From 59960986c9540295d7767b21f2d066ccf9544d48 Mon Sep 17 00:00:00 2001
From: Josh Deprez <josh.deprez@gmail.com>
Date: Fri, 5 Apr 2024 13:18:22 +1100
Subject: [PATCH] [WIP] AppleTalk listen loop

---
 atalk/raw.go | 22 ++++++++++++++++++++++
 config.go    |  1 +
 go.mod       |  5 +++++
 go.sum       | 15 +++++++++++++++
 jrouter.yaml |  1 +
 main.go      | 18 ++++++++++++++++++
 6 files changed, 62 insertions(+)
 create mode 100644 atalk/raw.go

diff --git a/atalk/raw.go b/atalk/raw.go
new file mode 100644
index 0000000..60950ce
--- /dev/null
+++ b/atalk/raw.go
@@ -0,0 +1,22 @@
+package atalk
+
+import (
+	"fmt"
+
+	"github.com/google/gopacket/pcap"
+)
+
+// StartPcap opens an AppleTalk and AARP listening session on a network device.
+func StartPcap(device string) (*pcap.Handle, error) {
+	handle, err := pcap.OpenLive(device, 4096, false, pcap.BlockForever)
+	if err != nil {
+		return nil, fmt.Errorf("opening device %q: %w", device, err)
+	}
+
+	if err := handle.SetBPFFilter("atalk or aarp"); err != nil {
+		handle.Close()
+		return nil, fmt.Errorf("setting BPF filter: %w", err)
+	}
+
+	return handle, nil
+}
diff --git a/config.go b/config.go
index 2a3adf7..6a5ab93 100644
--- a/config.go
+++ b/config.go
@@ -35,6 +35,7 @@ type config struct {
 
 	// Required for routing a local EtherTalk network.
 	EtherTalk struct {
+		Device   string `yaml:"device"`
 		ZoneName string `yaml:"zone_name"`
 		NetStart uint16 `yaml:"net_start"`
 		NetEnd   uint16 `yaml:"net_end"`
diff --git a/go.mod b/go.mod
index 52b4ad9..8c85068 100644
--- a/go.mod
+++ b/go.mod
@@ -6,3 +6,8 @@ require (
 	github.com/google/go-cmp v0.6.0
 	gopkg.in/yaml.v3 v3.0.1
 )
+
+require (
+	github.com/google/gopacket v1.1.19 // indirect
+	golang.org/x/sys v0.0.0-20190412213103-97732733099d // indirect
+)
diff --git a/go.sum b/go.sum
index 9d8a8fa..982cfb6 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,20 @@
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
+github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/jrouter.yaml b/jrouter.yaml
index 861a5d5..d5e6e38 100644
--- a/jrouter.yaml
+++ b/jrouter.yaml
@@ -1,4 +1,5 @@
 ethertalk:
+    device: enp1s0
     zone_name: The Twilight Zone
     net_start: 100
     net_end: 100
diff --git a/main.go b/main.go
index 192adcc..8b3bb28 100644
--- a/main.go
+++ b/main.go
@@ -29,6 +29,7 @@ import (
 	"sync"
 	"time"
 
+	"gitea.drjosh.dev/josh/jrouter/atalk"
 	"gitea.drjosh.dev/josh/jrouter/aurp"
 )
 
@@ -133,6 +134,23 @@ func main() {
 		goHandler(peer)
 	}
 
+	// AppleTalk packet loop
+	go func() {
+		handle, err := atalk.StartPcap(cfg.EtherTalk.Device)
+		if err != nil {
+			log.Fatalf("Couldn't open network device for AppleTalk: %v", err)
+		}
+		defer handle.Close()
+
+		for {
+			packet, _, err := handle.ReadPacketData()
+			if err != nil {
+				log.Fatalf("Couldn't read packet data: %v", err)
+			}
+			log.Printf("%x", packet)
+		}
+	}()
+
 	// Incoming packet loop
 	for {
 		if ctx.Err() != nil {