 65,535 bytes or 65.535 Kb)
 
 A length of `0` is not a valid length. (And instead refers to a [End-of-stream chunk](#end-of-stream-chunk))
 
@@ -106,9 +106,9 @@ We encrypt and authenticate the length with ChaCha20-Poly1305 into the following
 
 A content chunk is simply the content.
 
-From 0 to 2^16 (65,536) bytes. (Matching the length in the previous chunk.)
+From $`0`$ to $`2^{16} - 1`$ (65,535) bytes. (Matching the length in the previous chunk.)
 
-If content is larger than 2^16 (65,536) bytes, split the bytes across multiple chunks.
+If content is larger than $`2^{16} - 1`$ (65,535) bytes, split the bytes across multiple chunks.
 
 ```txt
 Variable length content (plaintext):

js/pull-secret-channel/package.json

@@ -51,6 +51,7 @@
     "secret-channel": "^1.0.0"
   },
   "devDependencies": {
+    "pull-bitflipper": "^0.1.1",
     "pull-stream": "^3.7.0"
   }
 }

js/pull-secret-channel/src/index.js

@@ -9,6 +9,7 @@ const {
   NONCE_SIZE,
   LENGTH_OR_END_CIPHERTEXT,
   TAG_SIZE,
+  MAX_CONTENT_LENGTH,
 } = require('secret-channel')
 
 module.exports = {
@@ -25,6 +26,7 @@ module.exports = {
   @typedef {(end: End, cb: (end: End, data?: any) => void) => void} Source
   @typedef {{
      queue: (buf: B4A | null) => void
+     emit: (event: 'data' | 'end' | 'error', data?: any) => void
   }} PullThroughThis
 */
 
@@ -41,9 +43,23 @@ function pullEncrypter(key, nonce) {
      * @param {B4A} contentPlaintext
      */
     function pullEncrypterData(contentPlaintext) {
-      const [lengthCiphertext, contentCiphertext] = encrypter.next(contentPlaintext)
-      this.queue(lengthCiphertext)
-      this.queue(contentCiphertext)
+      if (contentPlaintext.length === 0) {
+        return // skip
+      }
+
+      try {
+        let totalContentPlaintext = contentPlaintext
+        while (totalContentPlaintext.length > 0) {
+          const nextContentPlaintext = totalContentPlaintext.subarray(0, MAX_CONTENT_LENGTH)
+          totalContentPlaintext = totalContentPlaintext.subarray(MAX_CONTENT_LENGTH)
+
+          const [lengthCiphertext, contentCiphertext] = encrypter.next(nextContentPlaintext)
+          this.queue(lengthCiphertext)
+          this.queue(contentCiphertext)
+        }
+      } catch (err) {
+        this.emit('error', err)
+      }
     },
 
     /**

js/pull-secret-channel/test/index.js

@@ -0,0 +1,265 @@
+const test = require('node:test')
+const assert = require('node:assert')
+const pull = require('pull-stream')
+const pullBitflipper = require('pull-bitflipper')
+const { randomBytes } = require('crypto')
+const { pullEncrypter, pullDecrypter, KEY_SIZE, NONCE_SIZE } = require('../')
+const { randomInt } = require('node:crypto')
+
+test('encrypt and decrypt: simple', async (t) => {
+  // generate a random secret, `KEYBYTES` bytes long.
+  const key = randomBytes(KEY_SIZE)
+  // generate a random nonce, `NONCE_SIZE` bytes long.
+  const nonce = randomBytes(NONCE_SIZE)
+
+  const plaintext1 = Buffer.from('hello world')
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values([plaintext1]),
+      pullEncrypter(key, nonce),
+      pullDecrypter(key, nonce),
+      pull.concat((err, plaintext2) => {
+        assert.ifError(err)
+        assert.equal(plaintext2.toString('utf8'), plaintext1.toString('utf8'))
+        resolve()
+      }),
+    )
+  })
+})
+
+test('encrypt and decrypt: random buffers', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+  const inputBuffers = randomBuffers(randomInt(1e2, 1e3), () => randomInt(1, 1e5))
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values(inputBuffers),
+      pullEncrypter(key, nonce),
+      pullDecrypter(key, nonce),
+      pull.collect((err, outputBuffers) => {
+        assert.ifError(err)
+
+        const input = Buffer.concat(inputBuffers)
+        const output = Buffer.concat(outputBuffers)
+        assert.equal(output.length, input.length)
+        assert.equal(output.toString('utf8'), input.toString('utf8'))
+
+        resolve()
+      }),
+    )
+  })
+})
+
+test('detect flipped bits', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+  const inputBuffers = randomBuffers(100, () => 1024)
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values(inputBuffers),
+      pullEncrypter(key, nonce),
+      pullBitflipper(0.2),
+      pullDecrypter(key, nonce),
+      pull.collect((err, outputBuffers) => {
+        assert.ok(err)
+        assert.equal(err.message, 'could not verify data')
+        assert.notEqual(outputBuffers.length, inputBuffers.length)
+        resolve()
+      }),
+    )
+  })
+})
+
+test('protect against reordering', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+  const inputBuffers = randomBuffers(100, () => 1024)
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values(inputBuffers),
+      pullEncrypter(key, nonce),
+      pull.collect((err, valid) => {
+        assert.ifError(err)
