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-rw-r--r--transport/mesh/discovery.go332
1 files changed, 332 insertions, 0 deletions
diff --git a/transport/mesh/discovery.go b/transport/mesh/discovery.go
new file mode 100644
index 0000000..2cfad32
--- /dev/null
+++ b/transport/mesh/discovery.go
@@ -0,0 +1,332 @@
+// Package mesh - Peer discovery for military mesh networking
+package mesh
+
+import (
+ "encoding/json"
+ "fmt"
+ "net"
+ "sync"
+ "time"
+)
+
+// PeerDiscovery manages automatic peer discovery via mDNS and UDP broadcast
+type PeerDiscovery struct {
+ localPeer *PeerInfo
+ discoveredPeers map[string]*PeerInfo // address -> peer info
+ mu sync.RWMutex
+ udpConn *net.UDPConn
+ running bool
+ onPeerFound func(*PeerInfo) // Callback when new peer found
+ onPeerLost func(string) // Callback when peer lost
+}
+
+// PeerInfo contains information about a discovered peer
+type PeerInfo struct {
+ Address string `json:"address"` // IP:Port
+ PublicKey string `json:"public_key"` // Ed25519 public key hex
+ Nickname string `json:"nickname"` // Optional display name
+ Timestamp time.Time `json:"timestamp"` // Last seen
+ IsRelay bool `json:"is_relay"` // Can relay messages?
+ Hops int `json:"hops"` // Distance in hops
+}
+
+// DiscoveryConfig holds peer discovery configuration
+type DiscoveryConfig struct {
+ BroadcastPort int // UDP broadcast port
+ BroadcastInterval time.Duration // How often to announce
+ PeerTimeout time.Duration // Remove peer if not seen
+ EnableMDNS bool // Use mDNS (Bonjour)
+ EnableBroadcast bool // Use UDP broadcast
+}
+
+// NewPeerDiscovery creates a new peer discovery instance
+func NewPeerDiscovery(localPeer *PeerInfo, config *DiscoveryConfig) (*PeerDiscovery, error) {
+ if config == nil {
+ config = &DiscoveryConfig{
+ BroadcastPort: 9876,
+ BroadcastInterval: 10 * time.Second,
+ PeerTimeout: 60 * time.Second,
+ EnableBroadcast: true,
+ EnableMDNS: false, // mDNS requires external library
+ }
+ }
+
+ pd := &PeerDiscovery{
+ localPeer: localPeer,
+ discoveredPeers: make(map[string]*PeerInfo),
+ }
+
+ // Setup UDP broadcast listener
+ if config.EnableBroadcast {
+ addr := &net.UDPAddr{
+ IP: net.IPv4zero,
+ Port: config.BroadcastPort,
+ }
+
+ conn, err := net.ListenUDP("udp4", addr)
+ if err != nil {
+ return nil, fmt.Errorf("failed to create UDP listener: %w", err)
+ }
+
+ pd.udpConn = conn
+ }
+
+ return pd, nil
+}
+
+// Start starts peer discovery
+func (pd *PeerDiscovery) Start(config *DiscoveryConfig) error {
+ pd.mu.Lock()
+ if pd.running {
+ pd.mu.Unlock()
+ return fmt.Errorf("discovery already running")
+ }
+ pd.running = true
+ pd.mu.Unlock()
+
+ if config == nil {
+ config = &DiscoveryConfig{
+ BroadcastPort: 9876,
+ BroadcastInterval: 10 * time.Second,
+ PeerTimeout: 60 * time.Second,
+ EnableBroadcast: true,
+ }
+ }
+
+ // Start UDP broadcast announcer
+ if config.EnableBroadcast {
+ go pd.broadcastAnnouncer(config)
+ go pd.broadcastListener(config)
+ }
+
+ // Start peer timeout checker
+ go pd.peerTimeoutChecker(config)
+
+ return nil
+}
+
+// Stop stops peer discovery
+func (pd *PeerDiscovery) Stop() error {
+ pd.mu.Lock()
+ defer pd.mu.Unlock()
+
+ if !pd.running {
+ return nil
+ }
+
+ pd.running = false
+
+ if pd.udpConn != nil {
+ pd.udpConn.Close()
+ }
+
+ return nil
+}
+
+// broadcastAnnouncer periodically broadcasts our presence
+func (pd *PeerDiscovery) broadcastAnnouncer(config *DiscoveryConfig) {
+ ticker := time.NewTicker(config.BroadcastInterval)
+ defer ticker.Stop()
+
+ for {
+ pd.mu.RLock()
+ if !pd.running {
+ pd.mu.RUnlock()
+ return
+ }
+ pd.mu.RUnlock()
+
+ <-ticker.C
+
+ // Create announcement message
+ announcement := map[string]interface{}{
+ "type": "peer_announcement",
+ "address": pd.localPeer.Address,
+ "public_key": pd.localPeer.PublicKey,
+ "nickname": pd.localPeer.Nickname,
+ "is_relay": pd.localPeer.IsRelay,
+ "timestamp": time.Now().Unix(),
+ }
+
+ data, err := json.Marshal(announcement)
+ if err != nil {
+ continue
+ }
+
+ // Broadcast to LAN
+ broadcastAddr := &net.UDPAddr{
