// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause

package tsnet

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"net/netip"
	"os"
	"path/filepath"
	"testing"
	"time"

	"golang.org/x/net/proxy"
	"tailscale.com/ipn/store/mem"
	"tailscale.com/net/netns"
	"tailscale.com/tailcfg"
	"tailscale.com/tstest/integration"
	"tailscale.com/tstest/integration/testcontrol"
	"tailscale.com/types/logger"
)

// TestListener_Server ensures that the listener type always keeps the Server
// method, which is used by some external applications to identify a tsnet.Listener
// from other net.Listeners, as well as access the underlying Server.
func TestListener_Server(t *testing.T) {
	s := &Server{}
	ln := listener{s: s}
	if ln.Server() != s {
		t.Errorf("listener.Server() returned %v, want %v", ln.Server(), s)
	}
}

func TestListenerPort(t *testing.T) {
	errNone := errors.New("sentinel start error")

	tests := []struct {
		network string
		addr    string
		wantErr bool
	}{
		{"tcp", ":80", false},
		{"foo", ":80", true},
		{"tcp", ":http", false},  // built-in name to Go; doesn't require cgo, /etc/services
		{"tcp", ":https", false}, // built-in name to Go; doesn't require cgo, /etc/services
		{"tcp", ":gibberishsdlkfj", true},
		{"tcp", ":%!d(string=80)", true}, // issue 6201
		{"udp", ":80", false},
		{"udp", "100.102.104.108:80", false},
		{"udp", "not-an-ip:80", true},
		{"udp4", ":80", false},
		{"udp4", "100.102.104.108:80", false},
		{"udp4", "not-an-ip:80", true},

		// Verify network type matches IP
		{"tcp4", "1.2.3.4:80", false},
		{"tcp6", "1.2.3.4:80", true},
		{"tcp4", "[12::34]:80", true},
		{"tcp6", "[12::34]:80", false},
	}
	for _, tt := range tests {
		s := &Server{}
		s.initOnce.Do(func() { s.initErr = errNone })
		_, err := s.Listen(tt.network, tt.addr)
		gotErr := err != nil && err != errNone
		if gotErr != tt.wantErr {
			t.Errorf("Listen(%q, %q) error = %v, want %v", tt.network, tt.addr, gotErr, tt.wantErr)
		}
	}
}

var verboseDERP = flag.Bool("verbose-derp", false, "if set, print DERP and STUN logs")
var verboseNodes = flag.Bool("verbose-nodes", false, "if set, print tsnet.Server logs")

func startControl(t *testing.T) (controlURL string) {
	// Corp#4520: don't use netns for tests.
	netns.SetEnabled(false)
	t.Cleanup(func() {
		netns.SetEnabled(true)
	})

	derpLogf := logger.Discard
	if *verboseDERP {
		derpLogf = t.Logf
	}
	derpMap := integration.RunDERPAndSTUN(t, derpLogf, "127.0.0.1")
	control := &testcontrol.Server{
		DERPMap: derpMap,
	}
	control.HTTPTestServer = httptest.NewUnstartedServer(control)
	control.HTTPTestServer.Start()
	t.Cleanup(control.HTTPTestServer.Close)
	controlURL = control.HTTPTestServer.URL
	t.Logf("testcontrol listening on %s", controlURL)
	return controlURL
}

func startServer(t *testing.T, ctx context.Context, controlURL, hostname string) (*Server, netip.Addr) {
	t.Helper()

	tmp := filepath.Join(t.TempDir(), hostname)
	os.MkdirAll(tmp, 0755)
	s := &Server{
		Dir:        tmp,
		ControlURL: controlURL,
		Hostname:   hostname,
		Store:      new(mem.Store),
		Ephemeral:  true,
	}
	if !*verboseNodes {
		s.Logf = logger.Discard
	}
	t.Cleanup(func() { s.Close() })

	status, err := s.Up(ctx)
	if err != nil {
		t.Fatal(err)
	}
	return s, status.TailscaleIPs[0]
}

func TestConn(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	controlURL := startControl(t)
	s1, s1ip := startServer(t, ctx, controlURL, "s1")
	s2, _ := startServer(t, ctx, controlURL, "s2")

	lc2, err := s2.LocalClient()
	if err != nil {
		t.Fatal(err)
	}

	// ping to make sure the connection is up.
	res, err := lc2.Ping(ctx, s1ip, tailcfg.PingICMP)
	if err != nil {
		t.Fatal(err)
	}
	t.Logf("ping success: %#+v", res)

