373 lines
13 KiB
Go
373 lines
13 KiB
Go
|
package v3
|
||
|
|
|
||
|
|
import (
|
||
|
|
"encoding/binary"
|
||
|
|
"net/netip"
|
||
|
|
"time"
|
||
|
|
)
|
||
|
|
|
||
|
|
type DatagramType byte
|
||
|
|
|
||
|
|
const (
|
||
|
|
// UDP Registration
|
||
|
|
UDPSessionRegistrationType DatagramType = 0x0
|
||
|
|
// UDP Session Payload
|
||
|
|
UDPSessionPayloadType DatagramType = 0x1
|
||
|
|
// DatagramTypeICMP (supporting both ICMPv4 and ICMPv6)
|
||
|
|
ICMPType DatagramType = 0x2
|
||
|
|
// UDP Session Registration Response
|
||
|
|
UDPSessionRegistrationResponseType DatagramType = 0x3
|
||
|
|
)
|
||
|
|
|
||
|
|
const (
|
||
|
|
// Total number of bytes representing the [DatagramType]
|
||
|
|
datagramTypeLen = 1
|
||
|
|
|
||
|
|
// 1280 is the default datagram packet length used before MTU discovery: https://github.com/quic-go/quic-go/blob/v0.45.0/internal/protocol/params.go#L12
|
||
|
|
maxDatagramLen = 1280
|
||
|
|
)
|
||
|
|
|
||
|
|
func parseDatagramType(data []byte) (DatagramType, error) {
|
||
|
|
if len(data) < datagramTypeLen {
|
||
|
|
return 0, ErrDatagramHeaderTooSmall
|
||
|
|
}
|
||
|
|
return DatagramType(data[0]), nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// UDPSessionRegistrationDatagram handles a request to initialize a UDP session on the remote client.
|
||
|
|
type UDPSessionRegistrationDatagram struct {
|
||
|
|
RequestID RequestID
|
||
|
|
Dest netip.AddrPort
|
||
|
|
Traced bool
|
||
|
|
IdleDurationHint time.Duration
|
||
|
|
Payload []byte
|
||
|
|
}
|
||
|
|
|
||
|
|
const (
|
||
|
|
sessionRegistrationFlagsIPMask byte = 0b0000_0001
|
||
|
|
sessionRegistrationFlagsTracedMask byte = 0b0000_0010
|
||
|
|
sessionRegistrationFlagsBundledMask byte = 0b0000_0100
|
||
|
|
|
||
|
|
sessionRegistrationIPv4DatagramHeaderLen = datagramTypeLen +
|
||
|
|
1 + // Flag length
|
||
|
|
2 + // Destination port length
|
||
|
|
2 + // Idle duration seconds length
|
||
|
|
datagramRequestIdLen + // Request ID length
|
||
|
|
4 // IPv4 address length
|
||
|
|
|
||
|
|
// The IPv4 and IPv6 address share space, so adding 12 to the header length gets the space taken by the IPv6 field.
|
||
|
|
sessionRegistrationIPv6DatagramHeaderLen = sessionRegistrationIPv4DatagramHeaderLen + 12
|
||
|
|
)
|
||
|
|
|
||
|
|
// The datagram structure for UDPSessionRegistrationDatagram is:
|
||
|
|
//
|
||
|
|
// 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 0| Type | Flags | Destination Port |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 4| Idle Duration Seconds | |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|
||
|
|
// 8| |
|
||
|
|
// + Session Identifier +
|
||
|
|
// 12| (16 Bytes) |
|
||
|
|
// + +
|
||
|
|
// 16| |
|
||
|
|
// + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 20| | Destination IPv4 Address |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - - - - - - - -+
|
||
|
|
// 24| Destination IPv4 Address cont | |
|
||
|
|
// +- - - - - - - - - - - - - - - - +
|
||
|
|
// 28| Destination IPv6 Address |
|
||
|
|
// + (extension of IPv4 region) +
|
||
|
|
// 32| |
|
||
|
|
// + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 36| | |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|
||
|
|
// . .
|
||
|
|
// . Bundle Payload .
|
||
|
|
// . .
