From f3af5c902029d4802dc554d0a3f5050322597960 Mon Sep 17 00:00:00 2001
From: David Ashby <delta.mu.alpha@gmail.com>
Date: Sat, 12 Sep 2020 17:13:58 -0400
Subject: [PATCH] add recovery handler

---
 main.go | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/main.go b/main.go
index 4b6ccb6..a218d59 100644
--- a/main.go
+++ b/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() {