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// 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 GO_LICENSE file.
package sctp
import (
"net"
"os"
"sync"
"syscall"
)
//from https://github.com/golang/go
// Boolean to int.
func boolint(b bool) int {
if b {
return 1
}
return 0
}
//from https://github.com/golang/go
func ipToSockaddr(family int, ip net.IP, port int, zone string) (syscall.Sockaddr, error) {
switch family {
case syscall.AF_INET:
if len(ip) == 0 {
ip = net.IPv4zero
}
ip4 := ip.To4()
if ip4 == nil {
return nil, &net.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(net.IPv4zero) {
ip = net.IPv6zero
}
// We accept any IPv6 address including IPv4-mapped
// IPv6 address.
ip6 := ip.To16()
if ip6 == nil {
return nil, &net.AddrError{Err: "non-IPv6 address", Addr: ip.String()}
}
//we set ZoneId to 0, as currently we use this functon only to probe the IP capabilities of the host
//if real Zone handling is required, the zone cache implementation in golang/net should be pulled here
sa := &syscall.SockaddrInet6{Port: port, ZoneId: 0}
copy(sa.Addr[:], ip6)
return sa, nil
}
return nil, &net.AddrError{Err: "invalid address family", Addr: ip.String()}
}
//from https://github.com/golang/go
func sockaddr(a *net.TCPAddr, family int) (syscall.Sockaddr, error) {
if a == nil {
return nil, nil
}
return ipToSockaddr(family, a.IP, a.Port, a.Zone)
}
//from https://github.com/golang/go
type ipStackCapabilities struct {
sync.Once // guards following
ipv4Enabled bool
ipv6Enabled bool
ipv4MappedIPv6Enabled bool
}
//from https://github.com/golang/go
var ipStackCaps ipStackCapabilities
//from https://github.com/golang/go
// supportsIPv4 reports whether the platform supports IPv4 networking
// functionality.
func supportsIPv4() bool {
ipStackCaps.Once.Do(ipStackCaps.probe)
return ipStackCaps.ipv4Enabled
}
//from https://github.com/golang/go
// supportsIPv6 reports whether the platform supports IPv6 networking
// functionality.
func supportsIPv6() bool {
ipStackCaps.Once.Do(ipStackCaps.probe)
return ipStackCaps.ipv6Enabled
}
//from https://github.com/golang/go
// supportsIPv4map reports whether the platform supports mapping an
// IPv4 address inside an IPv6 address at transport layer
// protocols. See RFC 4291, RFC 4038 and RFC 3493.
func supportsIPv4map() bool {
ipStackCaps.Once.Do(ipStackCaps.probe)
return ipStackCaps.ipv4MappedIPv6Enabled
}
//from https://github.com/golang/go
// 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 (p *ipStackCapabilities) probe() {
s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
switch err {
case syscall.EAFNOSUPPORT, syscall.EPROTONOSUPPORT:
case nil:
syscall.Close(s)
p.ipv4Enabled = true
}
var probes = []struct {
laddr net.TCPAddr
value int
}{
// IPv6 communication capability
{laddr: net.TCPAddr{IP: net.IPv6loopback}, value: 1},
// IPv4-mapped IPv6 address communication capability
{laddr: net.TCPAddr{IP: net.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 syscall.Close(s)
syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, probes[i].value)
sa, err := sockaddr(&(probes[i].laddr), 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
}
}
}
//from https://github.com/golang/go
//Change: we check the first IP address in the list of candidate SCTP IP addresses
func (a *SCTPAddr) isWildcard() bool {
if a == nil {
return true
}
if 0 == len(a.IPAddrs) {
return true
}
return a.IPAddrs[0].IP.IsUnspecified()
}
func (a *SCTPAddr) family() int {
if a != nil {
for _, ip := range a.IPAddrs {
if ip.IP.To4() == nil {
return syscall.AF_INET6
}
}
}
return syscall.AF_INET
}
//from https://github.com/golang/go
func favoriteAddrFamily(network string, laddr *SCTPAddr, raddr *SCTPAddr, 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
}
//from https://github.com/golang/go
//Changes: it is for SCTP only
func setDefaultSockopts(s int, family int, ipv6only bool) error {
if family == syscall.AF_INET6 {
// Allow both IP versions even if the OS default
// is otherwise. Note that some operating systems
// never admit this option.
syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, boolint(ipv6only))
}
// Allow broadcast.
return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1))
}
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