	// pass some data through TCP.
	ln, err := s1.Listen("tcp", ":8081")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()

	w, err := s2.Dial(ctx, "tcp", fmt.Sprintf("%s:8081", s1ip))
	if err != nil {
		t.Fatal(err)
	}

	r, err := ln.Accept()
	if err != nil {
		t.Fatal(err)
	}

	want := "hello"
	if _, err := io.WriteString(w, want); err != nil {
		t.Fatal(err)
	}

	got := make([]byte, len(want))
	if _, err := io.ReadAtLeast(r, got, len(got)); err != nil {
		t.Fatal(err)
	}
	t.Logf("got: %q", got)
	if string(got) != want {
		t.Errorf("got %q, want %q", got, want)
	}

	_, err = s2.Dial(ctx, "tcp", fmt.Sprintf("%s:8082", s1ip)) // some random port
	if err == nil {
		t.Fatalf("unexpected success; should have seen a connection refused error")
	}
}

func TestLoopbackLocalAPI(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	controlURL := startControl(t)
	s1, _ := startServer(t, ctx, controlURL, "s1")

	addr, proxyCred, localAPICred, err := s1.Loopback()
	if err != nil {
		t.Fatal(err)
	}
	if proxyCred == localAPICred {
		t.Fatal("proxy password matches local API password, they should be different")
	}

	url := "http://" + addr + "/localapi/v0/status"
	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		t.Fatal(err)
	}
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	res.Body.Close()
	if res.StatusCode != 403 {
		t.Errorf("GET %s returned %d, want 403 without Sec- header", url, res.StatusCode)
	}

	req, err = http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		t.Fatal(err)
	}
	req.Header.Set("Sec-Tailscale", "localapi")
	res, err = http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	res.Body.Close()
	if res.StatusCode != 401 {
		t.Errorf("GET %s returned %d, want 401 without basic auth", url, res.StatusCode)
	}

	req, err = http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		t.Fatal(err)
	}
	req.SetBasicAuth("", localAPICred)
	res, err = http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	res.Body.Close()
	if res.StatusCode != 403 {
		t.Errorf("GET %s returned %d, want 403 without Sec- header", url, res.StatusCode)
	}

	req, err = http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		t.Fatal(err)
	}
	req.Header.Set("Sec-Tailscale", "localapi")
	req.SetBasicAuth("", localAPICred)
	res, err = http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	res.Body.Close()
	if res.StatusCode != 200 {
		t.Errorf("GET /status returned %d, want 200", res.StatusCode)
	}
}

func TestLoopbackSOCKS5(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	controlURL := startControl(t)
	s1, s1ip := startServer(t, ctx, controlURL, "s1")
	s2, _ := startServer(t, ctx, controlURL, "s2")

	addr, proxyCred, _, err := s2.Loopback()
	if err != nil {
		t.Fatal(err)
	}

	ln, err := s1.Listen("tcp", ":8081")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()

	auth := &proxy.Auth{User: "tsnet", Password: proxyCred}
	socksDialer, err := proxy.SOCKS5("tcp", addr, auth, proxy.Direct)
	if err != nil {
		t.Fatal(err)
	}

	w, err := socksDialer.Dial("tcp", fmt.Sprintf("%s:8081", s1ip))
	if err != nil {
		t.Fatal(err)
	}

	r, err := ln.Accept()
	if err != nil {
		t.Fatal(err)
	}

	want := "hello"
	if _, err := io.WriteString(w, want); err != nil {
		t.Fatal(err)
	}

	got := make([]byte, len(want))
	if _, err := io.ReadAtLeast(r, got, len(got)); err != nil {
		t.Fatal(err)
	}
	t.Logf("got: %q", got)
	if string(got) != want {
		t.Errorf("got %q, want %q", got, want)
	}
}

func TestTailscaleIPs(t *testing.T) {
	controlURL := startControl(t)

	tmp := t.TempDir()
	tmps1 := filepath.Join(tmp, "s1")
	os.MkdirAll(tmps1, 0755)
	s1 := &Server{
		Dir:        tmps1,
		ControlURL: controlURL,
		Hostname:   "s1",
		Store:      new(mem.Store),
		Ephemeral:  true,
	}
	defer s1.Close()

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	s1status, err := s1.Up(ctx)
	if err != nil {
		t.Fatal(err)
	}

	var upIp4, upIp6 netip.Addr
	for _, ip := range s1status.TailscaleIPs {
		if ip.Is6() {
			upIp6 = ip
		}
		if ip.Is4() {
			upIp4 = ip
		}
	}

	sIp4, sIp6 := s1.TailscaleIPs()
	if !(upIp4 == sIp4 && upIp6 == sIp6) {
		t.Errorf("s1.TailscaleIPs returned a different result than S1.Up, (%s, %s) != (%s, %s)",
			sIp4, upIp4, sIp6, upIp6)
	}
}