lib/controller/proxy.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package controller
   6
   7 import (
   8         "context"
   9         "io"
  10         "net/http"
  11         "net/url"
  12         "time"
  13
  14         "git.curoverse.com/arvados.git/sdk/go/httpserver"
  15 )
  16
  17 type proxy struct {
  18         Name           string // to use in Via header
  19         RequestTimeout time.Duration
  20 }
  21
  22 // headers that shouldn't be forwarded when proxying. See
  23 // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers
  24 var dropHeaders = map[string]bool{
  25         "Connection":          true,
  26         "Keep-Alive":          true,
  27         "Proxy-Authenticate":  true,
  28         "Proxy-Authorization": true,
  29         "TE":                true,
  30         "Trailer":           true,
  31         "Transfer-Encoding": true,
  32         "Upgrade":           true,
  33 }
  34
  35 func (p *proxy) Do(w http.ResponseWriter, reqIn *http.Request, urlOut *url.URL, client *http.Client) {
  36         // Copy headers from incoming request, then add/replace proxy
  37         // headers like Via and X-Forwarded-For.
  38         hdrOut := http.Header{}
  39         for k, v := range reqIn.Header {
  40                 if !dropHeaders[k] {
  41                         hdrOut[k] = v
  42                 }
  43         }
  44         xff := reqIn.RemoteAddr
  45         if xffIn := reqIn.Header.Get("X-Forwarded-For"); xffIn != "" {
  46                 xff = xffIn + "," + xff
  47         }
  48         hdrOut.Set("X-Forwarded-For", xff)
  49         if hdrOut.Get("X-Forwarded-Proto") == "" {
  50                 hdrOut.Set("X-Forwarded-Proto", reqIn.URL.Scheme)
  51         }
  52         hdrOut.Add("Via", reqIn.Proto+" arvados-controller")
  53
  54         ctx := reqIn.Context()
  55         if p.RequestTimeout > 0 {
  56                 var cancel context.CancelFunc
  57                 ctx, cancel = context.WithDeadline(ctx, time.Now().Add(time.Duration(p.RequestTimeout)))
  58                 defer cancel()
  59         }
  60
  61         reqOut := (&http.Request{
  62                 Method: reqIn.Method,
  63                 URL:    urlOut,
  64                 Host:   reqIn.Host,
  65                 Header: hdrOut,
  66                 Body:   reqIn.Body,
  67         }).WithContext(ctx)
  68         resp, err := client.Do(reqOut)
  69         if err != nil {
  70                 httpserver.Error(w, err.Error(), http.StatusBadGateway)
  71                 return
  72         }
  73         for k, v := range resp.Header {
  74                 for _, v := range v {
  75                         w.Header().Add(k, v)
  76                 }
  77         }
  78         w.WriteHeader(resp.StatusCode)
  79         n, err := io.Copy(w, resp.Body)
  80         if err != nil {
  81                 httpserver.Logger(reqIn).WithError(err).WithField("bytesCopied", n).Error("error copying response body")
  82         }
  83 }