| // 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 |
| |
| package net |
| |
| import ( |
| "context" |
| "runtime" |
| "syscall" |
| ) |
| |
| // BUG(rsc,mikio): On DragonFly BSD and OpenBSD, listening on the |
| // "tcp" and "udp" networks does not listen for both IPv4 and IPv6 |
| // connections. This is due to the fact that IPv4 traffic will not be |
| // routed to an IPv6 socket - two separate sockets are required if |
| // both address families are to be supported. |
| // See inet6(4) for details. |
| |
| func probeIPv4Stack() bool { |
| s, err := socketFunc(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP) |
| switch err { |
| case syscall.EAFNOSUPPORT, syscall.EPROTONOSUPPORT: |
| return false |
| case nil: |
| closeFunc(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 |
| }{ |
| // 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}, |
| } |
| var supps [2]bool |
| switch runtime.GOOS { |
| case "dragonfly", "openbsd": |
| // Some released versions of DragonFly BSD pretend to |
| // accept IPV6_V6ONLY=0 successfully, but the state |
| // still stays IPV6_V6ONLY=1. Eventually DragonFly BSD |
| // stops pretending, but the transition period would |
| // cause unpredictable behavior and we need to avoid |
| // it. |
| // |
| // OpenBSD also doesn't support IPV6_V6ONLY=0 but it |
| // never pretends to accept IPV6_V6OLY=0. It always |
| // returns an error and we don't need to probe the |
| // capability. |
| probes = probes[:1] |
| } |
| |
| for i := range probes { |
| s, err := socketFunc(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP) |
| if err != nil { |
| continue |
| } |
| defer 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 |
| } |
| supps[i] = true |
| } |
| |
| return supps[0], supps[1] |
| } |
| |
| // 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, or does not support IPv4, we assume that |
| // the user wants to listen on both IPv4 and IPv6 wildcard |
| // addresses 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 || !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 |
| } |
| |
| // Internet sockets (TCP, UDP, IP) |
| func internetSocket(ctx context.Context, net string, laddr, raddr sockaddr, sotype, proto int, mode string) (fd *netFD, err error) { |
| family, ipv6only := favoriteAddrFamily(net, laddr, raddr, mode) |
| return socket(ctx, net, family, sotype, proto, ipv6only, laddr, raddr) |
| } |
| |
| 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 |
| } |
| ip4 := ip.To4() |
| if ip4 == nil { |
| return nil, &AddrError{Err: "non-IPv4 address", Addr: ip.String()} |
| } |
| sa := &syscall.SockaddrInet4{Port: port} |
| copy(sa.Addr[:], ip4) |
| return sa, nil |
| case syscall.AF_INET6: |
| // 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 an 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 nil, &AddrError{Err: "non-IPv6 address", Addr: ip.String()} |
| } |
| sa := &syscall.SockaddrInet6{Port: port, ZoneId: uint32(zoneToInt(zone))} |
| copy(sa.Addr[:], ip6) |
| return sa, nil |
| } |
| return nil, &AddrError{Err: "invalid address family", Addr: ip.String()} |
| } |
