From 6c1f2af53ac0920d6e27f843444efd5e676417bf Mon Sep 17 00:00:00 2001
From: Simon Jefford <simon.jefford@fourth.com>
Date: Fri, 12 Jun 2015 17:21:19 +0100
Subject: [PATCH 1/2] log: ensure the correct status is always logged

in the case of error (>=400) then no response may have been sent
---
 middleware/log/log.go      |  6 +++++
 middleware/log/log_test.go | 48 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 middleware/log/log_test.go

diff --git a/middleware/log/log.go b/middleware/log/log.go
index f4329d21..7c206458 100644
--- a/middleware/log/log.go
+++ b/middleware/log/log.go
@@ -2,6 +2,7 @@
 package log
 
 import (
+	"fmt"
 	"log"
 	"net/http"
 
@@ -19,6 +20,11 @@ func (l Logger) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 		if middleware.Path(r.URL.Path).Matches(rule.PathScope) {
 			responseRecorder := middleware.NewResponseRecorder(w)
 			status, err := l.Next.ServeHTTP(responseRecorder, r)
+			if status >= 400 {
+				responseRecorder.WriteHeader(status)
+				fmt.Fprintf(responseRecorder, "%d %s", status, http.StatusText(status))
+				status = 0
+			}
 			rep := middleware.NewReplacer(r, responseRecorder)
 			rule.Log.Println(rep.Replace(rule.Format))
 			return status, err
diff --git a/middleware/log/log_test.go b/middleware/log/log_test.go
new file mode 100644
index 00000000..40560e4c
--- /dev/null
+++ b/middleware/log/log_test.go
@@ -0,0 +1,48 @@
+package log
+
+import (
+	"bytes"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+type erroringMiddleware struct{}
+
+func (erroringMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
+	return http.StatusNotFound, nil
+}
+
+func TestLoggedStatus(t *testing.T) {
+	var f bytes.Buffer
+	var next erroringMiddleware
+	rule := Rule{
+		PathScope: "/",
+		Format:    DefaultLogFormat,
+		Log:       log.New(&f, "", 0),
+	}
+
+	logger := Logger{
+		Rules: []Rule{rule},
+		Next:  next,
+	}
+
+	r, err := http.NewRequest("GET", "/", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rec := httptest.NewRecorder()
+
+	status, err := logger.ServeHTTP(rec, r)
+	if status != 0 {
+		t.Error("Expected status to be 0 - was", status)
+	}
+
+	logged := f.String()
+	if !strings.Contains(logged, "404 13") {
+		t.Error("Expected 404 to be logged. Logged string -", logged)
+	}
+}

From c811d416a7024cf71c854e8903e6efd483a398af Mon Sep 17 00:00:00 2001
From: Matthew Holt <Matthew.Holt+git@gmail.com>
Date: Mon, 15 Jun 2015 10:17:09 -0600
Subject: [PATCH 2/2] log: Customizable default error function

---
 config/setup/log.go   |  3 ++-
 middleware/log/log.go | 16 ++++++++++++----
 server/server.go      |  8 ++++++--
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/config/setup/log.go b/config/setup/log.go
index 4b5e11c6..694f3625 100644
--- a/config/setup/log.go
+++ b/config/setup/log.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/mholt/caddy/middleware"
 	caddylog "github.com/mholt/caddy/middleware/log"
+	"github.com/mholt/caddy/server"
 )
 
 // Log sets up the logging middleware.
@@ -39,7 +40,7 @@ func Log(c *Controller) (middleware.Middleware, error) {
 	})
 
 	return func(next middleware.Handler) middleware.Handler {
-		return caddylog.Logger{Next: next, Rules: rules}
+		return caddylog.Logger{Next: next, Rules: rules, ErrorFunc: server.DefaultErrorFunc}
 	}, nil
 }
 
diff --git a/middleware/log/log.go b/middleware/log/log.go
index 7c206458..d6b147b8 100644
--- a/middleware/log/log.go
+++ b/middleware/log/log.go
@@ -11,8 +11,9 @@ import (
 
 // Logger is a basic request logging middleware.
 type Logger struct {
-	Next  middleware.Handler
-	Rules []Rule
+	Next      middleware.Handler
+	Rules     []Rule
+	ErrorFunc func(http.ResponseWriter, *http.Request, int) // failover error handler
 }
 
 func (l Logger) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
@@ -21,8 +22,15 @@ func (l Logger) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 			responseRecorder := middleware.NewResponseRecorder(w)
 			status, err := l.Next.ServeHTTP(responseRecorder, r)
 			if status >= 400 {
-				responseRecorder.WriteHeader(status)
-				fmt.Fprintf(responseRecorder, "%d %s", status, http.StatusText(status))
+				// There was an error up the chain, but no response has been written yet.
+				// The error must be handled here so the log entry will record the response size.
+				if l.ErrorFunc != nil {
+					l.ErrorFunc(responseRecorder, r, status)
+				} else {
+					// Default failover error handler
+					responseRecorder.WriteHeader(status)
+					fmt.Fprintf(responseRecorder, "%d %s", status, http.StatusText(status))
+				}
 				status = 0
 			}
 			rep := middleware.NewReplacer(r, responseRecorder)
diff --git a/server/server.go b/server/server.go
index a97f68f4..4a751de6 100644
--- a/server/server.go
+++ b/server/server.go
@@ -221,11 +221,15 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		// Fallback error response in case error handling wasn't chained in
 		if status >= 400 {
-			w.WriteHeader(status)
-			fmt.Fprintf(w, "%d %s", status, http.StatusText(status))
+			DefaultErrorFunc(w, r, status)
 		}
 	} else {
 		w.WriteHeader(http.StatusNotFound)
 		fmt.Fprintf(w, "No such host at %s", s.address)
 	}
 }
+
+func DefaultErrorFunc(w http.ResponseWriter, r *http.Request, status int) {
+	w.WriteHeader(status)
+	fmt.Fprintf(w, "%d %s", status, http.StatusText(status))
+}