55 lines
1.3 KiB
Go
55 lines
1.3 KiB
Go
package peer
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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 createLocalDiscoveryPacket(localIP byte, signingKey []byte) []byte {
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h := header{
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SourceIP: localIP,
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DestIP: 255,
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}
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buf := make([]byte, headerSize)
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h.Marshal(buf)
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out := make([]byte, headerSize+signOverhead)
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return sign.Sign(out[:0], buf, (*[64]byte)(signingKey))
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}
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func headerFromLocalDiscoveryPacket(pkt []byte) (h header, ok bool) {
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if len(pkt) != headerSize+signOverhead {
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return
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}
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h.Parse(pkt[signOverhead:])
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ok = true
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return
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}
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func verifyLocalDiscoveryPacket(pkt, buf []byte, pubSignKey []byte) bool {
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_, ok := sign.Open(buf[:0], pkt, (*[32]byte)(pubSignKey))
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return ok
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}
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// ----------------------------------------------------------------------------
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func runMCWriter(localIP byte, signingKey []byte) {
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discoveryPacket := createLocalDiscoveryPacket(localIP, signingKey)
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conn, err := net.ListenMulticastUDP("udp", nil, multicastAddr)
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if err != nil {
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log.Fatalf("[MCWriter] Failed to bind to multicast address: %v", err)
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}
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for range time.Tick(broadcastInterval) {
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log.Printf("[MCWriter] Broadcasting on %v...", multicastAddr)
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_, err := conn.WriteToUDP(discoveryPacket, multicastAddr)
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if err != nil {
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log.Printf("[MCWriter] Failed to write multicast: %v", err)
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}
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}
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}
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