Add support for .tif/.tiff files (#32)

Author: detilium

src/ByteGuard.FileValidator/FileExtensions.cs

@@ -134,5 +134,15 @@ public static class FileExtensions
         /// Graphics Interchange Format.
         /// </summary>
         public const string Gif = ".gif";
+
+        /// <summary>
+        /// Tag Image File Format.
+        /// </summary>
+        public const string Tif = ".tif";
+
+        /// <summary>
+        /// Tag Image File Format.
+        /// </summary>
+        public const string Tiff = ".tiff";
     }
 }

src/ByteGuard.FileValidator/FileValidator.cs

@@ -265,6 +265,28 @@ public class FileValidator
                 {
                     new byte[] { 0x47, 0x49, 0x46, 0x38 }, // GIF8
                 }
+            },
+            new FileDefinition
+            {
+                FileType = FileExtensions.Tif,
+                ValidSignatures = new List<byte[]>
+                {
+                    new byte[] { 0x49, 0x49, 0x2A, 0x00 }, // II*␀ (Intel byte order)
+                    new byte[] { 0x4D, 0x4D, 0x00, 0x2A }, // MM␀* (Motorola byte order)
+                    new byte[] { 0x49, 0x49, 0x2B, 0x00 }, // II+␀ (BigTIFF, Intel byte order)
+                    new byte[] { 0x4D, 0x4D, 0x00, 0x2B }  // MM␀+ (BigTIFF, Motorola byte order)
+                }
+            },
+            new FileDefinition
+            {
+                FileType = FileExtensions.Tiff,
+                ValidSignatures = new List<byte[]>
+                {
+                    new byte[] { 0x49, 0x49, 0x2A, 0x00 }, // II*␀ (Intel byte order)
+                    new byte[] { 0x4D, 0x4D, 0x00, 0x2A }, // MM␀* (Motorola byte order)
+                    new byte[] { 0x49, 0x49, 0x2B, 0x00 }, // II+␀ (BigTIFF, Intel byte order)
+                    new byte[] { 0x4D, 0x4D, 0x00, 0x2B }  // MM␀+ (BigTIFF, Motorola byte order)
+                }
             }
         };