josh/jrouter
josh/jrouter
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Josh Deprez 2024-03-22 16:14:55 +11:00
parent b43fabc5b6
commit 19f9d1c891
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5 changed files with 168 additions and 55 deletions
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2
aurp/aurp.go
View file

@ -91,7 +91,7 @@ type Packet interface {
//
// (This function contains the big switch statement.)
func ParsePacket(p []byte) (Packet, error) {
dh, p, err := parseDomainHeader(p)
dh, p, err := ParseDomainHeader(p)
if err != nil {
return nil, err
}

4
aurp/domain.go
View file

@ -37,9 +37,9 @@ 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) {
func ParseDomainHeader(b []byte) (DomainHeader, []byte, error) {
ddi, b, err := parseDomainIdentifier(b)
if err != nil {
return DomainHeader{}, b, err

16
aurp/errors.go
View file

@ -1,14 +1,14 @@
package aurp
type ErrorCode int16
type ErrorCode = int16
// Various error codes.
const (
ErrCodeNormalClose ErrorCode = -1
ErrCodeRoutingLoop ErrorCode = -2
ErrCodeOutOfSync ErrorCode = -3
ErrCodeOptionNegotiation ErrorCode = -4
ErrCodeInvalidVersion ErrorCode = -5
ErrCodeInsufficientResources ErrorCode = -6
ErrCodeAuthentication ErrorCode = -7
ErrCodeNormalClose = -1
ErrCodeRoutingLoop = -2
ErrCodeOutOfSync = -3
ErrCodeOptionNegotiation = -4
ErrCodeInvalidVersion = -5
ErrCodeInsufficientResources = -6
ErrCodeAuthentication = -7
)

95
aurp/transport.go
View file

@ -34,62 +34,62 @@ func parseTrHeader(p []byte) (TrHeader, []byte, error) {
}, p[4:], nil
}
// incSequence increments the sequence number.
// Note that 0 is special and 65535+1 = 1, according to AURP.
func (tr *TrHeader) incSequence() {
tr.Sequence++
if tr.Sequence == 0 {
tr.Sequence = 1
type Transport struct {
// LocalDI and RemoteDI are used for producing packets.
// When sending a packet, we use LocalDI as SourceDI and RemoteDI as
// DestinationDI.
// (When receiving a packet, we expect to see LocalDI as DestinationDI
// - but it might not be - and we expect to see RemoteDI as SourceDI.)
LocalDI, RemoteDI DomainIdentifier
// LocalConnID is used for packets sent in the role of data receiver.
// RemoteConnID is used for packets sent in the role of data sender.
LocalConnID, RemoteConnID uint16
// LocalSeq is used for packets sent (as data sender)
// RemoteSeq is used to check packets received (remote is the data sender).
LocalSeq, RemoteSeq uint16
}
// domainHeader returns a new domain header suitable for sending a packet.
func (tr *Transport) domainHeader(pt PacketType) DomainHeader {
return DomainHeader{
DestinationDI: tr.RemoteDI,
SourceDI: tr.LocalDI,
Version: 1,
Reserved: 0,
PacketType: pt,
}
}
// transaction returns a new TrHeader based on this one, usable for transaction
// requests or responses.
func (tr *TrHeader) transaction() TrHeader {
// transaction returns a new TrHeader, usable for transaction requests or
// responses. Both data senders and data receivers can send transactions.
// It should be given one of tr.LocalConnID (as data receiver) or
// tr.RemoteConnID (as data sender).
func (tr *Transport) transaction(connID uint16) TrHeader {
return TrHeader{
DomainHeader: DomainHeader{
DestinationDI: tr.DestinationDI,
SourceDI: tr.SourceDI,
Version: 1,
Reserved: 0,
PacketType: PacketTypeRouting,
},
ConnectionID: tr.ConnectionID,
DomainHeader: tr.domainHeader(PacketTypeRouting),
ConnectionID: connID,
Sequence: 0, // Transaction packets all use sequence number 0.
}
}
// DataSender is used to track sender state in a one-way AURP connection.
// Note that both data senders and data recievers can send packets.
type DataSender struct {
TrHeader
}
// NewOpenRspPacket returns a new Open-Rsp packet structure.
func (ds *DataSender) NewOpenRspPacket(envFlags RoutingFlag, rateOrErr int16, opts Options) *OpenRspPacket {
return &OpenRspPacket{
Header: Header{
TrHeader: ds.transaction(),
CommandCode: CmdCodeOpenRsp,
Flags: envFlags,
},
RateOrErrCode: rateOrErr,
Options: opts,
// sequenced returns a new TrHeader usable for sending a sequenced data packet.
// Only data senders send sequenced data.
func (tr *Transport) sequenced(connID, seq uint16) TrHeader {
return TrHeader{
DomainHeader: tr.domainHeader(PacketTypeRouting),
ConnectionID: connID,
Sequence: seq,
}
}
// DataReceiver is used to track reciever state in a one-way AURP connection.
// Note that both data senders and data recievers can send packets.
type DataReceiver struct {
TrHeader
}
// NewOpenReqPacket returns a new Open-Req packet structure. By default it sets
// all SUI flags and uses version 1.
func (dr *DataReceiver) NewOpenReqPacket(opts Options) *OpenReqPacket {
func (tr *Transport) NewOpenReqPacket(opts Options) *OpenReqPacket {
return &OpenReqPacket{
Header: Header{
TrHeader: dr.transaction(),
TrHeader: tr.transaction(tr.LocalConnID),
CommandCode: CmdCodeOpenReq,
Flags: RoutingFlagAllSUI,
},
@ -97,3 +97,16 @@ func (dr *DataReceiver) NewOpenReqPacket(opts Options) *OpenReqPacket {
Options: opts,
}
}
// NewOpenRspPacket returns a new Open-Rsp packet structure.
func (tr *Transport) NewOpenRspPacket(envFlags RoutingFlag, rateOrErr int16, opts Options) *OpenRspPacket {
return &OpenRspPacket{
Header: Header{
TrHeader: tr.transaction(tr.RemoteConnID),
CommandCode: CmdCodeOpenRsp,
Flags: envFlags,
},
RateOrErrCode: rateOrErr,
Options: opts,
}
}

