Add configuration option Lang

CONFIGURATION.md

@@ -133,6 +133,10 @@ Request sensitive text input from the user. Text will not be shown as it is ente
 When enabled, directories without an index file will serve a list of their
 contents.  This attribute is disabled by default.
 
+##### Lang
+
+Specifies content language. This is sent to clients via the MIME type `lang` parameter.
+
 ##### Log
 
 Path to log file. Requests are logged in [Apache format](https://httpd.apache.org/docs/2.2/logs.html#combined),
@@ -199,6 +203,7 @@ hosts:
   default: # Default host configuration
     paths: # Default path attributes
       -
+        lang: en
         log: /srv/log/gemini.log
         symlinks: true # Follow symbolic links
   gemini.rocks:

config.go

@@ -50,6 +50,9 @@ type pathConfig struct {
 	// FastCGI server address
 	FastCGI string
 
+	// Language
+	Lang string
+
 	// Log file
 	Log string
 
@@ -188,6 +191,9 @@ func readconfig(configPath string) error {
 					if defaultPath.FastCGI != "" && serve.FastCGI == "" {
 						serve.FastCGI = defaultPath.FastCGI
 					}
+					if defaultPath.Lang != "" && serve.Lang == "" {
+						serve.Lang = defaultPath.Lang
+					}
 					if defaultPath.Log != "" && serve.Log == "" {
 						serve.Log = defaultPath.Log
 					}

server.go

@@ -82,19 +82,27 @@ func writeStatus(c net.Conn, code int) int {
 }
 
 func writeSuccess(c net.Conn, serve *pathConfig, contentType string, size int64) int {
+	// Content type
 	meta := contentType
 	if serve.Type != "" {
 		meta = serve.Type
 	}
 
-	if !config.DisableSize && size >= 0 {
-		meta += fmt.Sprintf("; size=%d", size)
-	}
-
+	// Cache
 	if serve.cache != cacheUnset {
 		meta += fmt.Sprintf("; cache=%d", serve.cache)
 	}
 
+	// Language
+	if serve.Lang != "" {
+		meta += fmt.Sprintf("; lang=%s", serve.Lang)
+	}
+
+	// Size
+	if !config.DisableSize && size >= 0 {
+		meta += fmt.Sprintf("; size=%d", size)
+	}
+
 	writeHeader(c, statusSuccess, meta)
 	return statusSuccess
 }