josh/jrouter
josh/jrouter
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Josh Deprez 2024-03-15 16:15:24 +11:00
parent 30f8d709d2
commit 5bb3435dc9
No known key found for this signature in database
3 changed files with 170 additions and 38 deletions
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189
aurp/aurp.go
View file

@ -39,14 +39,14 @@ func (dh *DomainHeader) WriteTo(w io.Writer) (int64, error) {
return a.ret()
}
// ParseDomainHeader parses a domain header, returning the DH and the remainder
// parseDomainHeader parses a domain header, returning the DH and the remainder
// of the input slice. It does not validate the version or packet type fields.
func ParseDomainHeader(b []byte) (*DomainHeader, []byte, error) {
ddi, b, err := ParseDomainIdentifier(b)
func parseDomainHeader(b []byte) (*DomainHeader, []byte, error) {
ddi, b, err := parseDomainIdentifier(b)
if err != nil {
return nil, b, err
}
sdi, b, err := ParseDomainIdentifier(b)
sdi, b, err := parseDomainIdentifier(b)
if err != nil {
return nil, b, err
}
@ -110,9 +110,9 @@ const (
AuthorityIP
)
// ParseDomainIdentifier parses a DI from the front of b, and returns the DI and
// the remainder of the input slice.
func ParseDomainIdentifier(b []byte) (DomainIdentifier, []byte, error) {
// parseDomainIdentifier parses a DI from the front of b, and returns the DI and
// the remainder of the input slice or an error.
func parseDomainIdentifier(b []byte) (DomainIdentifier, []byte, error) {
if len(b) < 2 {
return nil, b, fmt.Errorf("insufficient input length %d for domain identifier", len(b))
}
@ -140,25 +140,36 @@ func ParseDomainIdentifier(b []byte) (DomainIdentifier, []byte, error) {
// TrHeader represent an AURP-Tr packet header. It includes the domain header.
type TrHeader struct {
DomainHeader
*DomainHeader
ConnectionID uint16
Sequence uint16 // Note: 65535 is succeeded by 1, not 0
}
// WriteTo writes the encoded form of the header to w.
// WriteTo writes the encoded form of the header to w, including the domain
// header.
func (h *TrHeader) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.writeTo(&h.DomainHeader)
a.writeTo(h.DomainHeader)
a.write16(h.ConnectionID)
a.write16(h.Sequence)
return a.ret()
}
func parseTrHeader(p []byte) (*TrHeader, []byte, error) {
if len(p) < 4 {
return nil, p, fmt.Errorf("insufficient input length %d for tr header", len(p))
}
return &TrHeader{
ConnectionID: binary.BigEndian.Uint16(p[:2]),
Sequence: binary.BigEndian.Uint16(p[2:4]),
}, p[4:], nil
}
// Header represents an AURP packet header. It includes the AURP-Tr header,
// which includes the domain header.
type Header struct {
TrHeader
*TrHeader
CommandCode CmdCode
Flags RoutingFlag
@ -167,12 +178,22 @@ type Header struct {
// WriteTo writes the encoded form of the header to w.
func (h *Header) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.writeTo(&h.TrHeader)
a.writeTo(h.TrHeader)
a.write16(uint16(h.CommandCode))
a.write16(uint16(h.Flags))
return a.ret()
}
func parseHeader(p []byte) (*Header, []byte, error) {
if len(p) < 4 {
return nil, p, fmt.Errorf("insufficient input length %d for header", len(p))
}
return &Header{
CommandCode: CmdCode(binary.BigEndian.Uint16(p[:2])),
Flags: RoutingFlag(binary.BigEndian.Uint16(p[2:4])),
}, p[4:], nil
}
// CmdCode is the command code used in AURP packets.
type CmdCode uint16
@ -233,6 +254,10 @@ type OptionTuple struct {
}
func (ot *OptionTuple) WriteTo(w io.Writer) (int64, error) {
if len(ot.Data) > 254 {
return 0, fmt.Errorf("option tuple data too long [%d > 254]", len(ot.Data))
}
a := acc(w)
a.write8(uint8(len(ot.Data) + 1))
a.write8(uint8(ot.Type))
@ -240,6 +265,20 @@ func (ot *OptionTuple) WriteTo(w io.Writer) (int64, error) {
return a.ret()
}
func parseOptionTuple(p []byte) (OptionTuple, []byte, error) {
if len(p) < 2 {
return OptionTuple{}, p, fmt.Errorf("insufficient input length %d for option tuple", len(p))
}
olen := int(p[0]) + 1
if len(p) < olen {
return OptionTuple{}, p, fmt.Errorf("insufficient input for option tuple data length %d", olen)
}
return OptionTuple{
Type: OptionType(p[1]),
Data: p[2:olen],
}, p[olen:], nil
}
// OptionType is used to distinguish different options.
type OptionType uint8
