forked from etcd-io/etcd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
reverse.go
207 lines (179 loc) · 5.15 KB
/
reverse.go
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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package httpproxy
import (
"bytes"
"context"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"net/url"
"strings"
"sync/atomic"
"time"
"github.com/coreos/etcd/etcdserver/api/v2http/httptypes"
"github.com/coreos/pkg/capnslog"
)
var (
plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "proxy/httpproxy")
// Hop-by-hop headers. These are removed when sent to the backend.
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html
// This list of headers borrowed from stdlib httputil.ReverseProxy
singleHopHeaders = []string{
"Connection",
"Keep-Alive",
"Proxy-Authenticate",
"Proxy-Authorization",
"Te", // canonicalized version of "TE"
"Trailers",
"Transfer-Encoding",
"Upgrade",
}
)
func removeSingleHopHeaders(hdrs *http.Header) {
for _, h := range singleHopHeaders {
hdrs.Del(h)
}
}
type reverseProxy struct {
director *director
transport http.RoundTripper
}
func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request) {
reportIncomingRequest(clientreq)
proxyreq := new(http.Request)
*proxyreq = *clientreq
startTime := time.Now()
var (
proxybody []byte
err error
)
if clientreq.Body != nil {
proxybody, err = ioutil.ReadAll(clientreq.Body)
if err != nil {
msg := fmt.Sprintf("failed to read request body: %v", err)
plog.Println(msg)
e := httptypes.NewHTTPError(http.StatusInternalServerError, "httpproxy: "+msg)
if we := e.WriteTo(rw); we != nil {
plog.Debugf("error writing HTTPError (%v) to %s", we, clientreq.RemoteAddr)
}
return
}
}
// deep-copy the headers, as these will be modified below
proxyreq.Header = make(http.Header)
copyHeader(proxyreq.Header, clientreq.Header)
normalizeRequest(proxyreq)
removeSingleHopHeaders(&proxyreq.Header)
maybeSetForwardedFor(proxyreq)
endpoints := p.director.endpoints()
if len(endpoints) == 0 {
msg := "zero endpoints currently available"
reportRequestDropped(clientreq, zeroEndpoints)
// TODO: limit the rate of the error logging.
plog.Println(msg)
e := httptypes.NewHTTPError(http.StatusServiceUnavailable, "httpproxy: "+msg)
if we := e.WriteTo(rw); we != nil {
plog.Debugf("error writing HTTPError (%v) to %s", we, clientreq.RemoteAddr)
}
return
}
var requestClosed int32
completeCh := make(chan bool, 1)
closeNotifier, ok := rw.(http.CloseNotifier)
ctx, cancel := context.WithCancel(context.Background())
proxyreq = proxyreq.WithContext(ctx)
defer cancel()
if ok {
closeCh := closeNotifier.CloseNotify()
go func() {
select {
case <-closeCh:
atomic.StoreInt32(&requestClosed, 1)
plog.Printf("client %v closed request prematurely", clientreq.RemoteAddr)
case <-completeCh:
}
}()
defer func() {
completeCh <- true
}()
}
var res *http.Response
for _, ep := range endpoints {
if proxybody != nil {
proxyreq.Body = ioutil.NopCloser(bytes.NewBuffer(proxybody))
}
redirectRequest(proxyreq, ep.URL)
res, err = p.transport.RoundTrip(proxyreq)
if atomic.LoadInt32(&requestClosed) == 1 {
return
}
if err != nil {
reportRequestDropped(clientreq, failedSendingRequest)
plog.Printf("failed to direct request to %s: %v", ep.URL.String(), err)
ep.Failed()
continue
}
break
}
if res == nil {
// TODO: limit the rate of the error logging.
msg := fmt.Sprintf("unable to get response from %d endpoint(s)", len(endpoints))
reportRequestDropped(clientreq, failedGettingResponse)
plog.Println(msg)
e := httptypes.NewHTTPError(http.StatusBadGateway, "httpproxy: "+msg)
if we := e.WriteTo(rw); we != nil {
plog.Debugf("error writing HTTPError (%v) to %s", we, clientreq.RemoteAddr)
}
return
}
defer res.Body.Close()
reportRequestHandled(clientreq, res, startTime)
removeSingleHopHeaders(&res.Header)
copyHeader(rw.Header(), res.Header)
rw.WriteHeader(res.StatusCode)
io.Copy(rw, res.Body)
}
func copyHeader(dst, src http.Header) {
for k, vv := range src {
for _, v := range vv {
dst.Add(k, v)
}
}
}
func redirectRequest(req *http.Request, loc url.URL) {
req.URL.Scheme = loc.Scheme
req.URL.Host = loc.Host
}
func normalizeRequest(req *http.Request) {
req.Proto = "HTTP/1.1"
req.ProtoMajor = 1
req.ProtoMinor = 1
req.Close = false
}
func maybeSetForwardedFor(req *http.Request) {
clientIP, _, err := net.SplitHostPort(req.RemoteAddr)
if err != nil {
return
}
// If we aren't the first proxy retain prior
// X-Forwarded-For information as a comma+space
// separated list and fold multiple headers into one.
if prior, ok := req.Header["X-Forwarded-For"]; ok {
clientIP = strings.Join(prior, ", ") + ", " + clientIP
}
req.Header.Set("X-Forwarded-For", clientIP)
}