// Copyright 2012 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 ipv4_test

import (
	"bytes"
	"fmt"
	"net"
	"runtime"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/net/internal/iana"
	"golang.org/x/net/ipv4"
	"golang.org/x/net/nettest"
)

func BenchmarkReadWriteUnicast(b *testing.B) {
	switch runtime.GOOS {
	case "fuchsia", "hurd", "js", "nacl", "plan9", "windows":
		b.Skipf("not supported on %s", runtime.GOOS)
	}

	c, err := nettest.NewLocalPacketListener("udp4")
	if err != nil {
		b.Skipf("not supported on %s/%s: %v", runtime.GOOS, runtime.GOARCH, err)
	}
	defer c.Close()

	dst := c.LocalAddr()
	wb, rb := []byte("HELLO-R-U-THERE"), make([]byte, 128)

	b.Run("NetUDP", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			if _, err := c.WriteTo(wb, dst); err != nil {
				b.Fatal(err)
			}
			if _, _, err := c.ReadFrom(rb); err != nil {
				b.Fatal(err)
			}
		}
	})
	b.Run("IPv4UDP", func(b *testing.B) {
		p := ipv4.NewPacketConn(c)
		cf := ipv4.FlagTTL | ipv4.FlagInterface
		if err := p.SetControlMessage(cf, true); err != nil {
			b.Fatal(err)
		}
		cm := ipv4.ControlMessage{TTL: 1}
		ifi, _ := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
		if ifi != nil {
			cm.IfIndex = ifi.Index
		}

		for i := 0; i < b.N; i++ {
			if _, err := p.WriteTo(wb, &cm, dst); err != nil {
				b.Fatal(err)
			}
			if _, _, _, err := p.ReadFrom(rb); err != nil {
				b.Fatal(err)
			}
		}
	})
}

func BenchmarkPacketConnReadWriteUnicast(b *testing.B) {
	switch runtime.GOOS {
	case "fuchsia", "hurd", "js", "nacl", "plan9", "windows":
		b.Skipf("not supported on %s", runtime.GOOS)
	}

	payload := []byte("HELLO-R-U-THERE")
	iph, err := (&ipv4.Header{
		Version:  ipv4.Version,
		Len:      ipv4.HeaderLen,
		TotalLen: ipv4.HeaderLen + len(payload),
		TTL:      1,
		Protocol: iana.ProtocolReserved,
		Src:      net.IPv4(192, 0, 2, 1),
		Dst:      net.IPv4(192, 0, 2, 254),
	}).Marshal()
	if err != nil {
		b.Fatal(err)
	}
	greh := []byte{0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00}
	datagram := append(greh, append(iph, payload...)...)
	bb := make([]byte, 128)
	cm := ipv4.ControlMessage{
		Src: net.IPv4(127, 0, 0, 1),
	}
	ifi, _ := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
	if ifi != nil {
		cm.IfIndex = ifi.Index
	}

	b.Run("UDP", func(b *testing.B) {
		c, err := nettest.NewLocalPacketListener("udp4")
		if err != nil {
			b.Skipf("not supported on %s/%s: %v", runtime.GOOS, runtime.GOARCH, err)
		}
		defer c.Close()
		p := ipv4.NewPacketConn(c)
		dst := c.LocalAddr()
		cf := ipv4.FlagTTL | ipv4.FlagInterface
		if err := p.SetControlMessage(cf, true); err != nil {
			b.Fatal(err)
		}
		wms := []ipv4.Message{
			{
				Buffers: [][]byte{payload},
				Addr:    dst,
				OOB:     cm.Marshal(),
			},
		}
		rms := []ipv4.Message{
			{
				Buffers: [][]byte{bb},
				OOB:     ipv4.NewControlMessage(cf),
			},
		}
		b.Run("Net", func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				if _, err := c.WriteTo(payload, dst); err != nil {
					b.Fatal(err)
				}
				if _, _, err := c.ReadFrom(bb); err != nil {
					b.Fatal(err)
				}
			}
		})
		b.Run("ToFrom", func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				if _, err := p.WriteTo(payload, &cm, dst); err != nil {
					b.Fatal(err)
				}
				if _, _, _, err := p.ReadFrom(bb); err != nil {
					b.Fatal(err)
				}
			}
		})
		b.Run("Batch", func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				if _, err := p.WriteBatch(wms, 0); err != nil {
					b.Fatal(err)
				}
				if _, err := p.ReadBatch(rms, 0); err != nil {
					b.Fatal(err)
				}
			}
		})
	})
	b.Run("IP", func(b *testing.B) {
		switch runtime.GOOS {
		case "netbsd":
			b.Skip("need to configure gre on netbsd")
		case "openbsd":
			b.Skip("net.inet.gre.allow=0 by default on openbsd")
		}

