Stricter UTF-8, so ascii characters can't get encoded as multi-bytes and pass validations

nel/src/misc/utf_string_view.cpp

@@ -287,6 +287,12 @@ u32char CUtfStringView::utf8Iterator(const void **addr)
 								// Replacement character <20>
 								return 0xFFFD;
 							}
+							else if (c0 < 0x10000)
+							{
+								// Invalid encoding
+								// Replacement character <20>
+								return 0xFFFD;
+							}
 						}
 						else
 						{
@@ -320,6 +326,12 @@ u32char CUtfStringView::utf8Iterator(const void **addr)
 						// Replacement character <20>
 						return 0xFFFD;
 					}
+					else if (c0 < 0x0800)
+					{
+						// Invalid encoding
+						// Replacement character <20>
+						return 0xFFFD;
+					}
 				}
 				else
 				{
@@ -327,6 +339,12 @@ u32char CUtfStringView::utf8Iterator(const void **addr)
 					return 0xFFFD;
 				}
 			}
+			else if (c0 < 0x80)
+			{
+				// Invalid encoding
+				// Replacement character <20>
+				return 0xFFFD;
+			}
 		}
 		else
 		{