2017-12-12 19:27:43 +00:00
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// HTTP reverse proxy handler
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package vhost
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import (
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"context"
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"fmt"
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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/textproto"
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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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2018-01-22 17:29:52 +00:00
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2019-08-06 08:49:22 +00:00
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"golang.org/x/net/http/httpguts"
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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.
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//
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// ReverseProxy by default sets the client IP as the value of the
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// X-Forwarded-For header.
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//
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// If an X-Forwarded-For header already exists, the client IP is
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// appended to the existing values. As a special case, if the header
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// exists in the Request.Header map but has a nil value (such as when
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// set by the Director func), the X-Forwarded-For header is
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// not modified.
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//
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// To prevent IP spoofing, be sure to delete any pre-existing
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// X-Forwarded-For header coming from the client or
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// an untrusted proxy.
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type ReverseProxy struct {
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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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// If nil, http.DefaultTransport is used.
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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.
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// If zero, no periodic flushing is done.
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// A negative value means to flush immediately
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// after each write to the client.
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// The FlushInterval is ignored when ReverseProxy
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// recognizes a response as a streaming response, or
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// if its ContentLength is -1; for such responses, writes
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// are flushed to the client immediately.
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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 is done via the log package's standard logger.
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ErrorLog *log.Logger
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// BufferPool optionally specifies a buffer pool to
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// get byte slices for use by io.CopyBuffer when
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// copying HTTP response bodies.
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BufferPool BufferPool
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// ModifyResponse is an optional function that modifies the
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// Response from the backend. It is called if the backend
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// returns a response at all, with any HTTP status code.
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// If the backend is unreachable, the optional ErrorHandler is
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// called without any call to ModifyResponse.
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//
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// If ModifyResponse returns an error, ErrorHandler is called
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// with its error value. If ErrorHandler is nil, its default
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// implementation is used.
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ModifyResponse func(*http.Response) error
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// ErrorHandler is an optional function that handles errors
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// reaching the backend or errors from ModifyResponse.
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//
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// If nil, the default is to log the provided error and return
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// a 502 Status Bad Gateway response.
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ErrorHandler func(http.ResponseWriter, *http.Request, error)
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}
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// A BufferPool is an interface for getting and returning temporary
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// byte slices for use by io.CopyBuffer.
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type BufferPool interface {
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Get() []byte
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Put([]byte)
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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 joinURLPath(a, b *url.URL) (path, rawpath string) {
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if a.RawPath == "" && b.RawPath == "" {
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return singleJoiningSlash(a.Path, b.Path), ""
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}
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// Same as singleJoiningSlash, but uses EscapedPath to determine
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// whether a slash should be added
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apath := a.EscapedPath()
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bpath := b.EscapedPath()
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aslash := strings.HasSuffix(apath, "/")
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bslash := strings.HasPrefix(bpath, "/")
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switch {
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case aslash && bslash:
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return a.Path + b.Path[1:], apath + bpath[1:]
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case !aslash && !bslash:
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return a.Path + "/" + b.Path, apath + "/" + bpath
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}
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return a.Path + b.Path, apath + bpath
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}
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// NewSingleHostReverseProxy 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.
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// NewSingleHostReverseProxy 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 NewSingleHostReverseProxy(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, req.URL.RawPath = joinURLPath(target, req.URL)
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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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// explicitly disable User-Agent so it's not set to default value
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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}
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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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// As of RFC 7230, hop-by-hop headers are required to appear in the
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// Connection header field. These are the headers defined by the
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// obsoleted RFC 2616 (section 13.5.1) and are used for backward
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// compatibility.
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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; https://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) defaultErrorHandler(rw http.ResponseWriter, req *http.Request, err error) {
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p.logf("http: proxy error: %v", err)
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rw.WriteHeader(http.StatusBadGateway)
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}
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func (p *ReverseProxy) getErrorHandler() func(http.ResponseWriter, *http.Request, error) {
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if p.ErrorHandler != nil {
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return p.ErrorHandler
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}
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return p.defaultErrorHandler
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}
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// modifyResponse conditionally runs the optional ModifyResponse hook
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// and reports whether the request should proceed.