		c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", iana.ProtocolGRE), "127.0.0.1")
		if err != nil {
			b.Skipf("not supported on %s/%s: %v", runtime.GOOS, runtime.GOARCH, err)
		}
		defer c.Close()
		p := ipv4.NewPacketConn(c)
		dst := c.LocalAddr()
		cf := ipv4.FlagTTL | ipv4.FlagInterface
		if err := p.SetControlMessage(cf, true); err != nil {
			b.Fatal(err)
		}
		wms := []ipv4.Message{
			{
				Buffers: [][]byte{datagram},
				Addr:    dst,
				OOB:     cm.Marshal(),
			},
		}
		rms := []ipv4.Message{
			{
				Buffers: [][]byte{bb},
				OOB:     ipv4.NewControlMessage(cf),
			},
		}
		b.Run("Net", func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				if _, err := c.WriteTo(datagram, dst); err != nil {
					b.Fatal(err)
				}
				if _, _, err := c.ReadFrom(bb); err != nil {
					b.Fatal(err)
				}
			}
		})
		b.Run("ToFrom", func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				if _, err := p.WriteTo(datagram, &cm, dst); err != nil {
					b.Fatal(err)
				}
				if _, _, _, err := p.ReadFrom(bb); err != nil {
					b.Fatal(err)
				}
			}
		})
		b.Run("Batch", func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				if _, err := p.WriteBatch(wms, 0); err != nil {
					b.Fatal(err)
				}
				if _, err := p.ReadBatch(rms, 0); err != nil {
					b.Fatal(err)
				}
			}
		})
	})
}

func TestPacketConnConcurrentReadWriteUnicastUDP(t *testing.T) {
	switch runtime.GOOS {
	case "fuchsia", "hurd", "js", "nacl", "plan9", "windows":
		t.Skipf("not supported on %s", runtime.GOOS)
	}

	c, err := nettest.NewLocalPacketListener("udp4")
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()
	p := ipv4.NewPacketConn(c)
	defer p.Close()

	dst := c.LocalAddr()
	ifi, _ := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
	cf := ipv4.FlagTTL | ipv4.FlagSrc | ipv4.FlagDst | ipv4.FlagInterface
	wb := []byte("HELLO-R-U-THERE")

	if err := p.SetControlMessage(cf, true); err != nil { // probe before test
		if protocolNotSupported(err) {
			t.Skipf("not supported on %s", runtime.GOOS)
		}
		t.Fatal(err)
	}

	var wg sync.WaitGroup
	reader := func() {
		defer wg.Done()
		rb := make([]byte, 128)
		if n, cm, _, err := p.ReadFrom(rb); err != nil {
			t.Error(err)
			return
		} else if !bytes.Equal(rb[:n], wb) {
			t.Errorf("got %v; want %v", rb[:n], wb)
			return
		} else {
			s := cm.String()
			if strings.Contains(s, ",") {
				t.Errorf("should be space-separated values: %s", s)
			}
		}
	}
	writer := func(toggle bool) {
		defer wg.Done()
		cm := ipv4.ControlMessage{
			Src: net.IPv4(127, 0, 0, 1),
		}
		if ifi != nil {
			cm.IfIndex = ifi.Index
		}
		if err := p.SetControlMessage(cf, toggle); err != nil {
			t.Error(err)
			return
		}
		if n, err := p.WriteTo(wb, &cm, dst); err != nil {
			t.Error(err)
			return
		} else if n != len(wb) {
			t.Errorf("got %d; want %d", n, len(wb))
			return
		}
	}

