From 2ddc013c84a048caf82f0787855d1b35c7ce82e3 Mon Sep 17 00:00:00 2001
From: Jan Dittberner <jandd@cacert.org>
Date: Sun, 22 May 2022 12:19:25 +0200
Subject: [PATCH] Add panic recovery middleware

---
 cmd/boardvoting/handlers.go   | 32 ++++++++++++++++----------------
 cmd/boardvoting/middleware.go | 18 +++++++++++++++++-
 cmd/boardvoting/routes.go     |  3 ++-
 3 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/cmd/boardvoting/handlers.go b/cmd/boardvoting/handlers.go
index 9459e1d..45de331 100644
--- a/cmd/boardvoting/handlers.go
+++ b/cmd/boardvoting/handlers.go
@@ -71,7 +71,19 @@ func newTemplateCache() (map[string]*template.Template, error) {
 	return cache, nil
 }
 
-func (app *application) render(w http.ResponseWriter, status int, page string, data interface{}) {
+type templateData struct {
+	Voter   *models.Voter
+	Flashes []string
+	Params  struct {
+		Flags struct {
+			Unvoted bool
+		}
+	}
+	PrevPage, NextPage string
+	Motions            []*models.MotionForDisplay
+}
+
+func (app *application) render(w http.ResponseWriter, status int, page string, data *templateData) {
 	ts, ok := app.templateCache[page]
 	if !ok {
 		app.serverError(w, fmt.Errorf("the template %s does not exist", page))
@@ -93,19 +105,7 @@ func (app *application) render(w http.ResponseWriter, status int, page string, d
 	_, _ = buf.WriteTo(w)
 }
 
-type motionListTemplateData struct {
-	Voter   *models.Voter
-	Flashes []string
-	Params  struct {
-		Flags struct {
-			Unvoted bool
-		}
-	}
-	PrevPage, NextPage string
-	Motions            []*models.MotionForDisplay
-}
-
-func (m *motionListTemplateData) setPaginationParameters(first, last *time.Time) error {
+func (m *templateData) setPaginationParameters(first, last *time.Time) error {
 	motions := m.Motions
 
 	if len(motions) > 0 && first.Before(motions[len(motions)-1].Proposed) {
@@ -164,7 +164,7 @@ func (app *application) motionList(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	templateData := &motionListTemplateData{Motions: motions}
+	templateData := &templateData{Motions: motions}
 
 	err = templateData.setPaginationParameters(first, last)
 	if err != nil {
@@ -173,7 +173,7 @@ func (app *application) motionList(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	app.render(w, http.StatusOK, "motions.html", &templateData)
+	app.render(w, http.StatusOK, "motions.html", templateData)
 }
 
 func calculateMotionListOptions(r *http.Request) (*models.MotionListOptions, error) {
diff --git a/cmd/boardvoting/middleware.go b/cmd/boardvoting/middleware.go
index 282f3f5..86303c8 100644
--- a/cmd/boardvoting/middleware.go
+++ b/cmd/boardvoting/middleware.go
@@ -17,7 +17,10 @@ limitations under the License.
 
 package main
 
-import "net/http"
+import (
+	"fmt"
+	"net/http"
+)
 
 func secureHeaders(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -39,3 +42,16 @@ func (app *application) logRequest(next http.Handler) http.Handler {
 		next.ServeHTTP(w, r)
 	})
 }
+
+func (app *application) recoverPanic(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer func() {
+			if err := recover(); err != nil {
+				w.Header().Set("Connection", "close")
+				app.serverError(w, fmt.Errorf("%s", err))
+			}
+		}()
+
+		next.ServeHTTP(w, r)
+	})
+}
diff --git a/cmd/boardvoting/routes.go b/cmd/boardvoting/routes.go
index 42155dc..3fbabe5 100644
--- a/cmd/boardvoting/routes.go
+++ b/cmd/boardvoting/routes.go
@@ -39,10 +39,11 @@ func (app *application) routes() http.Handler {
 
 	fileServer := statigz.FileServer(staticData, brotli.AddEncoding, statigz.EncodeOnInit)
 
+	mux.Handle("/favicon.ico", http.RedirectHandler("/static/images/favicon.ico", http.StatusMovedPermanently))
 	mux.Handle("/static/", http.StripPrefix("/static", fileServer))
 
 	mux.HandleFunc("/", app.home)
 	mux.HandleFunc("/motions/", app.motionList)
 
-	return app.logRequest(secureHeaders(mux))
+	return app.recoverPanic(app.logRequest(secureHeaders(mux)))
 }