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func (p *ReverseProxy) modifyResponse(rw http.ResponseWriter, res *http.Response, req *http.Request) bool {
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if p.ModifyResponse == nil {
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return true
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}
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if err := p.ModifyResponse(res); err != nil {
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res.Body.Close()
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p.getErrorHandler()(rw, req, err)
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return false
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}
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return true
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}
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func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
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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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ctx := req.Context()
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if cn, ok := rw.(http.CloseNotifier); ok {
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var cancel context.CancelFunc
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ctx, cancel = context.WithCancel(ctx)
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defer cancel()
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notifyChan := cn.CloseNotify()
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go func() {
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select {
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case <-notifyChan:
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cancel()
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case <-ctx.Done():
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}
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}()
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}
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outreq := req.Clone(ctx)
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if req.ContentLength == 0 {
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outreq.Body = nil // Issue 16036: nil Body for http.Transport retries
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}
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if outreq.Header == nil {
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outreq.Header = make(http.Header) // Issue 33142: historical behavior was to always allocate
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}
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// =============================
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// Modified for frp
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outreq = outreq.Clone(context.WithValue(outreq.Context(), RouteInfoURL, req.URL.Path))
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outreq = outreq.Clone(context.WithValue(outreq.Context(), RouteInfoHost, req.Host))
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outreq = outreq.Clone(context.WithValue(outreq.Context(), RouteInfoRemote, req.RemoteAddr))
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// =============================
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p.Director(outreq)
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outreq.Close = false
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reqUpType := upgradeType(outreq.Header)
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removeConnectionHeaders(outreq.Header)
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// Remove hop-by-hop headers to the backend. Especially
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// important is "Connection" because we want a persistent
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// connection, regardless of what the client sent to us.
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for _, h := range hopHeaders {
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hv := outreq.Header.Get(h)
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if hv == "" {
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continue
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}
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if h == "Te" && hv == "trailers" {
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// Issue 21096: tell backend applications that
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// care about trailer support that we support
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// trailers. (We do, but we don't go out of
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// our way to advertise that unless the
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// incoming client request thought it was
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// worth mentioning)
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continue
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}
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outreq.Header.Del(h)
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}
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// After stripping all the hop-by-hop connection headers above, add back any
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// necessary for protocol upgrades, such as for websockets.
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if reqUpType != "" {
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outreq.Header.Set("Connection", "Upgrade")
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outreq.Header.Set("Upgrade", reqUpType)
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}
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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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prior, ok := outreq.Header["X-Forwarded-For"]
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omit := ok && prior == nil // Issue 38079: nil now means don't populate the header
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if len(prior) > 0 {
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clientIP = strings.Join(prior, ", ") + ", " + clientIP
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}
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if !omit {
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outreq.Header.Set("X-Forwarded-For", clientIP)
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}
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}
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res, err := transport.RoundTrip(outreq)
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if err != nil {
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p.getErrorHandler()(rw, outreq, err)
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return
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}
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// Deal with 101 Switching Protocols responses: (WebSocket, h2c, etc)
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if res.StatusCode == http.StatusSwitchingProtocols {
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if !p.modifyResponse(rw, res, outreq) {
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return
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}
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p.handleUpgradeResponse(rw, outreq, res)
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return
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}
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removeConnectionHeaders(res.Header)
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for _, h := range hopHeaders {
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res.Header.Del(h)
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}
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if !p.modifyResponse(rw, res, outreq) {
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return
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}
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copyHeader(rw.Header(), res.Header)
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// The "Trailer" header isn't included in the Transport's response,
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// at least for *http.Transport. Build it up from Trailer.
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announcedTrailers := len(res.Trailer)
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if announcedTrailers > 0 {
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trailerKeys := make([]string, 0, len(res.Trailer))
|
|
|
|
for k := range res.Trailer {
|
|
|
|
trailerKeys = append(trailerKeys, k)
|
|
|
|
}
|
|
|
|
rw.Header().Add("Trailer", strings.Join(trailerKeys, ", "))
|
|
|
|
}
|
|
|
|
|
|
|
|
rw.WriteHeader(res.StatusCode)
|
2019-08-06 08:49:22 +00:00
|
|
|
|
2020-11-05 08:34:17 +00:00
|
|
|
err = p.copyResponse(rw, res.Body, p.flushInterval(res))
|
2019-08-06 08:49:22 +00:00
|
|
|
if err != nil {
|
|
|
|
defer res.Body.Close()
|
|
|
|
// Since we're streaming the response, if we run into an error all we can do
|
|
|
|
// is abort the request. Issue 23643: ReverseProxy should use ErrAbortHandler
|
|
|
|
// on read error while copying body.
|
|
|
|
if !shouldPanicOnCopyError(req) {
|
|
|
|
p.logf("suppressing panic for copyResponse error in test; copy error: %v", err)
|
|
|
|
return
|
|
|
|
}
|
|
|
|
panic(http.ErrAbortHandler)
|
|
|
|
}
|
|
|
|
res.Body.Close() // close now, instead of defer, to populate res.Trailer
|
|
|
|
|
2017-12-12 19:27:43 +00:00
|
|
|
if len(res.Trailer) > 0 {
|
|
|
|
// Force chunking if we saw a response trailer.
