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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.
//go:build linux
// +build linux
package server
import (
"fmt"
"net"
"os"
"strings"
"syscall"
"golang.org/x/sys/unix"
"github.com/osrg/gobgp/v3/pkg/log"
)
const (
ipv6MinHopCount = 73 // Generalized TTL Security Mechanism (RFC5082)
)
func buildTcpMD5Sig(address, key string) *unix.TCPMD5Sig {
t := unix.TCPMD5Sig{}
var addr net.IP
if strings.Contains(address, "/") {
var err error
var ipnet *net.IPNet
addr, ipnet, err = net.ParseCIDR(address)
if err != nil {
return nil
}
prefixlen, _ := ipnet.Mask.Size()
t.Prefixlen = uint8(prefixlen)
t.Flags = unix.TCP_MD5SIG_FLAG_PREFIX
} else {
addr = net.ParseIP(address)
}
if addr.To4() != nil {
t.Addr.Family = unix.AF_INET
copy(t.Addr.Data[2:], addr.To4())
} else {
t.Addr.Family = unix.AF_INET6
copy(t.Addr.Data[6:], addr.To16())
}
t.Keylen = uint16(len(key))
copy(t.Key[0:], []byte(key))
return &t
}
func setTCPMD5SigSockopt(l *net.TCPListener, address string, key string) error {
sc, err := l.SyscallConn()
if err != nil {
return err
}
var sockerr error
t := buildTcpMD5Sig(address, key)
if t == nil {
return fmt.Errorf("unable to generate TcpMD5Sig from %s", address)
}
if err := sc.Control(func(s uintptr) {
opt := unix.TCP_MD5SIG
if strings.Contains(address, "/") {
opt = unix.TCP_MD5SIG_EXT
}
sockerr = unix.SetsockoptTCPMD5Sig(int(s), unix.IPPROTO_TCP, opt, t)
}); err != nil {
return err
}
return sockerr
}
func setBindToDevSockopt(sc syscall.RawConn, device string) error {
return setsockOptString(sc, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, device)
}
func setTCPTTLSockopt(conn *net.TCPConn, ttl int) error {
family := extractFamilyFromTCPConn(conn)
sc, err := conn.SyscallConn()
if err != nil {
return err
}
return setsockoptIpTtl(sc, family, ttl)
}
func setTCPMinTTLSockopt(conn *net.TCPConn, ttl int) error {
family := extractFamilyFromTCPConn(conn)
sc, err := conn.SyscallConn()
if err != nil {
return err
}
level := syscall.IPPROTO_IP
name := syscall.IP_MINTTL
if family == syscall.AF_INET6 {
level = syscall.IPPROTO_IPV6
name = ipv6MinHopCount
}
return setsockOptInt(sc, level, name, ttl)
}
func setTCPMSSSockopt(conn *net.TCPConn, mss uint16) error {
family := extractFamilyFromTCPConn(conn)
sc, err := conn.SyscallConn()
if err != nil {
return err
}
return setsockoptTcpMss(sc, family, mss)
}
func dialerControl(logger log.Logger, network, address string, c syscall.RawConn, ttl, minTtl uint8, mss uint16, password string, bindInterface string) error {
family := syscall.AF_INET
raddr, _ := net.ResolveTCPAddr("tcp", address)
if raddr.IP.To4() == nil {
family = syscall.AF_INET6
}
var sockerr error
if password != "" {
addr, _, _ := net.SplitHostPort(address)
t := buildTcpMD5Sig(addr, password)
if err := c.Control(func(fd uintptr) {
sockerr = os.NewSyscallError("setsockopt", unix.SetsockoptTCPMD5Sig(int(fd), unix.IPPROTO_TCP, unix.TCP_MD5SIG, t))
}); err != nil {
return err
}
if sockerr != nil {
return sockerr
}
}
if ttl != 0 {
if err := c.Control(func(fd uintptr) {
level := syscall.IPPROTO_IP
name := syscall.IP_TTL
if family == syscall.AF_INET6 {
level = syscall.IPPROTO_IPV6
name = syscall.IPV6_UNICAST_HOPS
}
sockerr = os.NewSyscallError("setsockopt", syscall.SetsockoptInt(int(fd), level, name, int(ttl)))
}); err != nil {
return err
}
if sockerr != nil {
return sockerr
}
}
if minTtl != 0 {
if err := c.Control(func(fd uintptr) {
level := syscall.IPPROTO_IP
name := syscall.IP_MINTTL
if family == syscall.AF_INET6 {
level = syscall.IPPROTO_IPV6
name = ipv6MinHopCount
}
sockerr = os.NewSyscallError("setsockopt", syscall.SetsockoptInt(int(fd), level, name, int(minTtl)))
}); err != nil {
return err
}
if sockerr != nil {
return sockerr
}
}
if mss != 0 {
if err := c.Control(func(fd uintptr) {
level := syscall.IPPROTO_TCP
name := syscall.TCP_MAXSEG
sockerr = os.NewSyscallError("setsockopt", syscall.SetsockoptInt(int(fd), level, name, int(mss)))
}); err != nil {
return err
}
if sockerr != nil {
return sockerr
}
}
if bindInterface != "" {
if err := setBindToDevSockopt(c, bindInterface); err != nil {
return err
}
}
return nil
}
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