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>

net/memnet/conn.go

@@ -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()
+}