From b1168767d36baa59e9482ac859d505766bbb6246 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Wed, 8 Feb 2023 23:12:47 -0500
Subject: [PATCH 1/4] Move newTextEncoder/Decoder() to their own file,
 text_serializer.ts

---
 .../firestore/src/core/firestore_client.ts    |  3 +-
 .../src/platform/browser/serializer.ts        | 14 ------
 .../src/platform/browser/text_serializer.ts   | 30 ++++++++++++
 .../platform/browser_lite/text_serializer.ts  | 18 +++++++
 .../firestore/src/platform/node/serializer.ts | 16 -------
 .../src/platform/node/text_serializer.ts      | 32 +++++++++++++
 .../src/platform/node_lite/text_serializer.ts | 18 +++++++
 .../firestore/src/platform/rn/serializer.ts   |  6 +--
 .../src/platform/rn/text_serializer.ts        | 18 +++++++
 .../src/platform/rn_lite/text_serializer.ts   | 18 +++++++
 packages/firestore/src/platform/serializer.ts | 32 -------------
 .../firestore/src/platform/text_serializer.ts | 48 +++++++++++++++++++
 .../firestore/src/util/bundle_reader_impl.ts  |  2 +-
 .../test/unit/specs/spec_test_runner.ts       |  2 +-
 .../firestore/test/unit/util/bundle.test.ts   |  2 +-
 .../firestore/test/unit/util/bundle_data.ts   |  6 +--
 16 files changed, 190 insertions(+), 75 deletions(-)
 create mode 100644 packages/firestore/src/platform/browser/text_serializer.ts
 create mode 100644 packages/firestore/src/platform/browser_lite/text_serializer.ts
 create mode 100644 packages/firestore/src/platform/node/text_serializer.ts
 create mode 100644 packages/firestore/src/platform/node_lite/text_serializer.ts
 create mode 100644 packages/firestore/src/platform/rn/text_serializer.ts
 create mode 100644 packages/firestore/src/platform/rn_lite/text_serializer.ts
 create mode 100644 packages/firestore/src/platform/text_serializer.ts

diff --git a/packages/firestore/src/core/firestore_client.ts b/packages/firestore/src/core/firestore_client.ts
index 2c2c0af1771..a58786c6685 100644
--- a/packages/firestore/src/core/firestore_client.ts
+++ b/packages/firestore/src/core/firestore_client.ts
@@ -41,7 +41,8 @@ import { Document } from '../model/document';
 import { DocumentKey } from '../model/document_key';
 import { Mutation } from '../model/mutation';
 import { toByteStreamReader } from '../platform/byte_stream_reader';
-import { newSerializer, newTextEncoder } from '../platform/serializer';
+import { newSerializer } from '../platform/serializer';
+import { newTextEncoder } from '../platform/text_serializer';
 import { Datastore } from '../remote/datastore';
 import {
   canUseNetwork,
diff --git a/packages/firestore/src/platform/browser/serializer.ts b/packages/firestore/src/platform/browser/serializer.ts
index 722f40e605f..5e009d89f60 100644
--- a/packages/firestore/src/platform/browser/serializer.ts
+++ b/packages/firestore/src/platform/browser/serializer.ts
@@ -22,17 +22,3 @@ import { JsonProtoSerializer } from '../../remote/serializer';
 export function newSerializer(databaseId: DatabaseId): JsonProtoSerializer {
   return new JsonProtoSerializer(databaseId, /* useProto3Json= */ true);
 }
-
-/**
- * An instance of the Platform's 'TextEncoder' implementation.
- */
-export function newTextEncoder(): TextEncoder {
-  return new TextEncoder();
-}
-
-/**
- * An instance of the Platform's 'TextDecoder' implementation.
- */
-export function newTextDecoder(): TextDecoder {
-  return new TextDecoder('utf-8');
-}
diff --git a/packages/firestore/src/platform/browser/text_serializer.ts b/packages/firestore/src/platform/browser/text_serializer.ts
new file mode 100644
index 00000000000..6a53021f7c0
--- /dev/null
+++ b/packages/firestore/src/platform/browser/text_serializer.ts
@@ -0,0 +1,30 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * An instance of the Platform's 'TextEncoder' implementation.
+ */
+export function newTextEncoder(): TextEncoder {
+  return new TextEncoder();
+}
+
+/**
+ * An instance of the Platform's 'TextDecoder' implementation.
+ */
+export function newTextDecoder(): TextDecoder {
+  return new TextDecoder('utf-8');
+}
diff --git a/packages/firestore/src/platform/browser_lite/text_serializer.ts b/packages/firestore/src/platform/browser_lite/text_serializer.ts
new file mode 100644
index 00000000000..a9231f63914
--- /dev/null
+++ b/packages/firestore/src/platform/browser_lite/text_serializer.ts
@@ -0,0 +1,18 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export * from '../browser/text_serializer';
diff --git a/packages/firestore/src/platform/node/serializer.ts b/packages/firestore/src/platform/node/serializer.ts
index 1f61010902b..e19dbc8b1db 100644
--- a/packages/firestore/src/platform/node/serializer.ts
+++ b/packages/firestore/src/platform/node/serializer.ts
@@ -16,25 +16,9 @@
  */
 
