transport.go

     1  // Copyright 2018 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package transport provides a mechanism to send requests with https cert,
    16  // key, and CA.
    17  package transport
    18  
    19  import (
    20  	"crypto/tls"
    21  	"crypto/x509"
    22  	"fmt"
    23  	"io/ioutil"
    24  	"net/http"
    25  	"sync"
    26  
    27  	"github.com/google/pprof/internal/plugin"
    28  )
    29  
    30  type transport struct {
    31  	cert       *string
    32  	key        *string
    33  	ca         *string
    34  	caCertPool *x509.CertPool
    35  	certs      []tls.Certificate
    36  	initOnce   sync.Once
    37  	initErr    error
    38  }
    39  
    40  const extraUsage = `    -tls_cert             TLS client certificate file for fetching profile and symbols
    41      -tls_key              TLS private key file for fetching profile and symbols
    42      -tls_ca               TLS CA certs file for fetching profile and symbols`
    43  
    44  // New returns a round tripper for making requests with the
    45  // specified cert, key, and ca. The flags tls_cert, tls_key, and tls_ca are
    46  // added to the flagset to allow a user to specify the cert, key, and ca. If
    47  // the flagset is nil, no flags will be added, and users will not be able to
    48  // use these flags.
    49  func New(flagset plugin.FlagSet) http.RoundTripper {
    50  	if flagset == nil {
    51  		return &transport{}
    52  	}
    53  	flagset.AddExtraUsage(extraUsage)
    54  	return &transport{
    55  		cert: flagset.String("tls_cert", "", "TLS client certificate file for fetching profile and symbols"),
    56  		key:  flagset.String("tls_key", "", "TLS private key file for fetching profile and symbols"),
    57  		ca:   flagset.String("tls_ca", "", "TLS CA certs file for fetching profile and symbols"),
    58  	}
    59  }
    60  
    61  // initialize uses the cert, key, and ca to initialize the certs
    62  // to use these when making requests.
    63  func (tr *transport) initialize() error {
    64  	var cert, key, ca string
    65  	if tr.cert != nil {
    66  		cert = *tr.cert
    67  	}
    68  	if tr.key != nil {
    69  		key = *tr.key
    70  	}
    71  	if tr.ca != nil {
    72  		ca = *tr.ca
    73  	}
    74  
    75  	if cert != "" && key != "" {
    76  		tlsCert, err := tls.LoadX509KeyPair(cert, key)
    77  		if err != nil {
    78  			return fmt.Errorf("could not load certificate/key pair specified by -tls_cert and -tls_key: %v", err)
    79  		}
    80  		tr.certs = []tls.Certificate{tlsCert}
    81  	} else if cert == "" && key != "" {
    82  		return fmt.Errorf("-tls_key is specified, so -tls_cert must also be specified")
    83  	} else if cert != "" && key == "" {
    84  		return fmt.Errorf("-tls_cert is specified, so -tls_key must also be specified")
    85  	}
    86  
    87  	if ca != "" {
    88  		caCertPool := x509.NewCertPool()
    89  		caCert, err := ioutil.ReadFile(ca)
    90  		if err != nil {
    91  			return fmt.Errorf("could not load CA specified by -tls_ca: %v", err)
    92  		}
    93  		caCertPool.AppendCertsFromPEM(caCert)
    94  		tr.caCertPool = caCertPool
    95  	}
    96  
    97  	return nil
    98  }
    99  
   100  // RoundTrip executes a single HTTP transaction, returning
   101  // a Response for the provided Request.
   102  func (tr *transport) RoundTrip(req *http.Request) (*http.Response, error) {
   103  	tr.initOnce.Do(func() {
   104  		tr.initErr = tr.initialize()
   105  	})
   106  	if tr.initErr != nil {
   107  		return nil, tr.initErr
   108  	}
   109  
   110  	tlsConfig := &tls.Config{
   111  		RootCAs:      tr.caCertPool,
   112  		Certificates: tr.certs,
   113  	}
   114  
   115  	if req.URL.Scheme == "https+insecure" {
   116  		// Make shallow copy of request, and req.URL, so the request's URL can be
   117  		// modified.
   118  		r := *req
   119  		*r.URL = *req.URL
   120  		req = &r
   121  		tlsConfig.InsecureSkipVerify = true
   122  		req.URL.Scheme = "https"
   123  	}
   124  
   125  	transport := http.Transport{
   126  		Proxy:           http.ProxyFromEnvironment,
   127  		TLSClientConfig: tlsConfig,
   128  	}
   129  
   130  	return transport.RoundTrip(req)
   131  }
   132
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