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
|
||
|
|
func (s *UDPSessionRegistrationDatagram) MarshalBinary() (data []byte, err error) {
|
||
|
|
ipv6 := s.Dest.Addr().Is6()
|
||
|
|
var flags byte
|
||
|
|
if s.Traced {
|
||
|
|
flags |= sessionRegistrationFlagsTracedMask
|
||
|
|
}
|
||
|
|
hasPayload := len(s.Payload) > 0
|
||
|
|
if hasPayload {
|
||
|
|
flags |= sessionRegistrationFlagsBundledMask
|
||
|
|
}
|
||
|
|
var maxPayloadLen int
|
||
|
|
if ipv6 {
|
||
|
|
maxPayloadLen = maxDatagramLen - sessionRegistrationIPv6DatagramHeaderLen
|
||
|
|
flags |= sessionRegistrationFlagsIPMask
|
||
|
|
} else {
|
||
|
|
maxPayloadLen = maxDatagramLen - sessionRegistrationIPv4DatagramHeaderLen
|
||
|
|
}
|
||
|
|
// Make sure that the payload being bundled can actually fit in the payload destination
|
||
|
|
if len(s.Payload) > maxPayloadLen {
|
||
|
|
return nil, wrapMarshalErr(ErrDatagramPayloadTooLarge)
|
||
|
|
}
|
||
|
|
// Allocate the buffer with the right size for the destination IP family
|
||
|
|
if ipv6 {
|
||
|
|
data = make([]byte, sessionRegistrationIPv6DatagramHeaderLen+len(s.Payload))
|
||
|
|
} else {
|
||
|
|
data = make([]byte, sessionRegistrationIPv4DatagramHeaderLen+len(s.Payload))
|
||
|
|
}
|
||
|
|
data[0] = byte(UDPSessionRegistrationType)
|
||
|
|
data[1] = byte(flags)
|
||
|
|
binary.BigEndian.PutUint16(data[2:4], s.Dest.Port())
|
||
|
|
binary.BigEndian.PutUint16(data[4:6], uint16(s.IdleDurationHint.Seconds()))
|
||
|
|
err = s.RequestID.MarshalBinaryTo(data[6:22])
|
||
|
|
if err != nil {
|
||
|
|
return nil, wrapMarshalErr(err)
|
||
|
|
}
|
||
|
|
var end int
|
||
|
|
if ipv6 {
|
||
|
|
copy(data[22:38], s.Dest.Addr().AsSlice())
|
||
|
|
end = 38
|
||
|
|
} else {
|
||
|
|
copy(data[22:26], s.Dest.Addr().AsSlice())
|
||
|
|
end = 26
|
||
|
|
}
|
||
|
|
|
||
|
|
if hasPayload {
|
||
|
|
copy(data[end:], s.Payload)
|
||
|
|
}
|
||
|
|
|
||
|
|
return data, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *UDPSessionRegistrationDatagram) UnmarshalBinary(data []byte) error {
|
||
|
|
datagramType, err := parseDatagramType(data)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if datagramType != UDPSessionRegistrationType {
|
||
|
|
return wrapUnmarshalErr(ErrInvalidDatagramType)
|
||
|
|
}
|
||
|
|
|
||
|
|
requestID, err := RequestIDFromSlice(data[6:22])
|
||
|
|
if err != nil {
|
||
|
|
return wrapUnmarshalErr(err)
|
||
|
|
}
|
||
|
|
|
||
|
|
traced := (data[1] & sessionRegistrationFlagsTracedMask) == sessionRegistrationFlagsTracedMask
|
||
|
|
bundled := (data[1] & sessionRegistrationFlagsBundledMask) == sessionRegistrationFlagsBundledMask
|
||
|
|
ipv6 := (data[1] & sessionRegistrationFlagsIPMask) == sessionRegistrationFlagsIPMask
|
||
|
|
|
||
|
|
port := binary.BigEndian.Uint16(data[2:4])
|
||
|
|
var datagramHeaderSize int
|
||
|
|
var dest netip.AddrPort
|
||
|
|
if ipv6 {
|
||
|
|
datagramHeaderSize = sessionRegistrationIPv6DatagramHeaderLen
|
||
|
|
dest = netip.AddrPortFrom(netip.AddrFrom16([16]byte(data[22:38])), port)
|
||
|
|
} else {
|
||
|
|
datagramHeaderSize = sessionRegistrationIPv4DatagramHeaderLen
|
||
|
|
dest = netip.AddrPortFrom(netip.AddrFrom4([4]byte(data[22:26])), port)
|
||
|
|
}
|
||
|
|
|
||
|
|
idle := time.Duration(binary.BigEndian.Uint16(data[4:6])) * time.Second
|
||
|
|
|
||
|
|
var payload []byte
|
||
|
|
if bundled && len(data) >= datagramHeaderSize && len(data[datagramHeaderSize:]) > 0 {
|
||
|
|
payload = data[datagramHeaderSize:]
|
||
|
|
}
|
||
|
|
|
||
|
|
*s = UDPSessionRegistrationDatagram{
|
||
|
|
RequestID: requestID,
|
||
|
|
Dest: dest,
|
||
|
|
Traced: traced,
|
||
|
|
IdleDurationHint: idle,
|
||
|
|
Payload: payload,
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// UDPSessionPayloadDatagram provides the payload for a session to be send to either the origin or the client.