 /** Return the Platform-specific serializer monitor. */
-import { TextDecoder, TextEncoder } from 'util';
-
 import { DatabaseId } from '../../core/database_info';
 import { JsonProtoSerializer } from '../../remote/serializer';
 
 export function newSerializer(databaseId: DatabaseId): JsonProtoSerializer {
   return new JsonProtoSerializer(databaseId, /* useProto3Json= */ false);
 }
-
-/**
- * An instance of the Platform's 'TextEncoder' implementation.
- */
-export function newTextEncoder(): TextEncoder {
-  return new TextEncoder();
-}
-
-/**
- * An instance of the Platform's 'TextDecoder' implementation.
- */
-export function newTextDecoder(): TextDecoder {
-  return new TextDecoder('utf-8');
-}
diff --git a/packages/firestore/src/platform/node/text_serializer.ts b/packages/firestore/src/platform/node/text_serializer.ts
new file mode 100644
index 00000000000..cc7852e5f4b
--- /dev/null
+++ b/packages/firestore/src/platform/node/text_serializer.ts
@@ -0,0 +1,32 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { TextDecoder, TextEncoder } from 'util';
+
+/**
+ * An instance of the Platform's 'TextEncoder' implementation.
+ */
+export function newTextEncoder(): TextEncoder {
+  return new TextEncoder();
+}
+
+/**
+ * An instance of the Platform's 'TextDecoder' implementation.
+ */
+export function newTextDecoder(): TextDecoder {
+  return new TextDecoder('utf-8');
+}
diff --git a/packages/firestore/src/platform/node_lite/text_serializer.ts b/packages/firestore/src/platform/node_lite/text_serializer.ts
new file mode 100644
index 00000000000..efc3610847d
--- /dev/null
+++ b/packages/firestore/src/platform/node_lite/text_serializer.ts
@@ -0,0 +1,18 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export * from '../browser_lite/text_serializer';
diff --git a/packages/firestore/src/platform/rn/serializer.ts b/packages/firestore/src/platform/rn/serializer.ts
index 2b168a0dffa..c5ab7bf2bb5 100644
--- a/packages/firestore/src/platform/rn/serializer.ts
+++ b/packages/firestore/src/platform/rn/serializer.ts
@@ -15,8 +15,4 @@
  * limitations under the License.
  */
 