|
|
|
|
// This prevents net/http from calculating the length for short
|
|
|
|
// bodies and adding a Content-Length.
|
|
|
|
if fl, ok := rw.(http.Flusher); ok {
|
|
|
|
fl.Flush()
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if len(res.Trailer) == announcedTrailers {
|
|
|
|
copyHeader(rw.Header(), res.Trailer)
|
|
|
|
return
|
|
|
|
}
|
|
|
|
|
|
|
|
for k, vv := range res.Trailer {
|
|
|
|
k = http.TrailerPrefix + k
|
|
|
|
for _, v := range vv {
|
|
|
|
rw.Header().Add(k, v)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
var inOurTests bool // whether we're in our own tests
|
|
|
|
|
|
|
|
// shouldPanicOnCopyError reports whether the reverse proxy should
|
|
|
|
// panic with http.ErrAbortHandler. This is the right thing to do by
|
|
|
|
// default, but Go 1.10 and earlier did not, so existing unit tests
|
|
|
|
// weren't expecting panics. Only panic in our own tests, or when
|
|
|
|
// running under the HTTP server.
|
|
|
|
func shouldPanicOnCopyError(req *http.Request) bool {
|
|
|
|
if inOurTests {
|
|
|
|
// Our tests know to handle this panic.
|
|
|
|
return true
|
|
|
|
}
|
|
|
|
if req.Context().Value(http.ServerContextKey) != nil {
|
|
|
|
// We seem to be running under an HTTP server, so
|
|
|
|
// it'll recover the panic.
|
|
|
|
return true
|
|
|
|
}
|
|
|
|
// Otherwise act like Go 1.10 and earlier to not break
|
|
|
|
// existing tests.
|
|
|
|
return false
|
|
|
|
}
|
|
|
|
|
|
|
|
// removeConnectionHeaders removes hop-by-hop headers listed in the "Connection" header of h.
|
|
|
|
// See RFC 7230, section 6.1
|
|
|
|
func removeConnectionHeaders(h http.Header) {
|
|
|
|
for _, f := range h["Connection"] {
|
|
|
|
for _, sf := range strings.Split(f, ",") {
|
2020-11-05 08:34:17 +00:00
|
|
|
if sf = textproto.TrimString(sf); sf != "" {
|
2019-08-06 08:49:22 +00:00
|
|
|
h.Del(sf)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// flushInterval returns the p.FlushInterval value, conditionally
|
|
|
|
// overriding its value for a specific request/response.
|
2020-11-05 08:34:17 +00:00
|
|
|
func (p *ReverseProxy) flushInterval(res *http.Response) time.Duration {
|
2019-08-06 08:49:22 +00:00
|
|
|
resCT := res.Header.Get("Content-Type")
|
|
|
|
|
|
|
|
// For Server-Sent Events responses, flush immediately.
|
|
|
|
// The MIME type is defined in https://www.w3.org/TR/eventsource/#text-event-stream
|
|
|
|
if resCT == "text/event-stream" {
|
|
|
|
return -1 // negative means immediately
|
|
|
|
}
|
|
|
|
|
2020-11-05 08:34:17 +00:00
|
|
|
// We might have the case of streaming for which Content-Length might be unset.
|
|
|
|
if res.ContentLength == -1 {
|
|
|
|
return -1
|
|
|
|
}
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
return p.FlushInterval
|
|
|
|
}
|
|
|
|
|
|
|
|
func (p *ReverseProxy) copyResponse(dst io.Writer, src io.Reader, flushInterval time.Duration) error {
|
|
|
|
if flushInterval != 0 {
|
2017-12-12 19:27:43 +00:00
|
|
|
if wf, ok := dst.(writeFlusher); ok {
|
|
|
|
mlw := &maxLatencyWriter{
|
|
|
|
dst: wf,
|
2019-08-06 08:49:22 +00:00
|
|
|
latency: flushInterval,
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
|
|
|
defer mlw.stop()
|
2019-08-06 08:49:22 +00:00
|
|
|
|
|
|
|
// set up initial timer so headers get flushed even if body writes are delayed
|
|
|
|
mlw.flushPending = true
|
|
|
|
mlw.t = time.AfterFunc(flushInterval, mlw.delayedFlush)
|
|
|
|
|
2017-12-12 19:27:43 +00:00
|
|
|
dst = mlw
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
var buf []byte
|
|
|
|
if p.BufferPool != nil {
|
|
|
|
buf = p.BufferPool.Get()
|
2019-08-06 08:49:22 +00:00
|
|
|
defer p.BufferPool.Put(buf)
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
2019-08-06 08:49:22 +00:00
|
|
|
_, err := p.copyBuffer(dst, src, buf)
|
|
|
|
return err
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
// copyBuffer returns any write errors or non-EOF read errors, and the amount
|
|
|
|
// of bytes written.
