228 lines
7.5 KiB
Go
228 lines
7.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build aix || darwin || dragonfly || freebsd || hurd || (js && wasm) || linux || netbsd || openbsd || solaris || windows
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package net
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import (
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"context"
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"internal/poll"
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"net/netip"
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"runtime"
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"syscall"
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)
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// probe probes IPv4, IPv6 and IPv4-mapped IPv6 communication
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// capabilities which are controlled by the IPV6_V6ONLY socket option
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// and kernel configuration.
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//
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// Should we try to use the IPv4 socket interface if we're only
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// dealing with IPv4 sockets? As long as the host system understands
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// IPv4-mapped IPv6, it's okay to pass IPv4-mapped IPv6 addresses to
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// the IPv6 interface. That simplifies our code and is most
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// general. Unfortunately, we need to run on kernels built without
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// IPv6 support too. So probe the kernel to figure it out.
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func (p *ipStackCapabilities) probe() {
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s, err := sysSocket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
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switch err {
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case syscall.EAFNOSUPPORT, syscall.EPROTONOSUPPORT:
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case nil:
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poll.CloseFunc(s)
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p.ipv4Enabled = true
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}
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var probes = []struct {
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laddr TCPAddr
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value int
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}{
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// IPv6 communication capability
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{laddr: TCPAddr{IP: ParseIP("::1")}, value: 1},
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// IPv4-mapped IPv6 address communication capability
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{laddr: TCPAddr{IP: IPv4(127, 0, 0, 1)}, value: 0},
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}
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switch runtime.GOOS {
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case "dragonfly", "openbsd":
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// The latest DragonFly BSD and OpenBSD kernels don't
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// support IPV6_V6ONLY=0. They always return an error
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// and we don't need to probe the capability.
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probes = probes[:1]
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}
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for i := range probes {
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s, err := sysSocket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
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if err != nil {
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continue
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}
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defer poll.CloseFunc(s)
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syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, probes[i].value)
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sa, err := probes[i].laddr.sockaddr(syscall.AF_INET6)
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if err != nil {
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continue
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}
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if err := syscall.Bind(s, sa); err != nil {
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continue
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}
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if i == 0 {
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p.ipv6Enabled = true
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} else {
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p.ipv4MappedIPv6Enabled = true
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}
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}
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}
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// favoriteAddrFamily returns the appropriate address family for the
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// given network, laddr, raddr and mode.
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//
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// If mode indicates "listen" and laddr is a wildcard, we assume that
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// the user wants to make a passive-open connection with a wildcard
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// address family, both AF_INET and AF_INET6, and a wildcard address
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// like the following:
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//
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// - A listen for a wildcard communication domain, "tcp" or
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// "udp", with a wildcard address: If the platform supports
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// both IPv6 and IPv4-mapped IPv6 communication capabilities,
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// or does not support IPv4, we use a dual stack, AF_INET6 and
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// IPV6_V6ONLY=0, wildcard address listen. The dual stack
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// wildcard address listen may fall back to an IPv6-only,
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// AF_INET6 and IPV6_V6ONLY=1, wildcard address listen.
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// Otherwise we prefer an IPv4-only, AF_INET, wildcard address
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// listen.
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//
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// - A listen for a wildcard communication domain, "tcp" or
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// "udp", with an IPv4 wildcard address: same as above.
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//
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// - A listen for a wildcard communication domain, "tcp" or
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// "udp", with an IPv6 wildcard address: same as above.
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//
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// - A listen for an IPv4 communication domain, "tcp4" or "udp4",
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// with an IPv4 wildcard address: We use an IPv4-only, AF_INET,
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// wildcard address listen.
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//
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// - A listen for an IPv6 communication domain, "tcp6" or "udp6",
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// with an IPv6 wildcard address: We use an IPv6-only, AF_INET6
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// and IPV6_V6ONLY=1, wildcard address listen.
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//
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// Otherwise guess: If the addresses are IPv4 then returns AF_INET,
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// or else returns AF_INET6. It also returns a boolean value what
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// designates IPV6_V6ONLY option.
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//
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// Note that the latest DragonFly BSD and OpenBSD kernels allow
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// neither "net.inet6.ip6.v6only=1" change nor IPPROTO_IPV6 level
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// IPV6_V6ONLY socket option setting.
