Add channel handling to Link struct; implement methods for managing incoming channel packets, resource advertisements, and packet delivery. Enhance initialization with IncomingLinkHandler registration and improve error handling for resource requests.

pkg/link/link.go

@@ -13,6 +13,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/Sudo-Ivan/reticulum-go/pkg/channel"
 	"github.com/Sudo-Ivan/reticulum-go/pkg/common"
 	"github.com/Sudo-Ivan/reticulum-go/pkg/cryptography"
 	"github.com/Sudo-Ivan/reticulum-go/pkg/debug"
@@ -65,6 +66,16 @@ const (
 	WATCHDOG_INTERVAL  = 0.1
 )
 
+func init() {
+	destination.RegisterIncomingLinkHandler(func(pkt *packet.Packet, dest *destination.Destination, trans interface{}, networkIface common.NetworkInterface) (interface{}, error) {
+		transportObj, ok := trans.(*transport.Transport)
+		if !ok {
+			return nil, errors.New("invalid transport type")
+		}
+		return HandleIncomingLinkRequest(pkt, dest, transportObj, networkIface)
+	})
+}
+
 type Link struct {
 	mutex            sync.RWMutex
 	destination      *destination.Destination
@@ -127,6 +138,9 @@ type Link struct {
 
 	pendingRequests []*RequestReceipt
 	requestMutex    sync.RWMutex
+
+	channel      *channel.Channel
+	channelMutex sync.RWMutex
 }
 
 func NewLink(dest *destination.Destination, transport *transport.Transport, networkIface common.NetworkInterface, establishedCallback func(*Link), closedCallback func(*Link)) *Link {
@@ -691,7 +705,7 @@ func (l *Link) handleDataPacket(pkt *packet.Packet) error {
 	case packet.ContextResponse:
 		return l.handleResponse(plaintext)
 	case packet.ContextLinkIdentify:
-		return l.handleIdentification(plaintext)
+		return l.HandleIdentification(plaintext)
 	case packet.ContextKeepalive:
 		if !l.initiator && len(plaintext) == 1 && plaintext[0] == 0xFF {
 			keepaliveResp := []byte{0xFE}
@@ -737,6 +751,35 @@ func (l *Link) handleDataPacket(pkt *packet.Packet) error {
 		return l.handleResourceReject(pkt)
 	case packet.ContextResource:
 		return l.handleResourcePart(pkt)
+	case packet.ContextChannel:
+		return l.handleChannelPacket(pkt)
+	}
+
+	return nil
+}
+
+func (l *Link) GetChannel() *channel.Channel {
+	l.channelMutex.Lock()
+	defer l.channelMutex.Unlock()
+
+	if l.channel == nil {
+		l.channel = channel.NewChannel(l)
+	}
+	return l.channel
+}
+
+func (l *Link) handleChannelPacket(pkt *packet.Packet) error {
+	plaintext, err := l.decrypt(pkt.Data)
+	if err != nil {
+		return err
+	}
+
+	l.channelMutex.RLock()
+	ch := l.channel
+	l.channelMutex.RUnlock()
+
+	if ch != nil {
+		return ch.HandleInbound(plaintext)
 	}
 
 	return nil
@@ -748,6 +791,48 @@ func (l *Link) handleResourceAdvertisement(pkt *packet.Packet) error {
 		return err
 	}
 
+	adv, err := resource.UnpackResourceAdvertisement(plaintext)
+	if err != nil {
+		debug.Log(debug.DEBUG_INFO, "Failed to unpack resource advertisement", "error", err)
+		return err
+	}
+
+	if resource.IsRequestAdvertisement(plaintext) {
+		requestID := resource.ReadRequestID(plaintext)
+		if l.destination != nil {
+			handler := l.destination.GetRequestHandler(requestID)
+			if handler != nil {
+				response := handler(requestID, nil, requestID, l.remoteIdentity, time.Now())
+				if response != nil {
+					return l.sendResourceResponse(requestID, response)
+				}
+			}
+		}
+		return nil
+	}
+
+	if resource.IsResponseAdvertisement(plaintext) {
+		requestID := resource.ReadRequestID(plaintext)
+		l.requestMutex.Lock()
+		for i, req := range l.pendingRequests {
+			if string(req.requestID) == string(requestID) {
+				req.mutex.Lock()
+				req.status = STATUS_ACTIVE
+				req.receivedAt = time.Now()
+				req.mutex.Unlock()
+
+				if req.responseCb != nil {
+					go req.responseCb(req)
+				}
+
+				l.pendingRequests = append(l.pendingRequests[:i], l.pendingRequests[i+1:]...)
+				break
+			}
+		}
+		l.requestMutex.Unlock()
+		return nil
+	}
+
 	if l.resourceStrategy == ACCEPT_NONE {
 		return nil
 	}
@@ -756,20 +841,100 @@ func (l *Link) handleResourceAdvertisement(pkt *packet.Packet) error {
 	if l.resourceStrategy == ACCEPT_ALL {
 		allowed = true
 	} else if l.resourceStrategy == ACCEPT_APP && l.resourceCallback != nil {
-		allowed = l.resourceCallback(plaintext)
+		allowed = l.resourceCallback(adv)
 	}
 
 	if allowed {
 		if l.resourceStartedCallback != nil {
-			l.resourceStartedCallback(plaintext)
+			l.resourceStartedCallback(adv)
 		}
 	} else {
+		_ = l.rejectResource(adv.Hash) // #nosec G104 - best effort resource rejection
 		debug.Log(debug.DEBUG_INFO, "Resource advertisement rejected")
 	}
 
