internal/jsonrpc2_v2: an updated jsonrpc2 library

Change-Id: I609173baa6842d33068a7e9596d54f03d89c5401
Reviewed-on: https://go-review.googlesource.com/c/tools/+/292169
Run-TryBot: Ian Cottrell <iancottrell@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/jsonrpc2/net.go

@@ -0,0 +1,129 @@
+// Copyright 2018 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package jsonrpc2
+
+import (
+	"context"
+	"io"
+	"net"
+	"os"
+	"time"
+)
+
+// This file contains implementations of the transport primitives that use the standard network
+// package.
+
+// NetListenOptions is the optional arguments to the NetListen function.
+type NetListenOptions struct {
+	NetListenConfig net.ListenConfig
+	NetDialer       net.Dialer
+}
+
+// NetListener returns a new Listener that listents on a socket using the net package.
+func NetListener(ctx context.Context, network, address string, options NetListenOptions) (Listener, error) {
+	ln, err := options.NetListenConfig.Listen(ctx, network, address)
+	if err != nil {
+		return nil, err
+	}
+	return &netListener{net: ln}, nil
+}
+
+// netListener is the implementation of Listener for connections made using the net package.
+type netListener struct {
+	net net.Listener
+}
+
+// Accept blocks waiting for an incoming connection to the listener.
+func (l *netListener) Accept(ctx context.Context) (io.ReadWriteCloser, error) {
+	return l.net.Accept()
+}
+
+// Close will cause the listener to stop listening. It will not close any connections that have
+// already been accepted.
+func (l *netListener) Close() error {
+	addr := l.net.Addr()
+	err := l.net.Close()
+	if addr.Network() == "unix" {
+		rerr := os.Remove(addr.String())
+		if rerr != nil && err == nil {
+			err = rerr
+		}
+	}
+	return err
+}
+
+// Dialer returns a dialer that can be used to connect to the listener.
+func (l *netListener) Dialer() Dialer {
+	return NetDialer(l.net.Addr().Network(), l.net.Addr().String(), net.Dialer{
+		Timeout: 5 * time.Second,
+	})
+}
+
+// NetDialer returns a Dialer using the supplied standard network dialer.
+func NetDialer(network, address string, nd net.Dialer) Dialer {
+	return &netDialer{
+		network: network,
+		address: address,
+		dialer:  nd,
+	}
+}
+
+type netDialer struct {
+	network string
+	address string
+	dialer  net.Dialer
+}
+
+func (n *netDialer) Dial(ctx context.Context) (io.ReadWriteCloser, error) {
+	return n.dialer.DialContext(ctx, n.network, n.address)
+}
+
+// NetPipe returns a new Listener that listens using net.Pipe.
+// It is only possibly to connect to it using the Dialier returned by the
+// Dialer method, each call to that method will generate a new pipe the other
+// side of which will be returnd from the Accept call.
+func NetPipe(ctx context.Context) (Listener, error) {
+	return &netPiper{
+		done:   make(chan struct{}),
+		dialed: make(chan io.ReadWriteCloser),
+	}, nil
+}
+
+// netPiper is the implementation of Listener build on top of net.Pipes.
+type netPiper struct {
+	done   chan struct{}
+	dialed chan io.ReadWriteCloser
+}
+
+// Accept blocks waiting for an incoming connection to the listener.
+func (l *netPiper) Accept(ctx context.Context) (io.ReadWriteCloser, error) {
+	// block until we have a listener, or are closed or cancelled
+	select {
+	case rwc := <-l.dialed:
+		return rwc, nil
+	case <-l.done:
+		return nil, io.EOF
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
+// Close will cause the listener to stop listening. It will not close any connections that have
+// already been accepted.
+func (l *netPiper) Close() error {
+	// unblock any accept calls that are pending
+	close(l.done)
+	return nil
+}
+
+func (l *netPiper) Dialer() Dialer {
+	return l
+}
+
+func (l *netPiper) Dial(ctx context.Context) (io.ReadWriteCloser, error) {
+	client, server := net.Pipe()
+	l.dialed <- server
+	return client, nil
+}