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discovery.go
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discovery.go
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package main
import (
"bufio"
"context"
"encoding/binary"
"fmt"
"log"
"net"
"github.com/libp2p/go-libp2p/core/host"
"github.com/libp2p/go-libp2p/core/network"
"github.com/libp2p/go-libp2p/core/peer"
)
func discoveryHandler(stream network.Stream) {
defer stream.Close()
packetSize := make([]byte, 4)
for {
if _, err := stream.Read(packetSize); err != nil {
log.Printf("Error reading length from stream: %v\n", err)
return
}
address := make([]byte, binary.BigEndian.Uint32(packetSize))
if _, err := stream.Read(address); err != nil {
log.Printf("Error reading message from stream: %v\n", err)
return
}
ip, _, err := net.ParseCIDR(string(address))
if err != nil {
return
}
PeerTable[ip.String()] = stream.Conn().RemotePeer()
}
}
func discoveryWriter(ctx context.Context, h host.Host, address string, p peer.AddrInfo) error {
stream, err := h.NewStream(ctx, p.ID, DiscoveryProtocol.ID())
if err != nil {
return fmt.Errorf("Stream open failed %s: %w", p.ID, err)
}
defer stream.Close()
packetSize := make([]byte, 4)
binary.BigEndian.PutUint32(packetSize, uint32(len(address)))
writer := bufio.NewWriter(stream)
if _, err := writer.Write(packetSize); err != nil {
return fmt.Errorf("Error sending message length: %w", err)
}
if _, err := writer.WriteString(address); err != nil {
return fmt.Errorf("Error sending message: %w", err)
}
if err := writer.Flush(); err != nil {
return fmt.Errorf("Error flushing writer: %w", err)
}
return nil
}