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@@ -1,636 +0,0 @@
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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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-
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-// HTTP reverse proxy handler
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-
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-package vhost
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-
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-import (
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- "context"
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- "encoding/base64"
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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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-
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- "golang.org/x/net/http/httpguts"
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-)
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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- aslash := strings.HasSuffix(apath, "/")
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- bslash := strings.HasPrefix(bpath, "/")
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-
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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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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-
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-func parseBasicAuth(auth string) (username, password string, ok bool) {
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- const prefix = "Basic "
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- // Case insensitive prefix match. See Issue 22736.
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- if len(auth) < len(prefix) || !strings.EqualFold(auth[:len(prefix)], prefix) {
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- return
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- }
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- c, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
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- if err != nil {
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- return
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- }
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- cs := string(c)
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- s := strings.IndexByte(cs, ':')
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- if s < 0 {
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- return
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- }
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- return cs[:s], cs[s+1:], true
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-}
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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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-
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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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-
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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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- p.Director(outreq)
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- outreq.Close = false
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-
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- reqUpType := upgradeType(outreq.Header)
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- removeConnectionHeaders(outreq.Header)
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-
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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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-
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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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-
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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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-
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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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-
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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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-
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- removeConnectionHeaders(res.Header)
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-
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- for _, h := range hopHeaders {
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- res.Header.Del(h)
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- }
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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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-
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- copyHeader(rw.Header(), res.Header)
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-
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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))
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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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-
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- rw.WriteHeader(res.StatusCode)
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-
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- err = p.copyResponse(rw, res.Body, p.flushInterval(res))
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- if err != nil {
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- defer res.Body.Close()
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- // Since we're streaming the response, if we run into an error all we can do
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- // is abort the request. Issue 23643: ReverseProxy should use ErrAbortHandler
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- // on read error while copying body.
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- if !shouldPanicOnCopyError(req) {
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- p.logf("suppressing panic for copyResponse error in test; copy error: %v", err)
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- return
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- }
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- panic(http.ErrAbortHandler)
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- }
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- res.Body.Close() // close now, instead of defer, to populate res.Trailer
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-
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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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-
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- if len(res.Trailer) == announcedTrailers {
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- copyHeader(rw.Header(), res.Trailer)
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- return
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- }
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-
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- for k, vv := range res.Trailer {
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- k = http.TrailerPrefix + k
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- for _, v := range vv {
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- rw.Header().Add(k, v)
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- }
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- }
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-}
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-
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-var inOurTests bool // whether we're in our own tests
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-
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-// shouldPanicOnCopyError reports whether the reverse proxy should
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-// panic with http.ErrAbortHandler. This is the right thing to do by
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-// default, but Go 1.10 and earlier did not, so existing unit tests
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-// weren't expecting panics. Only panic in our own tests, or when
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-// running under the HTTP server.
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-func shouldPanicOnCopyError(req *http.Request) bool {
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- if inOurTests {
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- // Our tests know to handle this panic.
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- return true
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- }
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- if req.Context().Value(http.ServerContextKey) != nil {
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- // We seem to be running under an HTTP server, so
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- // it'll recover the panic.
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- return true
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- }
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- // Otherwise act like Go 1.10 and earlier to not break
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- // existing tests.
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- return false
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-}
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-
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-// removeConnectionHeaders removes hop-by-hop headers listed in the "Connection" header of h.
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-// See RFC 7230, section 6.1
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-func removeConnectionHeaders(h http.Header) {
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- for _, f := range h["Connection"] {
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- for _, sf := range strings.Split(f, ",") {
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- if sf = textproto.TrimString(sf); sf != "" {
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- h.Del(sf)
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- }
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- }
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- }
|
|
|
-}
|
|
|
-
|
|
|
-// flushInterval returns the p.FlushInterval value, conditionally
|
|
|
-// overriding its value for a specific request/response.
|
|
|
-func (p *ReverseProxy) flushInterval(res *http.Response) time.Duration {
|
|
|
- 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
|
|
|
- }
|
|
|
-
|
|
|
- // We might have the case of streaming for which Content-Length might be unset.
|
|
|
- if res.ContentLength == -1 {
|
|
|
- return -1
|
|
|
- }
|
|
|
-
|
|
|
- return p.FlushInterval
|
|
|
-}
|
|
|
-
|
|
|
-func (p *ReverseProxy) copyResponse(dst io.Writer, src io.Reader, flushInterval time.Duration) error {
|
|
|
- if flushInterval != 0 {
|
|
|
- if wf, ok := dst.(writeFlusher); ok {
|
|
|
- mlw := &maxLatencyWriter{
|
|
|
- dst: wf,
|
|
|
- latency: flushInterval,
|
|
|
- }
|
|
|
- defer mlw.stop()
|
|
|
-
|
|
|
- // set up initial timer so headers get flushed even if body writes are delayed
|
|
|
- mlw.flushPending = true
|
|
|
- mlw.t = time.AfterFunc(flushInterval, mlw.delayedFlush)
|
|
|
-
|
|
|
- dst = mlw
|
|
|
- }
|
|
|
- }
|
|
|
-
|
|
|
- var buf []byte
|
|
|
- if p.BufferPool != nil {
|
|
|
- buf = p.BufferPool.Get()
|
|
|
- defer p.BufferPool.Put(buf)
|
|
|
- }
|
|
|
- _, err := p.copyBuffer(dst, src, buf)
|
|
|
- return err
|
|
|
-}
|
|
|
-
|
|
|
-// copyBuffer returns any write errors or non-EOF read errors, and the amount
|
|
|
-// of bytes written.
|
|
|
-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 {
|
|
|
- if rerr == io.EOF {
|
|
|
- rerr = nil
|
|
|
- }
|
|
|
- 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
|
|
|
- latency time.Duration // non-zero; negative means to flush immediately
|
|
|
-
|
|
|
- mu sync.Mutex // protects t, flushPending, and dst.Flush
|
|
|
- t *time.Timer
|
|
|
- flushPending bool
|
|
|
-}
|
|
|
-
|
|
|
-func (m *maxLatencyWriter) Write(p []byte) (n int, err error) {
|
|
|
- m.mu.Lock()
|
|
|
- defer m.mu.Unlock()
|
|
|
- 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
|
|
|
-}
|
|
|
-
|
|
|
-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
|
|
|
- }
|
|
|
- m.dst.Flush()
|
|
|
- m.flushPending = false
|
|
|
-}
|
|
|
-
|
|
|
-func (m *maxLatencyWriter) stop() {
|
|
|
- m.mu.Lock()
|
|
|
- defer m.mu.Unlock()
|
|
|
- m.flushPending = false
|
|
|
- if m.t != nil {
|
|
|
- m.t.Stop()
|
|
|
- }
|
|
|
-}
|
|
|
-
|
|
|
-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
|
|
|
- }
|
|
|
- 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
|
|
|
- }
|
|
|
-
|
|
|
- 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)
|
|
|
-
|
|
|
- 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()
|
|
|
-
|
|
|
- copyHeader(rw.Header(), res.Header)
|
|
|
-
|
|
|
- res.Header = rw.Header()
|
|
|
- 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
|
|
|
-}
|