-
Notifications
You must be signed in to change notification settings - Fork 51
/
markedconn.go
242 lines (193 loc) · 6.13 KB
/
markedconn.go
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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
// +build linux
package markedconn
import (
"fmt"
"net"
"os"
"strconv"
"syscall"
"time"
"unsafe"
"github.com/rs/xid"
)
const (
sockOptOriginalDst = 80
)
// DialMarkedTCP creates a new TCP connection and marks it with the provided mark.
func DialMarkedTCP(network string, laddr, raddr *net.TCPAddr, mark int) (net.Conn, error) {
fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, 0)
if err != nil {
return nil, fmt.Errorf("Failed to create socket: %s", err)
}
f := os.NewFile(uintptr(fd), xid.New().String())
defer f.Close() // nolint
conn, err := net.FileConn(f)
if err != nil {
return nil, fmt.Errorf("Unable to create downstream connection: %s", err)
}
address := &syscall.SockaddrInet4{
Port: raddr.Port,
}
copy(address.Addr[:], raddr.IP.To4())
if err = syscall.SetNonblock(fd, false); err != nil {
conn.Close() // nolint
return nil, fmt.Errorf("unable to set socket options: %s", err)
}
err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_MARK, mark)
if err != nil {
conn.Close() // nolint
return nil, fmt.Errorf("Failed to assing mark to socket: %s", err)
}
if err := setSocketTimeout(fd, time.Second*5); err != nil {
return nil, fmt.Errorf("Failed to set connect timeout: %s", err)
}
if err := syscall.Connect(fd, address); err != nil {
conn.Close() // nolint
return nil, fmt.Errorf("Unable to connect: %s", err)
}
// if err := setSocketTimeout(fd, 0); err != nil {
// return nil, fmt.Errorf("Failed to set connect timeout: %s", err)
// }
return conn, nil
}
// MarkConnection marks an existing connection with a mark
func MarkConnection(conn net.Conn, mark int) error {
setMark := func(fd uintptr) {
syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_MARK, mark) // nolint
}
rawconn, err := conn.(*net.TCPConn).SyscallConn()
if err != nil {
return err
}
return rawconn.Control(setMark)
}
// SocketListener creates a TCP listener through system calls giving us more
// control over the specific parameters that we need.
func SocketListener(port string, mark int) (net.Listener, error) {
addr, err := net.ResolveTCPAddr("tcp4", port)
if err != nil {
return nil, fmt.Errorf("Cannot resolve v4 IP: %s", err)
}
fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, 0)
if err != nil {
return nil, err
}
if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err != nil {
return nil, fmt.Errorf("cannot set SO_REUSEADDR: %s", err)
}
if len(addr.IP) == 0 {
addr.IP = net.IPv4zero
}
socketAddress := &syscall.SockaddrInet4{Port: addr.Port}
copy(socketAddress.Addr[:], addr.IP.To4())
if err = syscall.Bind(fd, socketAddress); err != nil {
syscall.Close(fd) // nolint errcheck
return nil, err
}
if err = syscall.Listen(fd, 256); err != nil {
syscall.Close(fd) // nolint errcheck
return nil, err
}
f := os.NewFile(uintptr(fd), addr.String())
defer f.Close() // nolint errcheck
listener, err := net.FileListener(f)
if err != nil {
return nil, fmt.Errorf("Cannot bind listener: %s", err)
}
return ProxiedListener{netListener: listener, mark: mark}, nil
}
// ProxiedConnection is a proxied connection where we can recover the
// original destination.
type ProxiedConnection struct {
net.Conn
originalIP net.IP
originalPort int
originalTCPConnection *net.TCPConn
}
// GetOriginalDestination sets the original destination of the connection.
func (p *ProxiedConnection) GetOriginalDestination() (net.IP, int) {
return p.originalIP, p.originalPort
}
// GetTCPConnection returns the TCP connection object.
func (p *ProxiedConnection) GetTCPConnection() *net.TCPConn {
return p.originalTCPConnection
}
// LocalAddr implements the corresponding method of net.Conn, but returns the original
// address.
func (p *ProxiedConnection) LocalAddr() net.Addr {
addr, err := net.ResolveTCPAddr("tcp", p.originalIP.String()+":"+strconv.Itoa(p.originalPort))
if err != nil {
return nil
}
return addr
}
// ProxiedListener is a proxied listener that uses proxied connections.
type ProxiedListener struct {
netListener net.Listener
mark int
}
// Accept implements the accept method of the interface.
func (l ProxiedListener) Accept() (c net.Conn, err error) {
nc, err := l.netListener.Accept()
if err != nil {
fmt.Println("I got an error", err)
return nil, err
}
ip, port, err := GetOriginalDestination(nc)
if err != nil {
return nil, err
}
if err := MarkConnection(nc, l.mark); err != nil {
return nil, err
}
return &ProxiedConnection{nc, ip, port, nc.(*net.TCPConn)}, nil
}
// Addr implements the Addr method of net.Listener.
func (l ProxiedListener) Addr() net.Addr {
return l.netListener.Addr()
}
// Close implements the Close method of the net.Listener.
func (l ProxiedListener) Close() error {
return l.netListener.Close()
}
type sockaddr struct {
family uint16
data [14]byte
}
// GetOriginalDestination -- Func to get original destination a connection
func GetOriginalDestination(conn net.Conn) (net.IP, int, error) {
var addr sockaddr
size := uint32(unsafe.Sizeof(addr))
inFile, err := conn.(*net.TCPConn).File()
if err != nil {
return []byte{}, 0, err
}
err = getsockopt(int(inFile.Fd()), syscall.SOL_IP, sockOptOriginalDst, uintptr(unsafe.Pointer(&addr)), &size)
if err != nil {
return []byte{}, 0, err
}
if addr.family != syscall.AF_INET {
return []byte{}, 0, fmt.Errorf("invalid address family")
}
var ip net.IP
ip = addr.data[2:6]
port := int(addr.data[0])<<8 + int(addr.data[1])
return ip, port, nil
}
func getsockopt(s int, level int, name int, val uintptr, vallen *uint32) (err error) {
_, _, e1 := syscall.Syscall6(syscall.SYS_GETSOCKOPT, uintptr(s), uintptr(level), uintptr(name), uintptr(val), uintptr(unsafe.Pointer(vallen)), 0)
if e1 != 0 {
err = e1
}
return
}
// setSocketTimeout sets the receive and send timeouts on the given socket.
func setSocketTimeout(fd int, timeout time.Duration) error {
tv := syscall.NsecToTimeval(timeout.Nanoseconds())
for _, opt := range []int{syscall.SO_RCVTIMEO, syscall.SO_SNDTIMEO} {
if err := syscall.SetsockoptTimeval(fd, syscall.SOL_SOCKET, opt, &tv); err != nil {
return os.NewSyscallError("setsockopt", err)
}
}
return nil
}