1// Copyright 2020 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
6// +build darwin dragonfly freebsd linux netbsd openbsd solaris
7
8package lsprpc
9
10import (
11	"crypto/sha256"
12	"errors"
13	"fmt"
14	exec "golang.org/x/sys/execabs"
15	"log"
16	"os"
17	"os/user"
18	"path/filepath"
19	"strconv"
20	"syscall"
21
22	"golang.org/x/xerrors"
23)
24
25func init() {
26	startRemote = startRemotePosix
27	autoNetworkAddress = autoNetworkAddressPosix
28	verifyRemoteOwnership = verifyRemoteOwnershipPosix
29}
30
31func startRemotePosix(goplsPath string, args ...string) error {
32	cmd := exec.Command(goplsPath, args...)
33	cmd.SysProcAttr = &syscall.SysProcAttr{
34		Setsid: true,
35	}
36	if err := cmd.Start(); err != nil {
37		return xerrors.Errorf("starting remote gopls: %w", err)
38	}
39	return nil
40}
41
42// autoNetworkAddress resolves an id on the 'auto' pseduo-network to a
43// real network and address. On unix, this uses unix domain sockets.
44func autoNetworkAddressPosix(goplsPath, id string) (network string, address string) {
45	// Especially when doing local development or testing, it's important that
46	// the remote gopls instance we connect to is running the same binary as our
47	// forwarder. So we encode a short hash of the binary path into the daemon
48	// socket name. If possible, we also include the buildid in this hash, to
49	// account for long-running processes where the binary has been subsequently
50	// rebuilt.
51	h := sha256.New()
52	cmd := exec.Command("go", "tool", "buildid", goplsPath)
53	cmd.Stdout = h
54	var pathHash []byte
55	if err := cmd.Run(); err == nil {
56		pathHash = h.Sum(nil)
57	} else {
58		log.Printf("error getting current buildid: %v", err)
59		sum := sha256.Sum256([]byte(goplsPath))
60		pathHash = sum[:]
61	}
62	shortHash := fmt.Sprintf("%x", pathHash)[:6]
63	user := os.Getenv("USER")
64	if user == "" {
65		user = "shared"
66	}
67	basename := filepath.Base(goplsPath)
68	idComponent := ""
69	if id != "" {
70		idComponent = "-" + id
71	}
72	runtimeDir := os.TempDir()
73	if xdg := os.Getenv("XDG_RUNTIME_DIR"); xdg != "" {
74		runtimeDir = xdg
75	}
76	return "unix", filepath.Join(runtimeDir, fmt.Sprintf("%s-%s-daemon.%s%s", basename, shortHash, user, idComponent))
77}
78
79func verifyRemoteOwnershipPosix(network, address string) (bool, error) {
80	if network != "unix" {
81		return true, nil
82	}
83	fi, err := os.Stat(address)
84	if err != nil {
85		if os.IsNotExist(err) {
86			return true, nil
87		}
88		return false, xerrors.Errorf("checking socket owner: %w", err)
89	}
90	stat, ok := fi.Sys().(*syscall.Stat_t)
91	if !ok {
92		return false, errors.New("fi.Sys() is not a Stat_t")
93	}
94	user, err := user.Current()
95	if err != nil {
96		return false, xerrors.Errorf("checking current user: %w", err)
97	}
98	uid, err := strconv.ParseUint(user.Uid, 10, 32)
99	if err != nil {
100		return false, xerrors.Errorf("parsing current UID: %w", err)
101	}
102	return stat.Uid == uint32(uid), nil
103}
104