WIP
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parent
b8abe34c28
commit
30f8d709d2
3 changed files with 244 additions and 62 deletions
213
aurp/aurp.go
213
aurp/aurp.go
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@ -3,9 +3,9 @@
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package aurp
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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"net"
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)
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@ -15,88 +15,85 @@ type DomainHeader struct {
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DestinationDI DomainIdentifier
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SourceDI DomainIdentifier
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Version uint16 // Should always be 0x0001
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PacketType uint16 // 2 = AppleTalk data packet, 3 = AURP packet
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Reserved uint16
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PacketType PacketType // 2 = AppleTalk data packet, 3 = AURP packet
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}
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// Encode returns the encoded form of the header.
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func (dh *DomainHeader) Encode() ([]byte, error) {
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var b bytes.Buffer
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ddi, err := dh.DestinationDI.Encode()
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if err != nil {
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return nil, err
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}
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sdi, err := dh.SourceDI.Encode()
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if err != nil {
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return nil, err
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}
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b.Write(ddi)
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b.Write(sdi)
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binary.Write(&b, binary.BigEndian, dh.Version)
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binary.Write(&b, binary.BigEndian, uint16(0x0000)) // Reserved
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binary.Write(&b, binary.BigEndian, dh.PacketType)
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return b.Bytes(), nil
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// PacketType is used to distinguish domain-header encapsulated packets.
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type PacketType uint16
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// Various packet types.
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const (
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PacketTypeAppleTalk PacketType = 0x0002
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PacketTypeRouting PacketType = 0x0003
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)
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// WriteTo writes the encoded form of the domain header to w.
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func (dh *DomainHeader) WriteTo(w io.Writer) (int64, error) {
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a := acc(w)
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a.writeTo(dh.DestinationDI)
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a.writeTo(dh.SourceDI)
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a.write16(dh.Version)
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a.write16(dh.Reserved)
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a.write16(uint16(dh.PacketType))
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return a.ret()
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}
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// ParseDH parses a domain header, returning the DH and the remainder of the
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// input slice.
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func ParseDH(b []byte) (*DomainHeader, []byte, error) {
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ddi, b, err := ParseDI(b)
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// ParseDomainHeader parses a domain header, returning the DH and the remainder
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// of the input slice. It does not validate the version or packet type fields.
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func ParseDomainHeader(b []byte) (*DomainHeader, []byte, error) {
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ddi, b, err := ParseDomainIdentifier(b)
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if err != nil {
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return nil, b, err
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}
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sdi, b, err := ParseDI(b)
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sdi, b, err := ParseDomainIdentifier(b)
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if err != nil {
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return nil, b, err
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}
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if len(b) < 6 { // sizeof(version + reserved + packettype)
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return nil, b, fmt.Errorf("insufficient remaining input length %d < 6", len(b))
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}
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ver := binary.BigEndian.Uint16(b[:2])
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if ver != 1 {
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return nil, b, fmt.Errorf("unknown version %d", ver)
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}
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// Note: b[2:4] (reserved field) is ignored
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pt := binary.BigEndian.Uint16(b[4:6])
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if pt != 2 && pt != 3 {
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return nil, b, fmt.Errorf("unknown packet type %d", pt)
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}
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b = b[6:]
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return &DomainHeader{
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DestinationDI: ddi,
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SourceDI: sdi,
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Version: ver,
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PacketType: pt,
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}, b, nil
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Version: binary.BigEndian.Uint16(b[:2]),
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Reserved: binary.BigEndian.Uint16(b[2:4]),
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PacketType: PacketType(binary.BigEndian.Uint16(b[4:6])),
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}, b[6:], nil
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}
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// DomainIdentifier is the byte representation of a domain identifier.
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type DomainIdentifier interface {
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Encode() ([]byte, error)
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io.WriterTo
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}
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// NullDI represents a null domain identifier.
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type NullDI struct{}
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// NullDomainIdentifier represents a null domain identifier.
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type NullDomainIdentifier struct{}
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// Encode returns the encoded form of the identifier.
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func (NullDI) Encode() ([]byte, error) {
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return []byte{0x01, 0x00}, nil
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// WriteTo writes the encoded form of the domain identifier to w.
