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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"
"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
// padding the struct
_ uint16
keylen uint16
// padding the struct
_ 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 setsockoptTcpMD5Sig(fd int, address string, key string) error {
t, err := buildTcpMD5Sig(address, key)
if err != nil {
return err
}
b := *(*[unsafe.Sizeof(t)]byte)(unsafe.Pointer(&t))
return os.NewSyscallError("setsockopt", syscall.SetsockoptString(fd, syscall.IPPROTO_TCP, TCP_MD5SIG, string(b[:])))
}
func SetTcpMD5SigSockopt(l *net.TCPListener, address string, key string) error {
fi, _, err := extractFileAndFamilyFromTCPListener(l)
if err != nil {
return err
}
defer fi.Close()
return setsockoptTcpMD5Sig(int(fi.Fd()), address, key)
}
func setsockoptIpTtl(fd int, family int, value int) error {
level := syscall.IPPROTO_IP
name := syscall.IP_TTL
if family == syscall.AF_INET6 {
level = syscall.IPPROTO_IPV6
name = syscall.IPV6_UNICAST_HOPS
}
return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd, level, name, value))
}
func SetListenTcpTTLSockopt(l *net.TCPListener, ttl int) error {
fi, family, err := extractFileAndFamilyFromTCPListener(l)
if err != nil {
return err
}
defer fi.Close()
return setsockoptIpTtl(int(fi.Fd()), family, ttl)
}
func SetTcpTTLSockopt(conn *net.TCPConn, ttl int) error {
fi, family, err := extractFileAndFamilyFromTCPConn(conn)
if err != nil {
return err
}
defer fi.Close()
return setsockoptIpTtl(int(fi.Fd()), family, ttl)
}
func setsockoptIpMinTtl(fd int, family int, value int) error {
level := syscall.IPPROTO_IP
name := syscall.IP_MINTTL
if family == syscall.AF_INET6 {
level = syscall.IPPROTO_IPV6
name = IPV6_MINHOPCOUNT
}
return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd, level, name, value))
}
func SetTcpMinTTLSockopt(conn *net.TCPConn, ttl int) error {
fi, family, err := extractFileAndFamilyFromTCPConn(conn)
if err != nil {
return err
}
defer fi.Close()
return setsockoptIpMinTtl(int(fi.Fd()), family, ttl)
}
type TCPDialer struct {
net.Dialer
// MD5 authentication password.
AuthPassword string
// The TTL value to set outgoing connection.
Ttl uint8
// The minimum TTL value for incoming packets.
TtlMin uint8
}
func (d *TCPDialer) DialTCP(addr string, port int) (*net.TCPConn, error) {
var family int
var ra, la syscall.Sockaddr
raddr, err := net.ResolveTCPAddr("tcp", net.JoinHostPort(addr, fmt.Sprintf("%d", port)))
if err != nil {
return nil, fmt.Errorf("invalid remote address: %s", err)
}
laddr, err := net.ResolveTCPAddr("tcp", d.LocalAddr.String())
if err != nil {
return nil, fmt.Errorf("invalid local address: %s", err)
}
if raddr.IP.To4() != nil {
family = syscall.AF_INET
rsockaddr := &syscall.SockaddrInet4{Port: port}
copy(rsockaddr.Addr[:], raddr.IP.To4())
ra = rsockaddr
lsockaddr := &syscall.SockaddrInet4{}
copy(lsockaddr.Addr[:], laddr.IP.To4())
la = lsockaddr
} else {
family = syscall.AF_INET6
rsockaddr := &syscall.SockaddrInet6{Port: port}
copy(rsockaddr.Addr[:], raddr.IP.To16())
ra = rsockaddr
var zone uint32
if laddr.Zone != "" {
if intf, err := net.InterfaceByName(laddr.Zone); err != nil {
return nil, err
} else {
zone = uint32(intf.Index)
}
}
lsockaddr := &syscall.SockaddrInet6{ZoneId: zone}
copy(lsockaddr.Addr[:], laddr.IP.To16())
la = lsockaddr
}
sockType := syscall.SOCK_STREAM | syscall.SOCK_CLOEXEC | syscall.SOCK_NONBLOCK
proto := 0
fd, err := syscall.Socket(family, sockType, proto)
if err != nil {
return nil, err
}
fi := os.NewFile(uintptr(fd), "")
defer fi.Close()
// A new socket was created so we must close it before this
// function returns either on failure or success. On success,
// net.FileConn() in newTCPConn() increases the refcount of
// the socket so this fi.Close() doesn't destroy the socket.
// The caller must call Close() with the file later.
// Note that the above os.NewFile() doesn't play with the
// refcount.
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 d.AuthPassword != "" {
if err = setsockoptTcpMD5Sig(fd, addr, d.AuthPassword); err != nil {
return nil, err
}
}
if d.Ttl != 0 {
if err = setsockoptIpTtl(fd, family, int(d.Ttl)); err != nil {
return nil, err
}
}
if d.TtlMin != 0 {
if err = setsockoptIpMinTtl(fd, family, int(d.Ttl)); err != nil {
return nil, err
}
}
if err = syscall.Bind(fd, la); err != nil {
return nil, os.NewSyscallError("bind", err)
}
newTCPConn := func(fi *os.File) (*net.TCPConn, error) {
if conn, err := net.FileConn(fi); err != nil {
return nil, err
} else {
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 newTCPConn(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, int(d.Timeout/1000000) /*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 newTCPConn(fi)
default:
return nil, os.NewSyscallError("getsockopt", err)
}
} else {
return nil, fmt.Errorf("unexpected epoll behavior")
}
}
}
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