-export {
-  newSerializer,
-  newTextEncoder,
-  newTextDecoder
-} from '../browser/serializer';
+export { newSerializer } from '../browser/serializer';
diff --git a/packages/firestore/src/platform/rn/text_serializer.ts b/packages/firestore/src/platform/rn/text_serializer.ts
new file mode 100644
index 00000000000..8edf69e42f2
--- /dev/null
+++ b/packages/firestore/src/platform/rn/text_serializer.ts
@@ -0,0 +1,18 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export { newTextEncoder, newTextDecoder } from '../browser/text_serializer';
diff --git a/packages/firestore/src/platform/rn_lite/text_serializer.ts b/packages/firestore/src/platform/rn_lite/text_serializer.ts
new file mode 100644
index 00000000000..efc3610847d
--- /dev/null
+++ b/packages/firestore/src/platform/rn_lite/text_serializer.ts
@@ -0,0 +1,18 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export * from '../browser_lite/text_serializer';
diff --git a/packages/firestore/src/platform/serializer.ts b/packages/firestore/src/platform/serializer.ts
index 89e8fe650d1..47b659f5664 100644
--- a/packages/firestore/src/platform/serializer.ts
+++ b/packages/firestore/src/platform/serializer.ts
@@ -15,15 +15,9 @@
  * limitations under the License.
  */
 
-import { isNode, isReactNative } from '@firebase/util';
-
 import { DatabaseId } from '../core/database_info';
 import { JsonProtoSerializer } from '../remote/serializer';
 
-import * as browser from './browser/serializer';
-import * as node from './node/serializer';
-import * as rn from './rn/serializer';
-
 // This file is only used under ts-node.
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 const platform = require(`./${process.env.TEST_PLATFORM ?? 'node'}/serializer`);
@@ -31,29 +25,3 @@ const platform = require(`./${process.env.TEST_PLATFORM ?? 'node'}/serializer`);
 export function newSerializer(databaseId: DatabaseId): JsonProtoSerializer {
   return platform.newSerializer(databaseId);
 }
-
-/**
- * An instance of the Platform's 'TextEncoder' implementation.
- */
-export function newTextEncoder(): TextEncoder {
-  if (isNode()) {
-    return node.newTextEncoder();
-  } else if (isReactNative()) {
-    return rn.newTextEncoder();
-  } else {
-    return browser.newTextEncoder();
-  }
-}
-
-/**
- * An instance of the Platform's 'TextDecoder' implementation.
- */
-export function newTextDecoder(): TextDecoder {
-  if (isNode()) {
-    return node.newTextDecoder() as TextDecoder;
-  } else if (isReactNative()) {
-    return rn.newTextDecoder();
-  } else {
-    return browser.newTextDecoder();
-  }
-}
diff --git a/packages/firestore/src/platform/text_serializer.ts b/packages/firestore/src/platform/text_serializer.ts
new file mode 100644
index 00000000000..72ebba86c3c
--- /dev/null
+++ b/packages/firestore/src/platform/text_serializer.ts
@@ -0,0 +1,48 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { isNode, isReactNative } from '@firebase/util';
+
+import * as browser from './browser/text_serializer';
+import * as node from './node/text_serializer';
+import * as rn from './rn/text_serializer';
+
+/**
+ * An instance of the Platform's 'TextEncoder' implementation.
+ */
+export function newTextEncoder(): TextEncoder {
+  if (isNode()) {
+    return node.newTextEncoder();
+  } else if (isReactNative()) {
+    return rn.newTextEncoder();
+  } else {
+    return browser.newTextEncoder();
+  }
+}
+
+/**
+ * An instance of the Platform's 'TextDecoder' implementation.
+ */
+export function newTextDecoder(): TextDecoder {
+  if (isNode()) {
+    return node.newTextDecoder() as TextDecoder;
+  } else if (isReactNative()) {
+    return rn.newTextDecoder();
+  } else {
+    return browser.newTextDecoder();
+  }
+}
diff --git a/packages/firestore/src/util/bundle_reader_impl.ts b/packages/firestore/src/util/bundle_reader_impl.ts
index 3f08218d2fc..05875fce1af 100644
--- a/packages/firestore/src/util/bundle_reader_impl.ts
+++ b/packages/firestore/src/util/bundle_reader_impl.ts
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import { newTextDecoder } from '../platform/serializer';
+import { newTextDecoder } from '../platform/text_serializer';
 import { BundleMetadata } from '../protos/firestore_bundle_proto';
 import { JsonProtoSerializer } from '../remote/serializer';
 
