// 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 aix darwin dragonfly freebsd js,wasm linux netbsd openbsd solaris windows

package net

import (
	
	
	
	
)

// 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-mapeed 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 ( *ipStackCapabilities) () {
	,  := sysSocket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
	switch  {
	case syscall.EAFNOSUPPORT, syscall.EPROTONOSUPPORT:
	case nil:
		poll.CloseFunc()
		.ipv4Enabled = true
	}
	var  = []struct {
		 TCPAddr
		 int
	}{
		// IPv6 communication capability
		{: TCPAddr{IP: ParseIP("::1")}, : 1},
		// IPv4-mapped IPv6 address communication capability
		{: TCPAddr{IP: IPv4(127, 0, 0, 1)}, : 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.
		 = [:1]
	}
	for  := range  {
		,  := sysSocket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
		if  != nil {
			continue
		}
		defer poll.CloseFunc()
		syscall.SetsockoptInt(, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, [].)
		,  := []..sockaddr(syscall.AF_INET6)
		if  != nil {
			continue
		}
		if  := syscall.Bind(, );  != nil {
			continue
		}
		if  == 0 {
			.ipv6Enabled = true
		} else {
			.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( string, ,  sockaddr,  string) ( int,  bool) {
	switch [len()-1] {
	case '4':
		return syscall.AF_INET, false
	case '6':
		return syscall.AF_INET6, true
	}

	if  == "listen" && ( == nil || .isWildcard()) {
		if supportsIPv4map() || !supportsIPv4() {
			return syscall.AF_INET6, false
		}
		if  == nil {
			return syscall.AF_INET, false
		}
		return .family(), false
	}

	if ( == nil || .family() == syscall.AF_INET) &&
		( == nil || .family() == syscall.AF_INET) {
		return syscall.AF_INET, false
	}
	return syscall.AF_INET6, false
}

func internetSocket( context.Context,  string, ,  sockaddr, ,  int,  string,  func(string, string, syscall.RawConn) error) ( *netFD,  error) {
	if (runtime.GOOS == "aix" || runtime.GOOS == "windows" || runtime.GOOS == "openbsd") &&  == "dial" && .isWildcard() {
		 = .toLocal()
	}
	,  := favoriteAddrFamily(, , , )
	return socket(, , , , , , , , )
}

func ipToSockaddr( int,  IP,  int,  string) (syscall.Sockaddr, error) {
	switch  {
	case syscall.AF_INET:
		if len() == 0 {
			 = IPv4zero
		}
		 := .To4()
		if  == nil {
			return nil, &AddrError{Err: "non-IPv4 address", Addr: .String()}
		}
		 := &syscall.SockaddrInet4{Port: }
		copy(.Addr[:], )
		return , 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 a listener to listen to the wildcard
		// address of both IP addressing spaces by specifying
		// IPv6 wildcard address.
		if len() == 0 || .Equal(IPv4zero) {
			 = IPv6zero
		}
		// We accept any IPv6 address including IPv4-mapped
		// IPv6 address.
		 := .To16()
		if  == nil {
			return nil, &AddrError{Err: "non-IPv6 address", Addr: .String()}
		}
		 := &syscall.SockaddrInet6{Port: , ZoneId: uint32(zoneCache.index())}
		copy(.Addr[:], )
		return , nil
	}
	return nil, &AddrError{Err: "invalid address family", Addr: .String()}
}