// -*- Mode: Go; indent-tabs-mode: t -*-

/*
 * Copyright (C) 2018-2020 Canonical Ltd
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package httputil_test

import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"io"
	"math/big"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"path/filepath"
	"time"

	"gopkg.in/check.v1"

	"github.com/snapcore/snapd/dirs"
	"github.com/snapcore/snapd/httputil"
	"github.com/snapcore/snapd/logger"
	"github.com/snapcore/snapd/testutil"
)

type clientSuite struct{}

var _ = check.Suite(&clientSuite{})

func mustParse(c *check.C, rawurl string) *url.URL {
	url, err := url.Parse(rawurl)
	c.Assert(err, check.IsNil)
	return url
}

type proxyProvider struct {
	proxy *url.URL
}

func (p *proxyProvider) proxyCallback(*http.Request) (*url.URL, error) {
	return p.proxy, nil
}

func (s *clientSuite) TestClientOptionsWithProxy(c *check.C) {
	pp := proxyProvider{proxy: mustParse(c, "http://some-proxy:3128")}
	cli := httputil.NewHTTPClient(&httputil.ClientOptions{
		Proxy: pp.proxyCallback,
	})
	c.Assert(cli, check.NotNil)

	trans := cli.Transport.(*httputil.LoggedTransport).Transport.(*http.Transport)
	req, err := http.NewRequest("GET", "http://example.com", nil)
	c.Check(err, check.IsNil)
	url, err := trans.Proxy(req)
	c.Check(err, check.IsNil)
	c.Check(url.String(), check.Equals, "http://some-proxy:3128")
}

func (s *clientSuite) TestClientProxyTakesUserAgent(c *check.C) {
	myUserAgent := "snapd yadda yadda"

	called := false
	proxyServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		c.Check(r.UserAgent(), check.Equals, myUserAgent)
		called = true
	}))
	defer proxyServer.Close()
	cli := httputil.NewHTTPClient(&httputil.ClientOptions{
		Proxy: func(*http.Request) (*url.URL, error) {
			return mustParse(c, proxyServer.URL), nil
		},
		ProxyConnectHeader: http.Header{"User-Agent": []string{myUserAgent}},
	})
	_, err := cli.Get("https://localhost:9999")
	c.Check(err, check.NotNil) // because we didn't do anything in the handler

	c.Assert(called, check.Equals, true)
}

func (s *clientSuite) TestClientCheckRedirect(c *check.C) {
	cli := httputil.NewHTTPClient(&httputil.ClientOptions{})
	c.Assert(cli, check.NotNil)
	c.Assert(cli.CheckRedirect, check.NotNil)
}

var privKey, _ = rsa.GenerateKey(rand.Reader, 768)

// see crypto/tls/generate_cert.go
func generateTestCert(c *check.C, certpath, keypath string) {
	generateTestCertWithDates(c, certpath, keypath, time.Now(), time.Now().Add(24*time.Hour))
}

func generateTestCertWithDates(c *check.C, certpath, keypath string, notBefore, notAfter time.Time) {
	template := x509.Certificate{
		SerialNumber: big.NewInt(123456789),
		Subject: pkix.Name{
			Organization: []string{"Snapd testers"},
		},
		NotBefore:   notBefore,
		NotAfter:    notAfter,
		IPAddresses: []net.IP{net.IPv4(127, 0, 0, 1)},
		DNSNames:    []string{"localhost"},
		IsCA:        true,
		KeyUsage:    x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
	}
	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &privKey.PublicKey, privKey)
	c.Assert(err, check.IsNil)

	certOut, err := os.Create(certpath)
	c.Assert(err, check.IsNil)
	err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
	c.Assert(err, check.IsNil)
	err = certOut.Close()
	c.Assert(err, check.IsNil)

	if keypath != "" {
		keyOut, err := os.Create(keypath)
		c.Assert(err, check.IsNil)
		privBytes := x509.MarshalPKCS1PrivateKey(privKey)
		err = pem.Encode(keyOut, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes})
		c.Assert(err, check.IsNil)
		err = keyOut.Close()
		c.Assert(err, check.IsNil)
	}
}

type tlsSuite struct {
	testutil.BaseTest

	tmpdir            string
	certpath, keypath string
	logbuf            *bytes.Buffer

	srv *httptest.Server
}

var _ = check.Suite(&tlsSuite{})

func (s *tlsSuite) SetUpTest(c *check.C) {
	s.BaseTest.SetUpTest(c)

	s.tmpdir = c.MkDir()
	dirs.SetRootDir(s.tmpdir)
	err := os.MkdirAll(dirs.SnapdStoreSSLCertsDir, 0755)
	c.Assert(err, check.IsNil)

	s.certpath = filepath.Join(dirs.SnapdStoreSSLCertsDir, "good.pem")
	s.keypath = filepath.Join(c.MkDir(), "key.pem")
	generateTestCert(c, s.certpath, s.keypath)

	// create a server that uses our certs
	s.srv = httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, `all good`)
	}))
	cert, err := tls.LoadX509KeyPair(s.certpath, s.keypath)
	c.Assert(err, check.IsNil)
	s.srv.TLS = &tls.Config{Certificates: []tls.Certificate{cert}}
	s.srv.StartTLS()
	s.AddCleanup(s.srv.Close)

	logbuf, restore := logger.MockLogger()
	s.logbuf = logbuf
	s.AddCleanup(restore)
}

func (s *tlsSuite) TestClientNoExtraSSLCertsByDefault(c *check.C) {
	// no extra ssl certs by default
	cli := httputil.NewHTTPClient(nil)
	c.Assert(cli, check.NotNil)
	c.Assert(s.logbuf.String(), check.Equals, "")