diff --git a/packages/firestore/test/unit/specs/spec_test_runner.ts b/packages/firestore/test/unit/specs/spec_test_runner.ts
index e64dcbfd214..675e057ed42 100644
--- a/packages/firestore/test/unit/specs/spec_test_runner.ts
+++ b/packages/firestore/test/unit/specs/spec_test_runner.ts
@@ -90,7 +90,7 @@ import { Mutation } from '../../../src/model/mutation';
 import { JsonObject } from '../../../src/model/object_value';
 import { encodeBase64 } from '../../../src/platform/base64';
 import { toByteStreamReader } from '../../../src/platform/byte_stream_reader';
-import { newTextEncoder } from '../../../src/platform/serializer';
+import { newTextEncoder } from '../../../src/platform/text_serializer';
 import * as api from '../../../src/protos/firestore_proto_api';
 import { ExistenceFilter } from '../../../src/remote/existence_filter';
 import {
diff --git a/packages/firestore/test/unit/util/bundle.test.ts b/packages/firestore/test/unit/util/bundle.test.ts
index 9f225138491..b32ca0842b7 100644
--- a/packages/firestore/test/unit/util/bundle.test.ts
+++ b/packages/firestore/test/unit/util/bundle.test.ts
@@ -18,7 +18,7 @@ import { expect, use } from 'chai';
 import chaiAsPromised from 'chai-as-promised';
 
 import { toByteStreamReader } from '../../../src/platform/byte_stream_reader';
-import { newTextEncoder } from '../../../src/platform/serializer';
+import { newTextEncoder } from '../../../src/platform/text_serializer';
 import {
   BundleReader,
   SizedBundleElement
diff --git a/packages/firestore/test/unit/util/bundle_data.ts b/packages/firestore/test/unit/util/bundle_data.ts
index 03bc8b35f4c..92cfb8c30cd 100644
--- a/packages/firestore/test/unit/util/bundle_data.ts
+++ b/packages/firestore/test/unit/util/bundle_data.ts
@@ -22,10 +22,8 @@ import {
   queryWithLimit
 } from '../../../src/core/query';
 import { DocumentKey } from '../../../src/model/document_key';
-import {
-  newSerializer,
-  newTextEncoder
-} from '../../../src/platform/serializer';
+import { newSerializer } from '../../../src/platform/serializer';
+import { newTextEncoder } from '../../../src/platform/text_serializer';
 import {
   BundleElement,
   LimitType as BundleLimitType

From 897f9545bfef68e6b35d74b5a953a421097e458c Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Wed, 8 Feb 2023 23:26:37 -0500
Subject: [PATCH 2/4] Improve decodeBase64() to throw on invalid input rather
 than silently accept it

---
 common/api-review/util.api.md                 |  8 ++++++
 packages/firestore/src/platform/base64.ts     | 13 +++++++++-
 .../firestore/src/platform/browser/base64.ts  | 12 ++++++++-
 packages/firestore/src/platform/rn/base64.ts  | 26 +++++++++++++------
 .../firestore/src/util/base64_decode_error.ts | 23 ++++++++++++++++
 .../firestore/test/lite/integration.test.ts   |  2 +-
 packages/util/src/crypt.ts                    |  9 ++++++-
 7 files changed, 81 insertions(+), 12 deletions(-)
 create mode 100644 packages/firestore/src/util/base64_decode_error.ts

diff --git a/common/api-review/util.api.md b/common/api-review/util.api.md
index be8703adf3f..75e484edd50 100644
--- a/common/api-review/util.api.md
+++ b/common/api-review/util.api.md
@@ -93,6 +93,14 @@ export function createSubscribe<T>(executor: Executor<T>, onNoObservers?: Execut
 // @public
 export const decode: (token: string) => DecodedToken;
 
