vendor/golang.org/x/net/http2/configure_transport.go

   1 // Copyright 2015 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build go1.6
   6
   7 package http2
   8
   9 import (
  10         "crypto/tls"
  11         "fmt"
  12         "net/http"
  13 )
  14
  15 func configureTransport(t1 *http.Transport) (*Transport, error) {
  16         connPool := new(clientConnPool)
  17         t2 := &Transport{
  18                 ConnPool: noDialClientConnPool{connPool},
  19                 t1:       t1,
  20         }
  21         connPool.t = t2
  22         if err := registerHTTPSProtocol(t1, noDialH2RoundTripper{t2}); err != nil {
  23                 return nil, err
  24         }
  25         if t1.TLSClientConfig == nil {
  26                 t1.TLSClientConfig = new(tls.Config)
  27         }
  28         if !strSliceContains(t1.TLSClientConfig.NextProtos, "h2") {
  29                 t1.TLSClientConfig.NextProtos = append([]string{"h2"}, t1.TLSClientConfig.NextProtos...)
  30         }
  31         if !strSliceContains(t1.TLSClientConfig.NextProtos, "http/1.1") {
  32                 t1.TLSClientConfig.NextProtos = append(t1.TLSClientConfig.NextProtos, "http/1.1")
  33         }
  34         upgradeFn := func(authority string, c *tls.Conn) http.RoundTripper {
  35                 addr := authorityAddr("https", authority)
  36                 if used, err := connPool.addConnIfNeeded(addr, t2, c); err != nil {
  37                         go c.Close()
  38                         return erringRoundTripper{err}
  39                 } else if !used {
  40                         // Turns out we don't need this c.
  41                         // For example, two goroutines made requests to the same host
  42                         // at the same time, both kicking off TCP dials. (since protocol
  43                         // was unknown)
  44                         go c.Close()
  45                 }
  46                 return t2
  47         }
  48         if m := t1.TLSNextProto; len(m) == 0 {
  49                 t1.TLSNextProto = map[string]func(string, *tls.Conn) http.RoundTripper{
  50                         "h2": upgradeFn,
  51                 }
  52         } else {
  53                 m["h2"] = upgradeFn
  54         }
  55         return t2, nil
  56 }
  57
  58 // registerHTTPSProtocol calls Transport.RegisterProtocol but
  59 // converting panics into errors.
  60 func registerHTTPSProtocol(t *http.Transport, rt http.RoundTripper) (err error) {
  61         defer func() {
  62                 if e := recover(); e != nil {
  63                         err = fmt.Errorf("%v", e)
  64                 }
  65         }()
  66         t.RegisterProtocol("https", rt)
  67         return nil
  68 }
  69
  70 // noDialH2RoundTripper is a RoundTripper which only tries to complete the request
  71 // if there's already has a cached connection to the host.
  72 type noDialH2RoundTripper struct{ t *Transport }
  73
  74 func (rt noDialH2RoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
  75         res, err := rt.t.RoundTrip(req)
  76         if err == ErrNoCachedConn {
  77                 return nil, http.ErrSkipAltProtocol
  78         }
  79         return res, err
  80 }