|
2017-12-12 19:27:43 +00:00
|
|
|
func (p *ReverseProxy) copyBuffer(dst io.Writer, src io.Reader, buf []byte) (int64, error) {
|
|
|
|
if len(buf) == 0 {
|
|
|
|
buf = make([]byte, 32*1024)
|
|
|
|
}
|
|
|
|
var written int64
|
|
|
|
for {
|
|
|
|
nr, rerr := src.Read(buf)
|
|
|
|
if rerr != nil && rerr != io.EOF && rerr != context.Canceled {
|
|
|
|
p.logf("httputil: ReverseProxy read error during body copy: %v", rerr)
|
|
|
|
}
|
|
|
|
if nr > 0 {
|
|
|
|
nw, werr := dst.Write(buf[:nr])
|
|
|
|
if nw > 0 {
|
|
|
|
written += int64(nw)
|
|
|
|
}
|
|
|
|
if werr != nil {
|
|
|
|
return written, werr
|
|
|
|
}
|
|
|
|
if nr != nw {
|
|
|
|
return written, io.ErrShortWrite
|
|
|
|
}
|
|
|
|
}
|
|
|
|
if rerr != nil {
|
2019-08-06 08:49:22 +00:00
|
|
|
if rerr == io.EOF {
|
|
|
|
rerr = nil
|
|
|
|
}
|
2017-12-12 19:27:43 +00:00
|
|
|
return written, rerr
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
func (p *ReverseProxy) logf(format string, args ...interface{}) {
|
|
|
|
if p.ErrorLog != nil {
|
|
|
|
p.ErrorLog.Printf(format, args...)
|
|
|
|
} else {
|
|
|
|
log.Printf(format, args...)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
type writeFlusher interface {
|
|
|
|
io.Writer
|
|
|
|
http.Flusher
|
|
|
|
}
|
|
|
|
|
|
|
|
type maxLatencyWriter struct {
|
|
|
|
dst writeFlusher
|
2019-08-06 08:49:22 +00:00
|
|
|
latency time.Duration // non-zero; negative means to flush immediately
|
2017-12-12 19:27:43 +00:00
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
mu sync.Mutex // protects t, flushPending, and dst.Flush
|
|
|
|
t *time.Timer
|
|
|
|
flushPending bool
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
func (m *maxLatencyWriter) Write(p []byte) (n int, err error) {
|
2017-12-12 19:27:43 +00:00
|
|
|
m.mu.Lock()
|
|
|
|
defer m.mu.Unlock()
|
2019-08-06 08:49:22 +00:00
|
|
|
n, err = m.dst.Write(p)
|
|
|
|
if m.latency < 0 {
|
|
|
|
m.dst.Flush()
|
|
|
|
return
|
|
|
|
}
|
|
|
|
if m.flushPending {
|
|
|
|
return
|
|
|
|
}
|
|
|
|
if m.t == nil {
|
|
|
|
m.t = time.AfterFunc(m.latency, m.delayedFlush)
|
|
|
|
} else {
|
|
|
|
m.t.Reset(m.latency)
|
|
|
|
}
|
|
|
|
m.flushPending = true
|
|
|
|
return
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
func (m *maxLatencyWriter) delayedFlush() {
|
|
|
|
m.mu.Lock()
|
|
|
|
defer m.mu.Unlock()
|
|
|
|
if !m.flushPending { // if stop was called but AfterFunc already started this goroutine
|
|
|
|
return
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
2019-08-06 08:49:22 +00:00
|
|
|
m.dst.Flush()
|
|
|
|
m.flushPending = false
|
2017-12-12 19:27:43 +00:00
|
|
|
}
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
func (m *maxLatencyWriter) stop() {
|
|
|
|
m.mu.Lock()
|
|
|
|
defer m.mu.Unlock()
|
|
|
|
m.flushPending = false
|
|
|
|
if m.t != nil {
|
|
|
|
m.t.Stop()
|
|
|
|
}
|
|
|
|
}
|
2018-01-22 17:29:52 +00:00
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
func upgradeType(h http.Header) string {
|
|
|
|
