Copy logging handler from gorilla mux repo

Author: rohitsakala

pkg/server/logging.go

@@ -0,0 +1,185 @@
+// Copyright 2013 The Gorilla Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package server
+
+import (
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+	"time"
+	"unicode/utf8"
+)
+
+// loggingHandler is the http.Handler implementation for LoggingHandler.
+type loggingHandler struct {
+	writer  io.Writer
+	handler http.Handler
+}
+
+func (h loggingHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	t := time.Now()
+	logger := &responseLogger{w: w, status: http.StatusOK}
+	url := *req.URL
+
+	h.handler.ServeHTTP(logger, req)
+	if req.MultipartForm != nil {
+		req.MultipartForm.RemoveAll()
+	}
+
+	writeLog(h.writer, req, url, t, logger.status, logger.size)
+}
+
+// LoggingHandler returns a http.Handler that wraps h and logs requests to out in
+// Apache Common Log Format (CLF).
+//
+// See http://httpd.apache.org/docs/2.2/logs.html#common for a description of this format.
+func LoggingHandler(out io.Writer, h http.Handler) http.Handler {
+	return loggingHandler{out, h}
+}
+
+// responseLogger is wrapper of http.ResponseWriter that keeps track of its HTTP
+// status code and body size.
+type responseLogger struct {
+	w      http.ResponseWriter
+	status int
+	size   int
+}
+
+func (l *responseLogger) Header() http.Header {
+	return l.w.Header()
+}
+
+func (l *responseLogger) Write(b []byte) (int, error) {
+	size, err := l.w.Write(b)
+	l.size += size
+	return size, err
+}
+
+func (l *responseLogger) WriteHeader(s int) {
+	l.w.WriteHeader(s)
+	l.status = s
+}
+
+func (l *responseLogger) Flush() {
+	if f, ok := l.w.(http.Flusher); ok {
+		f.Flush()
+	}
+}
+
+const lowerhex = "0123456789abcdef"
+
+func appendQuoted(buf []byte, s string) []byte {
+	var runeTmp [utf8.UTFMax]byte
+	for width := 0; len(s) > 0; s = s[width:] {
+		r := rune(s[0])
+		width = 1
+		if r >= utf8.RuneSelf {
+			r, width = utf8.DecodeRuneInString(s)
+		}
+		if width == 1 && r == utf8.RuneError {
+			buf = append(buf, `\x`...)
+			buf = append(buf, lowerhex[s[0]>>4])
+			buf = append(buf, lowerhex[s[0]&0xF])
+			continue
+		}
+		if r == rune('"') || r == '\\' {
+			buf = append(buf, '\\')
+			buf = append(buf, byte(r))
+			continue
+		}
+		if strconv.IsPrint(r) {
+			n := utf8.EncodeRune(runeTmp[:], r)
+			buf = append(buf, runeTmp[:n]...)
+			continue
+		}
+		switch r {
+		case '\a':
+			buf = append(buf, `\a`...)
+		case '\b':
+			buf = append(buf, `\b`...)
+		case '\f':
+			buf = append(buf, `\f`...)
+		case '\n':
+			buf = append(buf, `\n`...)
+		case '\r':
+			buf = append(buf, `\r`...)
+		case '\t':
+			buf = append(buf, `\t`...)
+		case '\v':
+			buf = append(buf, `\v`...)
+		default:
+			switch {
+			case r < ' ':
+				buf = append(buf, `\x`...)
+				buf = append(buf, lowerhex[s[0]>>4])
+				buf = append(buf, lowerhex[s[0]&0xF])
+			case r > utf8.MaxRune:
+				r = 0xFFFD
+				fallthrough
+			case r < 0x10000:
+				buf = append(buf, `\u`...)
+				for s := 12; s >= 0; s -= 4 {
+					buf = append(buf, lowerhex[r>>uint(s)&0xF])
+				}
+			default:
+				buf = append(buf, `\U`...)
+				for s := 28; s >= 0; s -= 4 {
+					buf = append(buf, lowerhex[r>>uint(s)&0xF])
+				}
+			}
+		}
+	}
+	return buf
+}
+
+// buildCommonLogLine builds a log entry for req in Apache Common Log Format.
+func buildCommonLogLine(req *http.Request, url url.URL, ts time.Time, status int, size int) []byte {
+	username := "-"
+	if url.User != nil {
+		if name := url.User.Username(); name != "" {
+			username = name
+		}
+	}
+
+	host, _, err := net.SplitHostPort(req.RemoteAddr)
+	if err != nil {
+		host = req.RemoteAddr
+	}
+
+	uri := req.RequestURI
+	if req.ProtoMajor == 2 && req.Method == "CONNECT" {
+		uri = req.Host
+	}
+	if uri == "" {
+		uri = url.RequestURI()
+	}
+
+	buf := make([]byte, 0, 3*(len(host)+len(username)+len(req.Method)+len(uri)+len(req.Proto)+50)/2)
+	buf = append(buf, host...)
+	buf = append(buf, " - "...)
+	buf = append(buf, username...)
+	buf = append(buf, " ["...)
+	buf = append(buf, ts.Format("02/Jan/2006:15:04:05 -0700")...)
+	buf = append(buf, `] "`...)
+	buf = append(buf, req.Method...)
+	buf = append(buf, " "...)
+	buf = appendQuoted(buf, uri)
+	buf = append(buf, " "...)
+	buf = append(buf, req.Proto...)
+	buf = append(buf, `" `...)
+	buf = append(buf, strconv.Itoa(status)...)
+	buf = append(buf, " "...)
+	buf = append(buf, strconv.Itoa(size)...)
+	return buf
+}
+
+// writeLog writes a log entry for req to w in Apache Common Log Format.
+func writeLog(writer io.Writer, req *http.Request, url url.URL, ts time.Time, status int, size int) {
+	buf := buildCommonLogLine(req, url, ts, status, size)
+	buf = append(buf, '\n')
+	writer.Write(buf)
+}