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// Copyright (C) 2016 Nippon Telegraph and Telephone Corporation.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build linux
package server
import (
"fmt"
"net"
"os"
"strings"
"syscall"
"unsafe"
)
const (
TCP_MD5SIG = 14 // TCP MD5 Signature (RFC2385)
IPV6_MINHOPCOUNT = 73 // Generalized TTL Security Mechanism (RFC5082)
)
type tcpmd5sig struct {
ss_family uint16
ss [126]byte
pad1 uint16
keylen uint16
pad2 uint32
key [80]byte
}
func buildTcpMD5Sig(address string, key string) (tcpmd5sig, error) {
t := tcpmd5sig{}
addr := net.ParseIP(address)
if addr.To4() != nil {
t.ss_family = syscall.AF_INET
copy(t.ss[2:], addr.To4())
} else {
t.ss_family = syscall.AF_INET6
copy(t.ss[6:], addr.To16())
}
t.keylen = uint16(len(key))
copy(t.key[0:], []byte(key))
return t, nil
}
func SetTcpMD5SigSockopts(l *net.TCPListener, address string, key string) error {
t, _ := buildTcpMD5Sig(address, key)
fi, err := l.File()
defer fi.Close()
if err != nil {
return err
}
if l, err := net.FileListener(fi); err == nil {
defer l.Close()
}
b := *(*[unsafe.Sizeof(t)]byte)(unsafe.Pointer(&t))
if err := syscall.SetsockoptString(int(fi.Fd()),
syscall.IPPROTO_TCP, TCP_MD5SIG,
string(b[:])); err != nil {
return err
}
return nil
}
func setTcpSockoptInt(conn *net.TCPConn, level int, name int, value int) error {
fi, err := conn.File()
defer fi.Close()
if err != nil {
return err
}
if conn, err := net.FileConn(fi); err == nil {
defer conn.Close()
}
return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(int(fi.Fd()), level, name, value))
}
func SetTcpTTLSockopts(conn *net.TCPConn, ttl int) error {
level := syscall.IPPROTO_IP
name := syscall.IP_TTL
if strings.Contains(conn.RemoteAddr().String(), "[") {
level = syscall.IPPROTO_IPV6
name = syscall.IPV6_UNICAST_HOPS
}
return setTcpSockoptInt(conn, level, name, ttl)
}
func SetTcpMinTTLSockopts(conn *net.TCPConn, ttl int) error {
level := syscall.IPPROTO_IP
name := syscall.IP_MINTTL
if strings.Contains(conn.RemoteAddr().String(), "[") {
level = syscall.IPPROTO_IPV6
name = IPV6_MINHOPCOUNT
}
return setTcpSockoptInt(conn, level, name, ttl)
}
func DialTCPTimeoutWithMD5Sig(host string, port int, localAddr, key string, msec int) (*net.TCPConn, error) {
var family int
var ra, la syscall.Sockaddr
ip, err := net.ResolveIPAddr("ip", host)
if err != nil {
return nil, fmt.Errorf("invalid ip: %s", err)
}
l, err := net.ResolveIPAddr("ip", localAddr)
if l == nil {
return nil, fmt.Errorf("invalid local ip: %s", err)
}
if (ip.IP.To4() != nil) != (l.IP.To4() != nil) {
return nil, fmt.Errorf("remote and local ip address family is not same")
}
switch {
case ip.IP.To4() != nil:
family = syscall.AF_INET
i := &syscall.SockaddrInet4{
Port: port,
}
for idx, _ := range i.Addr {
i.Addr[idx] = ip.IP.To4()[idx]
}
ra = i
j := &syscall.SockaddrInet4{}
for idx, _ := range j.Addr {
j.Addr[idx] = l.IP.To4()[idx]
}
la = j
default:
family = syscall.AF_INET6
i := &syscall.SockaddrInet6{
Port: port,
}
for idx, _ := range i.Addr {
i.Addr[idx] = ip.IP[idx]
}
ra = i
var zone uint32
if l.Zone != "" {
intf, err := net.InterfaceByName(l.Zone)
if err != nil {
return nil, err
}
zone = uint32(intf.Index)
}
j := &syscall.SockaddrInet6{
ZoneId: zone,
}
for idx, _ := range j.Addr {
j.Addr[idx] = l.IP[idx]
}
la = j
}
sotype := syscall.SOCK_STREAM | syscall.SOCK_CLOEXEC | syscall.SOCK_NONBLOCK
proto := 0
fd, err := syscall.Socket(family, sotype, proto)
if err != nil {
return nil, err
}
fi := os.NewFile(uintptr(fd), "")
defer fi.Close()
t, err := buildTcpMD5Sig(host, key)
if err != nil {
return nil, err
}
b := *(*[unsafe.Sizeof(t)]byte)(unsafe.Pointer(&t))
if err := syscall.SetsockoptString(int(fi.Fd()),
syscall.IPPROTO_TCP, TCP_MD5SIG,
string(b[:])); err != nil {
return nil, os.NewSyscallError("setsockopt", err)
}
if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1); err != nil {
return nil, os.NewSyscallError("setsockopt", err)
}
if err = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_NODELAY, 1); err != nil {
return nil, os.NewSyscallError("setsockopt", err)
}
if err = syscall.Bind(fd, la); err != nil {
return nil, os.NewSyscallError("bind", err)
}
tcpconn := func(fi *os.File) (*net.TCPConn, error) {
conn, err := net.FileConn(fi)
return conn.(*net.TCPConn), err
}
err = syscall.Connect(fd, ra)
switch err {
case syscall.EINPROGRESS, syscall.EALREADY, syscall.EINTR:
// do timeout handling
case nil, syscall.EISCONN:
return tcpconn(fi)
default:
return nil, os.NewSyscallError("connect", err)
}
epfd, e := syscall.EpollCreate1(syscall.EPOLL_CLOEXEC)
if e != nil {
return nil, e
}
defer syscall.Close(epfd)
var event syscall.EpollEvent
events := make([]syscall.EpollEvent, 1)
event.Events = syscall.EPOLLIN | syscall.EPOLLOUT | syscall.EPOLLPRI
event.Fd = int32(fd)
if e = syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, fd, &event); e != nil {
return nil, e
}
for {
nevents, e := syscall.EpollWait(epfd, events, msec)
if e != nil {
return nil, e
}
if nevents == 0 {
return nil, fmt.Errorf("timeout")
} else if nevents == 1 && events[0].Fd == int32(fd) {
nerr, err := syscall.GetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_ERROR)
if err != nil {
return nil, os.NewSyscallError("getsockopt", err)
}
switch err := syscall.Errno(nerr); err {
case syscall.EINPROGRESS, syscall.EALREADY, syscall.EINTR:
case syscall.Errno(0), syscall.EISCONN:
return tcpconn(fi)
default:
return nil, os.NewSyscallError("getsockopt", err)
}
} else {
return nil, fmt.Errorf("unexpected epoll behavior")
}
}
}
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