97 lines
1.9 KiB
Go
97 lines
1.9 KiB
Go
package node
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import (
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"log"
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"net"
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"time"
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"golang.org/x/crypto/nacl/sign"
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)
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func localDiscovery() {
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conn, err := net.ListenMulticastUDP("udp", nil, multicastAddr)
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if err != nil {
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log.Printf("Failed to bind to multicast address: %v", err)
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return
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}
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go sendLocalDiscovery(conn)
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go recvLocalDiscovery(conn)
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}
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func sendLocalDiscovery(conn *net.UDPConn) {
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var (
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buf1 = make([]byte, bufferSize)
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buf2 = make([]byte, bufferSize)
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)
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for range time.Tick(32 * time.Second) {
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signed := buildLocalDiscoveryPacket(buf1, buf2)
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if _, err := conn.WriteToUDP(signed, multicastAddr); err != nil {
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log.Printf("Failed to write multicast UDP packet: %v", err)
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}
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}
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}
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func recvLocalDiscovery(conn *net.UDPConn) {
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var (
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raw = make([]byte, bufferSize)
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buf = make([]byte, bufferSize)
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)
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for {
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n, remoteAddr, err := conn.ReadFromUDPAddrPort(raw[:bufferSize])
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if err != nil {
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log.Fatalf("Failed to read from UDP port (multicast): %v", err)
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}
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raw = raw[:n]
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h, ok := openLocalDiscoveryPacket(raw, buf)
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if !ok {
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log.Printf("Failed to open discovery packet?")
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continue
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}
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msg := controlMsg[localDiscoveryPacket]{
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SrcIP: h.SourceIP,
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SrcAddr: remoteAddr,
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Packet: localDiscoveryPacket{},
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}
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select {
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case messages[h.SourceIP] <- msg:
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default:
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}
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}
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}
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func buildLocalDiscoveryPacket(buf1, buf2 []byte) []byte {
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h := header{
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StreamID: controlStreamID,
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Counter: 0,
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SourceIP: localIP,
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DestIP: 255,
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}
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out := buf1[:headerSize]
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h.Marshal(out)
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return sign.Sign(buf2[:0], out, (*[64]byte)(privSignKey))
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}
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func openLocalDiscoveryPacket(raw, buf []byte) (h header, ok bool) {
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if len(raw) != headerSize+signOverhead {
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ok = false
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return
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}
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h.Parse(raw[signOverhead:])
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route := routingTable[h.SourceIP].Load()
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if route == nil || route.PubSignKey == nil {
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log.Printf("Missing signing key")
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ok = false
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return
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}
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_, ok = sign.Open(buf[:0], raw, (*[32]byte)(route.PubSignKey))
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return
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}
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