From a9335ed4c7e5ad4f7f0bdfa1ddca7838c32961d1 Mon Sep 17 00:00:00 2001
From: Zach Anderson <zra@google.com>
Date: Tue, 13 Aug 2019 12:26:21 -0700
Subject: [PATCH] Catch FormatException in packet decoding.

---
 packages/multicast_dns/CHANGELOG.md          |   3 +
 packages/multicast_dns/lib/src/packet.dart   |   3 +
 packages/multicast_dns/pubspec.yaml          |   2 +-
 packages/multicast_dns/test/decode_test.dart | 259 +++++++++++++++++++
 4 files changed, 266 insertions(+), 1 deletion(-)

diff --git a/packages/multicast_dns/CHANGELOG.md b/packages/multicast_dns/CHANGELOG.md
index 29e2aefc1d..da11f54bb5 100644
--- a/packages/multicast_dns/CHANGELOG.md
+++ b/packages/multicast_dns/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 0.2.1
+* Fixes the handling of packets containing non-utf8 strings.
+
 ## 0.2.0
 * Allow configuration of the port and address the mdns query is performed on.
 
diff --git a/packages/multicast_dns/lib/src/packet.dart b/packages/multicast_dns/lib/src/packet.dart
index eac3f6793f..7e1e5e71af 100644
--- a/packages/multicast_dns/lib/src/packet.dart
+++ b/packages/multicast_dns/lib/src/packet.dart
@@ -366,6 +366,9 @@ List<ResourceRecord> decodeMDnsResponse(List<int> packet) {
   } on MDnsDecodeException {
     // If decoding fails return null.
     return null;
+  } on FormatException {
+    // If decoding fails on a non-utf8 packet, return null.
+    return null;
   }
   return result;
 }
diff --git a/packages/multicast_dns/pubspec.yaml b/packages/multicast_dns/pubspec.yaml
index 8eb23b7976..2c20513227 100644
--- a/packages/multicast_dns/pubspec.yaml
+++ b/packages/multicast_dns/pubspec.yaml
@@ -2,7 +2,7 @@ name: multicast_dns
 description: Dart package for mDNS queries (e.g. Bonjour, Avahi).
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/packages/tree/master/packages/multicast_dns
-version: 0.2.0
+version: 0.2.1
 
 dependencies:
   meta: ^1.1.6
diff --git a/packages/multicast_dns/test/decode_test.dart b/packages/multicast_dns/test/decode_test.dart
index 56aa02026a..637d3a0324 100644
--- a/packages/multicast_dns/test/decode_test.dart
+++ b/packages/multicast_dns/test/decode_test.dart
@@ -13,6 +13,7 @@ const int _kSrvHeaderSize = 6;
 void main() {
   testValidPackages();
   testBadPackages();
+  testNonUtf8Packages();
   // testHexDumpList();
   testPTRRData();
   testSRVRData();
@@ -175,6 +176,12 @@ void testBadPackages() {
   });
 }
 
