1 files changed, 282 insertions, 0 deletions
diff --git a/pkg/server/sockopt_linux.go b/pkg/server/sockopt_linux.go
new file mode 100644
index 00000000..9fe02ba5
--- /dev/null
+++ b/pkg/server/sockopt_linux.go
@@ -0,0 +1,282 @@
+// 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")
+		}
+	}
+}