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Removed alpha prototype source
This commit is contained in:
Toby Chui
@@ -1,405 +0,0 @@
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package reverseproxy
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import (
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"errors"
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"io"
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"log"
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"net"
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"net/http"
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"net/url"
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"strings"
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"sync"
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"time"
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)
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var onExitFlushLoop func()
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const (
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defaultTimeout = time.Minute * 5
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)
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// ReverseProxy is an HTTP Handler that takes an incoming request and
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// sends it to another server, proxying the response back to the
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// client, support http, also support https tunnel using http.hijacker
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type ReverseProxy struct {
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// Set the timeout of the proxy server, default is 5 minutes
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Timeout time.Duration
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// Director must be a function which modifies
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// the request into a new request to be sent
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// using Transport. Its response is then copied
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// back to the original client unmodified.
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// Director must not access the provided Request
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// after returning.
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Director func(*http.Request)
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// The transport used to perform proxy requests.
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// default is http.DefaultTransport.
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Transport http.RoundTripper
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// FlushInterval specifies the flush interval
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// to flush to the client while copying the
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// response body. If zero, no periodic flushing is done.
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FlushInterval time.Duration
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// ErrorLog specifies an optional logger for errors
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// that occur when attempting to proxy the request.
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// If nil, logging goes to os.Stderr via the log package's
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// standard logger.
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ErrorLog *log.Logger
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// ModifyResponse is an optional function that
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// modifies the Response from the backend.
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// If it returns an error, the proxy returns a StatusBadGateway error.
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ModifyResponse func(*http.Response) error
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Verbal bool
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}
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type requestCanceler interface {
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CancelRequest(req *http.Request)
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}
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// NewReverseProxy returns a new ReverseProxy that routes
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// URLs to the scheme, host, and base path provided in target. If the
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// target's path is "/base" and the incoming request was for "/dir",
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// the target request will be for /base/dir. if the target's query is a=10
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// and the incoming request's query is b=100, the target's request's query
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// will be a=10&b=100.
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// NewReverseProxy does not rewrite the Host header.
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// To rewrite Host headers, use ReverseProxy directly with a custom
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// Director policy.
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func NewReverseProxy(target *url.URL) *ReverseProxy {
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targetQuery := target.RawQuery
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director := func(req *http.Request) {
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req.URL.Scheme = target.Scheme
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req.URL.Host = target.Host
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req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
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// If Host is empty, the Request.Write method uses
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// the value of URL.Host.
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// force use URL.Host
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req.Host = req.URL.Host
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if targetQuery == "" || req.URL.RawQuery == "" {
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req.URL.RawQuery = targetQuery + req.URL.RawQuery
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} else {
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req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
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}
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if _, ok := req.Header["User-Agent"]; !ok {
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req.Header.Set("User-Agent", "")
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}
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}
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return &ReverseProxy{Director: director, Verbal: false}
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}
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func singleJoiningSlash(a, b string) string {
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aslash := strings.HasSuffix(a, "/")
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bslash := strings.HasPrefix(b, "/")
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switch {
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case aslash && bslash:
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return a + b[1:]
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case !aslash && !bslash:
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return a + "/" + b
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}
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return a + b
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}
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func copyHeader(dst, src http.Header) {
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for k, vv := range src {
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for _, v := range vv {
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dst.Add(k, v)
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}
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}
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}
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// Hop-by-hop headers. These are removed when sent to the backend.
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// http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html
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var hopHeaders = []string{
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//"Connection",
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"Proxy-Connection", // non-standard but still sent by libcurl and rejected by e.g. google
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"Keep-Alive",
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"Proxy-Authenticate",
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"Proxy-Authorization",
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"Te", // canonicalized version of "TE"
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"Trailer", // not Trailers per URL above; http://www.rfc-editor.org/errata_search.php?eid=4522
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"Transfer-Encoding",
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//"Upgrade",
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}
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func (p *ReverseProxy) copyResponse(dst io.Writer, src io.Reader) {
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if p.FlushInterval != 0 {
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if wf, ok := dst.(writeFlusher); ok {
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mlw := &maxLatencyWriter{
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dst: wf,
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latency: p.FlushInterval,
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done: make(chan bool),
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}
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go mlw.flushLoop()
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defer mlw.stop()
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dst = mlw
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}
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}
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io.Copy(dst, src)
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}
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type writeFlusher interface {
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io.Writer
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http.Flusher
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}
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type maxLatencyWriter struct {
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dst writeFlusher
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latency time.Duration
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mu sync.Mutex
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done chan bool
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}
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func (m *maxLatencyWriter) Write(b []byte) (int, error) {
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m.mu.Lock()
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defer m.mu.Unlock()
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return m.dst.Write(b)
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}
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func (m *maxLatencyWriter) flushLoop() {
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t := time.NewTicker(m.latency)
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defer t.Stop()
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for {
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select {
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case <-m.done:
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if onExitFlushLoop != nil {
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onExitFlushLoop()
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}
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return
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case <-t.C:
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m.mu.Lock()
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m.dst.Flush()
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m.mu.Unlock()
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}
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}
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}
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func (m *maxLatencyWriter) stop() {
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m.done <- true
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}
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func (p *ReverseProxy) logf(format string, args ...interface{}) {
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if p.ErrorLog != nil {
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p.ErrorLog.Printf(format, args...)
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} else {
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log.Printf(format, args...)