+// Warning: (ae-missing-release-tag) "DecodeBase64StringError" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
+//
+// @public
+export class DecodeBase64StringError extends Error {
+    // (undocumented)
+    readonly name = "DecodeBase64StringError";
+}
+
 // Warning: (ae-missing-release-tag) "deepCopy" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
 // @public
diff --git a/packages/firestore/src/platform/base64.ts b/packages/firestore/src/platform/base64.ts
index 877a78c732b..3efd0339e77 100644
--- a/packages/firestore/src/platform/base64.ts
+++ b/packages/firestore/src/platform/base64.ts
@@ -15,13 +15,24 @@
  * limitations under the License.
  */
 
+import { Base64DecodeError } from '../util/base64_decode_error';
+
 // This file is only used under ts-node.
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 const platform = require(`./${process.env.TEST_PLATFORM ?? 'node'}/base64`);
 
 /** Converts a Base64 encoded string to a binary string. */
 export function decodeBase64(encoded: string): string {
-  return platform.decodeBase64(encoded);
+  const decoded = platform.decodeBase64(encoded);
+
+  // A quick sanity check as node and rn will not throw error if input is an
+  // invalid base64 string, e.g., "A===".
+  const expectedEncodedLength = 4 * Math.ceil(decoded.length / 3);
+  if (encoded.length !== expectedEncodedLength) {
+    throw new Base64DecodeError('Invalid base64 string');
+  }
+
+  return decoded;
 }
 
 /** Converts a binary string to a Base64 encoded string. */
diff --git a/packages/firestore/src/platform/browser/base64.ts b/packages/firestore/src/platform/browser/base64.ts
index 6c068b17244..4cbbfe6ced9 100644
--- a/packages/firestore/src/platform/browser/base64.ts
+++ b/packages/firestore/src/platform/browser/base64.ts
@@ -15,9 +15,19 @@
  * limitations under the License.
  */
 
+import { Base64DecodeError } from '../../util/base64_decode_error';
+
 /** Converts a Base64 encoded string to a binary string. */
 export function decodeBase64(encoded: string): string {
-  return atob(encoded);
+  try {
+    return atob(encoded);
+  } catch (e) {
+    if (e instanceof DOMException) {
+      throw new Base64DecodeError('Invalid base64 string: ' + e);
+    } else {
+      throw e;
+    }
+  }
 }
 
 /** Converts a binary string to a Base64 encoded string. */
diff --git a/packages/firestore/src/platform/rn/base64.ts b/packages/firestore/src/platform/rn/base64.ts
index 4032190e5cd..f50c604ebf7 100644
--- a/packages/firestore/src/platform/rn/base64.ts
+++ b/packages/firestore/src/platform/rn/base64.ts
@@ -15,7 +15,9 @@
  * limitations under the License.
  */
 
-import { base64 } from '@firebase/util';
+import { base64, DecodeBase64StringError } from '@firebase/util';
+
+import { Base64DecodeError } from '../../util/base64_decode_error';
 
 // WebSafe uses a different URL-encoding safe alphabet that doesn't match
 // the encoding used on the backend.
@@ -23,13 +25,21 @@ const WEB_SAFE = false;
 
 /** Converts a Base64 encoded string to a binary string. */
 export function decodeBase64(encoded: string): string {
-  return String.fromCharCode.apply(
-    null,
-    // We use `decodeStringToByteArray()` instead of `decodeString()` since
-    // `decodeString()` returns Unicode strings, which doesn't match the values
-    // returned by `atob()`'s Latin1 representation.
-    base64.decodeStringToByteArray(encoded, WEB_SAFE)
-  );
+  try {
+    return String.fromCharCode.apply(
+      null,
+      // We use `decodeStringToByteArray()` instead of `decodeString()` since
+      // `decodeString()` returns Unicode strings, which doesn't match the values
+      // returned by `atob()`'s Latin1 representation.
+      base64.decodeStringToByteArray(encoded, WEB_SAFE)
+    );
+  } catch (e) {
+    if (e instanceof DecodeBase64StringError) {
+      throw new Base64DecodeError('Invalid base64 string: ' + e);
+    } else {
+      throw e;
+    }
+  }
 }
 