 	return nil
 }
 
+func (l *Link) rejectResource(resourceHash []byte) error {
+	rejectPkt := &packet.Packet{
+		HeaderType:      packet.HeaderType1,
+		PacketType:      packet.PacketTypeData,
+		TransportType:   0,
+		Context:         packet.ContextResourceRCL,
+		ContextFlag:     packet.FlagUnset,
+		Hops:            0,
+		DestinationType: 0x03,
+		DestinationHash: l.linkID,
+		Data:            resourceHash,
+		CreateReceipt:   false,
+	}
+	encrypted, err := l.encrypt(resourceHash)
+	if err != nil {
+		return err
+	}
+	rejectPkt.Data = encrypted
+	if err := rejectPkt.Pack(); err != nil {
+		return err
+	}
+	l.lastOutbound = time.Now()
+	return l.transport.SendPacket(rejectPkt)
+}
+
+func (l *Link) sendResourceResponse(requestID []byte, response interface{}) error {
+	resData, ok := response.([]byte)
+	if !ok {
+		return errors.New("response must be []byte")
+	}
+
+	res, err := resource.New(resData, false)
+	if err != nil {
+		return fmt.Errorf("failed to create resource: %w", err)
+	}
+
+	res.SetRequestID(requestID)
+	res.SetIsResponse(true)
+
+	return l.sendResourceAdvertisement(res)
+}
+
+func (l *Link) sendResourceAdvertisement(res *resource.Resource) error {
+	adv := resource.NewResourceAdvertisement(res)
+	if adv == nil {
+		return errors.New("failed to create resource advertisement")
+	}
+
+	advData, err := adv.Pack(0)
+	if err != nil {
+		return fmt.Errorf("failed to pack advertisement: %w", err)
+	}
+
+	encrypted, err := l.encrypt(advData)
+	if err != nil {
+		return err
+	}
+
+	advPkt := &packet.Packet{
+		HeaderType:      packet.HeaderType1,
+		PacketType:      packet.PacketTypeData,
+		TransportType:   0,
+		Context:         packet.ContextResourceAdv,
+		ContextFlag:     packet.FlagUnset,
+		Hops:            0,
+		DestinationType: 0x03,
+		DestinationHash: l.linkID,
+		Data:            encrypted,
+		CreateReceipt:   false,
+	}
+
+	if err := advPkt.Pack(); err != nil {
+		return err
+	}
+
+	l.lastOutbound = time.Now()
+	return l.transport.SendPacket(advPkt)
+}
+
 func (l *Link) handleResourceRequest(pkt *packet.Packet) error {
 	plaintext, err := l.decrypt(pkt.Data)
 	if err != nil {
@@ -1099,6 +1264,10 @@ func (l *Link) GetRTT() float64 {
 	return l.rtt
 }
 
+func (l *Link) RTT() float64 {
+	return l.GetRTT()
+}
+
 func (l *Link) SetRTT(rtt float64) {
 	l.mutex.Lock()
 	defer l.mutex.Unlock()
@@ -1111,6 +1280,67 @@ func (l *Link) GetStatus() byte {
 	return l.status
 }
 
+func (l *Link) Send(data []byte) interface{} {
+	pkt := &packet.Packet{
+		HeaderType:      packet.HeaderType1,
+		PacketType:      packet.PacketTypeData,
+		TransportType:   0,
+		Context:         packet.ContextChannel,
+		ContextFlag:     packet.FlagUnset,
+		Hops:            0,
+		DestinationType: 0x03,
+		DestinationHash: l.linkID,
+		Data:            data,
+		CreateReceipt:   false,
+	}
+
+	encrypted, err := l.encrypt(data)
+	if err != nil {
+		return nil
+	}
+	pkt.Data = encrypted
+
+	if err := pkt.Pack(); err != nil {
+		return nil
+	}
+
+	l.lastOutbound = time.Now()
+	if err := l.transport.SendPacket(pkt); err != nil {
+		return nil
+	}
+
+	return pkt
+}
+
+func (l *Link) SetPacketTimeout(pkt interface{}, callback func(interface{}), timeout time.Duration) {
+	if packetObj, ok := pkt.(*packet.Packet); ok {
+		go func() {
+			time.Sleep(timeout)
+			if callback != nil {
+				callback(packetObj)
+			}
+		}()
+	}
+}
+
+func (l *Link) SetPacketDelivered(pkt interface{}, callback func(interface{})) {
+	if callback != nil {
+		go callback(pkt)
+	}
+}
+
+func (l *Link) Resend(pkt interface{}) error {
+	packetObj, ok := pkt.(*packet.Packet)
+	if !ok {
+		return errors.New("invalid packet type")
+	}
+
+	if err := l.transport.SendPacket(packetObj); err != nil {
+		return err
+	}
+	return nil
+}
+
 func (l *Link) GetLinkID() []byte {
 	l.mutex.RLock()
 	defer l.mutex.RUnlock()
@@ -1362,7 +1592,7 @@ func (l *Link) watchdog() {
 				if l.initiator {
 					lastKeepalive := l.lastOutbound
 					if now.After(lastKeepalive.Add(l.keepalive)) {
-						l.sendKeepalive()
+						_ = l.sendKeepalive() // #nosec G104 - best effort keepalive
 					}
 				}
 
@@ -1378,7 +1608,7 @@ func (l *Link) watchdog() {
 			}
 		} else if l.status == STATUS_STALE {
 			sleepTime = 0.001
-			l.sendTeardownPacket()
+			_ = l.sendTeardownPacket() // #nosec G104 - best effort teardown
 			l.status = STATUS_CLOSED
 			l.teardownReason = STATUS_FAILED
 			if l.closedCallback != nil {