+ IP: net.IPv4bcast,
+ Port: config.BroadcastPort,
+ }
+
+ conn, err := net.DialUDP("udp4", nil, broadcastAddr)
+ if err != nil {
+ continue
+ }
+
+ conn.Write(data)
+ conn.Close()
+ }
+}
+
+// broadcastListener listens for peer announcements
+func (pd *PeerDiscovery) broadcastListener(config *DiscoveryConfig) {
+ buf := make([]byte, 4096)
+
+ for {
+ pd.mu.RLock()
+ if !pd.running {
+ pd.mu.RUnlock()
+ return
+ }
+ pd.mu.RUnlock()
+
+ // Set read deadline to allow periodic checks
+ pd.udpConn.SetReadDeadline(time.Now().Add(1 * time.Second))
+
+ n, remoteAddr, err := pd.udpConn.ReadFromUDP(buf)
+ if err != nil {
+ if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
+ continue // Timeout is expected
+ }
+ continue
+ }
+
+ // Parse announcement
+ var announcement map[string]interface{}
+ if err := json.Unmarshal(buf[:n], &announcement); err != nil {
+ continue
+ }
+
+ // Ignore our own announcements
+ if announcement["address"] == pd.localPeer.Address {
+ continue
+ }
+
+ // Extract peer info
+ peerInfo := &PeerInfo{
+ Address: fmt.Sprintf("%v", announcement["address"]),
+ PublicKey: fmt.Sprintf("%v", announcement["public_key"]),
+ Nickname: fmt.Sprintf("%v", announcement["nickname"]),
+ Timestamp: time.Now(),
+ IsRelay: announcement["is_relay"].(bool),
+ Hops: 1, // Direct peer
+ }
+
+ // If address is missing, use source address
+ if peerInfo.Address == "" || peerInfo.Address == "<nil>" {
+ peerInfo.Address = remoteAddr.IP.String()
+ }
+
+ pd.addPeer(peerInfo)
+ }
+}
+
+// addPeer adds or updates a discovered peer
+func (pd *PeerDiscovery) addPeer(peer *PeerInfo) {
+ pd.mu.Lock()
+ defer pd.mu.Unlock()
+
+ isNew := false
+ if _, exists := pd.discoveredPeers[peer.Address]; !exists {
+ isNew = true
+ }
+
+ pd.discoveredPeers[peer.Address] = peer
+
+ // Call callback if new peer
+ if isNew && pd.onPeerFound != nil {
+ go pd.onPeerFound(peer)
+ }
+}
+
+// peerTimeoutChecker removes stale peers
+func (pd *PeerDiscovery) peerTimeoutChecker(config *DiscoveryConfig) {
+ ticker := time.NewTicker(config.PeerTimeout / 2)
+ defer ticker.Stop()
+
+ for {
+ pd.mu.RLock()
+ if !pd.running {
+ pd.mu.RUnlock()
+ return
+ }
+ pd.mu.RUnlock()
+
+ <-ticker.C
+
+ pd.mu.Lock()
+ now := time.Now()
+ for addr, peer := range pd.discoveredPeers {
+ if now.Sub(peer.Timestamp) > config.PeerTimeout {
+ delete(pd.discoveredPeers, addr)
+
+ // Call callback
+ if pd.onPeerLost != nil {
+ go pd.onPeerLost(addr)
+ }
+ }
+ }
+ pd.mu.Unlock()
+ }
+}
+
+// GetPeers returns all discovered peers
+func (pd *PeerDiscovery) GetPeers() []*PeerInfo {
+ pd.mu.RLock()
+ defer pd.mu.RUnlock()
+
+ peers := make([]*PeerInfo, 0, len(pd.discoveredPeers))
+ for _, peer := range pd.discoveredPeers {
+ peers = append(peers, peer)
+ }
+ return peers
+}
+
+// GetPeerCount returns the number of discovered peers
+func (pd *PeerDiscovery) GetPeerCount() int {
+ pd.mu.RLock()
+ defer pd.mu.RUnlock()
+ return len(pd.discoveredPeers)
+}
+
+// SetOnPeerFound sets callback for when new peer is discovered
+func (pd *PeerDiscovery) SetOnPeerFound(callback func(*PeerInfo)) {
+ pd.mu.Lock()
+ defer pd.mu.Unlock()
+ pd.onPeerFound = callback
+}
+
+// SetOnPeerLost sets callback for when peer is lost
+func (pd *PeerDiscovery) SetOnPeerLost(callback func(string)) {
+ pd.mu.Lock()
+ defer pd.mu.Unlock()
+ pd.onPeerLost = callback
+}
+
+// FindPeerByPublicKey finds a peer by their public key
+func (pd *PeerDiscovery) FindPeerByPublicKey(publicKey string) (*PeerInfo, bool) {
+ pd.mu.RLock()
+ defer pd.mu.RUnlock()
+
+ for _, peer := range pd.discoveredPeers {
+ if peer.PublicKey == publicKey {
+ return peer, true
+ }
+ }
+ return nil, false
+}
+
+// String returns a string representation
+func (pd *PeerDiscovery) String() string {
+ pd.mu.RLock()
+ defer pd.mu.RUnlock()
+
+ status := "stopped"
+ if pd.running {
+ status = "running"
+ }
+
+ return fmt.Sprintf("PeerDiscovery(status=%s, peers=%d)",
+ status, len(pd.discoveredPeers))
+}
generated by cgit v1.2.3 (git 2.39.1) at 2026-07-13 02:11:51 +0000