aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/go/_std_1.22/src/net/ipsock_posix.go
blob: 67ce1479c647cd578464ddd7c2038c3295132707 (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
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
243
244
// 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.

//go:build unix || js || wasip1 || windows

package net

import (
	"context"
	"internal/poll"
	"net/netip"
	"runtime"
	"syscall"
)

// probe probes IPv4, IPv6 and IPv4-mapped IPv6 communication
// capabilities which are controlled by the IPV6_V6ONLY socket option
// and kernel configuration.
//
// Should we try to use the IPv4 socket interface if we're only
// dealing with IPv4 sockets? As long as the host system understands
// IPv4-mapped IPv6, it's okay to pass IPv4-mapped IPv6 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.
func (p *ipStackCapabilities) probe() {
	switch runtime.GOOS {
	case "js", "wasip1":
		// Both ipv4 and ipv6 are faked; see net_fake.go.
		p.ipv4Enabled = true
		p.ipv6Enabled = true
		p.ipv4MappedIPv6Enabled = true
		return
	}

	s, err := sysSocket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
	switch err {
	case syscall.EAFNOSUPPORT, syscall.EPROTONOSUPPORT:
	case nil:
		poll.CloseFunc(s)
		p.ipv4Enabled = true
	}
	var probes = []struct {
		laddr TCPAddr
		value int
	}{
		// IPv6 communication capability
		{laddr: TCPAddr{IP: ParseIP("::1")}, value: 1},
		// IPv4-mapped IPv6 address communication capability
		{laddr: TCPAddr{IP: IPv4(127, 0, 0, 1)}, value: 0},
	}
	switch runtime.GOOS {
	case "dragonfly", "openbsd":
		// The latest DragonFly BSD and OpenBSD kernels don't
		// support IPV6_V6ONLY=0. They always return an error
		// and we don't need to probe the capability.
		probes = probes[:1]
	}
	for i := range probes {
		s, err := sysSocket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
		if err != nil {
			continue
		}
		defer poll.CloseFunc(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
		}
		if i == 0 {
			p.ipv6Enabled = true
		} else {
			p.ipv4MappedIPv6Enabled = true
		}
	}
}

// favoriteAddrFamily returns the appropriate address family for the
// given network, laddr, raddr and mode.
//
// If mode indicates "listen" and laddr is a wildcard, we assume that
// the user wants to make a passive-open connection with a wildcard
// address family, both AF_INET and AF_INET6, and a wildcard address
// like the following:
//
//   - A listen for a wildcard communication domain, "tcp" or
//     "udp", with a wildcard address: If the platform supports
//     both IPv6 and IPv4-mapped IPv6 communication capabilities,
//     or does not support IPv4, we use a dual stack, AF_INET6 and
//     IPV6_V6ONLY=0, wildcard address listen. The dual stack
//     wildcard address listen may fall back to an IPv6-only,
//     AF_INET6 and IPV6_V6ONLY=1, wildcard address listen.
//     Otherwise we prefer an IPv4-only, AF_INET, wildcard address
//     listen.
//
//   - A listen for a wildcard communication domain, "tcp" or
//     "udp", with an IPv4 wildcard address: same as above.
//
//   - A listen for a wildcard communication domain, "tcp" or
//     "udp", with an IPv6 wildcard address: same as above.
//
//   - A listen for an IPv4 communication domain, "tcp4" or "udp4",
//     with an IPv4 wildcard address: We use an IPv4-only, AF_INET,
//     wildcard address listen.
//
//   - A listen for an IPv6 communication domain, "tcp6" or "udp6",
//     with an IPv6 wildcard address: We use an IPv6-only, AF_INET6
//     and 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 the latest DragonFly BSD and OpenBSD kernels allow
// neither "net.inet6.ip6.v6only=1" change nor IPPROTO_IPV6 level
// IPV6_V6ONLY socket option setting.
func favoriteAddrFamily(network string, laddr, raddr sockaddr, mode string) (family int, ipv6only bool) {
	switch network[len(network)-1] {
	case '4':
		return syscall.AF_INET, false
	case '6':
		return syscall.AF_INET6, true
	}

	if mode == "listen" && (laddr == nil || laddr.isWildcard()) {
		if supportsIPv4map() || !supportsIPv4() {
			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
}

