Initial commit

utils.go

@@ -0,0 +1,121 @@
+// Codehere is mostly taken from github.com/tailscale/tailscale
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package headscale
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+
+	mathrand "math/rand"
+
+	"github.com/tailscale/wireguard-go/wgcfg"
+	"golang.org/x/crypto/nacl/box"
+)
+
+func decode(msg []byte, v interface{}, pubKey *wgcfg.Key, privKey *wgcfg.PrivateKey) error {
+	return decodeMsg(msg, v, pubKey, privKey)
+}
+
+func decodeMsg(msg []byte, v interface{}, pubKey *wgcfg.Key, privKey *wgcfg.PrivateKey) error {
+	decrypted, err := decryptMsg(msg, pubKey, privKey)
+	if err != nil {
+		return err
+	}
+	// fmt.Println(string(decrypted))
+	if err := json.Unmarshal(decrypted, v); err != nil {
+		return fmt.Errorf("response: %v", err)
+	}
+	return nil
+}
+
+func decryptMsg(msg []byte, pubKey *wgcfg.Key, privKey *wgcfg.PrivateKey) ([]byte, error) {
+	var nonce [24]byte
+	if len(msg) < len(nonce)+1 {
+		return nil, fmt.Errorf("response missing nonce, len=%d", len(msg))
+	}
+	copy(nonce[:], msg)
+	msg = msg[len(nonce):]
+
+	pub, pri := (*[32]byte)(pubKey), (*[32]byte)(privKey)
+	decrypted, ok := box.Open(nil, msg, &nonce, pub, pri)
+	if !ok {
+		return nil, fmt.Errorf("cannot decrypt response")
+	}
+	return decrypted, nil
+}
+
+func encode(v interface{}, pubKey *wgcfg.Key, privKey *wgcfg.PrivateKey) ([]byte, error) {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return nil, err
+	}
+	return encodeMsg(b, pubKey, privKey)
+}
+
+func encodeMsg(b []byte, pubKey *wgcfg.Key, privKey *wgcfg.PrivateKey) ([]byte, error) {
+	var nonce [24]byte
+	if _, err := io.ReadFull(rand.Reader, nonce[:]); err != nil {
+		panic(err)
+	}
+	pub, pri := (*[32]byte)(pubKey), (*[32]byte)(privKey)
+	msg := box.Seal(nonce[:], b, &nonce, pub, pri)
+	return msg, nil
+}
+
+func (h *Headscale) getAvailableIP() (*net.IP, error) {
+	db, err := h.db()
+	if err != nil {
+		return nil, err
+	}
+	defer db.Close()
+	i := 0
+	for {
+		ip, err := getRandomIP()
+		if err != nil {
+			return nil, err
+		}
+		m := Machine{}
+		if db.First(&m, "ip_address = ?", ip.String()).RecordNotFound() {
+			return ip, nil
+		}
+		i++
+		if i == 100 { // really random number
+			break
+		}
+	}
+	return nil, errors.New("Could not find an available IP address in 100.64.0.0/10")
+}
+
+func getRandomIP() (*net.IP, error) {
+	ipo, ipnet, err := net.ParseCIDR("100.64.0.0/10")
+
+	if err == nil {
+		ip := ipo.To4()
+		fmt.Println("In Randomize IPAddr: IP ", ip, " IPNET: ", ipnet)
+		fmt.Println("Final address is ", ip)
+		// fmt.Println("Broadcast address is ", ipb)
+		// fmt.Println("Network address is ", ipn)
+
+		ipRaw := make([]byte, 4)
+		binary.LittleEndian.PutUint32(ipRaw, mathrand.Uint32())
+		// ipRaw[3] = 254
+		// fmt.Println("ipRaw is ", ipRaw)
+		for i, v := range ipRaw {
+			// fmt.Println("IP Before: ", ip[i], " v is ", v, " Mask is: ", ipnet.Mask[i])
+			ip[i] = ip[i] + (v &^ ipnet.Mask[i])
+			// fmt.Println("IP After: ", ip[i])
+		}
+		fmt.Println("FINAL IP: ", ip.String())
+		return &ip, nil
+	} else {
+		return nil, err
+	}
+}