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}
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}
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func removeHeaders(header http.Header) {
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// Remove hop-by-hop headers listed in the "Connection" header.
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if c := header.Get("Connection"); c != "" {
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for _, f := range strings.Split(c, ",") {
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if f = strings.TrimSpace(f); f != "" {
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header.Del(f)
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}
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}
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}
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// Remove hop-by-hop headers
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for _, h := range hopHeaders {
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if header.Get(h) != "" {
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header.Del(h)
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}
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}
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if header.Get("A-Upgrade") != "" {
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header.Set("Upgrade", header.Get("A-Upgrade"))
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header.Del("A-Upgrade")
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}
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}
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func addXForwardedForHeader(req *http.Request) {
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if clientIP, _, err := net.SplitHostPort(req.RemoteAddr); err == nil {
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// If we aren't the first proxy retain prior
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// X-Forwarded-For information as a comma+space
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// separated list and fold multiple headers into one.
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if prior, ok := req.Header["X-Forwarded-For"]; ok {
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clientIP = strings.Join(prior, ", ") + ", " + clientIP
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}
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req.Header.Set("X-Forwarded-For", clientIP)
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}
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}
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func (p *ReverseProxy) ProxyHTTP(rw http.ResponseWriter, req *http.Request) error {
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transport := p.Transport
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if transport == nil {
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transport = http.DefaultTransport
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}
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outreq := new(http.Request)
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// Shallow copies of maps, like header
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*outreq = *req
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if cn, ok := rw.(http.CloseNotifier); ok {
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if requestCanceler, ok := transport.(requestCanceler); ok {
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// After the Handler has returned, there is no guarantee
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// that the channel receives a value, so to make sure
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reqDone := make(chan struct{})
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defer close(reqDone)
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clientGone := cn.CloseNotify()
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go func() {
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select {
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case <-clientGone:
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requestCanceler.CancelRequest(outreq)
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case <-reqDone:
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}
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}()
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}
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}
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p.Director(outreq)
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outreq.Close = false
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// We may modify the header (shallow copied above), so we only copy it.
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outreq.Header = make(http.Header)
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copyHeader(outreq.Header, req.Header)
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// Remove hop-by-hop headers listed in the "Connection" header, Remove hop-by-hop headers.
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removeHeaders(outreq.Header)
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// Add X-Forwarded-For Header.
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addXForwardedForHeader(outreq)
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res, err := transport.RoundTrip(outreq)
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if err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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//rw.WriteHeader(http.StatusBadGateway)
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return err
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}
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// Remove hop-by-hop headers listed in the "Connection" header of the response, Remove hop-by-hop headers.
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removeHeaders(res.Header)
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if p.ModifyResponse != nil {
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if err := p.ModifyResponse(res); err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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//rw.WriteHeader(http.StatusBadGateway)
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return err
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}
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}
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// Copy header from response to client.
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copyHeader(rw.Header(), res.Header)
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// The "Trailer" header isn't included in the Transport's response, Build it up from Trailer.
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if len(res.Trailer) > 0 {
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trailerKeys := make([]string, 0, len(res.Trailer))
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for k := range res.Trailer {
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trailerKeys = append(trailerKeys, k)
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}
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rw.Header().Add("Trailer", strings.Join(trailerKeys, ", "))
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}
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rw.WriteHeader(res.StatusCode)
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if len(res.Trailer) > 0 {
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// Force chunking if we saw a response trailer.
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// This prevents net/http from calculating the length for short
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// bodies and adding a Content-Length.
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if fl, ok := rw.(http.Flusher); ok {
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fl.Flush()
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}
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}
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p.copyResponse(rw, res.Body)
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// close now, instead of defer, to populate res.Trailer
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res.Body.Close()
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copyHeader(rw.Header(), res.Trailer)
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return nil
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}
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func (p *ReverseProxy) ProxyHTTPS(rw http.ResponseWriter, req *http.Request) error {
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hij, ok := rw.(http.Hijacker)
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if !ok {
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p.logf("http server does not support hijacker")
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return errors.New("http server does not support hijacker")
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}
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clientConn, _, err := hij.Hijack()
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if err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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return err
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}
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proxyConn, err := net.Dial("tcp", req.URL.Host)
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if err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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return err
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}
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// The returned net.Conn may have read or write deadlines
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// already set, depending on the configuration of the
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// Server, to set or clear those deadlines as needed
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// we set timeout to 5 minutes
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deadline := time.Now()
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if p.Timeout == 0 {
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deadline = deadline.Add(time.Minute * 5)
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} else {
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deadline = deadline.Add(p.Timeout)
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}
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err = clientConn.SetDeadline(deadline)
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if err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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return err
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}
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err = proxyConn.SetDeadline(deadline)
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if err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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return err
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}
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_, err = clientConn.Write([]byte("HTTP/1.0 200 OK\r\n\r\n"))
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if err != nil {
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if p.Verbal {
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p.logf("http: proxy error: %v", err)
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}
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return err
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}
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go func() {
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io.Copy(clientConn, proxyConn)
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clientConn.Close()
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proxyConn.Close()
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}()
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io.Copy(proxyConn, clientConn)
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proxyConn.Close()
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clientConn.Close()
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return nil
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}
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func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) error {
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if req.Method == "CONNECT" {
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err := p.ProxyHTTPS(rw, req)
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return err
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} else {
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err := p.ProxyHTTP(rw, req)
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return err
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}
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}
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