1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
// Package gzip provides a middleware layer that performs
// gzip compression on the response.
package gzip
import (
"bufio"
"io"
"net"
"net/http"
"strings"
"errors"
"github.com/mholt/caddy"
"github.com/mholt/caddy/caddyhttp/httpserver"
)
func init() {
caddy.RegisterPlugin("gzip", caddy.Plugin{
ServerType: "http",
Action: setup,
})
initWriterPool()
}
// Gzip is a middleware type which gzips HTTP responses. It is
// imperative that any handler which writes to a gzipped response
// specifies the Content-Type, otherwise some clients will assume
// application/x-gzip and try to download a file.
type Gzip struct {
Next httpserver.Handler
Configs []Config
}
// Config holds the configuration for Gzip middleware
type Config struct {
RequestFilters []RequestFilter
ResponseFilters []ResponseFilter
Level int // Compression level
}
// ServeHTTP serves a gzipped response if the client supports it.
func (g Gzip) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
return g.Next.ServeHTTP(w, r)
}
outer:
for _, c := range g.Configs {
// Check request filters to determine if gzipping is permitted for this request
for _, filter := range c.RequestFilters {
if !filter.ShouldCompress(r) {
continue outer
}
}
// gzipWriter modifies underlying writer at init,
// use a discard writer instead to leave ResponseWriter in
// original form.
gzipWriter := getWriter(c.Level)
defer putWriter(c.Level, gzipWriter)
gz := &gzipResponseWriter{Writer: gzipWriter, ResponseWriter: w}
var rw http.ResponseWriter
// if no response filter is used
if len(c.ResponseFilters) == 0 {
// replace discard writer with ResponseWriter
gzipWriter.Reset(w)
rw = gz
} else {
// wrap gzip writer with ResponseFilterWriter
rw = NewResponseFilterWriter(c.ResponseFilters, gz)
}
// Any response in forward middleware will now be compressed
status, err := g.Next.ServeHTTP(rw, r)
// If there was an error that remained unhandled, we need
// to send something back before gzipWriter gets closed at
// the return of this method!
if status >= 400 {
httpserver.DefaultErrorFunc(w, r, status)
return 0, err
}
return status, err
}
// no matching filter
return g.Next.ServeHTTP(w, r)
}
// gzipResponeWriter wraps the underlying Write method
// with a gzip.Writer to compress the output.
type gzipResponseWriter struct {
io.Writer
http.ResponseWriter
statusCodeWritten bool
}
// WriteHeader wraps the underlying WriteHeader method to prevent
// problems with conflicting headers from proxied backends. For
// example, a backend system that calculates Content-Length would
// be wrong because it doesn't know it's being gzipped.
func (w *gzipResponseWriter) WriteHeader(code int) {
w.Header().Del("Content-Length")
w.Header().Set("Content-Encoding", "gzip")
w.Header().Add("Vary", "Accept-Encoding")
w.ResponseWriter.WriteHeader(code)
w.statusCodeWritten = true
}
// Write wraps the underlying Write method to do compression.
func (w *gzipResponseWriter) Write(b []byte) (int, error) {
if w.Header().Get("Content-Type") == "" {
w.Header().Set("Content-Type", http.DetectContentType(b))
}
if !w.statusCodeWritten {
w.WriteHeader(http.StatusOK)
}
n, err := w.Writer.Write(b)
return n, err
}
// Hijack implements http.Hijacker. It simply wraps the underlying
// ResponseWriter's Hijack method if there is one, or returns an error.
func (w *gzipResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
if hj, ok := w.ResponseWriter.(http.Hijacker); ok {
return hj.Hijack()
}
return nil, nil, httpserver.NonHijackerError{Underlying: w.ResponseWriter}
}
// Flush implements http.Flusher. It simply wraps the underlying
// ResponseWriter's Flush method if there is one, or panics.
func (w *gzipResponseWriter) Flush() {
if f, ok := w.ResponseWriter.(http.Flusher); ok {
f.Flush()
} else {
panic(httpserver.NonFlusherError{Underlying: w.ResponseWriter}) // should be recovered at the beginning of middleware stack
}
}
// CloseNotify implements http.CloseNotifier.
// It just inherits the underlying ResponseWriter's CloseNotify method.
func (w *gzipResponseWriter) CloseNotify() <-chan bool {
if cn, ok := w.ResponseWriter.(http.CloseNotifier); ok {
return cn.CloseNotify()
}
panic(httpserver.NonCloseNotifierError{Underlying: w.ResponseWriter})
}
func (w *gzipResponseWriter) Push(target string, opts *http.PushOptions) error {
if pusher, hasPusher := w.ResponseWriter.(http.Pusher); hasPusher {
return pusher.Push(target, opts)
}
return errors.New("push is unavailable (probably chained http.ResponseWriter does not implement http.Pusher)")
}
// Interface guards
var _ http.Pusher = (*gzipResponseWriter)(nil)
var _ http.Flusher = (*gzipResponseWriter)(nil)
var _ http.CloseNotifier = (*gzipResponseWriter)(nil)
var _ http.Hijacker = (*gzipResponseWriter)(nil)
|
