net/memnet: rename from net/nettest

This is just #cleanup to resolve a TODO Also add a package doc. Signed-off-by: Maisem Ali <maisem@tailscale.com>
2023-01-30 10:53:58 -08:00
parent 4441609d8f
commit 5bba65e978
13 changed files with 40 additions and 33 deletions
@@ -0,0 +1,110 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package memnet
+
+import (
+	"net"
+	"net/netip"
+	"time"
+)
+
+// Conn is a net.Conn that can additionally have its reads and writes blocked and unblocked.
+type Conn interface {
+	net.Conn
+
+	// SetReadBlock blocks or unblocks the Read method of this Conn.
+	// It reports an error if the existing value matches the new value,
+	// or if the Conn has been Closed.
+	SetReadBlock(bool) error
+
+	// SetWriteBlock blocks or unblocks the Write method of this Conn.
+	// It reports an error if the existing value matches the new value,
+	// or if the Conn has been Closed.
+	SetWriteBlock(bool) error
+}
+
+// NewConn creates a pair of Conns that are wired together by pipes.
+func NewConn(name string, maxBuf int) (Conn, Conn) {
+	r := NewPipe(name+"|0", maxBuf)
+	w := NewPipe(name+"|1", maxBuf)
+
+	return &connHalf{r: r, w: w}, &connHalf{r: w, w: r}
+}
+
+// NewTCPConn creates a pair of Conns that are wired together by pipes.
+func NewTCPConn(src, dst netip.AddrPort, maxBuf int) (local Conn, remote Conn) {
+	r := NewPipe(src.String(), maxBuf)
+	w := NewPipe(dst.String(), maxBuf)
+
+	lAddr := net.TCPAddrFromAddrPort(src)
+	rAddr := net.TCPAddrFromAddrPort(dst)
+
+	return &connHalf{r: r, w: w, remote: rAddr, local: lAddr}, &connHalf{r: w, w: r, remote: lAddr, local: rAddr}
+}
+
+type connAddr string
+
+func (a connAddr) Network() string { return "mem" }
+func (a connAddr) String() string  { return string(a) }
+
+type connHalf struct {
+	local, remote net.Addr
+	r, w          *Pipe
+}
+
+func (c *connHalf) LocalAddr() net.Addr {
+	if c.local != nil {
+		return c.local
+	}
+	return connAddr(c.r.name)
+}
+
+func (c *connHalf) RemoteAddr() net.Addr {
+	if c.remote != nil {
+		return c.remote
+	}
+	return connAddr(c.w.name)
+}
+
+func (c *connHalf) Read(b []byte) (n int, err error) {
+	return c.r.Read(b)
+}
+func (c *connHalf) Write(b []byte) (n int, err error) {
+	return c.w.Write(b)
+}
+
+func (c *connHalf) Close() error {
+	if err := c.w.Close(); err != nil {
+		return err
+	}
+	return c.r.Close()
+}
+
+func (c *connHalf) SetDeadline(t time.Time) error {
+	err1 := c.SetReadDeadline(t)
+	err2 := c.SetWriteDeadline(t)
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}
+func (c *connHalf) SetReadDeadline(t time.Time) error {
+	return c.r.SetReadDeadline(t)
+}
+func (c *connHalf) SetWriteDeadline(t time.Time) error {
+	return c.w.SetWriteDeadline(t)
+}
+
+func (c *connHalf) SetReadBlock(b bool) error {
+	if b {
+		return c.r.Block()
+	}
+	return c.r.Unblock()
+}
+func (c *connHalf) SetWriteBlock(b bool) error {
+	if b {
+		return c.w.Block()
+	}
+	return c.w.Unblock()
+}
@@ -0,0 +1,21 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package memnet
+
+import (
+	"net"
+	"testing"
+
+	"golang.org/x/net/nettest"
+)
+
+func TestConn(t *testing.T) {
+	nettest.TestConn(t, func() (c1 net.Conn, c2 net.Conn, stop func(), err error) {
+		c1, c2 = NewConn("test", bufferSize)
+		return c1, c2, func() {
+			c1.Close()
+			c2.Close()
+		}, nil
+	})
+}
@@ -0,0 +1,89 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package memnet
+
+import (
+	"context"
+	"net"
+	"strings"
+	"sync"
+)
+
+const (
+	bufferSize = 256 * 1024
+)
+
+// Listener is a net.Listener using NewConn to create pairs of network
+// connections connected in memory using a buffered pipe. It also provides a
+// Dial method to establish new connections.
