| // 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 && wasm) || 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() { |
| 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) { |
| if (runtime.GOOS == "aix" || runtime.GOOS == "windows" || runtime.GOOS == "openbsd") && 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 |
| } |
