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// Copyright 2021 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 lsprpc
import (
"context"
"fmt"
"io"
"net"
"os"
"time"
exec "golang.org/x/sys/execabs"
"golang.org/x/tools/internal/event"
errors "golang.org/x/xerrors"
)
// AutoNetwork is the pseudo network type used to signal that gopls should use
// automatic discovery to resolve a remote address.
const AutoNetwork = "auto"
// An AutoDialer is a jsonrpc2 dialer that understands the 'auto' network.
type AutoDialer struct {
network, addr string // the 'real' network and address
isAuto bool // whether the server is on the 'auto' network
executable string
argFunc func(network, addr string) []string
}
func NewAutoDialer(rawAddr string, argFunc func(network, addr string) []string) (*AutoDialer, error) {
d := AutoDialer{
argFunc: argFunc,
}
d.network, d.addr = ParseAddr(rawAddr)
if d.network == AutoNetwork {
d.isAuto = true
bin, err := os.Executable()
if err != nil {
return nil, errors.Errorf("getting executable: %w", err)
}
d.executable = bin
d.network, d.addr = autoNetworkAddress(bin, d.addr)
}
return &d, nil
}
// Dial implements the jsonrpc2.Dialer interface.
func (d *AutoDialer) Dial(ctx context.Context) (io.ReadWriteCloser, error) {
conn, err := d.dialNet(ctx)
return conn, err
}
// TODO(rFindley): remove this once we no longer need to integrate with v1 of
// the jsonrpc2 package.
func (d *AutoDialer) dialNet(ctx context.Context) (net.Conn, error) {
// Attempt to verify that we own the remote. This is imperfect, but if we can
// determine that the remote is owned by a different user, we should fail.
ok, err := verifyRemoteOwnership(d.network, d.addr)
if err != nil {
// If the ownership check itself failed, we fail open but log an error to
// the user.
event.Error(ctx, "unable to check daemon socket owner, failing open", err)
} else if !ok {
// We successfully checked that the socket is not owned by us, we fail
// closed.
return nil, fmt.Errorf("socket %q is owned by a different user", d.addr)
}
const dialTimeout = 1 * time.Second
// Try dialing our remote once, in case it is already running.
netConn, err := net.DialTimeout(d.network, d.addr, dialTimeout)
if err == nil {
return netConn, nil
}
if d.isAuto && d.argFunc != nil {
if d.network == "unix" {
// Sometimes the socketfile isn't properly cleaned up when the server
// shuts down. Since we have already tried and failed to dial this
// address, it should *usually* be safe to remove the socket before
// binding to the address.
// TODO(rfindley): there is probably a race here if multiple server
// instances are simultaneously starting up.
if _, err := os.Stat(d.addr); err == nil {
if err := os.Remove(d.addr); err != nil {
return nil, errors.Errorf("removing remote socket file: %w", err)
}
}
}
args := d.argFunc(d.network, d.addr)
cmd := exec.Command(d.executable, args...)
if err := runRemote(cmd); err != nil {
return nil, err
}
}
const retries = 5
// It can take some time for the newly started server to bind to our address,
// so we retry for a bit.
for retry := 0; retry < retries; retry++ {
startDial := time.Now()
netConn, err = net.DialTimeout(d.network, d.addr, dialTimeout)
if err == nil {
return netConn, nil
}
event.Log(ctx, fmt.Sprintf("failed attempt #%d to connect to remote: %v\n", retry+2, err))
// In case our failure was a fast-failure, ensure we wait at least
// f.dialTimeout before trying again.
if retry != retries-1 {
time.Sleep(dialTimeout - time.Since(startDial))
}
}
return nil, errors.Errorf("dialing remote: %w", err)
}
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