server_inspection.go

Documentation: k8s.io/client-go/util/cert

     1  /*
     2  Copyright 2019 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package cert
    18  
    19  import (
    20  	"crypto/tls"
    21  	"crypto/x509"
    22  	"fmt"
    23  	"net/url"
    24  	"strings"
    25  )
    26  
    27  // GetClientCANames gets the CA names for client certs that a server accepts.  This is useful when inspecting the
    28  // state of particular servers.  apiHost is "host:port"
    29  func GetClientCANames(apiHost string) ([]string, error) {
    30  	// when we run this the second time, we know which one we are expecting
    31  	acceptableCAs := []string{}
    32  	tlsConfig := &tls.Config{
    33  		InsecureSkipVerify: true, // this is insecure to always get to the GetClientCertificate
    34  		GetClientCertificate: func(hello *tls.CertificateRequestInfo) (*tls.Certificate, error) {
    35  			acceptableCAs = []string{}
    36  			for _, curr := range hello.AcceptableCAs {
    37  				acceptableCAs = append(acceptableCAs, string(curr))
    38  			}
    39  			return &tls.Certificate{}, nil
    40  		},
    41  	}
    42  
    43  	conn, err := tls.Dial("tcp", apiHost, tlsConfig)
    44  	if err != nil {
    45  		return nil, err
    46  	}
    47  	if err := conn.Close(); err != nil {
    48  		return nil, err
    49  	}
    50  
    51  	return acceptableCAs, nil
    52  }
    53  
    54  // GetClientCANamesForURL is GetClientCANames against a URL string like we use in kubeconfigs
    55  func GetClientCANamesForURL(kubeConfigURL string) ([]string, error) {
    56  	apiserverURL, err := url.Parse(kubeConfigURL)
    57  	if err != nil {
    58  		return nil, err
    59  	}
    60  	return GetClientCANames(apiserverURL.Host)
    61  }
    62  
    63  // GetServingCertificates returns the x509 certs used by a server as certificates and pem encoded bytes.
    64  // The serverName is optional for specifying a different name to get SNI certificates.  apiHost is "host:port"
    65  func GetServingCertificates(apiHost, serverName string) ([]*x509.Certificate, [][]byte, error) {
    66  	tlsConfig := &tls.Config{
    67  		InsecureSkipVerify: true, // this is insecure so that we always get connected
    68  	}
    69  	// if a name is specified for SNI, set it.
    70  	if len(serverName) > 0 {
    71  		tlsConfig.ServerName = serverName
    72  	}
    73  
    74  	conn, err := tls.Dial("tcp", apiHost, tlsConfig)
    75  	if err != nil {
    76  		return nil, nil, err
    77  	}
    78  	if err = conn.Close(); err != nil {
    79  		return nil, nil, fmt.Errorf("failed to close connection : %v", err)
    80  	}
    81  
    82  	peerCerts := conn.ConnectionState().PeerCertificates
    83  	peerCertBytes := [][]byte{}
    84  	for _, a := range peerCerts {
    85  		actualCert, err := EncodeCertificates(a)
    86  		if err != nil {
    87  			return nil, nil, err
    88  		}
    89  		peerCertBytes = append(peerCertBytes, []byte(strings.TrimSpace(string(actualCert))))
    90  	}
    91  
    92  	return peerCerts, peerCertBytes, err
    93  }
    94  
    95  // GetServingCertificatesForURL is GetServingCertificates against a URL string like we use in kubeconfigs
    96  func GetServingCertificatesForURL(kubeConfigURL, serverName string) ([]*x509.Certificate, [][]byte, error) {
    97  	apiserverURL, err := url.Parse(kubeConfigURL)
    98  	if err != nil {
    99  		return nil, nil, err
   100  	}
   101  	return GetServingCertificates(apiserverURL.Host, serverName)
   102  }
   103
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