 /** Converts a binary string to a Base64 encoded string. */
diff --git a/packages/firestore/src/util/base64_decode_error.ts b/packages/firestore/src/util/base64_decode_error.ts
new file mode 100644
index 00000000000..84a20c55d1d
--- /dev/null
+++ b/packages/firestore/src/util/base64_decode_error.ts
@@ -0,0 +1,23 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * An error encountered while decoding base64 string.
+ */
+export class Base64DecodeError extends Error {
+  readonly name = 'Base64DecodeError';
+}
diff --git a/packages/firestore/test/lite/integration.test.ts b/packages/firestore/test/lite/integration.test.ts
index 54c595f9684..0cb6170652c 100644
--- a/packages/firestore/test/lite/integration.test.ts
+++ b/packages/firestore/test/lite/integration.test.ts
@@ -852,7 +852,7 @@ describe('DocumentSnapshot', () => {
 
   it('returns Bytes', () => {
     return withTestDocAndInitialData(
-      { bytes: Bytes.fromBase64String('aa') },
+      { bytes: Bytes.fromBase64String('aa==') },
       async docRef => {
         const docSnap = await getDoc(docRef);
         const bytes = docSnap.get('bytes');
diff --git a/packages/util/src/crypt.ts b/packages/util/src/crypt.ts
index df1e058756f..7cd32125043 100644
--- a/packages/util/src/crypt.ts
+++ b/packages/util/src/crypt.ts
@@ -284,7 +284,7 @@ export const base64: Base64 = {
       ++i;
 
       if (byte1 == null || byte2 == null || byte3 == null || byte4 == null) {
-        throw Error();
+        throw new DecodeBase64StringError();
       }
 
       const outByte1 = (byte1 << 2) | (byte2 >> 4);
@@ -333,6 +333,13 @@ export const base64: Base64 = {
   }
 };
 
+/**
+ * An error encountered while decoding base64 string.
+ */
+export class DecodeBase64StringError extends Error {
+  readonly name = 'DecodeBase64StringError';
+}
+
 /**
  * URL-safe base64 encoding
  */

From f4eae6e9285f883d9771631fa3ab8c8430baeb02 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 10 Feb 2023 00:50:38 -0500
Subject: [PATCH 3/4] changeset added

---
 .changeset/large-lemons-relax.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .changeset/large-lemons-relax.md

diff --git a/.changeset/large-lemons-relax.md b/.changeset/large-lemons-relax.md
new file mode 100644
index 00000000000..8df076bb896
--- /dev/null
+++ b/.changeset/large-lemons-relax.md
@@ -0,0 +1,6 @@
+---
+'@firebase/firestore': patch
+'firebase': patch
+---
+
+Internal refactor of platform-specific logic to create TextEncoder and TextDecoder objects.

From 3f058974252a1d99620e28ce485c6275e368f335 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Fri, 10 Feb 2023 09:12:56 -0500
Subject: [PATCH 4/4] changeset added

---
 .changeset/popular-apples-peel.md | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 .changeset/popular-apples-peel.md

diff --git a/.changeset/popular-apples-peel.md b/.changeset/popular-apples-peel.md
new file mode 100644
index 00000000000..3269c43d903
--- /dev/null
+++ b/.changeset/popular-apples-peel.md
@@ -0,0 +1,7 @@
+---
+'@firebase/firestore': patch
+'@firebase/util': patch
+'firebase': patch
+---
+
+Modify base64 decoding logic to throw on invalid input, rather than silently truncating it.