fixed IndexOfBytes bug

RtspClientSharp.UnitTests/Utils/ArrayUtilsTests.cs

@@ -95,6 +95,17 @@ public void IndexOfBytes_PatternExists_ReturnsActualIndex()
             Assert.AreEqual(4, index);
         }
 
+        [TestMethod]
+        public void IndexOfBytes_PatternExists_BackTrack_ReturnsActualIndex()
+        {
+            var pattern = new byte[] { 0, 0, 1 };
+            var bytes = new byte[] { 0, 5, 0, 0, 0, 1, 3, 4 };
+
+            int index = ArrayUtils.IndexOfBytes(bytes, pattern, 1, bytes.Length - 1);
+
+            Assert.AreEqual(3, index);
+        }
+
         [TestMethod]
         public void IndexOfBytes_PatternNotExists_ReturnsMinusOne()
         {

RtspClientSharp/Utils/ArrayUtils.cs

@@ -57,7 +57,14 @@ public static int IndexOfBytes(byte[] array, byte[] pattern, int startIndex, int
             for (; startIndex < endIndex; startIndex++)
             {
                 if (array[startIndex] != pattern[foundIndex])
+                {
+                    // When the pattern is partially found but then mismatches, the start search index
+                    // must be moved back to index just after where the original successful matching started.
+                    // Otherwise, matches that begin within an attempted match would be missed.
+                    // e.g., array: 123400001567, pattern: 0001, would errnoneously return -1
+                    startIndex -= foundIndex; // for loop will then add 1
                     foundIndex = 0;
+                }
                 else if (++foundIndex == patternLength)
                     return startIndex - foundIndex + 1;
             }