Added ask for lan function

cmd/packets/main.go

@@ -7,22 +7,25 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"net"
 	"os"
 	"packets/internal"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"time"
 
 	"github.com/klauspost/compress/zstd"
 	"github.com/pelletier/go-toml/v2"
 	"github.com/spf13/cobra"
+	"golang.org/x/net/ipv4"
 	_ "modernc.org/sqlite"
 )
 
 // Consts
 
 const DefaultLinux_d = "/etc/packets"
-const DefaultLANDeadline = 2 * time.Second
+const LANDeadline = 2 * time.Second
 
 // Errors
 
@@ -39,6 +42,11 @@ type ConfigTOML struct {
 	} `toml:"Config"`
 }
 
+type Peer struct {
+	IP   net.IP
+	Port int
+}
+
 // init is doing some verifications
 func init() {
 
@@ -183,7 +191,72 @@ func Install(file *os.File) error {
 	return nil
 }
 
-// COBRA CMDS
+func AskLAN(filename string) ([]Peer, error) {
+	var peers []Peer
+	query := []byte("Q:" + filename)
 
+	pc, err := net.ListenPacket("udp", ":0")
+	if err != nil {
+		return []Peer{}, err
+	}
+	defer pc.Close()
+
+	if pconn := ipv4.NewPacketConn(pc); pconn != nil {
+		_ = pconn.SetTTL(1)
+	}
+
+	ifaces, _ := net.Interfaces()
+	for _, ifc := range ifaces {
+		if ifc.Flags&net.FlagUp == 0 || ifc.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+
+		addrs, _ := ifc.Addrs()
+		for _, a := range addrs {
+			ipnet, ok := a.(*net.IPNet)
+			if !ok || ipnet.IP.To4() == nil {
+				continue
+			}
+
+			bcast := internal.BroadcastAddr(ipnet.IP.To4(), ipnet.Mask)
+			dst := &net.UDPAddr{IP: bcast, Port: 1333}
+
+			_, err = pc.WriteTo(query, dst)
+			if err != nil {
+				fmt.Printf(":: (%s) can't send to  %s: %s\n", ifc.Name, bcast, err.Error())
+			}
+		}
+	}
+	_ = pc.SetDeadline(time.Now().Add(LANDeadline))
+	buf := make([]byte, 1500)
+
+	for {
+		n, addr, err := pc.ReadFrom(buf)
+		if err != nil {
+			break
+		}
+		msg := string(buf[:n])
+
+		if strings.HasPrefix(msg, "H:"+filename) {
+			parts := strings.Split(msg, ":")
+			port, _ := strconv.Atoi(parts[2])
+			peers = append(peers, Peer{IP: addr.(*net.UDPAddr).IP, Port: port})
+		}
+	}
+	return peers, nil
+}
+
+// COBRA CMDS
 var rootCmd = &cobra.Command{Use: "packets"}
-var installCmd = &cobra.Command{}
+var installCmd = &cobra.Command{
+	Use:   "install {package} [packages...]",
+	Short: "Install a package",
+	Args:  cobra.MinimumNArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+
+	},
+}
+
+func main() {
+	rootCmd.AddCommand(installCmd)
+}