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proxy: add an initial length to the marshalled frames

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Since the header is variable length it's useful to write a length
field first, so the peer can read the rest of the packet as a block.

Signed-off-by: David Scott <dave.scott@docker.com>
This commit is contained in:
David Scott 2016-04-22 11:42:24 +01:00
parent 03ea441933
commit caeb0d53cc
1 changed files with 20 additions and 6 deletions
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26
alpine/packages/proxy/libproxy/udp_encapsulation.go
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@ -91,30 +91,40 @@ type udpDatagram struct {
}
func (u *udpDatagram) Marshal(conn net.Conn) error {
// marshal the variable length header to a temporary buffer
var header bytes.Buffer
var length uint16
length = uint16(len(*u.IP))
if err := binary.Write(conn, binary.LittleEndian, &length); err != nil {
if err := binary.Write(&header, binary.LittleEndian, &length); err != nil {
return err
}
if err := binary.Write(conn, binary.LittleEndian, &u.IP); err != nil {
if err := binary.Write(&header, binary.LittleEndian, &u.IP); err != nil {
return err
}
if err := binary.Write(conn, binary.LittleEndian, &u.Port); err != nil {
if err := binary.Write(&header, binary.LittleEndian, &u.Port); err != nil {
return err
}
length = uint16(len(u.Zone))
if err := binary.Write(conn, binary.LittleEndian, &length); err != nil {
if err := binary.Write(&header, binary.LittleEndian, &length); err != nil {
return err
}
if err := binary.Write(conn, binary.LittleEndian, &u.Zone); err != nil {
if err := binary.Write(&header, binary.LittleEndian, &u.Zone); err != nil {
return nil
}
length = uint16(len(u.payload))
if err := binary.Write(&header, binary.LittleEndian, &length); err != nil {
return nil
}
length = uint16(header.Len() + len(u.payload))
if err := binary.Write(conn, binary.LittleEndian, &length); err != nil {
return nil
}
_, err := io.Copy(conn, &header)
if err != nil {
return err
}
payload := bytes.NewBuffer(u.payload)
_, err := io.Copy(conn, payload)
_, err = io.Copy(conn, payload)
if err != nil {
return err
}
@ -123,6 +133,10 @@ func (u *udpDatagram) Marshal(conn net.Conn) error {
func (u *udpDatagram) Unmarshal(conn net.Conn) error {
var length uint16
// frame length
if err := binary.Read(conn, binary.LittleEndian, &length); err != nil {
return err
}
if err := binary.Read(conn, binary.LittleEndian, &length); err != nil {
return err
}