server: use Dialer Control method instead of hack to modify connection before dialing

Use the feature of go 1.11 to remove the hack.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 46 insertions, 170 deletions

diff --git a/pkg/server/sockopt_linux.go b/pkg/server/sockopt_linux.go
index ac2ecdb2..31df8397 100644
--- a/pkg/server/sockopt_linux.go
+++ b/pkg/server/sockopt_linux.go
@@ -17,7 +17,6 @@
 package server
 
 import (
-	"fmt"
 	"net"
 	"os"
 	"syscall"
@@ -40,7 +39,7 @@ type tcpmd5sig struct {
 	key [80]byte
 }
 
-func buildTcpMD5Sig(address string, key string) (tcpmd5sig, error) {
+func buildTcpMD5Sig(address, key string) (tcpmd5sig, error) {
 	t := tcpmd5sig{}
 	addr := net.ParseIP(address)
 	if addr.To4() != nil {
@@ -104,186 +103,63 @@ func setTCPMinTTLSockopt(conn *net.TCPConn, ttl int) error {
 	return setsockOptInt(sc, level, name, ttl)
 }
 
-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, tcpMD5SIG, string(b[:])))
-}
-
-func setsockoptIpTtl2(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 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 = ipv6MinHopCount
-	}
-	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd, level, name, value))
-}
-
-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 {
+func dialerControl(network, address string, c syscall.RawConn, ttl, minTtl uint8, password string) error {
+	family := syscall.AF_INET
+	raddr, _ := net.ResolveTCPAddr("tcp", address)
+	if raddr.IP.To4() == nil {
 		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
+	var sockerr error
+	if password != "" {
+		addr, _, _ := net.SplitHostPort(address)
+		t, err := buildTcpMD5Sig(addr, password)
+		if err != nil {
+			return err
 		}
-	}
-
-	if d.TTL != 0 {
-		if err = setsockoptIpTtl2(fd, family, int(d.TTL)); err != nil {
-			return nil, err
+		b := *(*[unsafe.Sizeof(t)]byte)(unsafe.Pointer(&t))
+		if err := c.Control(func(fd uintptr) {
+			sockerr = os.NewSyscallError("setsockopt", syscall.SetsockoptString(int(fd), syscall.IPPROTO_TCP, tcpMD5SIG, string(b[:])))
+		}); err != nil {
+			return err
 		}
-	}
-
-	if d.TTLMin != 0 {
-		if err = setsockoptIpMinTtl(fd, family, int(d.TTL)); err != nil {
-			return nil, err
+		if sockerr != nil {
+			return sockerr
 		}
 	}
 
-	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
+	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
 		}
 	}
 
-	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)
+	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
 			}
-		} else {
-			return nil, fmt.Errorf("unexpected epoll behavior")
+			sockerr = os.NewSyscallError("setsockopt", syscall.SetsockoptInt(int(fd), level, name, int(minTtl)))
+		}); err != nil {
+			return err
+		}
+		if sockerr != nil {
+			return sockerr
 		}
 	}
+	return nil
 }