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
|
// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build linux
// Package rawfile contains utilities for using the netstack with raw host
// files on Linux hosts.
package rawfile
import (
"syscall"
"unsafe"
"gvisor.googlesource.com/gvisor/pkg/tcpip"
)
// GetMTU determines the MTU of a network interface device.
func GetMTU(name string) (uint32, error) {
fd, err := syscall.Socket(syscall.AF_UNIX, syscall.SOCK_DGRAM, 0)
if err != nil {
return 0, err
}
defer syscall.Close(fd)
var ifreq struct {
name [16]byte
mtu int32
_ [20]byte
}
copy(ifreq.name[:], name)
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.SIOCGIFMTU, uintptr(unsafe.Pointer(&ifreq)))
if errno != 0 {
return 0, errno
}
return uint32(ifreq.mtu), nil
}
// NonBlockingWrite writes the given buffer to a file descriptor. It fails if
// partial data is written.
func NonBlockingWrite(fd int, buf []byte) *tcpip.Error {
var ptr unsafe.Pointer
if len(buf) > 0 {
ptr = unsafe.Pointer(&buf[0])
}
_, _, e := syscall.RawSyscall(syscall.SYS_WRITE, uintptr(fd), uintptr(ptr), uintptr(len(buf)))
if e != 0 {
return TranslateErrno(e)
}
return nil
}
// NonBlockingWrite2 writes up to two byte slices to a file descriptor in a
// single syscall. It fails if partial data is written.
func NonBlockingWrite2(fd int, b1, b2 []byte) *tcpip.Error {
// If the is no second buffer, issue a regular write.
if len(b2) == 0 {
return NonBlockingWrite(fd, b1)
}
// We have two buffers. Build the iovec that represents them and issue
// a writev syscall.
iovec := [...]syscall.Iovec{
{
Base: &b1[0],
Len: uint64(len(b1)),
},
{
Base: &b2[0],
Len: uint64(len(b2)),
},
}
_, _, e := syscall.RawSyscall(syscall.SYS_WRITEV, uintptr(fd), uintptr(unsafe.Pointer(&iovec[0])), uintptr(len(iovec)))
if e != 0 {
return TranslateErrno(e)
}
return nil
}
type pollEvent struct {
fd int32
events int16
revents int16
}
// BlockingRead reads from a file descriptor that is set up as non-blocking. If
// no data is available, it will block in a poll() syscall until the file
// descirptor becomes readable.
func BlockingRead(fd int, b []byte) (int, *tcpip.Error) {
for {
n, _, e := syscall.RawSyscall(syscall.SYS_READ, uintptr(fd), uintptr(unsafe.Pointer(&b[0])), uintptr(len(b)))
if e == 0 {
return int(n), nil
}
event := pollEvent{
fd: int32(fd),
events: 1, // POLLIN
}
_, e = blockingPoll(&event, 1, -1)
if e != 0 && e != syscall.EINTR {
return 0, TranslateErrno(e)
}
}
}
// BlockingReadv reads from a file descriptor that is set up as non-blocking and
// stores the data in a list of iovecs buffers. If no data is available, it will
// block in a poll() syscall until the file descriptor becomes readable.
func BlockingReadv(fd int, iovecs []syscall.Iovec) (int, *tcpip.Error) {
for {
n, _, e := syscall.RawSyscall(syscall.SYS_READV, uintptr(fd), uintptr(unsafe.Pointer(&iovecs[0])), uintptr(len(iovecs)))
if e == 0 {
return int(n), nil
}
event := pollEvent{
fd: int32(fd),
events: 1, // POLLIN
}
_, e = blockingPoll(&event, 1, -1)
if e != 0 && e != syscall.EINTR {
return 0, TranslateErrno(e)
}
}
}
// MMsgHdr represents the mmsg_hdr structure required by recvmmsg() on linux.
type MMsgHdr struct {
Msg syscall.Msghdr
Len uint32
_ [4]byte
}
// BlockingRecvMMsg reads from a file descriptor that is set up as non-blocking
// and stores the received messages in a slice of MMsgHdr structures. If no data
// is available, it will block in a poll() syscall until the file descriptor
// becomes readable.
func BlockingRecvMMsg(fd int, msgHdrs []MMsgHdr) (int, *tcpip.Error) {
for {
n, _, e := syscall.RawSyscall6(syscall.SYS_RECVMMSG, uintptr(fd), uintptr(unsafe.Pointer(&msgHdrs[0])), uintptr(len(msgHdrs)), syscall.MSG_DONTWAIT, 0, 0)
if e == 0 {
return int(n), nil
}
event := pollEvent{
fd: int32(fd),
events: 1, // POLLIN
}
if _, e := blockingPoll(&event, 1, -1); e != 0 && e != syscall.EINTR {
return 0, TranslateErrno(e)
}
}
}
|