|
||
|
|
type UDPSessionPayloadDatagram struct {
|
||
|
|
RequestID RequestID
|
||
|
|
Payload []byte
|
||
|
|
}
|
||
|
|
|
||
|
|
const (
|
||
|
|
datagramPayloadHeaderLen = datagramTypeLen + datagramRequestIdLen
|
||
|
|
|
||
|
|
// The maximum size that a proxied UDP payload can be in a [UDPSessionPayloadDatagram]
|
||
|
|
maxPayloadPlusHeaderLen = maxDatagramLen - datagramPayloadHeaderLen
|
||
|
|
)
|
||
|
|
|
||
|
|
// The datagram structure for UDPSessionPayloadDatagram is:
|
||
|
|
//
|
||
|
|
// 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 0| Type | |
|
||
|
|
// +-+-+-+-+-+-+-+-+ +
|
||
|
|
// 4| |
|
||
|
|
// + +
|
||
|
|
// 8| Session Identifier |
|
||
|
|
// + (16 Bytes) +
|
||
|
|
// 12| |
|
||
|
|
// + +-+-+-+-+-+-+-+-+
|
||
|
|
// 16| | |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|
||
|
|
// . .
|
||
|
|
// . Payload .
|
||
|
|
// . .
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
|
||
|
|
// MarshalPayloadHeaderTo provides a way to insert the Session Payload header into an already existing byte slice
|
||
|
|
// without having to allocate and copy the payload into the destination.
|
||
|
|
//
|
||
|
|
// This method should be used in-place of MarshalBinary which will allocate in-place the required byte array to return.
|
||
|
|
func MarshalPayloadHeaderTo(requestID RequestID, payload []byte) error {
|
||
|
|
if len(payload) < 17 {
|
||
|
|
return wrapMarshalErr(ErrDatagramPayloadHeaderTooSmall)
|
||
|
|
}
|
||
|
|
payload[0] = byte(UDPSessionPayloadType)
|
||
|
|
return requestID.MarshalBinaryTo(payload[1:17])
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *UDPSessionPayloadDatagram) UnmarshalBinary(data []byte) error {
|
||
|
|
datagramType, err := parseDatagramType(data)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if datagramType != UDPSessionPayloadType {
|
||
|
|
return wrapUnmarshalErr(ErrInvalidDatagramType)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Make sure that the slice provided is the right size to be parsed.
|
||
|
|
if len(data) < 17 || len(data) > maxPayloadPlusHeaderLen {
|
||
|
|
return wrapUnmarshalErr(ErrDatagramPayloadInvalidSize)
|
||
|
|
}
|
||
|
|
|
||
|
|
requestID, err := RequestIDFromSlice(data[1:17])
|
||
|
|
if err != nil {
|
||
|
|
return wrapUnmarshalErr(err)
|
||
|
|
}
|
||
|
|
|
||
|
|
*s = UDPSessionPayloadDatagram{
|
||
|
|
RequestID: requestID,
|
||
|
|
Payload: data[17:],
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// UDPSessionRegistrationResponseDatagram is used to either return a successful registration or error to the client
|
||
|
|
// that requested the registration of a UDP session.
|
||
|
|
type UDPSessionRegistrationResponseDatagram struct {
|
||
|
|
RequestID RequestID
|
||
|
|
ResponseType SessionRegistrationResp
|
||
|
|
ErrorMsg string
|
||
|
|
}
|
||
|
|
|
||
|
|
const (
|
||
|
|
datagramRespTypeLen = 1
|
||
|
|
datagramRespErrMsgLen = 2
|
||
|
|
|
||
|
|
datagramSessionRegistrationResponseLen = datagramTypeLen + datagramRespTypeLen + datagramRequestIdLen + datagramRespErrMsgLen
|
||
|
|
|
||
|
|
// The maximum size that an error message can be in a [UDPSessionRegistrationResponseDatagram].
|
||
|
|
maxResponseErrorMessageLen = maxDatagramLen - datagramSessionRegistrationResponseLen
|
||
|
|
)
|
||
|
|
|
||
|
|
// SessionRegistrationResp represents all of the responses that a UDP session registration response
|
||
|
|
// can return back to the client.