+type Listener struct {
+	addr      connAddr
+	ch        chan Conn
+	closeOnce sync.Once
+	closed    chan struct{}
+}
+
+// Listen returns a new Listener for the provided address.
+func Listen(addr string) *Listener {
+	return &Listener{
+		addr:   connAddr(addr),
+		ch:     make(chan Conn),
+		closed: make(chan struct{}),
+	}
+}
+
+// Addr implements net.Listener.Addr.
+func (l *Listener) Addr() net.Addr {
+	return l.addr
+}
+
+// Close closes the pipe listener.
+func (l *Listener) Close() error {
+	l.closeOnce.Do(func() {
+		close(l.closed)
+	})
+	return nil
+}
+
+// Accept blocks until a new connection is available or the listener is closed.
+func (l *Listener) Accept() (net.Conn, error) {
+	select {
+	case c := <-l.ch:
+		return c, nil
+	case <-l.closed:
+		return nil, net.ErrClosed
+	}
+}
+
+// Dial connects to the listener using the provided context.
+// The provided Context must be non-nil. If the context expires before the
+// connection is complete, an error is returned. Once successfully connected
+// any expiration of the context will not affect the connection.
+func (l *Listener) Dial(ctx context.Context, network, addr string) (_ net.Conn, err error) {
+	if !strings.HasSuffix(network, "tcp") {
+		return nil, net.UnknownNetworkError(network)
+	}
+	if connAddr(addr) != l.addr {
+		return nil, &net.AddrError{
+			Err:  "invalid address",
+			Addr: addr,
+		}
+	}
+	c, s := NewConn(addr, bufferSize)
+	defer func() {
+		if err != nil {
+			c.Close()
+			s.Close()
+		}
+	}()
+
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case <-l.closed:
+		return nil, net.ErrClosed
+	case l.ch <- s:
+		return c, nil
+	}
+}
@@ -0,0 +1,33 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package memnet
+
+import (
+	"context"
+	"testing"
+)
+
+func TestListener(t *testing.T) {
+	l := Listen("srv.local")
+	defer l.Close()
+	go func() {
+		c, err := l.Accept()
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		defer c.Close()
+	}()
+
+	if c, err := l.Dial(context.Background(), "tcp", "invalid"); err == nil {
+		c.Close()
+		t.Fatalf("dial to invalid address succeeded")
+	}
+	c, err := l.Dial(context.Background(), "tcp", "srv.local")
+	if err != nil {
+		t.Fatalf("dial failed: %v", err)
+		return
+	}
+	c.Close()
+}
@@ -0,0 +1,8 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package memnet implements an in-memory network implementation.
+// It is useful for dialing and listening on in-memory addresses
+// in tests and other situations where you don't want to use the
+// network.
+package memnet
@@ -0,0 +1,244 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package memnet
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"os"
+	"sync"
+	"time"
+)
+
+const debugPipe = false
+
+// Pipe implements an in-memory FIFO with timeouts.
+type Pipe struct {
+	name   string
+	maxBuf int
+	mu     sync.Mutex
+	cnd    *sync.Cond
+
+	blocked          bool
+	closed           bool
+	buf              bytes.Buffer
+	readTimeout      time.Time
+	writeTimeout     time.Time
+	cancelReadTimer  func()
+	cancelWriteTimer func()
+}
+
+// NewPipe creates a Pipe with a buffer size fixed at maxBuf.
+func NewPipe(name string, maxBuf int) *Pipe {
+	p := &Pipe{
+		name:   name,
+		maxBuf: maxBuf,
+	}
+	p.cnd = sync.NewCond(&p.mu)
+	return p
+}
+
+// readOrBlock attempts to read from the buffer, if the buffer is empty and
+// the connection hasn't been closed it will block until there is a change.
+func (p *Pipe) readOrBlock(b []byte) (int, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if !p.readTimeout.IsZero() && !time.Now().Before(p.readTimeout) {
+		return 0, os.ErrDeadlineExceeded
+	}
+	if p.blocked {
+		p.cnd.Wait()
+		return 0, nil
+	}
+
+	n, err := p.buf.Read(b)
+	// err will either be nil or io.EOF.
+	if err == io.EOF {
+		if p.closed {
+			return n, err
+		}
+		// Wait for something to change.
+		p.cnd.Wait()
+	}
+	return n, nil
+}
+
+// Read implements io.Reader.
