changed old manifest.toml to Packet.lua and some improvements for future 100% Packet.lua implementation

pkg/lan.go

@@ -0,0 +1,80 @@
+package packets
+
+import (
+	"fmt"
+	"net"
+	"packets/internal/consts"
+	"strconv"
+	"strings"
+	"time"
+
+	"golang.org/x/net/ipv4"
+)
+
+type Peer struct {
+	IP   net.IP
+	Port int
+}
+
+func BroadcastAddr(ip net.IP, mask net.IPMask) net.IP {
+	b := make(net.IP, len(ip))
+	for i := range ip {
+		b[i] = ip[i] | ^mask[i]
+	}
+	return b
+}
+
+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 := 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(consts.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
+}