|
||
|
|
type SessionRegistrationResp byte
|
||
|
|
|
||
|
|
const (
|
||
|
|
// Session was received and is ready to proxy.
|
||
|
|
ResponseOk SessionRegistrationResp = 0x00
|
||
|
|
// Session registration was unable to reach the requested origin destination.
|
||
|
|
ResponseDestinationUnreachable SessionRegistrationResp = 0x01
|
||
|
|
// Session registration was unable to bind to a local UDP socket.
|
||
|
|
ResponseUnableToBindSocket SessionRegistrationResp = 0x02
|
||
|
|
// Session registration failed with an unexpected error but provided a message.
|
||
|
|
ResponseErrorWithMsg SessionRegistrationResp = 0xff
|
||
|
|
)
|
||
|
|
|
||
|
|
// The datagram structure for UDPSessionRegistrationResponseDatagram is:
|
||
|
|
//
|
||
|
|
// 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 0| Type | Resp Type | |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|
||
|
|
// 4| |
|
||
|
|
// + Session Identifier +
|
||
|
|
// 8| (16 Bytes) |
|
||
|
|
// + +
|
||
|
|
// 12| |
|
||
|
|
// + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// 16| | Error Length |
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
// . .
|
||
|
|
// . .
|
||
|
|
// . .
|
||
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||
|
|
|
||
|
|
func (s *UDPSessionRegistrationResponseDatagram) MarshalBinary() (data []byte, err error) {
|
||
|
|
if len(s.ErrorMsg) > maxResponseErrorMessageLen {
|
||
|
|
return nil, wrapMarshalErr(ErrDatagramResponseMsgInvalidSize)
|
||
|
|
}
|
||
|
|
errMsgLen := uint16(len(s.ErrorMsg))
|
||
|
|
|
||
|
|
data = make([]byte, datagramSessionRegistrationResponseLen+errMsgLen)
|
||
|
|
data[0] = byte(UDPSessionRegistrationResponseType)
|
||
|
|
data[1] = byte(s.ResponseType)
|
||
|
|
err = s.RequestID.MarshalBinaryTo(data[2:18])
|
||
|
|
if err != nil {
|
||
|
|
return nil, wrapMarshalErr(err)
|
||
|
|
}
|
||
|
|
|
||
|
|
if errMsgLen > 0 {
|
||
|
|
binary.BigEndian.PutUint16(data[18:20], errMsgLen)
|
||
|
|
copy(data[20:], []byte(s.ErrorMsg))
|
||
|
|
}
|
||
|
|
|
||
|
|
return data, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *UDPSessionRegistrationResponseDatagram) UnmarshalBinary(data []byte) error {
|
||
|
|
datagramType, err := parseDatagramType(data)
|
||
|
|
if err != nil {
|
||
|
|
return wrapUnmarshalErr(err)
|
||
|
|
}
|
||
|
|
if datagramType != UDPSessionRegistrationResponseType {
|
||
|
|
return wrapUnmarshalErr(ErrInvalidDatagramType)
|
||
|
|
}
|
||
|
|
|
||
|
|
if len(data) < datagramSessionRegistrationResponseLen {
|
||
|
|
return wrapUnmarshalErr(ErrDatagramResponseInvalidSize)
|
||
|
|
}
|
||
|
|
|
||
|
|
respType := SessionRegistrationResp(data[1])
|
||
|
|
|
||
|
|
requestID, err := RequestIDFromSlice(data[2:18])
|
||
|
|
if err != nil {
|
||
|
|
return wrapUnmarshalErr(err)
|
||
|
|
}
|
||
|
|
|
||
|
|
errMsgLen := binary.BigEndian.Uint16(data[18:20])
|
||
|
|
if errMsgLen > maxResponseErrorMessageLen {
|
||
|
|
return wrapUnmarshalErr(ErrDatagramResponseMsgTooLargeMaximum)
|
||
|
|
}
|
||
|
|
|
||
|
|
if len(data[20:]) < int(errMsgLen) {
|
||
|
|
return wrapUnmarshalErr(ErrDatagramResponseMsgTooLargeDatagram)
|
||
|
|
}
|
||
|
|
|
||
|
|
var errMsg string
|
||
|
|
if errMsgLen > 0 {
|
||
|
|
errMsg = string(data[20:])
|
||
|
|
}
|
||
|
|
|
||
|
|
*s = UDPSessionRegistrationResponseDatagram{
|
||
|
|
RequestID: requestID,
|
||
|
|
ResponseType: respType,
|
||
|
|
ErrorMsg: errMsg,
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|