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Implement TLS VerifyPeerCertificate callback to skip hostname verfication #238

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Implement TLS VerifyPeerCertificate callback to skip hostname verfication #238

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66e589a
VerifyPeerCertificate callback to implement skip Hostname verification
zzzming May 3, 2020
9fd6cdd
fix linting - comment line too long
zzzming May 3, 2020
0b331e1
always set ServerName
zzzming May 26, 2020
cd2a103
only verify cert if it exists
zzzming May 26, 2020
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18 changes: 18 additions & 0 deletions pulsar/client_impl_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,24 @@ func TestTLSInsecureConnection(t *testing.T) {
client.Close()
}

func TestTLSInsecureConnectionWithCerts(t *testing.T) {
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@EronWright EronWright Jun 11, 2020

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This test doesn't seem to do anything substantive. I'd expect it to exercise the resultant tls.Config in some way, maybe by making an actual TLS connection.

client, err := NewClient(ClientOptions{
URL: serviceURLTLS,
TLSAllowInsecureConnection: true,
TLSTrustCertsFilePath: caCertsPath,
})
assert.NoError(t, err)

producer, err := client.CreateProducer(ProducerOptions{
Topic: newTopicName(),
})

assert.NoError(t, err)
assert.NotNil(t, producer)

client.Close()
}

func TestTLSConnection(t *testing.T) {
client, err := NewClient(ClientOptions{
URL: serviceURLTLS,
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42 changes: 40 additions & 2 deletions pulsar/internal/connection.go
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Expand Up @@ -711,8 +711,46 @@ func (c *connection) getTLSConfig() (*tls.Config, error) {
}
}

if c.tlsOptions.ValidateHostname {
tlsConfig.ServerName = c.physicalAddr.Hostname()
tlsConfig.ServerName = c.physicalAddr.Hostname()

if tlsConfig.InsecureSkipVerify {
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@EronWright EronWright Jun 11, 2020

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Why isn't c.tlsOptions.ValidateHostname used anywhere? I was thinking:

tlsConfig := &tls.Config{
    // disable built-in verification if hostname verification is to be skipped
		InsecureSkipVerify: c.tlsOptions.AllowInsecureConnection || !c.tlsOptions.ValidateHostname
	}

if !c.tlsOptions.AllowInsecureConnection && tlsConfig.InsecureSkipVerify {
  // implement a limited verification routine that checks the certificate but skips hostname verification 
  tlsConfig.VerifyPeerCertificate = func() {...}
}

// Solution is credited to https://github.com/golang/go/issues/21971
// Code is adapted from the original implementation of handshake_client.go at
// https://github.com/golang/go/blob/master/src/crypto/tls/handshake_client.go#L804
// disable the default verification; use customized VerifyPeerCertificate
tlsConfig.VerifyPeerCertificate = func(rawCerts [][]byte, certChain [][]*x509.Certificate) error {
// If this is the first handshake on a connection, process and
// (optionally) verify the server's certificates.
certs := make([]*x509.Certificate, len(rawCerts))
for i, asn1Data := range rawCerts {
cert, err := x509.ParseCertificate(asn1Data)
if err != nil {
return fmt.Errorf("tls: failed to parse server certificate error: %s", err.Error())
}
certs[i] = cert
}

if tlsConfig.RootCAs == nil {
return nil
}
Comment on lines +733 to +735
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@EronWright EronWright Jun 11, 2020

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How would this deal with the common scenario where the client is using the system's bundle? I am unsure of whether RootCAs is nil in that scenario.

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@jdkuki jdkuki Aug 25, 2021

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Just ran into this. As-is verification will return success when no roots are loaded.


// Verify certs if they exist but skip ServerName validation
opts := x509.VerifyOptions{
Roots: tlsConfig.RootCAs,
CurrentTime: time.Now(),
DNSName: "", // skip hostname verification
Intermediates: x509.NewCertPool(),
}

for i, cert := range certs {
if i == 0 {
continue
}
opts.Intermediates.AddCert(cert)
}
_, err := certs[0].Verify(opts)
return err
}
}

cert, err := c.auth.GetTLSCertificate()
Expand Down