Add support for OGG files (#33)

Author: detilium

src/ByteGuard.FileValidator/FileExtensions.cs

@@ -144,5 +144,25 @@ public static class FileExtensions
         /// Tag Image File Format.
         /// </summary>
         public const string Tiff = ".tiff";
+
+        /// <summary>
+        /// Ogg Vorbis Audio.
+        /// </summary>
+        public const string Ogg = ".ogg";
+
+        /// <summary>
+        /// Ogg Vorbis Audio.
+        /// </summary>
+        public const string Oga = ".oga";
+
+        /// <summary>
+        /// Ogg Video.
+        /// </summary>
+        public const string Ogv = ".ogv";
+
+        /// <summary>
+        /// Ogg Multiplex.
+        /// </summary>
+        public const string Ogx = ".ogx";
     }
 }

src/ByteGuard.FileValidator/FileValidator.cs

@@ -287,6 +287,38 @@ public class FileValidator
                     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.Ogg,
+                ValidSignatures = new List<byte[]>
+                {
+                    new byte[] { 0x4F, 0x67, 0x67, 0x53 } // OggS
+                }
+            },
+            new FileDefinition
+            {
+                FileType = FileExtensions.Oga,
+                ValidSignatures = new List<byte[]>
+                {
+                    new byte[] { 0x4F, 0x67, 0x67, 0x53 } // OggS
+                }
+            },
+            new FileDefinition
+            {
+                FileType = FileExtensions.Ogv,
+                ValidSignatures = new List<byte[]>
+                {
+                    new byte[] { 0x4F, 0x67, 0x67, 0x53 } // OggS
+                }
+            },
+            new FileDefinition
+            {
+                FileType = FileExtensions.Ogx,
+                ValidSignatures = new List<byte[]>
+                {
+                    new byte[] { 0x4F, 0x67, 0x67, 0x53 } // OggS
+                }
             }
         };