@ -249,6 +288,39 @@ const (
// All other types reserved
)
type Options []OptionTuple
func (o Options) WriteTo(w io.Writer) (int64, error) {
if len(o) > 255 {
return 0, fmt.Errorf("too many options [%d > 255]", len(o))
}
a := acc(w)
a.write8(uint8(len(o)))
for _, ot := range o {
a.writeTo(&ot)
}
return a.ret()
}
func parseOptions(p []byte) (Options, error) {
if len(p) < 1 {
return nil, fmt.Errorf("insufficint input length %d for options", len(p))
}
optc := p[0]
opts := make([]OptionTuple, optc)
for i := range optc {
ot, np, err := parseOptionTuple(p)
if err != nil {
return nil, fmt.Errorf("parsing option %d: %w", i, err)
}
opts[i] = ot
p = np
}
// TODO: warn about trailing data?
return opts, nil
}
// Packet represents a full AURP packet, not including UDP or lower layers, but
// including the domain header and higher layers.
type Packet interface {
@ -257,42 +329,99 @@ type Packet interface {
// AppleTalkPacket is for encapsulated AppleTalk traffic.
type AppleTalkPacket struct {
DomainHeader // where PacketTypeAppleTalk
Data []byte
*DomainHeader // where PacketTypeAppleTalk
Data []byte
}
func (p *AppleTalkPacket) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.writeTo(&p.DomainHeader)
a.writeTo(p.DomainHeader)
a.write(p.Data)
return a.ret()
}
// OpenReq is used to open a one-way connection between AIRs.
type OpenReqPacket struct {
Header
*Header
Version uint16 // currently always 1
//OptionCount uint8 = len(Options)
Options []OptionTuple
Options Options
}
func (p *OpenReqPacket) WriteTo(w io.Writer) (int64, error) {
if len(p.Options) > 255 {
return 0, fmt.Errorf("too many options [%d > 255]", len(p.Options))
}
a := acc(w)
a.writeTo(&p.Header)
a.writeTo(p.Header)
a.write16(p.Version)
a.write8(uint8(len(p.Options)))
for _, o := range p.Options {
a.writeTo(&o)
}
a.writeTo(p.Options)
return a.ret()
}
func ParsePacket(p []byte) (Packet, error) {
// TODO
return nil, nil
func parseOpenReq(p []byte) (*OpenReqPacket, error) {
if len(p) < 3 {
return nil, fmt.Errorf("insufficient input length %d for Open-Req packet", len(p))
}
opts, err := parseOptions(p[2:])
if err != nil {
return nil, err
}
return &OpenReqPacket{
Version: binary.BigEndian.Uint16(p[:2]),
Options: opts,
}, nil
}
// ParsePacket parses the body of a UDP packet for a domain header, and then
// based on the packet type, an AURP-Tr header, an AURP routing header, and
// then a particular packet type.
//
// (This function contains the big switch statement.)
func ParsePacket(p []byte) (Packet, error) {
dh, p, err := parseDomainHeader(p)
if err != nil {
return nil, err
}
if dh.Version != 1 {
return nil, fmt.Errorf("unsupported domain header version %d", dh.Version)
}
switch dh.PacketType {
case PacketTypeAppleTalk:
return &AppleTalkPacket{
DomainHeader: dh,
Data: p,
}, nil
case PacketTypeRouting:
tr, p, err := parseTrHeader(p)
if err != nil {
return nil, err
}
tr.DomainHeader = dh
h, p, err := parseHeader(p)
if err != nil {
return nil, err
}
h.TrHeader = tr
switch h.CommandCode {
case CmdCodeOpenReq:
oreq, err := parseOpenReq(p)
if err != nil {
return nil, err
}
oreq.Header = h
return oreq, nil
case CmdCodeOpenRsp:
orsp, err := parseOpenRsp(p)
if err != nil {
return nil, err
}
orsp.Header = h
return orsp, nil
}
default:
return nil, fmt.Errorf("unsupported domain header packet type %d", dh.PacketType)
}
}

2
aurp/wtacc.go
View file

@ -24,7 +24,7 @@ func (a *wtacc) write8(x uint8) {
if a.err != nil {
return
}
a.err = binary.Write(a.w, binary.BigEndian, x)
_, a.err = a.w.Write([]byte{x})
if a.err != nil {
return
}

17
main.go
View file

@ -18,15 +18,18 @@ func main() {
// Incoming packet loop
pb := make([]byte, 65536)
for {
plen, _, err := ln.ReadFromUDP(pb)
if err != nil {
log.Printf("Failed to read packet: %v", err)
continue
pktlen, _, readErr := ln.ReadFromUDP(pb)
// "Callers should always process
// the n > 0 bytes returned before considering the error err."
_, parseErr := aurp.ParsePacket(pb[:pktlen])
if parseErr != nil {
log.Printf("Failed to parse packet: %v", parseErr)
}
_, err = aurp.ParsePacket(pb[:plen])
if err != nil {
log.Printf("Failed to parse packet: %v", err)
if readErr != nil {
log.Printf("Failed to read packet: %v", readErr)
continue
}
}