Added fix for duplication scenario (#16)

* Added fix for duplication scenario

* Minor whitespace fix

.gitignore

@@ -1,2 +1,2 @@
 .vscode/settings.json
-.build-*
+.build*

include/Hdlcpp.hpp

@@ -290,7 +290,8 @@ class Hdlcpp {
                 result = -EIO;
             }
 
-            discardBytes = i;
+            // Be sure to discard bytes (could be that destinationIndex > i in some cases)
+            discardBytes = destinationIndex > i ? destinationIndex : i;
             resetValues();
         }
 

test/src/TestHdlcpp.cpp

@@ -228,4 +228,22 @@ TEST_CASE_METHOD(HdlcppFixture, "hdlcpp test", "[single-file]")
         readBuffer.assign(frame1, frame1 + sizeof(frame1));
         CHECK(hdlcpp->read(buffer, sizeof(buffer)) == 2);
     }
+
+    SECTION("Test duplication scenario")
+    {
+        // Frames captured from duplication scenario
+        const uint8_t frame1[] = { 0x7e, 0xff };
+        const uint8_t frame2[] = { 0x12, 0x4a, 0x07, 0x0a, 0x01, 0x03, 0x18, 0x07, 0x20, 0x64, 0xd5, 0x97 };
+        const uint8_t frame3[] = { 0x7e };
+        const uint8_t frame4[] = { 0x7e, 0xff, 0x61, 0x08, 0x82 };
+
+        readBuffer.assign(frame1, frame1 + sizeof(frame1));
+        CHECK(hdlcpp->read(buffer, sizeof(buffer)) == -ENOMSG);
+        readBuffer.assign(frame2, frame2 + sizeof(frame2));
+        CHECK(hdlcpp->read(buffer, sizeof(buffer)) == -ENOMSG);
+        readBuffer.assign(frame3, frame3 + sizeof(frame3));
+        CHECK(hdlcpp->read(buffer, sizeof(buffer)) == 9);
+        readBuffer.assign(frame4, frame4 + sizeof(frame4));
+        CHECK(hdlcpp->read(buffer, sizeof(buffer)) == -ENOMSG);
+    }
 }