Add support for GIF banners with validation and improved error messages

- Add custom validator for banner file extensions (.jpg, .jpeg, .gif)
- Update HandleTranAgreed to dynamically detect banner type from file extension
- Export FileTypeFromFilename function for use across packages
- Add comprehensive test coverage for banner validation and type detection
- Improve error messages to clearly communicate allowed file extensions

2 files changed, 5 insertions, 5 deletions

diff --git a/hotline/config.go b/hotline/config.go
index a7bd81e..75d5c4d 100644
--- a/hotline/config.go
+++ b/hotline/config.go
@@ -3,7 +3,7 @@ package hotline
 type Config struct {
 	Name                      string   `yaml:"Name" validate:"required,max=50"`         // Name used for Tracker registration
 	Description               string   `yaml:"Description" validate:"required,max=200"` // Description used for Tracker registration
-	BannerFile                string   `yaml:"BannerFile"`                              // Path to Banner jpg
+	BannerFile                string   `yaml:"BannerFile" validate:"omitempty,bannerext"` // Path to Banner jpg or gif
 	FileRoot                  string   `yaml:"FileRoot" validate:"required"`            // Path to Files
 	EnableTrackerRegistration bool     `yaml:"EnableTrackerRegistration"`               // Toggle Tracker Registration
 	Trackers                  []string `yaml:"Trackers" validate:"dive,hostname_port"`  // List of trackers that the server should register with
diff --git a/hotline/files.go b/hotline/files.go
index a1db329..e9f7b4f 100644
--- a/hotline/files.go
+++ b/hotline/files.go
@@ -12,7 +12,7 @@ import (
 	"strings"
 )
 
-func fileTypeFromFilename(filename string) fileType {
+func FileTypeFromFilename(filename string) fileType {
 	fileExt := strings.ToLower(filepath.Ext(filename))
 	ft, ok := fileTypes[fileExt]
 	if ok {
@@ -26,7 +26,7 @@ func fileTypeFromInfo(info fs.FileInfo) (ft fileType, err error) {
 		ft.CreatorCode = "n/a "
 		ft.TypeCode = "fldr"
 	} else {
-		ft = fileTypeFromFilename(info.Name())
+		ft = FileTypeFromFilename(info.Name())
 	}
 
 	return ft, nil
@@ -87,8 +87,8 @@ func GetFileNameList(path string, ignoreList []string) (fields []Field, err erro
 				copy(fnwi.Creator[:], fileCreator)
 			} else {
 				binary.BigEndian.PutUint32(fnwi.FileSize[:], uint32(rFile.Size()))
-				copy(fnwi.Type[:], fileTypeFromFilename(rFile.Name()).TypeCode)
-				copy(fnwi.Creator[:], fileTypeFromFilename(rFile.Name()).CreatorCode)
+				copy(fnwi.Type[:], FileTypeFromFilename(rFile.Name()).TypeCode)
+				copy(fnwi.Creator[:], FileTypeFromFilename(rFile.Name()).CreatorCode)
 			}
 		} else if file.IsDir() {
 			dir, err := os.ReadDir(filepath.Join(path, file.Name()))