Definition of platform specific socket bind

src/conn.go

@@ -56,7 +56,7 @@ func updateUDPConn(device *Device) error {
 
 		// set fwmark
 
-		err = setMark(netc.conn, netc.fwmark)
+		err = SetMark(netc.conn, netc.fwmark)
 		if err != nil {
 			return err
 		}

src/conn_default.go

@@ -6,6 +6,6 @@ import (
 	"net"
 )
 
-func setMark(conn *net.UDPConn, value uint32) error {
+func SetMark(conn *net.UDPConn, value uint32) error {
 	return nil
 }

src/conn_linux.go

@@ -14,23 +14,30 @@ import (
 	"unsafe"
 )
 
+import "fmt"
+
 /* Supports source address caching
- *
- * It is important that the endpoint is only updated after the packet content has been authenticated.
  *
  * Currently there is no way to achieve this within the net package:
  * See e.g. https://github.com/golang/go/issues/17930
+ * So this code is platform dependent.
+ *
+ * It is important that the endpoint is only updated after the packet content has been authenticated!
  */
+
 type Endpoint struct {
 	// source (selected based on dst type)
 	// (could use RawSockaddrAny and unsafe)
-	srcIPv6 unix.RawSockaddrInet6
-	srcIPv4 unix.RawSockaddrInet4
-	srcIf4  int32
+	src6   unix.RawSockaddrInet6
+	src4   unix.RawSockaddrInet4
+	src4if int32
 
 	dst unix.RawSockaddrAny
 }
 
+type IPv4Socket int
+type IPv6Socket int
+
 func zoneToUint32(zone string) (uint32, error) {
 	if zone == "" {
 		return 0, nil
@@ -42,10 +49,115 @@ func zoneToUint32(zone string) (uint32, error) {
 	return uint32(n), err
 }
 
+func CreateIPv4Socket(port int) (IPv4Socket, error) {
+
+	// create socket
+
+	fd, err := unix.Socket(
+		unix.AF_INET,
+		unix.SOCK_DGRAM,
+		0,
+	)
+
+	if err != nil {
+		return -1, err
+	}
+
+	// set sockopts and bind
+
+	if err := func() error {
+
+		if err := unix.SetsockoptInt(
+			fd,
+			unix.SOL_SOCKET,
+			unix.SO_REUSEADDR,
+			1,
+		); err != nil {
+			return err
+		}
+
+		if err := unix.SetsockoptInt(
+			fd,
+			unix.IPPROTO_IP,
+			unix.IP_PKTINFO,
+			1,
+		); err != nil {
+			return err
+		}
+
+		addr := unix.SockaddrInet4{
+			Port: port,
+		}
+		return unix.Bind(fd, &addr)
+
+	}(); err != nil {
+		unix.Close(fd)
+	}
+
+	return IPv4Socket(fd), err
+}
+
+func CreateIPv6Socket(port int) (IPv6Socket, error) {
+
+	// create socket
+
+	fd, err := unix.Socket(
+		unix.AF_INET,
+		unix.SOCK_DGRAM,
+		0,
+	)
+
+	if err != nil {
+		return -1, err
+	}
+
+	// set sockopts and bind
+
+	if err := func() error {
+
+		if err := unix.SetsockoptInt(
+			fd,
+			unix.SOL_SOCKET,
+			unix.SO_REUSEADDR,
+			1,
+		); err != nil {
+			return err
+		}
+
+		if err := unix.SetsockoptInt(
+			fd,
+			unix.IPPROTO_IPV6,
+			unix.IPV6_RECVPKTINFO,
+			1,
+		); err != nil {
+			return err
+		}
+
+		if err := unix.SetsockoptInt(
+			fd,
+			unix.IPPROTO_IPV6,
+			unix.IPV6_V6ONLY,
+			1,
+		); err != nil {
+			return err
+		}
+
+		addr := unix.SockaddrInet6{
+			Port: port,
+		}
+		return unix.Bind(fd, &addr)
+
+	}(); err != nil {
+		unix.Close(fd)
+	}
+
+	return IPv6Socket(fd), err
+}
+
 func (end *Endpoint) ClearSrc() {
-	end.srcIf4 = 0
-	end.srcIPv4 = unix.RawSockaddrInet4{}
-	end.srcIPv6 = unix.RawSockaddrInet6{}
+	end.src4if = 0
+	end.src4 = unix.RawSockaddrInet4{}
+	end.src6 = unix.RawSockaddrInet6{}
 }
 