+
+        // randomly switch two blocks
+        const invalid = valid.slice()
+        // since every even packet is a header,
+        // moving those will produce valid messages
+        // but the counters will be wrong.
+        const i = randomInt(valid.length)
+        let j
+        do j = randomInt(valid.length)
+        while (j === i)
+        invalid[i] = valid[j]
+        invalid[i + 1] = valid[j + 1]
+        invalid[j] = valid[i]
+        invalid[j + 1] = valid[i + 1]
+
+        pull(
+          pull.values(invalid),
+          pullDecrypter(key, nonce),
+          pull.collect((err, outputBuffers) => {
+            assert.ok(err)
+            assert.equal(err.message, 'could not verify data')
+            assert.notEqual(outputBuffers.length, inputBuffers.length)
+            resolve()
+          }),
+        )
+      }),
+    )
+  })
+})
+
+test('detect unexpected hangup', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+
+  const inputBuffers = [
+    Buffer.from('I <3 TLS\n'),
+    Buffer.from('...\n'),
+    Buffer.from('NOT!!!!!!!!!!!!!!!\n'),
+  ]
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values(inputBuffers),
+      pullEncrypter(key, nonce),
+      pull.take(4), // header content header content.
+      pullDecrypter(key, nonce),
+      pull.collect((err, outputBuffers) => {
+        assert.ok(err) // expects an error
+        assert.equal(
+          err.message,
+          'pull-secret-channel/decrypter: stream ended before end-of-stream message',
+        )
+        assert.equal(outputBuffers.length, 2)
+        assert.equal(Buffer.concat(outputBuffers).toString('utf8'), 'I <3 TLS\n...\n')
+        resolve()
+      }),
+    )
+  })
+})
+
+test('immediately hangup', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values([]),
+      pullEncrypter(key, nonce),
+      pullDecrypter(key, nonce),
+      pull.collect((err, outputBuffers) => {
+        assert.ifError(err)
+        assert.deepEqual(outputBuffers, [])
+        resolve()
+      }),
+    )
+  })
+})
+
+test('skip empty buffers', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+
+  const inputBuffers = [
+    Buffer.alloc(0),
+    Buffer.from('hello'),
+    Buffer.alloc(0),
+    Buffer.from('world'),
+  ]
+  let chunks = 0
+
+  await new Promise((resolve, _reject) => {
+    pull(
+      pull.values(inputBuffers),
+      pullEncrypter(key, nonce),
+      pull.through(() => {
+        chunks++
+      }),
+      pullDecrypter(key, nonce),
+      pull.collect((err, outputBuffers) => {
+        assert.ifError(err)
+
+        const input = Buffer.concat(inputBuffers)
+        const output = Buffer.concat(outputBuffers)
+        assert.equal(output.length, input.length)
+        assert.equal(output.toString('utf8'), input.toString('utf8'))
+
+        assert.equal(chunks, 5) // header, content, header, content, end-of-stream
+
+        resolve()
+      }),
+    )
+  })
+})
+
+function randomBuffers(bufferCount, getBufferLength) {
+  const buffers = []
+  for (let i = 0; i < bufferCount; i++) {
+    buffers.push(randomBytes(getBufferLength()))
+  }
+  return buffers
+}
+
+test('stalled abort: encrypter', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+
+  const stallErr = new Error('intentional stall')
+  const read = pull(stall(), pullEncrypter(key, nonce))
+
+  let i = 0
+
+  await new Promise((resolve, _reject) => {
+    read(null, function (err, _data) {
+      assert.equal(err, stallErr)
+      assert.equal(++i, 1)
+    })
+
+    read(stallErr, function () {
+      assert.ok(true)
+      assert.equal(++i, 2)
+      resolve()
+    })
+  })
+})
+
+test('stalled abort: decrypter', async (t) => {
+  const key = randomBytes(KEY_SIZE)
+  const nonce = randomBytes(NONCE_SIZE)
+
+  const stallErr = new Error('intentional stall')
+  const read = pull(stall(), pullDecrypter(key, nonce))
+
+  let i = 0
+
+  await new Promise((resolve, _reject) => {
+    read(null, function (err, _data) {
+      assert.equal(err, stallErr)
+      assert.equal(++i, 1)
+    })
+
+    read(stallErr, function () {
+      assert.ok(true)
+      assert.equal(++i, 2)
+      resolve()
+    })
+  })
+})
+
+function stall() {
+  var _cb
+  return function (abort, cb) {
+    if (abort) {
+      _cb && _cb(abort)
+      cb && cb(abort)
+    } else {
+      _cb = cb
+    }
+  }
+}

js/secret-channel/package.json

@@ -48,5 +48,6 @@
     "b4a": "^1.6.4",
     "debug": "^4.3.4",
     "sodium-native": "^4.0.4"
-  }
+  },
+  "devDependencies": {}
 }

js/secret-channel/src/constants.js

@@ -5,10 +5,13 @@ const TAG_SIZE = 16
 const LENGTH_OR_END_PLAINTEXT = 2
 const LENGTH_OR_END_CIPHERTEXT = LENGTH_OR_END_PLAINTEXT + TAG_SIZE
 
+const MAX_CONTENT_LENGTH = 2 ** 16 - 1
+
 module.exports = {
   KEY_SIZE,
   NONCE_SIZE,
   TAG_SIZE,
   LENGTH_OR_END_PLAINTEXT,
   LENGTH_OR_END_CIPHERTEXT,
+  MAX_CONTENT_LENGTH,
 }