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func favoriteAddrFamily(network string, laddr, raddr sockaddr, mode string) (family int, ipv6only bool) {
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switch network[len(network)-1] {
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case '4':
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return syscall.AF_INET, false
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case '6':
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return syscall.AF_INET6, true
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}
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if mode == "listen" && (laddr == nil || laddr.isWildcard()) {
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if supportsIPv4map() || !supportsIPv4() {
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return syscall.AF_INET6, false
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}
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if laddr == nil {
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return syscall.AF_INET, false
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}
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return laddr.family(), false
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}
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if (laddr == nil || laddr.family() == syscall.AF_INET) &&
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(raddr == nil || raddr.family() == syscall.AF_INET) {
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return syscall.AF_INET, false
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}
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return syscall.AF_INET6, false
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}
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func internetSocket(ctx context.Context, net string, laddr, raddr sockaddr, sotype, proto int, mode string, ctrlFn func(string, string, syscall.RawConn) error) (fd *netFD, err error) {
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if (runtime.GOOS == "aix" || runtime.GOOS == "windows" || runtime.GOOS == "openbsd") && mode == "dial" && raddr.isWildcard() {
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raddr = raddr.toLocal(net)
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}
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family, ipv6only := favoriteAddrFamily(net, laddr, raddr, mode)
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return socket(ctx, net, family, sotype, proto, ipv6only, laddr, raddr, ctrlFn)
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}
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func ipToSockaddrInet4(ip IP, port int) (syscall.SockaddrInet4, error) {
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if len(ip) == 0 {
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ip = IPv4zero
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}
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ip4 := ip.To4()
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if ip4 == nil {
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return syscall.SockaddrInet4{}, &AddrError{Err: "non-IPv4 address", Addr: ip.String()}
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}
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sa := syscall.SockaddrInet4{Port: port}
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copy(sa.Addr[:], ip4)
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return sa, nil
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}
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func ipToSockaddrInet6(ip IP, port int, zone string) (syscall.SockaddrInet6, error) {
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// In general, an IP wildcard address, which is either
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// "0.0.0.0" or "::", means the entire IP addressing
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// space. For some historical reason, it is used to
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// specify "any available address" on some operations
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// of IP node.
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//
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// When the IP node supports IPv4-mapped IPv6 address,
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// we allow a listener to listen to the wildcard
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// address of both IP addressing spaces by specifying
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// IPv6 wildcard address.
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if len(ip) == 0 || ip.Equal(IPv4zero) {
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ip = IPv6zero
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}
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// We accept any IPv6 address including IPv4-mapped
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// IPv6 address.
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ip6 := ip.To16()
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if ip6 == nil {
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return syscall.SockaddrInet6{}, &AddrError{Err: "non-IPv6 address", Addr: ip.String()}
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}
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sa := syscall.SockaddrInet6{Port: port, ZoneId: uint32(zoneCache.index(zone))}
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copy(sa.Addr[:], ip6)
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return sa, nil
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}
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func ipToSockaddr(family int, ip IP, port int, zone string) (syscall.Sockaddr, error) {
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switch family {
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case syscall.AF_INET:
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sa, err := ipToSockaddrInet4(ip, port)
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if err != nil {
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return nil, err
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}
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return &sa, nil
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case syscall.AF_INET6:
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sa, err := ipToSockaddrInet6(ip, port, zone)
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if err != nil {
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return nil, err
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}
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return &sa, nil
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}
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return nil, &AddrError{Err: "invalid address family", Addr: ip.String()}
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}
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func addrPortToSockaddrInet4(ap netip.AddrPort) (syscall.SockaddrInet4, error) {
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// ipToSockaddrInet4 has special handling here for zero length slices.
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// We do not, because netip has no concept of a generic zero IP address.
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addr := ap.Addr()
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if !addr.Is4() {
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return syscall.SockaddrInet4{}, &AddrError{Err: "non-IPv4 address", Addr: addr.String()}
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}
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sa := syscall.SockaddrInet4{
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Addr: addr.As4(),
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Port: int(ap.Port()),
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}
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return sa, nil
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}
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func addrPortToSockaddrInet6(ap netip.AddrPort) (syscall.SockaddrInet6, error) {
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// ipToSockaddrInet6 has special handling here for zero length slices.
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// We do not, because netip has no concept of a generic zero IP address.
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addr := ap.Addr()
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if !addr.Is6() {
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return syscall.SockaddrInet6{}, &AddrError{Err: "non-IPv6 address", Addr: addr.String()}
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}
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sa := syscall.SockaddrInet6{
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Addr: addr.As16(),
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Port: int(ap.Port()),
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ZoneId: uint32(zoneCache.index(addr.Zone())),
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}
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return sa, nil
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}
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