From 9b2c8fbfbc2d86ae15313d1a8d7896598bc8a22f Mon Sep 17 00:00:00 2001
From: Andreas Huber <andreas.huber@lawo.com>
Date: Wed, 30 Nov 2016 13:52:16 +0100
Subject: [PATCH] Ignore invalid frames

Closes #30
---
 Lawo.EmberPlusSharp/S101/DeframingStream.cs    | 10 +++++++---
 Lawo.EmberPlusSharpTest/S101/S101ReaderTest.cs | 15 +++++++++++----
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/Lawo.EmberPlusSharp/S101/DeframingStream.cs b/Lawo.EmberPlusSharp/S101/DeframingStream.cs
index f4e54eff..07e2966f 100644
--- a/Lawo.EmberPlusSharp/S101/DeframingStream.cs
+++ b/Lawo.EmberPlusSharp/S101/DeframingStream.cs
@@ -112,18 +112,22 @@ private bool ReadByte(ReadBuffer readBuffer)
                             case Frame.EscapeByte:
                                 this.state = State.InFrameEscaped;
                                 break;
+                            case Frame.BeginOfFrame:
+                                this.decodedQueue.Clear();
+                                break;
                             case Frame.EndOfFrame:
                                 this.state = State.AfterFrame;
 
                                 if (this.crc != 0xF0B8)
                                 {
-                                    throw new S101Exception("CRC failed.");
+                                    this.decodedQueue.Clear();
                                 }
 
                                 return false;
                             default:
                                 this.state = State.AfterFrame;
-                                throw new S101Exception("Invalid byte in frame.");
+                                this.decodedQueue.Clear();
+                                break;
                         }
                     }
 
@@ -132,7 +136,7 @@ private bool ReadByte(ReadBuffer readBuffer)
                     if (currentByte >= Frame.InvalidStart)
                     {
                         this.state = State.AfterFrame;
-                        throw new S101Exception("Invalid escaped byte.");
+                        this.decodedQueue.Clear();
                     }
 
                     currentByte = (byte)(currentByte ^ Frame.EscapeXor);
diff --git a/Lawo.EmberPlusSharpTest/S101/S101ReaderTest.cs b/Lawo.EmberPlusSharpTest/S101/S101ReaderTest.cs
index 494585f3..57017ece 100644
--- a/Lawo.EmberPlusSharpTest/S101/S101ReaderTest.cs
+++ b/Lawo.EmberPlusSharpTest/S101/S101ReaderTest.cs
@@ -80,17 +80,17 @@ public void ExceptionTest()
                             () => reader.Message.Ignore(), () => reader.Payload.Ignore());
                     }
 
-                    await AssertS101Exception("CRC failed.", 0xFE, 0xFF);
-                    await AssertS101Exception("Invalid byte in frame.", 0xFE, 0xFE);
+                    await AssertEmpty(0xFE, 0xFF);
+                    await AssertEmpty(0xFE, 0xFE);
 
                     for (byte invalid = 0xF8; invalid < 0xFD; ++invalid)
                     {
-                        await AssertS101Exception("Invalid byte in frame.", 0xFE, invalid);
+                        await AssertEmpty(0xFE, invalid);
                     }
 
                     for (ushort invalid = 0xF8; invalid < 0x100; ++invalid)
                     {
-                        await AssertS101Exception("Invalid escaped byte.", 0xFE, 0xFD, (byte)invalid);
+                        await AssertEmpty(0xFE, 0xFD, (byte)invalid);
                     }
 
                     await AssertS101Exception("Unexpected end of stream.", 0xFE, 0x00, 0x00, 0x00);
@@ -186,6 +186,13 @@ await AssertThrowAsync<ObjectDisposedException>(
             }
         }
 
+        private static async Task AssertEmpty(params byte[] input)
+        {
+            var reader = CreateAsyncReader(input);
+            Assert.IsFalse(await reader.ReadAsync(CancellationToken.None));
+            await reader.DisposeAsync(CancellationToken.None);
+        }
+
         private static async Task AssertS101Exception(string message, params byte[] input)
         {
             var reader = CreateAsyncReader(input);