+// Once the buffer is drained (i.e. after Close), subsequent calls will
+// return io.EOF.
+func (p *Pipe) Read(b []byte) (n int, err error) {
+	if debugPipe {
+		orig := b
+		defer func() {
+			log.Printf("Pipe(%q).Read(%q) n=%d, err=%v", p.name, string(orig[:n]), n, err)
+		}()
+	}
+	for n == 0 {
+		n2, err := p.readOrBlock(b)
+		if err != nil {
+			return n2, err
+		}
+		n += n2
+	}
+	p.cnd.Signal()
+	return n, nil
+}
+
+// writeOrBlock attempts to write to the buffer, if the buffer is full it will
+// block until there is a change.
+func (p *Pipe) writeOrBlock(b []byte) (int, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.closed {
+		return 0, net.ErrClosed
+	}
+	if !p.writeTimeout.IsZero() && !time.Now().Before(p.writeTimeout) {
+		return 0, os.ErrDeadlineExceeded
+	}
+	if p.blocked {
+		p.cnd.Wait()
+		return 0, nil
+	}
+
+	// Optimistically we want to write the entire slice.
+	n := len(b)
+	if limit := p.maxBuf - p.buf.Len(); limit < n {
+		// However, we don't have enough capacity to write everything.
+		n = limit
+	}
+	if n == 0 {
+		// Wait for something to change.
+		p.cnd.Wait()
+		return 0, nil
+	}
+
+	p.buf.Write(b[:n])
+	p.cnd.Signal()
+	return n, nil
+}
+
+// Write implements io.Writer.
+func (p *Pipe) Write(b []byte) (n int, err error) {
+	if debugPipe {
+		orig := b
+		defer func() {
+			log.Printf("Pipe(%q).Write(%q) n=%d, err=%v", p.name, string(orig), n, err)
+		}()
+	}
+	for len(b) > 0 {
+		n2, err := p.writeOrBlock(b)
+		if err != nil {
+			return n + n2, err
+		}
+		n += n2
+		b = b[n2:]
+	}
+	return n, nil
+}
+
+// Close closes the pipe.
+func (p *Pipe) Close() error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.closed = true
+	p.blocked = false
+	if p.cancelWriteTimer != nil {
+		p.cancelWriteTimer()
+		p.cancelWriteTimer = nil
+	}
+	if p.cancelReadTimer != nil {
+		p.cancelReadTimer()
+		p.cancelReadTimer = nil
+	}
+	p.cnd.Broadcast()
+
+	return nil
+}
+
+func (p *Pipe) deadlineTimer(t time.Time) func() {
+	if t.IsZero() {
+		return nil
+	}
+	if t.Before(time.Now()) {
+		p.cnd.Broadcast()
+		return nil
+	}
+	ctx, cancel := context.WithDeadline(context.Background(), t)
+	go func() {
+		<-ctx.Done()
+		if ctx.Err() == context.DeadlineExceeded {
+			p.cnd.Broadcast()
+		}
+	}()
+	return cancel
+}
+
+// SetReadDeadline sets the deadline for future Read calls.
+func (p *Pipe) SetReadDeadline(t time.Time) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.readTimeout = t
+	// If we already have a deadline, cancel it and create a new one.
+	if p.cancelReadTimer != nil {
+		p.cancelReadTimer()
+		p.cancelReadTimer = nil
+	}
+	p.cancelReadTimer = p.deadlineTimer(t)
+	return nil
+}
+
+// SetWriteDeadline sets the deadline for future Write calls.
+func (p *Pipe) SetWriteDeadline(t time.Time) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.writeTimeout = t
+	// If we already have a deadline, cancel it and create a new one.
+	if p.cancelWriteTimer != nil {
+		p.cancelWriteTimer()
+		p.cancelWriteTimer = nil
+	}
+	p.cancelWriteTimer = p.deadlineTimer(t)
+	return nil
+}
+
+// Block will cause all calls to Read and Write to block until they either
+// timeout, are unblocked or the pipe is closed.
+func (p *Pipe) Block() error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	closed := p.closed
+	blocked := p.blocked
+	p.blocked = true
+
+	if closed {
+		return fmt.Errorf("memnet.Pipe(%q).Block: closed", p.name)
+	}
+	if blocked {
+		return fmt.Errorf("memnet.Pipe(%q).Block: already blocked", p.name)
+	}
+	p.cnd.Broadcast()
+	return nil
+}
+
+// Unblock will cause all blocked Read/Write calls to continue execution.