 func (end *Endpoint) Set(s string) error {
@@ -85,8 +197,10 @@ func (end *Endpoint) Set(s string) error {
 }
 
 func send6(sock uintptr, end *Endpoint, buff []byte) error {
-	var iovec unix.Iovec
 
+	// construct message header
+
+	var iovec unix.Iovec
 	iovec.Base = (*byte)(unsafe.Pointer(&buff[0]))
 	iovec.SetLen(len(buff))
 
@@ -100,8 +214,8 @@ func send6(sock uintptr, end *Endpoint, buff []byte) error {
 			Len:   unix.SizeofInet6Pktinfo,
 		},
 		unix.Inet6Pktinfo{
-			Addr:    end.srcIPv6.Addr,
-			Ifindex: end.srcIPv6.Scope_id,
+			Addr:    end.src6.Addr,
+			Ifindex: end.src6.Scope_id,
 		},
 	}
 
@@ -130,8 +244,10 @@ func send6(sock uintptr, end *Endpoint, buff []byte) error {
 }
 
 func send4(sock uintptr, end *Endpoint, buff []byte) error {
-	var iovec unix.Iovec
 
+	// construct message header
+
+	var iovec unix.Iovec
 	iovec.Base = (*byte)(unsafe.Pointer(&buff[0]))
 	iovec.SetLen(len(buff))
 
@@ -142,11 +258,11 @@ func send4(sock uintptr, end *Endpoint, buff []byte) error {
 		unix.Cmsghdr{
 			Level: unix.IPPROTO_IP,
 			Type:  unix.IP_PKTINFO,
-			Len:   unix.SizeofInet6Pktinfo,
+			Len:   unix.SizeofInet4Pktinfo,
 		},
 		unix.Inet4Pktinfo{
-			Spec_dst: end.srcIPv4.Addr,
-			Ifindex:  end.srcIf4,
+			Spec_dst: end.src4.Addr,
+			Ifindex:  end.src4if,
 		},
 	}
 
@@ -174,7 +290,7 @@ func send4(sock uintptr, end *Endpoint, buff []byte) error {
 	return errno
 }
 
-func send(c *net.UDPConn, end *Endpoint, buff []byte) error {
+func (end *Endpoint) Send(c *net.UDPConn, buff []byte) error {
 
 	// extract underlying file descriptor
 
@@ -195,12 +311,9 @@ func send(c *net.UDPConn, end *Endpoint, buff []byte) error {
 	return errors.New("Unknown address family of source")
 }
 
-func receiveIPv4(end *Endpoint, c *net.UDPConn, buff []byte) (error, *net.UDPAddr, *net.UDPAddr) {
+func (end *Endpoint) ReceiveIPv4(sock IPv4Socket, buff []byte) (int, error) {
 
-	file, err := c.File()
-	if err != nil {
-		return err, nil, nil
-	}
+	// contruct message header
 
 	var iovec unix.Iovec
 	iovec.Base = (*byte)(unsafe.Pointer(&buff[0]))
@@ -208,47 +321,92 @@ func receiveIPv4(end *Endpoint, c *net.UDPConn, buff []byte) (error, *net.UDPAdd
 
