/usr/share/gocode/src/github.com/Azure/azure-sdk-for-go/core/http/httputil/reverseproxy.go is in golang-github-azure-azure-sdk-for-go-dev 1.2~git20150611.0.97d9593-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 | // Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// HTTP reverse proxy handler
package httputil
import (
"io"
"log"
"net"
"net/http"
"net/url"
"strings"
"sync"
"time"
)
// onExitFlushLoop is a callback set by tests to detect the state of the
// flushLoop() goroutine.
var onExitFlushLoop func()
// ReverseProxy is an HTTP Handler that takes an incoming request and
// sends it to another server, proxying the response back to the
// client.
type ReverseProxy struct {
// Director must be a function which modifies
// the request into a new request to be sent
// using Transport. Its response is then copied
// back to the original client unmodified.
Director func(*http.Request)
// The transport used to perform proxy requests.
// If nil, http.DefaultTransport is used.
Transport http.RoundTripper
// FlushInterval specifies the flush interval
// to flush to the client while copying the
// response body.
// If zero, no periodic flushing is done.
FlushInterval time.Duration
}
func singleJoiningSlash(a, b string) string {
aslash := strings.HasSuffix(a, "/")
bslash := strings.HasPrefix(b, "/")
switch {
case aslash && bslash:
return a + b[1:]
case !aslash && !bslash:
return a + "/" + b
}
return a + b
}
// NewSingleHostReverseProxy returns a new ReverseProxy that rewrites
// URLs to the scheme, host, and base path provided in target. If the
// target's path is "/base" and the incoming request was for "/dir",
// the target request will be for /base/dir.
func NewSingleHostReverseProxy(target *url.URL) *ReverseProxy {
targetQuery := target.RawQuery
director := func(req *http.Request) {
req.URL.Scheme = target.Scheme
req.URL.Host = target.Host
req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
if targetQuery == "" || req.URL.RawQuery == "" {
req.URL.RawQuery = targetQuery + req.URL.RawQuery
} else {
req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
}
}
return &ReverseProxy{Director: director}
}
func copyHeader(dst, src http.Header) {
for k, vv := range src {
for _, v := range vv {
dst.Add(k, v)
}
}
}
// Hop-by-hop headers. These are removed when sent to the backend.
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html
var hopHeaders = []string{
"Connection",
"Keep-Alive",
"Proxy-Authenticate",
"Proxy-Authorization",
"Te", // canonicalized version of "TE"
"Trailers",
"Transfer-Encoding",
"Upgrade",
}
func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
transport := p.Transport
if transport == nil {
transport = http.DefaultTransport
}
outreq := new(http.Request)
*outreq = *req // includes shallow copies of maps, but okay
p.Director(outreq)
outreq.Proto = "HTTP/1.1"
outreq.ProtoMajor = 1
outreq.ProtoMinor = 1
outreq.Close = false
// Remove hop-by-hop headers to the backend. Especially
// important is "Connection" because we want a persistent
// connection, regardless of what the client sent to us. This
// is modifying the same underlying map from req (shallow
// copied above) so we only copy it if necessary.
copiedHeaders := false
for _, h := range hopHeaders {
if outreq.Header.Get(h) != "" {
if !copiedHeaders {
outreq.Header = make(http.Header)
copyHeader(outreq.Header, req.Header)
copiedHeaders = true
}
outreq.Header.Del(h)
}
}
if clientIP, _, err := net.SplitHostPort(req.RemoteAddr); err == nil {
// 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 := outreq.Header["X-Forwarded-For"]; ok {
clientIP = strings.Join(prior, ", ") + ", " + clientIP
}
outreq.Header.Set("X-Forwarded-For", clientIP)
}
res, err := transport.RoundTrip(outreq)
if err != nil {
log.Printf("http: proxy error: %v", err)
rw.WriteHeader(http.StatusInternalServerError)
return
}
defer res.Body.Close()
for _, h := range hopHeaders {
res.Header.Del(h)
}
copyHeader(rw.Header(), res.Header)
rw.WriteHeader(res.StatusCode)
p.copyResponse(rw, res.Body)
}
func (p *ReverseProxy) copyResponse(dst io.Writer, src io.Reader) {
if p.FlushInterval != 0 {
if wf, ok := dst.(writeFlusher); ok {
mlw := &maxLatencyWriter{
dst: wf,
latency: p.FlushInterval,
done: make(chan bool),
}
go mlw.flushLoop()
defer mlw.stop()
dst = mlw
}
}
io.Copy(dst, src)
}
type writeFlusher interface {
io.Writer
http.Flusher
}
type maxLatencyWriter struct {
dst writeFlusher
latency time.Duration
lk sync.Mutex // protects Write + Flush
done chan bool
}
func (m *maxLatencyWriter) Write(p []byte) (int, error) {
m.lk.Lock()
defer m.lk.Unlock()
return m.dst.Write(p)
}
func (m *maxLatencyWriter) flushLoop() {
t := time.NewTicker(m.latency)
defer t.Stop()
for {
select {
case <-m.done:
if onExitFlushLoop != nil {
onExitFlushLoop()
}
return
case <-t.C:
m.lk.Lock()
m.dst.Flush()
m.lk.Unlock()
}
}
}
func (m *maxLatencyWriter) stop() { m.done <- true }
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