+func (p *Pipe) Unblock() error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	closed := p.closed
+	blocked := p.blocked
+	p.blocked = false
+
+	if closed {
+		return fmt.Errorf("memnet.Pipe(%q).Block: closed", p.name)
+	}
+	if !blocked {
+		return fmt.Errorf("memnet.Pipe(%q).Block: already unblocked", p.name)
+	}
+	p.cnd.Broadcast()
+	return nil
+}
@@ -0,0 +1,117 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package memnet
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestPipeHello(t *testing.T) {
+	p := NewPipe("p1", 1<<16)
+	msg := "Hello, World!"
+	if n, err := p.Write([]byte(msg)); err != nil {
+		t.Fatal(err)
+	} else if n != len(msg) {
+		t.Errorf("p.Write(%q) n=%d, want %d", msg, n, len(msg))
+	}
+	b := make([]byte, len(msg))
+	if n, err := p.Read(b); err != nil {
+		t.Fatal(err)
+	} else if n != len(b) {
+		t.Errorf("p.Read(%q) n=%d, want %d", string(b[:n]), n, len(b))
+	}
+	if got := string(b); got != msg {
+		t.Errorf("p.Read: %q, want %q", got, msg)
+	}
+}
+
+func TestPipeTimeout(t *testing.T) {
+	t.Run("write", func(t *testing.T) {
+		p := NewPipe("p1", 1<<16)
+		p.SetWriteDeadline(time.Now().Add(-1 * time.Second))
+		n, err := p.Write([]byte{'h'})
+		if !errors.Is(err, os.ErrDeadlineExceeded) {
+			t.Errorf("missing write timeout got err: %v", err)
+		}
+		if n != 0 {
+			t.Errorf("n=%d on timeout", n)
+		}
+	})
+	t.Run("read", func(t *testing.T) {
+		p := NewPipe("p1", 1<<16)
+		p.Write([]byte{'h'})
+
+		p.SetReadDeadline(time.Now().Add(-1 * time.Second))
+		b := make([]byte, 1)
+		n, err := p.Read(b)
+		if !errors.Is(err, os.ErrDeadlineExceeded) {
+			t.Errorf("missing read timeout got err: %v", err)
+		}
+		if n != 0 {
+			t.Errorf("n=%d on timeout", n)
+		}
+	})
+	t.Run("block-write", func(t *testing.T) {
+		p := NewPipe("p1", 1<<16)
+		p.SetWriteDeadline(time.Now().Add(10 * time.Millisecond))
+		if err := p.Block(); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := p.Write([]byte{'h'}); !errors.Is(err, os.ErrDeadlineExceeded) {
+			t.Fatalf("want write timeout got: %v", err)
+		}
+	})
+	t.Run("block-read", func(t *testing.T) {
+		p := NewPipe("p1", 1<<16)
+		p.Write([]byte{'h', 'i'})
+		p.SetReadDeadline(time.Now().Add(10 * time.Millisecond))
+		b := make([]byte, 1)
+		if err := p.Block(); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := p.Read(b); !errors.Is(err, os.ErrDeadlineExceeded) {
+			t.Fatalf("want read timeout got: %v", err)
+		}
+	})
+}
+
+func TestLimit(t *testing.T) {
+	p := NewPipe("p1", 1)
+	errCh := make(chan error)
+	go func() {
+		n, err := p.Write([]byte{'a', 'b', 'c'})
+		if err != nil {
+			errCh <- err
+		} else if n != 3 {
+			errCh <- fmt.Errorf("p.Write n=%d, want 3", n)
+		} else {
+			errCh <- nil
+		}
+	}()
+	b := make([]byte, 3)
+
+	if n, err := p.Read(b); err != nil {
+		t.Fatal(err)
+	} else if n != 1 {
+		t.Errorf("Read(%q): n=%d want 1", string(b), n)
+	}
+	if n, err := p.Read(b); err != nil {
+		t.Fatal(err)
+	} else if n != 1 {
+		t.Errorf("Read(%q): n=%d want 1", string(b), n)
+	}
+	if n, err := p.Read(b); err != nil {
+		t.Fatal(err)
+	} else if n != 1 {
+		t.Errorf("Read(%q): n=%d want 1", string(b), n)
+	}
+
+	if err := <-errCh; err != nil {
+		t.Error(err)
+	}
+}