 	var cmsg struct {
 		cmsghdr unix.Cmsghdr
-		pktinfo unix.Inet6Pktinfo // big enough
+		pktinfo unix.Inet4Pktinfo
+	}
+
+	var msghdr unix.Msghdr
+	msghdr.Iov = &iovec
+	msghdr.Iovlen = 1
+	msghdr.Name = (*byte)(unsafe.Pointer(&end.dst))
+	msghdr.Namelen = unix.SizeofSockaddrInet4
+	msghdr.Control = (*byte)(unsafe.Pointer(&cmsg))
+	msghdr.SetControllen(int(unsafe.Sizeof(cmsg)))
+
+	// recvmsg(sock, &mskhdr, 0)
+
+	size, _, errno := unix.Syscall(
+		unix.SYS_RECVMSG,
+		uintptr(sock),
+		uintptr(unsafe.Pointer(&msghdr)),
+		0,
+	)
+
+	if errno != 0 {
+		return 0, errno
+	}
+
+	fmt.Println(msghdr)
+	fmt.Println(cmsg)
+
+	// update source cache
+
+	if cmsg.cmsghdr.Level == unix.IPPROTO_IP &&
+		cmsg.cmsghdr.Type == unix.IP_PKTINFO &&
+		cmsg.cmsghdr.Len >= unix.SizeofInet4Pktinfo {
+		end.src4.Addr = cmsg.pktinfo.Spec_dst
+		end.src4if = cmsg.pktinfo.Ifindex
+	}
+
+	return int(size), nil
+}
+
+func (end *Endpoint) ReceiveIPv6(sock IPv6Socket, buff []byte) error {
+
+	// contruct message header
+
+	var iovec unix.Iovec
+	iovec.Base = (*byte)(unsafe.Pointer(&buff[0]))
+	iovec.SetLen(len(buff))
+
+	var cmsg struct {
+		cmsghdr unix.Cmsghdr
+		pktinfo unix.Inet6Pktinfo
 	}
 
 	var msg unix.Msghdr
 	msg.Iov = &iovec
 	msg.Iovlen = 1
 	msg.Name = (*byte)(unsafe.Pointer(&end.dst))
-	msg.Namelen = uint32(unix.SizeofSockaddrAny)
+	msg.Namelen = uint32(unix.SizeofSockaddrInet6)
 	msg.Control = (*byte)(unsafe.Pointer(&cmsg))
 	msg.SetControllen(int(unsafe.Sizeof(cmsg)))
 
+	// recvmsg(sock, &mskhdr, 0)
+
 	_, _, errno := unix.Syscall(
 		unix.SYS_RECVMSG,
-		file.Fd(),
+		uintptr(sock),
 		uintptr(unsafe.Pointer(&msg)),
 		0,
 	)
 
 	if errno != 0 {
-		return errno, nil, nil
+		return errno
 	}
 
+	// update source cache
+
 	if cmsg.cmsghdr.Level == unix.IPPROTO_IPV6 &&
 		cmsg.cmsghdr.Type == unix.IPV6_PKTINFO &&
 		cmsg.cmsghdr.Len >= unix.SizeofInet6Pktinfo {
-
+		end.src6.Addr = cmsg.pktinfo.Addr
+		end.src6.Scope_id = cmsg.pktinfo.Ifindex
 	}
 
-	if cmsg.cmsghdr.Level == unix.IPPROTO_IP &&
-		cmsg.cmsghdr.Type == unix.IP_PKTINFO &&
-		cmsg.cmsghdr.Len >= unix.SizeofInet4Pktinfo {
-
-		info := (*unix.Inet4Pktinfo)(unsafe.Pointer(&cmsg.pktinfo))
-		println(info)
-
+	return nil
 }
 
-	return nil, nil, nil
-}
-
-func setMark(conn *net.UDPConn, value uint32) error {
+func SetMark(conn *net.UDPConn, value uint32) error {
 	if conn == nil {
 		return nil
 	}

src/uapi.go

@@ -166,7 +166,7 @@ func ipcSetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 				device.net.mutex.Lock()
 				if fwmark > 0 || device.net.fwmark > 0 {
 					device.net.fwmark = uint32(fwmark)
-					err := setMark(
+					err := SetMark(
 						device.net.conn,
 						device.net.fwmark,
 					)