func internetSocket(ctx context.Context, net string, laddr, raddr sockaddr, sotype, proto int, mode string, ctrlCtxFn func(context.Context, string, string, syscall.RawConn) error) (fd *netFD, err error) {
	switch runtime.GOOS {
	case "aix", "windows", "openbsd", "js", "wasip1":
		if mode == "dial" && raddr.isWildcard() {
			raddr = raddr.toLocal(net)
		}
	}
	family, ipv6only := favoriteAddrFamily(net, laddr, raddr, mode)
	return socket(ctx, net, family, sotype, proto, ipv6only, laddr, raddr, ctrlCtxFn)
}

func ipToSockaddrInet4(ip IP, port int) (syscall.SockaddrInet4, error) {
	if len(ip) == 0 {
		ip = IPv4zero
	}
	ip4 := ip.To4()
	if ip4 == nil {
		return syscall.SockaddrInet4{}, &AddrError{Err: "non-IPv4 address", Addr: ip.String()}
	}
	sa := syscall.SockaddrInet4{Port: port}
	copy(sa.Addr[:], ip4)
	return sa, nil
}

func ipToSockaddrInet6(ip IP, port int, zone string) (syscall.SockaddrInet6, error) {
	// In general, an IP wildcard address, which is either
	// "0.0.0.0" or "::", means the entire IP addressing
	// space. For some historical reason, it is used to
	// specify "any available address" on some operations
	// of IP node.
	//
	// When the IP node supports IPv4-mapped IPv6 address,
	// we allow a listener to listen to the wildcard
	// address of both IP addressing spaces by specifying
	// IPv6 wildcard address.
	if len(ip) == 0 || ip.Equal(IPv4zero) {
		ip = IPv6zero
	}
	// We accept any IPv6 address including IPv4-mapped
	// IPv6 address.
	ip6 := ip.To16()
	if ip6 == nil {
		return syscall.SockaddrInet6{}, &AddrError{Err: "non-IPv6 address", Addr: ip.String()}
	}
	sa := syscall.SockaddrInet6{Port: port, ZoneId: uint32(zoneCache.index(zone))}
	copy(sa.Addr[:], ip6)
	return sa, nil
}

func ipToSockaddr(family int, ip IP, port int, zone string) (syscall.Sockaddr, error) {
	switch family {
	case syscall.AF_INET:
		sa, err := ipToSockaddrInet4(ip, port)
		if err != nil {
			return nil, err
		}
		return &sa, nil
	case syscall.AF_INET6:
		sa, err := ipToSockaddrInet6(ip, port, zone)
		if err != nil {
			return nil, err
		}
		return &sa, nil
	}
	return nil, &AddrError{Err: "invalid address family", Addr: ip.String()}
}

func addrPortToSockaddrInet4(ap netip.AddrPort) (syscall.SockaddrInet4, error) {
	// ipToSockaddrInet4 has special handling here for zero length slices.
	// We do not, because netip has no concept of a generic zero IP address.
	addr := ap.Addr()
	if !addr.Is4() {
		return syscall.SockaddrInet4{}, &AddrError{Err: "non-IPv4 address", Addr: addr.String()}
	}
	sa := syscall.SockaddrInet4{
		Addr: addr.As4(),
		Port: int(ap.Port()),
	}
	return sa, nil
}

func addrPortToSockaddrInet6(ap netip.AddrPort) (syscall.SockaddrInet6, error) {
	// ipToSockaddrInet6 has special handling here for zero length slices.
	// We do not, because netip has no concept of a generic zero IP address.
	//
	// addr is allowed to be an IPv4 address, because As16 will convert it
	// to an IPv4-mapped IPv6 address.
	// The error message is kept consistent with ipToSockaddrInet6.
	addr := ap.Addr()
	if !addr.IsValid() {
		return syscall.SockaddrInet6{}, &AddrError{Err: "non-IPv6 address", Addr: addr.String()}
	}
	sa := syscall.SockaddrInet6{
		Addr:   addr.As16(),
		Port:   int(ap.Port()),
		ZoneId: uint32(zoneCache.index(addr.Zone())),
	}
	return sa, nil
}