Improve renaming of files for http-uplad

Characters get replaced by `_` now instead of being removed and
`-`, `_`, `.` and `+` won't be removed anymore. (Thx Holger Weiß)

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## [Unreleased]
 ### Changed
-- Rename files to use alpha numerical file name before uploading. Workaround for https://github.com/mattn/go-xmpp/issues/132
+- Rename files to use a limited character set (alpha numerical and some extra characters) file name before uploading. Workaround for https://github.com/mattn/go-xmpp/issues/132
 
 ## [v0.1.2]
 ### Changed

httpupload.go

@@ -134,11 +134,11 @@ func httpUpload(client *xmpp.Client, jserver string, filePath string) string {
 	fileName := filepath.Base(filePath)
 	// Just use alphanumerical characters for now to work around
 	// https://github.com/mattn/go-xmpp/issues/132
-	reg, err := regexp.Compile("[^a-zA-Z0-9.]+")
+	reg, err := regexp.Compile(`[^a-zA-Z0-9\+\-\_\.]+`)
 	if err != nil {
 		log.Fatal(err)
 	}
-	fileNameEscaped := reg.ReplaceAllString(fileName, "")
+	fileNameEscaped := reg.ReplaceAllString(fileName, "_")
 	//var fileNameEscaped bytes.Buffer
 	//xml.Escape(&fileNameEscaped, []byte(fileName))