// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package tls

import (
	"crypto"
	"crypto/x509"
	"encoding/asn1"
	"encoding/pem"
	"fmt"
	"testing"
	"time"
)

// A PEM-encoded "delegation certificate", an X.509 certificate with the
// DelegationUsage extension. The extension is defined in
// specified in https://tools.ietf.org/html/draft-ietf-tls-subcerts-01.
var dcDelegationCertPEM = `-----BEGIN CERTIFICATE-----
MIIBdzCCAR2gAwIBAgIQLVIvEpo0/0TzRja4ImvB1TAKBggqhkjOPQQDAjASMRAw
DgYDVQQKEwdBY21lIENvMB4XDTE4MDcwMzE2NTE1M1oXDTE5MDcwMzE2NTE1M1ow
EjEQMA4GA1UEChMHQWNtZSBDbzBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABOhB
U6adaAgliLaFc1PAo9HBO4Wish1G4df3IK5EXLy+ooYfmkfzT1FxqbNLZufNYzve
25fmpal/1VJAjpVyKq2jVTBTMA4GA1UdDwEB/wQEAwIFoDATBgNVHSUEDDAKBggr
BgEFBQcDATAMBgNVHRMBAf8EAjAAMA8GA1UdEQQIMAaHBH8AAAEwDQYJKwYBBAGC
2kssBAAwCgYIKoZIzj0EAwIDSAAwRQIhAPNwRk6cygm6zO5rjOzohKYWS+1KuWCM
OetDIvU4mdyoAiAGN97y3GJccYn9ZOJS4UOqhr9oO8PuZMLgdq4OrMRiiA==
-----END CERTIFICATE-----
`

// The PEM-encoded "delegation key", the secret key associated with the
// delegation certificate.
var dcDelegationKeyPEM = `-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIJDVlo+sJolMcNjMkfCGDUjMJcE4UgclcXGCrOtbJAi2oAoGCCqGSM49
AwEHoUQDQgAE6EFTpp1oCCWItoVzU8Cj0cE7haKyHUbh1/cgrkRcvL6ihh+aR/NP
UXGps0tm581jO97bl+alqX/VUkCOlXIqrQ==
-----END EC PRIVATE KEY-----
`

// A certificate without the DelegationUsage extension.
var dcCertPEM = `-----BEGIN CERTIFICATE-----
MIIBaTCCAQ6gAwIBAgIQSUo+9uaip3qCW+1EPeHZgDAKBggqhkjOPQQDAjASMRAw
DgYDVQQKEwdBY21lIENvMB4XDTE4MDYxMjIzNDAyNloXDTE5MDYxMjIzNDAyNlow
EjEQMA4GA1UEChMHQWNtZSBDbzBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABLf7
fiznPVdc3V5mM3ymswU2/IoJaq/deA6dgdj50ozdYyRiAPjxzcz9zRsZw1apTF/h
yNfiLhV4EE1VrwXcT5OjRjBEMA4GA1UdDwEB/wQEAwIFoDATBgNVHSUEDDAKBggr
BgEFBQcDATAMBgNVHRMBAf8EAjAAMA8GA1UdEQQIMAaHBH8AAAEwCgYIKoZIzj0E
AwIDSQAwRgIhANXG0zmrVtQBK0TNZZoEGMOtSwxmiZzXNe+IjdpxO3TiAiEA5VYx
0CWJq5zqpVXbJMeKVMASo2nrXZoA6NhJvFQ97hw=
-----END CERTIFICATE-----
`

// The secret key associatted with dcCertPEM.
var dcKeyPEM = `-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIMw9DiOfGI1E/XZrrW2huZSjYi0EKwvVjAe+dYtyFsSloAoGCCqGSM49
AwEHoUQDQgAEt/t+LOc9V1zdXmYzfKazBTb8iglqr914Dp2B2PnSjN1jJGIA+PHN
zP3NGxnDVqlMX+HI1+IuFXgQTVWvBdxPkw==
-----END EC PRIVATE KEY-----
`