+void testNonUtf8Packages() {
+  test('Returns null for non-utf8 text resource', () {
+    expect(decodeMDnsResponse(nonUtf8Package), isNull);
+  });
+}
+
 void testPTRRData() {
   test('Can read FQDN from PTR data', () {
     expect('sgjesse-macbookpro2 [78:31:c1:b8:55:38]._workstation._tcp.local',
@@ -1178,3 +1185,255 @@ const List<int> packetWithoutQuestionWithAnArCount = <int>[
   50,
   51,
 ];
+
+// Package with a text resource that is not valid utf8.
+const List<int> nonUtf8Package = <int>[
+  0x00,
+  0x00,
+  0x84,
+  0x00,
+  0x00,
+  0x00,
+  0x00,
+  0x08,
+  0x00,
+  0x00,
+  0x00,
+  0x00,
+  0x1f,
+  0x72,
+  0x61,
+  0x73,
+  0x70,
+  0x62,
+  0x65,
+  0x72,
+  0x72,
+  0x79,
+  0x70,
+  0x69,
+  0x20,
+  0x5b,
+  0x62,
+  0x38,
+  0x3a,
+  0x32,
+  0x37,
+  0x3a,
+  0x65,
+  0x62,
+  0xd2,
+  0x30,
+  0x33,
+  0x3a,
+  0x39,
+  0x32,
+  0x3a,
+  0x34,
+  0x62,
+  0x5d,
+  0x0c,
+  0x5f,
+  0x77,
+  0x6f,
+  0x72,
+  0x6b,
+  0x73,
+  0x74,
+  0x61,
+  0x74,
+  0x69,
+  0x6f,
+  0x6e,
+  0x04,
+  0x5f,
+  0x74,
+  0x63,
+  0x70,
+  0x05,
+  0x6c,
+  0x6f,
+  0x63,
+  0x61,
+  0x6c,
+  0x00,
+  0x00,
+  0x10,
+  0x80,
+  0x01,
+  0x00,
+  0x00,
+  0x11,
+  0x94,
+  0x00,
+  0x01,
+  0x00,
+  0x0b,
+  0x5f,
+  0x75,
+  0x64,
+  0x69,
+  0x73,
+  0x6b,
+  0x73,
+  0x2d,
+  0x73,
+  0x73,
+  0x68,
+  0xc0,
+  0x39,
+  0x00,
+  0x0c,
+  0x00,
+  0x01,
+  0x00,
+  0x00,
+  0x11,
+  0x94,
+  0x00,
+  0x0e,
+  0x0b,
+  0x72,
+  0x61,
+  0x73,
+  0x70,
+  0x62,
+  0x65,
+  0x72,
+  0x72,
+  0x79,
+  0x70,
+  0x69,
+  0xc0,
+  0x50,
+  0xc0,
+  0x68,
+  0x00,
+  0x21,
+  0x80,
+  0x01,
+  0x00,
+  0x00,
+  0x00,
+  0x78,
+  0x00,
+  0x14,
+  0x00,
+  0x00,
+  0x00,
+  0x00,
+  0x00,
+  0x16,
+  0x0b,
+  0x72,
+  0x61,
+  0x73,
+  0x70,
+  0x62,
+  0x65,
+  0x72,
+  0x72,
+  0x79,
+  0x70,
+  0x69,
+  0xc0,
+  0x3e,
+  0xc0,
+  0x68,
+  0x00,
+  0x10,
+  0x80,
+  0x01,
+  0x00,
+  0x00,
+  0x11,
+  0x94,
+  0x00,
+  0x01,
+  0x00,
+  0x09,
+  0x5f,
+  0x73,
+  0x65,
+  0x72,
+  0x76,
+  0x69,
+  0x63,
+  0x65,
+  0x73,
+  0x07,
+  0x5f,
+  0x64,
+  0x6e,
+  0x73,
+  0x2d,
+  0x73,
+  0x64,
+  0x04,
+  0x5f,
+  0x75,
+  0x64,
+  0x70,
+  0xc0,
+  0x3e,
+  0x00,
+  0x0c,
+  0x00,
+  0x01,
+  0x00,
+  0x00,
+  0x11,
+  0x94,
+  0x00,
+  0x02,
+  0xc0,
+  0x50,
+  0xc0,
+  0x2c,
+  0x00,
+  0x0c,
+  0x00,
+  0x01,
+  0x00,
+  0x00,
+  0x11,
+  0x94,
+  0x00,
+  0x02,
+  0xc0,
+  0x0c,
+  0xc0,
+  0x0c,
+  0x00,
+  0x21,
+  0x80,
+  0x01,
+  0x00,
+  0x00,
+  0x00,
+  0x78,
+  0x00,
+  0x08,
+  0x00,
+  0x00,
+  0x00,
+  0x00,
+  0x00,
+  0x09,
+  0xc0,
+  0x88,
+  0xc0,
+  0xa3,
+  0x00,
+  0x0c,
+  0x00,
+  0x01,
+  0x00,
+  0x00,
+  0x11,
+  0x94,
+  0x00,
+  0x02,
+  0xc0,
+  0x2c
+];