aboutsummaryrefslogtreecommitdiffstats
path: root/dll.go
blob: ba9cad7bda8f44866893f830e5ce3c1207779ad2 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
//go:build windows

/* SPDX-License-Identifier: MIT
 *
 * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
 */

package wintun

import (
	"fmt"
	"sync"
	"sync/atomic"
	"unsafe"

	"golang.org/x/sys/windows"
)

func newLazyDLL(name string, onLoad func(d *lazyDLL)) *lazyDLL {
	return &lazyDLL{Name: name, onLoad: onLoad}
}

func (d *lazyDLL) NewProc(name string) *lazyProc {
	return &lazyProc{dll: d, Name: name}
}

type lazyProc struct {
	Name string
	mu   sync.Mutex
	dll  *lazyDLL
	addr uintptr
}

func (p *lazyProc) Find() error {
	if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&p.addr))) != nil {
		return nil
	}
	p.mu.Lock()
	defer p.mu.Unlock()
	if p.addr != 0 {
		return nil
	}

	err := p.dll.Load()
	if err != nil {
		return fmt.Errorf("Error loading %v DLL: %w", p.dll.Name, err)
	}
	addr, err := p.nameToAddr()
	if err != nil {
		return fmt.Errorf("Error getting %v address: %w", p.Name, err)
	}

	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&p.addr)), unsafe.Pointer(addr))
	return nil
}

func (p *lazyProc) Addr() uintptr {
	err := p.Find()
	if err != nil {
		panic(err)
	}
	return p.addr
}

type lazyDLL struct {
	Name   string
	mu     sync.Mutex
	module windows.Handle
	onLoad func(d *lazyDLL)
}

func (d *lazyDLL) Load() error {
	if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&d.module))) != nil {
		return nil
	}
	d.mu.Lock()
	defer d.mu.Unlock()
	if d.module != 0 {
		return nil
	}

	const (
		LOAD_LIBRARY_SEARCH_APPLICATION_DIR = 0x00000200
		LOAD_LIBRARY_SEARCH_SYSTEM32        = 0x00000800
	)
	module, err := windows.LoadLibraryEx(d.Name, 0, LOAD_LIBRARY_SEARCH_APPLICATION_DIR|LOAD_LIBRARY_SEARCH_SYSTEM32)
	if err != nil {
		return fmt.Errorf("Unable to load library: %w", err)
	}

	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&d.module)), unsafe.Pointer(module))
	if d.onLoad != nil {
		d.onLoad(d)
	}
	return nil
}

func (p *lazyProc) nameToAddr() (uintptr, error) {
	return windows.GetProcAddress(p.dll.module, p.Name)
}

// Version returns the version of the Wintun DLL.
func Version() string {
	if modwintun.Load() != nil {
		return "unknown"
	}
	resInfo, err := windows.FindResource(modwintun.module, windows.ResourceID(1), windows.RT_VERSION)
	if err != nil {
		return "unknown"
	}
	data, err := windows.LoadResourceData(modwintun.module, resInfo)
	if err != nil {
		return "unknown"
	}

	var fixedInfo *windows.VS_FIXEDFILEINFO
	fixedInfoLen := uint32(unsafe.Sizeof(*fixedInfo))
	err = windows.VerQueryValue(unsafe.Pointer(&data[0]), `\`, unsafe.Pointer(&fixedInfo), &fixedInfoLen)
	if err != nil {
		return "unknown"
	}
	version := fmt.Sprintf("%d.%d", (fixedInfo.FileVersionMS>>16)&0xff, (fixedInfo.FileVersionMS>>0)&0xff)
	if nextNibble := (fixedInfo.FileVersionLS >> 16) & 0xff; nextNibble != 0 {
		version += fmt.Sprintf(".%d", nextNibble)
	}
	if nextNibble := (fixedInfo.FileVersionLS >> 0) & 0xff; nextNibble != 0 {
		version += fmt.Sprintf(".%d", nextNibble)
	}
	return version
}