// dcTestDC stores delegated credentials and their secret keys.
type dcTestDC struct {
	Name       string
	Version    int
	Scheme     int
	DC         []byte
	PrivateKey []byte
}

// Test data used for testing the TLS handshake with the delegated creedential
// extension. The PEM block encodes a DER encoded slice of dcTestDC's.
var dcTestDCsPEM = `-----BEGIN DC TEST DATA-----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-----END DC TEST DATA-----
`

var dcTestDCs []dcTestDC
var dcTestConfig *Config
var dcTestDelegationCert Certificate
var dcTestCert Certificate
var dcTestNow time.Time

func init() {
	// Parse the PEM block containing the test DCs.
	block, _ := pem.Decode([]byte(dcTestDCsPEM))
	if block == nil {
		panic("failed to decode DC tests PEM block")
	}

	// Parse the DER-encoded test DCs.
	_, err := asn1.Unmarshal(block.Bytes, &dcTestDCs)
	if err != nil {
		panic("failed to unmarshal DC test ASN.1 data")
	}

	// Use a static time for testing. This is the point at which the test DCs
	// were generated.
	dcTestNow = time.Date(2018, 07, 03, 18, 0, 0, 234234, time.UTC)

	// The base configuration for the client and server.
	dcTestConfig = &Config{
		Time: func() time.Time {
			return dcTestNow
		},
		Rand:         zeroSource{},
		Certificates: nil,
		MinVersion:   VersionTLS10,
		MaxVersion:   VersionTLS13,
		CipherSuites: allCipherSuites(),
	}

	// The delegation certificate.
	dcTestDelegationCert, err = X509KeyPair([]byte(dcDelegationCertPEM), []byte(dcDelegationKeyPEM))
	if err != nil {
		panic(err)
	}
	dcTestDelegationCert.Leaf, err = x509.ParseCertificate(dcTestDelegationCert.Certificate[0])
	if err != nil {
		panic(err)
	}

	// A certificate without the the DelegationUsage extension for X.509.
	dcTestCert, err = X509KeyPair([]byte(dcCertPEM), []byte(dcKeyPEM))
	if err != nil {
		panic(err)
	}
	dcTestCert.Leaf, err = x509.ParseCertificate(dcTestCert.Certificate[0])
	if err != nil {
		panic(err)
	}

	// Make these roots of these certificates the client's trusted CAs.
	dcTestConfig.RootCAs = x509.NewCertPool()

	raw := dcTestDelegationCert.Certificate[len(dcTestDelegationCert.Certificate)-1]
	root, err := x509.ParseCertificate(raw)
	if err != nil {
		panic(err)
	}
	dcTestConfig.RootCAs.AddCert(root)

	raw = dcTestCert.Certificate[len(dcTestCert.Certificate)-1]
	root, err = x509.ParseCertificate(raw)
	if err != nil {
		panic(err)
	}
	dcTestConfig.RootCAs.AddCert(root)
}

// Executes the handshake with the given configuration and returns true if the
// delegated credential extension was successfully negotiated.
func testConnWithDC(t *testing.T, clientConfig, serverConfig *Config) (bool, error) {
	ln := newLocalListener(t)
	defer ln.Close()

	// Listen for and serve a single client connection.
	srvCh := make(chan *Conn, 1)
	var serr error
	go func() {
		sconn, err := ln.Accept()
		if err != nil {
			serr = err
			srvCh <- nil
			return
		}
		srv := Server(sconn, serverConfig)
		if err := srv.Handshake(); err != nil {
			serr = fmt.Errorf("handshake: %v", err)
			srvCh <- nil
			return
		}
		srvCh <- srv
	}()

	// Dial the server.
	cli, err := Dial("tcp", ln.Addr().String(), clientConfig)
	if err != nil {
		return false, err
	}
	defer cli.Close()

	srv := <-srvCh
	if srv == nil {
		return false, serr
	}

	// Return true if the client's conn.dc structure was instantiated.
	st := cli.ConnectionState()
	return (st.DelegatedCredential != nil), nil
}