if !httpguts.HeaderValuesContainsToken(h["Connection"], "Upgrade") {
|
|
|
|
return ""
|
|
|
|
}
|
|
|
|
return strings.ToLower(h.Get("Upgrade"))
|
|
|
|
}
|
|
|
|
|
|
|
|
func (p *ReverseProxy) handleUpgradeResponse(rw http.ResponseWriter, req *http.Request, res *http.Response) {
|
|
|
|
reqUpType := upgradeType(req.Header)
|
|
|
|
resUpType := upgradeType(res.Header)
|
|
|
|
if reqUpType != resUpType {
|
|
|
|
p.getErrorHandler()(rw, req, fmt.Errorf("backend tried to switch protocol %q when %q was requested", resUpType, reqUpType))
|
|
|
|
return
|
|
|
|
}
|
|
|
|
|
|
|
|
hj, ok := rw.(http.Hijacker)
|
|
|
|
if !ok {
|
|
|
|
p.getErrorHandler()(rw, req, fmt.Errorf("can't switch protocols using non-Hijacker ResponseWriter type %T", rw))
|
|
|
|
return
|
2018-01-22 17:29:52 +00:00
|
|
|
}
|
2019-08-06 08:49:22 +00:00
|
|
|
backConn, ok := res.Body.(io.ReadWriteCloser)
|
|
|
|
if !ok {
|
|
|
|
p.getErrorHandler()(rw, req, fmt.Errorf("internal error: 101 switching protocols response with non-writable body"))
|
|
|
|
return
|
|
|
|
}
|
2020-11-05 08:34:17 +00:00
|
|
|
|
|
|
|
backConnCloseCh := make(chan bool)
|
|
|
|
go func() {
|
|
|
|
// Ensure that the cancelation of a request closes the backend.
|
|
|
|
// See issue https://golang.org/issue/35559.
|
|
|
|
select {
|
|
|
|
case <-req.Context().Done():
|
|
|
|
case <-backConnCloseCh:
|
|
|
|
}
|
|
|
|
backConn.Close()
|
|
|
|
}()
|
|
|
|
|
|
|
|
defer close(backConnCloseCh)
|
|
|
|
|
2019-08-06 08:49:22 +00:00
|
|
|
conn, brw, err := hj.Hijack()
|
|
|
|
if err != nil {
|
|
|
|
p.getErrorHandler()(rw, req, fmt.Errorf("Hijack failed on protocol switch: %v", err))
|
|
|
|
return
|
|
|
|
}
|
|
|
|
defer conn.Close()
|
2020-11-05 08:34:17 +00:00
|
|
|
|
|
|
|
copyHeader(rw.Header(), res.Header)
|
|
|
|
|
|
|
|
res.Header = rw.Header()
|
2019-08-06 08:49:22 +00:00
|
|
|
res.Body = nil // so res.Write only writes the headers; we have res.Body in backConn above
|
|
|
|
if err := res.Write(brw); err != nil {
|
|
|
|
p.getErrorHandler()(rw, req, fmt.Errorf("response write: %v", err))
|
|
|
|
return
|
|
|
|
}
|
|
|
|
if err := brw.Flush(); err != nil {
|
|
|
|
p.getErrorHandler()(rw, req, fmt.Errorf("response flush: %v", err))
|
|
|
|
return
|
|
|
|
}
|
|
|
|
errc := make(chan error, 1)
|
|
|
|
spc := switchProtocolCopier{user: conn, backend: backConn}
|
|
|
|
go spc.copyToBackend(errc)
|
|
|
|
go spc.copyFromBackend(errc)
|
|
|
|
<-errc
|
|
|
|
return
|
|
|
|
}
|
|
|
|
|
|
|
|
// switchProtocolCopier exists so goroutines proxying data back and
|
|
|
|
// forth have nice names in stacks.
|
|
|
|
type switchProtocolCopier struct {
|
|
|
|
user, backend io.ReadWriter
|
|
|
|
}
|
|
|
|
|
|
|
|
func (c switchProtocolCopier) copyFromBackend(errc chan<- error) {
|
|
|
|
_, err := io.Copy(c.user, c.backend)
|
|
|
|
errc <- err
|
|
|
|
}
|
|
|
|
|
|
|
|
func (c switchProtocolCopier) copyToBackend(errc chan<- error) {
|
|
|
|
_, err := io.Copy(c.backend, c.user)
|
|
|
|
errc <- err
|
2018-01-22 17:29:52 +00:00
|
|
|
}
|