106
main.go
View file

@ -1,15 +1,50 @@
package main
import (
"bytes"
"encoding/binary"
"flag"
"log"
"net"
"gitea.drjosh.dev/josh/jrouter/aurp"
)
var localIPAddr = flag.String("local-ip", "", "IPv4 address to use as the Source Domain Identifier")
func main() {
flag.Parse()
log.Println("jrouter")
localIP := net.ParseIP(*localIPAddr).To4()
if localIP == nil {
iaddrs, err := net.InterfaceAddrs()
if err != nil {
log.Fatalf("Couldn't read network interface addresses: %v", err)
}
for _, iaddr := range iaddrs {
inet, ok := iaddr.(*net.IPNet)
if !ok {
continue
}
if !inet.IP.IsGlobalUnicast() {
continue
}
localIP = inet.IP.To4()
if localIP != nil {
break
}
}
if localIP == nil {
log.Fatalf("No global unicast IPv4 addresses on any network interfaces, and no valid address passed with --local-ip")
}
}
log.Printf("Using %v as local domain identifier", localIP)
peers := make(map[uint32]*aurp.Transport)
var nextConnID uint16
ln, err := net.ListenUDP("udp4", &net.UDPAddr{Port: 387})
if err != nil {
log.Fatalf("Couldn't listen on udp4:387: %v", err)
@ -18,11 +53,16 @@ func main() {
// Incoming packet loop
pb := make([]byte, 65536)
for {
pktlen, _, readErr := ln.ReadFromUDP(pb)
// "Callers should always process
pktlen, raddr, readErr := ln.ReadFromUDP(pb)
// net.PacketConn.ReadFrom: "Callers should always process
// the n > 0 bytes returned before considering the error err."
_, parseErr := aurp.ParsePacket(pb[:pktlen])
dh, _, err := aurp.ParseDomainHeader(pb[:pktlen])
if err != nil {
log.Printf("Failed to parse domain header: %v", err)
}
pkt, parseErr := aurp.ParsePacket(pb[:pktlen])
if parseErr != nil {
log.Printf("Failed to parse packet: %v", parseErr)
}
@ -31,5 +71,65 @@ func main() {
log.Printf("Failed to read packet: %v", readErr)
continue
}
// Existing peer?
rip := binary.BigEndian.Uint32(raddr.IP)
tr := peers[rip]
if tr == nil {
// New peer!
tr = &aurp.Transport{
LocalDI: aurp.IPDomainIdentifier(localIP),
RemoteDI: dh.SourceDI,
LocalConnID: nextConnID,
}
nextConnID++
peers[rip] = tr
}
switch p := pkt.(type) {
case *aurp.AppleTalkPacket:
// Probably something like:
//
// * parse the DDP header
// * check that this is headed for our local network
// * write the packet out in an EtherTalk frame
//
// or maybe if we were implementing a "central hub"
//
// * parse the DDP header
// * see if we know the network
// * forward to the peer with that network and lowest metric
case *aurp.OpenReqPacket:
// The peer tells us their connection ID in Open-Req.
tr.RemoteConnID = p.ConnectionID
// Formulate a response.
var rp *aurp.OpenRspPacket
if p.Version != 1 {
// Respond with Open-Rsp with unknown version error.
rp = tr.NewOpenRspPacket(0, aurp.ErrCodeInvalidVersion, nil)
} else {
// Accept the connection, I guess?
rp = tr.NewOpenRspPacket(0, 1, nil)
}
// Write an Open-Rsp packet
var b bytes.Buffer
if _, err := rp.WriteTo(&b); err != nil {
log.Printf("Couldn't create response packet: %v", err)
break
}
if _, err := ln.WriteToUDP(b.Bytes(), raddr); err != nil {
log.Printf("Couldn't write response packet to UDP peer %v: %v", raddr, err)
}
case *aurp.OpenRspPacket:
if p.RateOrErrCode < 0 {
// It's an error code.
log.Printf("Open-Rsp error code from peer %v: %d", raddr.IP, p.RateOrErrCode)
}
}
}
}