// Checks that the client suppports a version >= 1.2 and accepts delegated
// credentials. If so, it returns the delegation certificate; otherwise it
// returns a plain certificate.
func testServerGetCertificate(ch *ClientHelloInfo) (*Certificate, error) {
	versOk := false
	for _, vers := range ch.SupportedVersions {
		versOk = versOk || (vers >= uint16(VersionTLS12))
	}

	if versOk && ch.AcceptsDelegatedCredential {
		return &dcTestDelegationCert, nil
	}
	return &dcTestCert, nil
}

// Various test cases for handshakes involving DCs.
var dcTesters = []struct {
	clientDC         bool
	serverDC         bool
	clientSkipVerify bool
	clientMaxVers    uint16
	serverMaxVers    uint16
	nowOffset        time.Duration
	dcTestName       string
	expectSuccess    bool
	expectDC         bool
	name             string
}{
	{true, true, false, VersionTLS12, VersionTLS12, 0, "tls12", true, true, "tls12"},
	{true, true, false, VersionTLS13, VersionTLS13, 0, "tls13", true, true, "tls13"},
	{true, true, false, VersionTLS12, VersionTLS12, 0, "malformed12", false, false, "tls12, malformed dc"},
	{true, true, false, VersionTLS13, VersionTLS13, 0, "malformed13", false, false, "tls13, malformed dc"},
	{true, true, true, VersionTLS12, VersionTLS12, 0, "invalid", true, true, "tls12, invalid dc, skip verify"},
	{true, true, true, VersionTLS13, VersionTLS13, 0, "invalid", true, true, "tls13, invalid dc, skip verify"},
	{false, true, false, VersionTLS12, VersionTLS12, 0, "tls12", true, false, "client no dc"},
	{true, false, false, VersionTLS12, VersionTLS12, 0, "tls12", true, false, "server no dc"},
	{true, true, false, VersionTLS11, VersionTLS12, 0, "tls12", true, false, "client old"},
	{true, true, false, VersionTLS12, VersionTLS11, 0, "tls12", true, false, "server old"},
	{true, true, false, VersionTLS13, VersionTLS13, dcMaxTTL, "tls13", false, false, "expired dc"},
}

// Tests the handshake with the delegated credential extension for each test
// case in dcTests.
func TestDCHandshake(t *testing.T) {
	clientConfig := dcTestConfig.Clone()
	serverConfig := dcTestConfig.Clone()
	serverConfig.GetCertificate = testServerGetCertificate

	for i, tester := range dcTesters {
		clientConfig.MaxVersion = tester.clientMaxVers
		serverConfig.MaxVersion = tester.serverMaxVers
		clientConfig.InsecureSkipVerify = tester.clientSkipVerify
		clientConfig.AcceptDelegatedCredential = tester.clientDC
		clientConfig.Time = func() time.Time {
			return dcTestNow.Add(time.Duration(tester.nowOffset))
		}

		if tester.serverDC {
			serverConfig.GetDelegatedCredential = func(
				ch *ClientHelloInfo, vers uint16) ([]byte, crypto.PrivateKey, error) {
				for _, test := range dcTestDCs {
					if test.Name == tester.dcTestName {
						sk, err := x509.ParseECPrivateKey(test.PrivateKey)
						if err != nil {
							return nil, nil, err
						}
						return test.DC, sk, nil
					}
				}
				return nil, nil, fmt.Errorf("Test DC with name '%s' not found", tester.dcTestName)
			}
		} else {
			serverConfig.GetDelegatedCredential = nil
		}

		usedDC, err := testConnWithDC(t, clientConfig, serverConfig)
		if err != nil && tester.expectSuccess {
			t.Errorf("test #%d (%s) fails: %s", i+1, tester.name, err)
		} else if err == nil && !tester.expectSuccess {
			t.Errorf("test #%d (%s) succeeds; expected failure", i+1, tester.name)
		}

		if usedDC != tester.expectDC {
			t.Errorf("test #%d (%s) usedDC = %v; expected %v", i+1, tester.name, usedDC, tester.expectDC)
		}
	}
}