	const N = 10
	wg.Add(N)
	for i := 0; i < N; i++ {
		go reader()
	}
	wg.Add(2 * N)
	for i := 0; i < 2*N; i++ {
		go writer(i%2 != 0)
	}
	wg.Add(N)
	for i := 0; i < N; i++ {
		go reader()
	}
	wg.Wait()
}

func TestPacketConnConcurrentReadWriteUnicast(t *testing.T) {
	switch runtime.GOOS {
	case "fuchsia", "hurd", "js", "nacl", "plan9", "windows":
		t.Skipf("not supported on %s", runtime.GOOS)
	}

	payload := []byte("HELLO-R-U-THERE")
	iph, err := (&ipv4.Header{
		Version:  ipv4.Version,
		Len:      ipv4.HeaderLen,
		TotalLen: ipv4.HeaderLen + len(payload),
		TTL:      1,
		Protocol: iana.ProtocolReserved,
		Src:      net.IPv4(192, 0, 2, 1),
		Dst:      net.IPv4(192, 0, 2, 254),
	}).Marshal()
	if err != nil {
		t.Fatal(err)
	}
	greh := []byte{0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00}
	datagram := append(greh, append(iph, payload...)...)

	t.Run("UDP", func(t *testing.T) {
		c, err := nettest.NewLocalPacketListener("udp4")
		if err != nil {
			t.Skipf("not supported on %s/%s: %v", runtime.GOOS, runtime.GOARCH, err)
		}
		defer c.Close()
		p := ipv4.NewPacketConn(c)
		t.Run("ToFrom", func(t *testing.T) {
			testPacketConnConcurrentReadWriteUnicast(t, p, payload, c.LocalAddr(), false)
		})
		t.Run("Batch", func(t *testing.T) {
			testPacketConnConcurrentReadWriteUnicast(t, p, payload, c.LocalAddr(), true)
		})
	})
	t.Run("IP", func(t *testing.T) {
		switch runtime.GOOS {
		case "netbsd":
			t.Skip("need to configure gre on netbsd")
		case "openbsd":
			t.Skip("net.inet.gre.allow=0 by default on openbsd")
		}

		c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", iana.ProtocolGRE), "127.0.0.1")
		if err != nil {
			t.Skipf("not supported on %s/%s: %v", runtime.GOOS, runtime.GOARCH, err)
		}
		defer c.Close()
		p := ipv4.NewPacketConn(c)
		t.Run("ToFrom", func(t *testing.T) {
			testPacketConnConcurrentReadWriteUnicast(t, p, datagram, c.LocalAddr(), false)
		})
		t.Run("Batch", func(t *testing.T) {
			testPacketConnConcurrentReadWriteUnicast(t, p, datagram, c.LocalAddr(), true)
		})
	})
}

func testPacketConnConcurrentReadWriteUnicast(t *testing.T, p *ipv4.PacketConn, data []byte, dst net.Addr, batch bool) {
	t.Helper()

	ifi, _ := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
	cf := ipv4.FlagTTL | ipv4.FlagSrc | ipv4.FlagDst | ipv4.FlagInterface

	if err := p.SetControlMessage(cf, true); err != nil { // probe before test
		if protocolNotSupported(err) {
			t.Skipf("not supported on %s", runtime.GOOS)
		}
		t.Fatal(err)
	}

	var firstError sync.Once
	fatalf := func(format string, args ...interface{}) {
		// On the first error, close the PacketConn to unblock the remaining
		// goroutines. Suppress any further errors, which may occur simply due to
		// closing the PacketConn.
		first := false
		firstError.Do(func() {
			first = true
			p.Close()
		})
		if first {
			t.Helper()
			t.Errorf(format, args...)
		}
		runtime.Goexit()
	}