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func (NullDomainIdentifier) WriteTo(w io.Writer) (int64, error) {
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n, err := w.Write([]byte{0x01, 0x00})
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return int64(n), err
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}
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// IPDI represents an IP address in a domain identifier.
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type IPDI net.IP
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// IPDomainIdentifier represents an IP address in a domain identifier.
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type IPDomainIdentifier net.IP
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// Encode returns the encoded form of the identifier.
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func (i IPDI) Encode() ([]byte, error) {
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// WriteTo writes the encoded form of the domain identifier to w.
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func (i IPDomainIdentifier) WriteTo(w io.Writer) (int64, error) {
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v4 := net.IP(i).To4()
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if v4 == nil {
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return nil, fmt.Errorf("need v4 IP address, got %v", i)
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return 0, fmt.Errorf("need v4 IP address, got %v", i)
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}
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return append([]byte{
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0x07, // byte 1: length of the DI in bytes
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a := acc(w)
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a.write([]byte{
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0x07, // byte 1: length of the DI, in bytes
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0x01, // byte 2: authority: 1 = IP address
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0x00, 0x00, // bytes 3, 4: distinguisher: reserved
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}, v4...), // bytes 5-8: the IP address
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nil
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0x00, 0x00, // bytes 3, 4: distinguisher: reserved)
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})
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a.write(v4) // bytes 5-8: IP address
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return a.ret()
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}
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// Authority represents the different possible authorities ("types") for domain
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@ -113,9 +110,9 @@ const (
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AuthorityIP
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)
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// ParseDI parses a DI from the front of b, and returns the DI and the remainder
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// of the input slice.
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func ParseDI(b []byte) (DomainIdentifier, []byte, error) {
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// ParseDomainIdentifier parses a DI from the front of b, and returns the DI and
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// the remainder of the input slice.
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func ParseDomainIdentifier(b []byte) (DomainIdentifier, []byte, error) {
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if len(b) < 2 {
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return nil, b, fmt.Errorf("insufficient input length %d for domain identifier", len(b))
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}
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@ -128,31 +125,54 @@ func ParseDI(b []byte) (DomainIdentifier, []byte, error) {
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switch Authority(b[1]) {
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case AuthorityNull:
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// That's it, that's the whole DI.
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return NullDI{}, b[2:], nil
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return NullDomainIdentifier{}, b[2:], nil
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case AuthorityIP:
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if lf != 7 {
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return nil, b, fmt.Errorf("incorrect length %d for IP domain identifier", lf)
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}
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return IPDI(b[5:8]), b[8:], nil
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return IPDomainIdentifier(b[5:8]), b[8:], nil
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default:
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return nil, b, fmt.Errorf("unknown domain identifier authority %d", b[1])
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}
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}
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// TrHeader represent an AURP-Tr packet header.
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// TrHeader represent an AURP-Tr packet header. It includes the domain header.
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type TrHeader struct {
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DomainHeader
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ConnectionID uint16
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Sequence uint16 // Note: 65535 is succeeded by 1, not 0
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}
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// Header represents an AURP packet header.
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// WriteTo writes the encoded form of the header to w.
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func (h *TrHeader) WriteTo(w io.Writer) (int64, error) {
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a := acc(w)
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a.writeTo(&h.DomainHeader)
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a.write16(h.ConnectionID)
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a.write16(h.Sequence)
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return a.ret()
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}
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// Header represents an AURP packet header. It includes the AURP-Tr header,
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// which includes the domain header.
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type Header struct {
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TrHeader
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CommandCode CmdCode
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Flags RoutingFlag
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}
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// WriteTo writes the encoded form of the header to w.
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func (h *Header) WriteTo(w io.Writer) (int64, error) {
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a := acc(w)
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a.writeTo(&h.TrHeader)
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a.write16(uint16(h.CommandCode))
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a.write16(uint16(h.Flags))
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return a.ret()
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}
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// CmdCode is the command code used in AURP packets.
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type CmdCode uint16
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@ -203,3 +223,76 @@ const (
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// RI-Ack
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RoutingFlagSendZoneInfo RoutingFlag = 0x4000
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)
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// OptionTuple is used to pass option information in Open-Req and Open-Rsp
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// packets.