	_, err := cli.Get(s.srv.URL)
	c.Assert(err, check.ErrorMatches, ".* certificate signed by unknown authority")
}

func (s *tlsSuite) TestClientEmptyExtraSSLCertsDirWorks(c *check.C) {
	cli := httputil.NewHTTPClient(&httputil.ClientOptions{
		ExtraSSLCerts: &httputil.ExtraSSLCertsFromDir{
			// empty extra ssl certs dir
			Dir: c.MkDir(),
		},
	})
	c.Assert(cli, check.NotNil)
	c.Assert(s.logbuf.String(), check.Equals, "")

	_, err := cli.Get(s.srv.URL)
	c.Assert(err, check.ErrorMatches, ".* certificate signed by unknown authority")
}

func (s *tlsSuite) TestClientExtraSSLCertInvalidCertWarnsAndRefuses(c *check.C) {
	err := os.WriteFile(filepath.Join(dirs.SnapdStoreSSLCertsDir, "garbage.pem"), []byte("garbage"), 0644)
	c.Assert(err, check.IsNil)

	cli := httputil.NewHTTPClient(&httputil.ClientOptions{
		ExtraSSLCerts: &httputil.ExtraSSLCertsFromDir{
			Dir: dirs.SnapdStoreSSLCertsDir,
		},
	})
	c.Assert(cli, check.NotNil)

	_, err = cli.Get(s.srv.URL)
	c.Assert(err, check.IsNil)

	c.Assert(s.logbuf.String(), check.Matches, "(?m).* cannot load ssl certificate: .*/var/lib/snapd/ssl/store-certs/garbage.pem")
}

func (s *tlsSuite) TestClientExtraSSLCertIntegration(c *check.C) {
	// create a client that will load our cert
	cli := httputil.NewHTTPClient(&httputil.ClientOptions{
		ExtraSSLCerts: &httputil.ExtraSSLCertsFromDir{
			Dir: dirs.SnapdStoreSSLCertsDir,
		},
	})
	c.Assert(cli, check.NotNil)
	c.Assert(s.logbuf.String(), check.Equals, "")
	res, err := cli.Get(s.srv.URL)
	c.Assert(err, check.IsNil)
	c.Assert(res.StatusCode, check.Equals, 200)
}

func (s *tlsSuite) TestClientMaxTLS11Error(c *check.C) {
	// create a server that uses our certs
	srv := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, `all good`)
	}))
	cert, err := tls.LoadX509KeyPair(s.certpath, s.keypath)
	c.Assert(err, check.IsNil)
	srv.TLS = &tls.Config{
		Certificates: []tls.Certificate{cert},
		MaxVersion:   tls.VersionTLS11,
	}
	srv.StartTLS()
	s.AddCleanup(srv.Close)

	// Server running only TLS1.1 doesn't work
	cli := httputil.NewHTTPClient(nil)
	c.Assert(cli, check.NotNil)
	c.Assert(s.logbuf.String(), check.Equals, "")

	_, err = cli.Get(srv.URL)
	// The protocol check is done prior to the certificate check
	// - golang < 1.12: tls: server selected unsupported protocol version 302
	// - golang >= 1.12: tls: protocol version not supported
	c.Assert(err, check.ErrorMatches, ".* tls: (server selected unsupported protocol version 302|protocol version not supported)")
	c.Check(httputil.IsCertExpiredOrNotValidYetError(err), check.Equals, false)
}

func (s *tlsSuite) TestClientMaxTLS12Ok(c *check.C) {
	// create a server that uses our certs
	srv := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, `all good`)
	}))
	cert, err := tls.LoadX509KeyPair(s.certpath, s.keypath)
	c.Assert(err, check.IsNil)
	srv.TLS = &tls.Config{
		Certificates: []tls.Certificate{cert},
		MaxVersion:   tls.VersionTLS12,
	}
	srv.StartTLS()
	s.AddCleanup(srv.Close)

	// Server running our current minimum of TLS1.2. This test will notice
	// if our expected minimum default (TLS1.2) changes.
	cli := httputil.NewHTTPClient(nil)
	c.Assert(cli, check.NotNil)
	c.Assert(s.logbuf.String(), check.Equals, "")

	_, err = cli.Get(srv.URL)
	// The protocol check is done prior to the certificate check and since
	// this is testing the protocol, the self-signed certificate error is
	// fine and expected.
	c.Assert(err, check.ErrorMatches, ".* certificate signed by unknown authority")
	c.Check(httputil.IsCertExpiredOrNotValidYetError(err), check.Equals, false)
}

func (s *tlsSuite) TestCertExpireOrNotValidYet(c *check.C) {
	generateTestCertWithDates(c, s.certpath, s.keypath, time.Time{}, time.Time{})

	// create a server that uses our certs
	srv := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, `all good`)
	}))
	cert, err := tls.LoadX509KeyPair(s.certpath, s.keypath)
	c.Assert(err, check.IsNil)
	srv.TLS = &tls.Config{
		Certificates: []tls.Certificate{cert},
	}
	srv.StartTLS()
	s.AddCleanup(srv.Close)

	// Server running only TLS1.1 doesn't work
	cli := httputil.NewHTTPClient(nil)
	c.Assert(cli, check.NotNil)
	c.Assert(s.logbuf.String(), check.Equals, "")

	_, err = cli.Get(srv.URL)
	c.Assert(err, check.ErrorMatches, ".*: x509: certificate has expired or is not yet valid.*")
	c.Check(httputil.IsCertExpiredOrNotValidYetError(err), check.Equals, true)
}