	var wg sync.WaitGroup
	reader := func() {
		defer wg.Done()
		b := make([]byte, 128)
		n, cm, _, err := p.ReadFrom(b)
		if err != nil {
			fatalf("%v", err)
		}
		if !bytes.Equal(b[:n], data) {
			fatalf("got %#v; want %#v", b[:n], data)
		}
		s := cm.String()
		if strings.Contains(s, ",") {
			fatalf("should be space-separated values: %s", s)
		}
	}
	batchReader := func() {
		defer wg.Done()
		ms := []ipv4.Message{
			{
				Buffers: [][]byte{make([]byte, 128)},
				OOB:     ipv4.NewControlMessage(cf),
			},
		}
		n, err := p.ReadBatch(ms, 0)
		if err != nil {
			fatalf("%v", err)
		}
		if n != len(ms) {
			fatalf("got %d; want %d", n, len(ms))
		}
		var cm ipv4.ControlMessage
		if err := cm.Parse(ms[0].OOB[:ms[0].NN]); err != nil {
			fatalf("%v", err)
		}
		var b []byte
		if _, ok := dst.(*net.IPAddr); ok {
			var h ipv4.Header
			if err := h.Parse(ms[0].Buffers[0][:ms[0].N]); err != nil {
				fatalf("%v", err)
			}
			b = ms[0].Buffers[0][h.Len:ms[0].N]
		} else {
			b = ms[0].Buffers[0][:ms[0].N]
		}
		if !bytes.Equal(b, data) {
			fatalf("got %#v; want %#v", b, data)
		}
		s := cm.String()
		if strings.Contains(s, ",") {
			fatalf("should be space-separated values: %s", s)
		}
	}
	writer := func(toggle bool) {
		defer wg.Done()
		cm := ipv4.ControlMessage{
			Src: net.IPv4(127, 0, 0, 1),
		}
		if ifi != nil {
			cm.IfIndex = ifi.Index
		}
		if err := p.SetControlMessage(cf, toggle); err != nil {
			fatalf("%v", err)
		}

		backoff := time.Millisecond
		for {
			n, err := p.WriteTo(data, &cm, dst)
			if err != nil {
				if n == 0 && isENOBUFS(err) {
					time.Sleep(backoff)
					backoff *= 2
					continue
				}
				fatalf("%v", err)
			}
			if n != len(data) {
				fatalf("got %d; want %d", n, len(data))
			}
			break
		}
	}
	batchWriter := func(toggle bool) {
		defer wg.Done()
		cm := ipv4.ControlMessage{
			Src: net.IPv4(127, 0, 0, 1),
		}
		if ifi != nil {
			cm.IfIndex = ifi.Index
		}
		if err := p.SetControlMessage(cf, toggle); err != nil {
			fatalf("%v", err)
		}
		ms := []ipv4.Message{
			{
				Buffers: [][]byte{data},
				OOB:     cm.Marshal(),
				Addr:    dst,
			},
		}

		backoff := time.Millisecond
		for {
			n, err := p.WriteBatch(ms, 0)
			if err != nil {
				if n == 0 && isENOBUFS(err) {
					time.Sleep(backoff)
					backoff *= 2
					continue
				}
				fatalf("%v", err)
			}
			if n != len(ms) {
				fatalf("got %d; want %d", n, len(ms))
			}
			if ms[0].N != len(data) {
				fatalf("got %d; want %d", ms[0].N, len(data))
			}
			break
		}
	}

	const N = 10
	wg.Add(N)
	for i := 0; i < N; i++ {
		if batch {
			go batchReader()
		} else {
			go reader()
		}
	}
	wg.Add(2 * N)
	for i := 0; i < 2*N; i++ {
		if batch {
			go batchWriter(i%2 != 0)
		} else {
			go writer(i%2 != 0)
		}

	}
	wg.Add(N)
	for i := 0; i < N; i++ {
		if batch {
			go batchReader()
		} else {
			go reader()
		}
	}
	wg.Wait()
}