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
|
// Copyright 2009 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.
// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
// Internet protocol family sockets for POSIX
package net
import (
"syscall"
"time"
)
func probeIPv4Stack() bool {
s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
switch err {
case syscall.EAFNOSUPPORT, syscall.EPROTONOSUPPORT:
return false
case nil:
closesocket(s)
}
return true
}
// Should we try to use the IPv4 socket interface if we're
// only dealing with IPv4 sockets? As long as the host system
// understands IPv6, it's okay to pass IPv4 addresses to the IPv6
// interface. That simplifies our code and is most general.
// Unfortunately, we need to run on kernels built without IPv6
// support too. So probe the kernel to figure it out.
//
// probeIPv6Stack probes both basic IPv6 capability and IPv6 IPv4-
// mapping capability which is controlled by IPV6_V6ONLY socket
// option and/or kernel state "net.inet6.ip6.v6only".
// It returns two boolean values. If the first boolean value is
// true, kernel supports basic IPv6 functionality. If the second
// boolean value is true, kernel supports IPv6 IPv4-mapping.
func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
var probes = []struct {
laddr TCPAddr
value int
ok bool
}{
// IPv6 communication capability
{laddr: TCPAddr{IP: ParseIP("::1")}, value: 1},
// IPv6 IPv4-mapped address communication capability
{laddr: TCPAddr{IP: IPv4(127, 0, 0, 1)}, value: 0},
}
for i := range probes {
s, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
if err != nil {
continue
}
defer closesocket(s)
syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, probes[i].value)
sa, err := probes[i].laddr.sockaddr(syscall.AF_INET6)
if err != nil {
continue
}
if err := syscall.Bind(s, sa); err != nil {
continue
}
probes[i].ok = true
}
return probes[0].ok, probes[1].ok
}
// favoriteAddrFamily returns the appropriate address family to
// the given net, laddr, raddr and mode. At first it figures
// address family out from the net. If mode indicates "listen"
// and laddr is a wildcard, it assumes that the user wants to
// make a passive connection with a wildcard address family, both
// AF_INET and AF_INET6, and a wildcard address like following:
//
// 1. A wild-wild listen, "tcp" + ""
// If the platform supports both IPv6 and IPv6 IPv4-mapping
// capabilities, we assume that the user want to listen on
// both IPv4 and IPv6 wildcard address over an AF_INET6
// socket with IPV6_V6ONLY=0. Otherwise we prefer an IPv4
// wildcard address listen over an AF_INET socket.
//
// 2. A wild-ipv4wild listen, "tcp" + "0.0.0.0"
// Same as 1.
//
// 3. A wild-ipv6wild listen, "tcp" + "[::]"
// Almost same as 1 but we prefer an IPv6 wildcard address
// listen over an AF_INET6 socket with IPV6_V6ONLY=0 when
// the platform supports IPv6 capability but not IPv6 IPv4-
// mapping capability.
//
// 4. A ipv4-ipv4wild listen, "tcp4" + "" or "0.0.0.0"
// We use an IPv4 (AF_INET) wildcard address listen.
//
// 5. A ipv6-ipv6wild listen, "tcp6" + "" or "[::]"
// We use an IPv6 (AF_INET6, IPV6_V6ONLY=1) wildcard address
// listen.
//
// Otherwise guess: if the addresses are IPv4 then returns AF_INET,
// or else returns AF_INET6. It also returns a boolean value what
// designates IPV6_V6ONLY option.
//
// Note that OpenBSD allows neither "net.inet6.ip6.v6only=1" change
// nor IPPROTO_IPV6 level IPV6_V6ONLY socket option setting.
func favoriteAddrFamily(net string, laddr, raddr sockaddr, mode string) (family int, ipv6only bool) {
switch net[len(net)-1] {
case '4':
return syscall.AF_INET, false
case '6':
return syscall.AF_INET6, true
}
if mode == "listen" && (laddr == nil || laddr.isWildcard()) {
if supportsIPv4map {
return syscall.AF_INET6, false
}
if laddr == nil {
return syscall.AF_INET, false
}
return laddr.family(), false
}
if (laddr == nil || laddr.family() == syscall.AF_INET) &&
(raddr == nil || raddr.family() == syscall.AF_INET) {
return syscall.AF_INET, false
}
return syscall.AF_INET6, false
}
// Internet sockets (TCP, UDP, IP)
func internetSocket(net string, laddr, raddr sockaddr, deadline time.Time, sotype, proto int, mode string) (fd *netFD, err error) {
family, ipv6only := favoriteAddrFamily(net, laddr, raddr, mode)
return socket(net, family, sotype, proto, ipv6only, laddr, raddr, deadline)
}
func ipToSockaddr(family int, ip IP, port int, zone string) (syscall.Sockaddr, error) {
switch family {
case syscall.AF_INET:
if len(ip) == 0 {
ip = IPv4zero
}
if ip = ip.To4(); ip == nil {
return nil, InvalidAddrError("non-IPv4 address")
}
sa := new(syscall.SockaddrInet4)
for i := 0; i < IPv4len; i++ {
sa.Addr[i] = ip[i]
}
sa.Port = port
return sa, nil
case syscall.AF_INET6:
if len(ip) == 0 {
ip = IPv6zero
}
// IPv4 callers use 0.0.0.0 to mean "announce on any available address".
// In IPv6 mode, Linux treats that as meaning "announce on 0.0.0.0",
// which it refuses to do. Rewrite to the IPv6 unspecified address.
if ip.Equal(IPv4zero) {
ip = IPv6zero
}
if ip = ip.To16(); ip == nil {
return nil, InvalidAddrError("non-IPv6 address")
}
sa := new(syscall.SockaddrInet6)
for i := 0; i < IPv6len; i++ {
sa.Addr[i] = ip[i]
}
sa.Port = port
sa.ZoneId = uint32(zoneToInt(zone))
return sa, nil
}
return nil, InvalidAddrError("unexpected socket family")
}
|
