add recovery handler

main.go

@@ -91,6 +91,13 @@ type geminiHandler interface {
 	Handle(geminiResponse, geminiRequest)
 }
 
+type geminiHandlerFunc func(geminiResponse, geminiRequest)
+
+// Handle calls f(w, r).
+func (f geminiHandlerFunc) Handle(w geminiResponse, r geminiRequest) {
+	f(w, r)
+}
+
 // implementations
 type staticGeminiHandler struct {
 	StaticString string
@@ -163,6 +170,21 @@ func (h fsGeminiHandler) Handle(w geminiResponse, r geminiRequest) {
 	io.Copy(w, source)
 }
 
+func recoveryHandler(next geminiHandler) geminiHandler {
+	return geminiHandlerFunc(func(w geminiResponse, r geminiRequest) {
+		defer func() {
+			err := recover()
+			if err != nil {
+				log.Println(err)
+				w.WriteStatus(responseCodes["TEMPORARYFAILURE"], "Internal Error")
+				return
+			}
+		}()
+
+		next.Handle(w, r)
+	})
+}
+
 // handler for general http queries (fallthrough for certmagic)
 type genericHTTPHandler struct {
 	StaticString string
@@ -192,7 +214,7 @@ func handleConnection(log Logger, conn net.Conn, h geminiHandler) {
 	r := request{
 		url: u,
 	}
-	h.Handle(&w, r)
+	recoveryHandler(h).Handle(&w, r)
 }
 
 func main() {