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type OptionTuple struct {
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// Length uint8 = 1(for Type) + len(Data)
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Type OptionType
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Data []byte
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}
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func (ot *OptionTuple) WriteTo(w io.Writer) (int64, error) {
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a := acc(w)
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a.write8(uint8(len(ot.Data) + 1))
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a.write8(uint8(ot.Type))
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a.write(ot.Data)
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return a.ret()
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}
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// OptionType is used to distinguish different options.
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type OptionType uint8
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// Various option types
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const (
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OptionTypeAuthentication OptionType = 0x01
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// All other types reserved
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)
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// Packet represents a full AURP packet, not including UDP or lower layers, but
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// including the domain header and higher layers.
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type Packet interface {
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io.WriterTo
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}
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// AppleTalkPacket is for encapsulated AppleTalk traffic.
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type AppleTalkPacket struct {
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DomainHeader // where PacketTypeAppleTalk
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Data []byte
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}
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func (p *AppleTalkPacket) WriteTo(w io.Writer) (int64, error) {
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a := acc(w)
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a.writeTo(&p.DomainHeader)
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a.write(p.Data)
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return a.ret()
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}
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// OpenReq is used to open a one-way connection between AIRs.
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type OpenReqPacket struct {
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Header
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Version uint16 // currently always 1
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//OptionCount uint8 = len(Options)
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Options []OptionTuple
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}
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func (p *OpenReqPacket) WriteTo(w io.Writer) (int64, error) {
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if len(p.Options) > 255 {
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return 0, fmt.Errorf("too many options [%d > 255]", len(p.Options))
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}
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a := acc(w)
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a.writeTo(&p.Header)
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a.write16(p.Version)
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a.write8(uint8(len(p.Options)))
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for _, o := range p.Options {
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a.writeTo(&o)
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}
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return a.ret()
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}
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func ParsePacket(p []byte) (Packet, error) {
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// TODO
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return nil, nil
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}
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61
aurp/wtacc.go
Normal file
61
aurp/wtacc.go
Normal file
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@ -0,0 +1,61 @@
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package aurp
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import (
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"encoding/binary"
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"io"
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)
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// wtacc is a helper for io.WriterTo implementations.
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// It sacrifices early returns for a shorter syntax. However, it refuses to
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// continue writing to the destination writer after detecting an error.
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type wtacc struct {
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w io.Writer
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n int64
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err error
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}
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func acc(w io.Writer) wtacc { return wtacc{w: w} }
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func (a *wtacc) ret() (int64, error) {
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return a.n, a.err
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}
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func (a *wtacc) write8(x uint8) {
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if a.err != nil {
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return
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}
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a.err = binary.Write(a.w, binary.BigEndian, x)
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if a.err != nil {
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return
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}
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a.n++
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}
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func (a *wtacc) write16(x uint16) {
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if a.err != nil {
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return
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}
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a.err = binary.Write(a.w, binary.BigEndian, x)
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if a.err != nil {
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return
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}
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a.n += 2
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}
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func (a *wtacc) write(b []byte) {
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if a.err != nil {
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return
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}
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n, err := a.w.Write(b)
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a.n += int64(n)
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a.err = err
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}
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func (a *wtacc) writeTo(wt io.WriterTo) {
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if a.err != nil {
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return
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}
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n, err := wt.WriteTo(a.w)
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a.n += n
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a.err = err
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}
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28
main.go
28
main.go
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@ -1,5 +1,33 @@
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package main
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import (
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"log"
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"net"
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"gitea.drjosh.dev/josh/jrouter/aurp"
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)
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func main() {
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log.Println("jrouter")
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ln, err := net.ListenUDP("udp4", &net.UDPAddr{Port: 387})
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if err != nil {
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log.Fatalf("Couldn't listen on udp4:387: %v", err)
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}
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// Incoming packet loop
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pb := make([]byte, 65536)
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for {
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plen, _, err := ln.ReadFromUDP(pb)
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if err != nil {
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log.Printf("Failed to read packet: %v", err)
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continue
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}
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_, err = aurp.ParsePacket(pb[:plen])
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if err != nil {
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log.Printf("Failed to parse packet: %v", err)
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}
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}
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}
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