Written a start mostly using 'water' and 'netlink' libraries to form

a basic TUN interface. Doesn't really work, since the tunnel gets formed
but nothing can properly bind to it.
I should probably rethink what i'm doing before moving forward lol

Signed-off-by: JAMES RYAN <james.paul9889@gmail.com>

go.mod

@@ -0,0 +1,12 @@
+module jptrlanding.dev/jptr/ssh-orchestrate
+
+go 1.22.3
+
+require (
+	github.com/Psiphon-Labs/psiphon-tunnel-core v1.0.11-0.20240607114104-c1011b0e0261 // indirect
+	github.com/songgao/packets v0.0.0-20160404182456-549a10cd4091 // indirect
+	github.com/songgao/water v0.0.0-20200317203138-2b4b6d7c09d8 // indirect
+	github.com/vishvananda/netlink v1.1.0 // indirect
+	github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df // indirect
+	golang.org/x/sys v0.21.0 // indirect
+)

go.sum

@@ -0,0 +1,13 @@
+github.com/Psiphon-Labs/psiphon-tunnel-core v1.0.11-0.20240607114104-c1011b0e0261 h1:QCbphNE60nTOGdEjFHQgymSKhMkJ9bdeCgTfqSaSJfI=
+github.com/Psiphon-Labs/psiphon-tunnel-core v1.0.11-0.20240607114104-c1011b0e0261/go.mod h1:Z5txHi6IF67uDg206QnSxkgE1I3FJUDDJ3n0pa+bKRs=
+github.com/songgao/packets v0.0.0-20160404182456-549a10cd4091 h1:1zN6ImoqhSJhN8hGXFaJlSC8msLmIbX8bFqOfWLKw0w=
+github.com/songgao/packets v0.0.0-20160404182456-549a10cd4091/go.mod h1:N20Z5Y8oye9a7HmytmZ+tr8Q2vlP0tAHP13kTHzwvQY=
+github.com/songgao/water v0.0.0-20200317203138-2b4b6d7c09d8 h1:TG/diQgUe0pntT/2D9tmUCz4VNwm9MfrtPr0SU2qSX8=
+github.com/songgao/water v0.0.0-20200317203138-2b4b6d7c09d8/go.mod h1:P5HUIBuIWKbyjl083/loAegFkfbFNx5i2qEP4CNbm7E=
+github.com/vishvananda/netlink v1.1.0 h1:1iyaYNBLmP6L0220aDnYQpo1QEV4t4hJ+xEEhhJH8j0=
+github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYppBueQtXaqoE=
+github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df h1:OviZH7qLw/7ZovXvuNyL3XQl8UFofeikI1NW1Gypu7k=
+github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df/go.mod h1:JP3t17pCcGlemwknint6hfoeCVQrEMVwxRLRjXpq+BU=
+golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
+golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

main.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+    "bufio"
+    "fmt"
+    "log"
+    "os"
+//	"time"
+	"strconv"
+
+	"math/rand"
+
+	"github.com/songgao/packets/ethernet"
+	"github.com/songgao/water"
+
+    "github.com/vishvananda/netlink"
+)
+
+type Client struct {
+	ifce *water.Interface
+	hostname string
+	addr *netlink.Addr
+}
+
+// -- funcs --
+
+// writes out desired hostname to file. generates a small bash script for 
+// the client to run
+//func generateNewClient() {
+//
+//	var desired_hostname string
+//	fmt.Printf("Please enter a desired hostname for the new client: ")
+//	
+//    scanner := bufio.NewScanner(os.Stdin)
+//    scanner.Scan()
+//    err := scanner.Err()
+//    if err != nil {
+//        log.Fatal(err)
+//    	panic(err)
+//	}
+//	desired_hostname = scanner.Text()
+//
+//	
+//}
+
+// maps ip --> hostname
+// used to verify collisions
+var client_leases = make(map[string]string)
+
+func generateClientTUN(hn string) Client {
+
+	// configure TUN interface	
+	config := water.Config{
+		DeviceType: water.TUN,
+	}
+	config.Name = "tun_"+hn
+	
+
+	cl_ifce, err := water.New(config)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Generate a free address to assign
+	var cl_Addr_str string
+
+	// This is a bad way of doing it, and only accounts for local conflicts
+	// theres definitely a way to find if it conflicts somewhere else
+	// ideally, it shouldnt be locked to this 16 block, either. eventually,
+	// the allowed range (CIDR included) should be defined.
+	// this is an alpha for now, just to get *something* nice working	
+	r := rand.New(rand.NewSource(255))
+	for {
+		var b1 int = int(r.Int31n(255))	
+		var b2 int = int(r.Int31n(255))
+		cl_Addr_str = "." + strconv.Itoa(b1) + "." + strconv.Itoa(b2)
+
+		fmt.Println(cl_Addr_str)
+
+		_, isLeased := client_leases[cl_Addr_str]
+		if !isLeased {
+			break
+		}
+	}
+	
+	cl_Link, err := netlink.LinkByName(config.Name)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	cl_Addr, err := netlink.ParseAddr("169.254"+cl_Addr_str+"/16")
+	if err != nil {
+		log.Fatal(err)
+	}
+	
+	// register addr -> ifce with host
+	netlink.AddrAdd(cl_Link, cl_Addr)
+
+	return Client {
+		ifce: cl_ifce,
+		hostname: hn,
+		addr: cl_Addr,
+	}
+}
+
+func main() {
+	var desired_hostname string
+	fmt.Printf("your nosthanem is ")
+	hn, _ := os.Hostname()
+	fmt.Println(hn)
+	fmt.Printf("Please enter a desired hostname for the new client: ")
+
+    scanner := bufio.NewScanner(os.Stdin)
+    scanner.Scan()
+    err := scanner.Err()
+    if err != nil {
+        log.Fatal(err)
+	}
+	desired_hostname = scanner.Text()
+	var registered_client Client = generateClientTUN(desired_hostname)
+	log.Printf("interface name: %s\n", registered_client.ifce.Name())
+
+	var frame ethernet.Frame
+	ifce := registered_client.ifce
+	for {
+		frame.Resize(1500)
+		n, err := ifce.Read([]byte(frame))
+		if err != nil {
+			log.Fatal(err)
+		}
+		frame = frame[:n]
+		log.Printf("Dst: %s\n", frame.Destination())
+		log.Printf("Src: %s\n", frame.Source())
+		log.Printf("Ethertype: % x\n", frame.Ethertype())
+		log.Printf("Payload: % x\n", frame.Payload())
+	}
+
+//	generateNewClient()
+}