1 files changed, 177 insertions, 0 deletions
diff --git a/src/net/ipsock_posix.go b/src/net/ipsock_posix.go
new file mode 100644
index 000000000..f9ebe40a2
--- /dev/null
+++ b/src/net/ipsock_posix.go
@@ -0,0 +1,177 @@
+// 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")
+}