basic data packet handling

srt/data_chain.go

@@ -0,0 +1,116 @@
+package srt
+
+import (
+	"math"
+	"sort"
+)
+
+type Datum struct {
+	seq_num uint32
+	data []byte
+	next *Datum
+}
+
+type DatumLink struct {
+	queued int
+	root *Datum
+	end *Datum
+}
+
+type chains []*DatumLink
+
+func (c chains) Len() (int) {
+	return len(c)
+}
+
+func (c chains) Swap(i, j int) {
+	c[i], c[j] = c[j], c[i]
+}
+
+func (c chains) Less(i, j int) (bool) {
+	x_1 := c[i].end.seq_num
+	x_2 := c[j].root.seq_num
+	serial_add_limit := uint32(math.Pow(2, 30))
+	if (x_1 < x_2 && x_2 - x_1 < serial_add_limit) || (x_1 > x_2 && x_1 - x_2 > serial_add_limit) {
+		return true
+	}
+	return false
+}
+
+type DatumStorage struct {
+	main *DatumLink
+	offshoots chains
+}
+
+func (buffer *DatumLink) NewDatum(pkt *Packet) {
+	datum := new(Datum)
+	datum.seq_num = pkt.header_info.(*DataHeader).seq_num
+	datum.data = pkt.cif.([]byte)
+
+	buffer.queued += 1
+	buffer.end.next = datum
+	buffer.end = datum
+}
+
+func NewDatumLink(pkt *Packet) (*DatumLink) {
+	buffer := new(DatumLink)
+	root_datum := new(Datum)
+	root_datum.seq_num = pkt.header_info.(*DataHeader).seq_num
+	root_datum.data = pkt.cif.([]byte)
+
+	buffer.root = root_datum
+	buffer.end = root_datum
+	buffer.queued = 1
+	return buffer
+}
+
+func NewDatumStorage(packet *Packet) (*DatumStorage) {
+	storage := new(DatumStorage)
+	storage.main = NewDatumLink(packet)
+	return storage
+}
+
+func (storage *DatumStorage) NewDatum(pkt *Packet) {
+	prev_num := (pkt.header_info.(*DataHeader).seq_num - 1) % uint32(math.Pow(2, 31))
+	if storage.main.end.seq_num == prev_num {
+		storage.main.NewDatum(pkt)
+	} else {
+		for _, v := range storage.offshoots {
+			if v.end.seq_num == prev_num {
+				v.NewDatum(pkt)
+				break
+			}
+		}
+	}
+}
+
+func (buffer *DatumLink) Link(buffer_next *DatumLink) {
+	buffer.end.next = buffer_next.root
+	buffer.end = buffer_next.end
+	buffer.queued += buffer_next.queued
+}
+
+func check_append_serial_next(buffer *DatumLink, buffer_next *DatumLink) (bool) {
+	seq_1 := buffer.end.seq_num
+	seq_2 := (seq_1 + 1) % uint32(math.Pow(2, 31))
+	if seq_1 == seq_2 {
+		buffer.Link(buffer_next)
+		return true
+	}
+	return false
+}
+
+func (storage *DatumStorage) Relink() {
+	sort.Sort(storage.offshoots)
+	buffer := storage.main
+	i := 0
+	for i < len(storage.offshoots) {
+		if check_append_serial_next(buffer, storage.offshoots[i]) {
+			storage.offshoots = append(storage.offshoots[:i], storage.offshoots[i + 1:]...)
+		} else {
+			buffer = storage.offshoots[i]
+			i++
+		}
+	}
+}
+

srt/intake.go

@@ -26,7 +26,7 @@ func (intake *Intake) NewTunnel(l net.PacketConn, peer net.Addr) (*Tunnel) {
 		tunnel := new(Tunnel)
 		tunnel.socket = l
 		tunnel.peer = peer
-		tunnel.queue = make(chan []byte, 10)
+		tunnel.queue = make(chan []byte, 100)
 		intake.tunnels = append(intake.tunnels, tunnel)
 		go tunnel.Start()
 		return tunnel
@@ -38,6 +38,7 @@ func (intake *Intake) get_tunnel(peer net.Addr) (*Tunnel) {
 	var tunnel *Tunnel
 	for i := 0; i < len(intake.tunnels); i++ {
 		if intake.tunnels[i].broken {
+			intake.tunnels[i].Shutdown()
 			intake.tunnels = append(intake.tunnels[:i], intake.tunnels[i+1:]...)
 			i--
 			continue
@@ -52,6 +53,8 @@ func (intake *Intake) get_tunnel(peer net.Addr) (*Tunnel) {
 	return tunnel
 }
 
+
+
 func (intake *Intake) Read() {
 	n, peer, err := intake.socket.ReadFrom(intake.buffer)
 	if err != nil {

srt/packet.go

@@ -118,6 +118,10 @@ func marshall_ctrl_packet(packet *Packet, header []byte) ([]byte, error) {
 		}
 		cif := marshall_hs_cif(data)
 		return append(header, cif...), nil
+	case SHUTDOWN:
+		header[1] |= 5
+		cif := make([]byte, 4)
+		return append(header, cif...), nil
 	}
 	return header, errors.New("Control packet type not recognized")
 }

srt/protocol.go

@@ -20,12 +20,15 @@ type SRTManager struct {
 	syn_cookie uint32
 	socket net.PacketConn
 	ctrl_sock_peer uint32
+	storage *DatumStorage
+	ack_interval uint8
 }
 
 func NewSRTManager(l net.PacketConn) (*SRTManager) {
 	agent := new(SRTManager)
 	agent.init = time.Now()
 	agent.socket = l
+	agent.ack_interval = 25
 	return agent
 }
 
@@ -72,16 +75,16 @@ func (agent *SRTManager) make_syn_cookie(peer net.Addr) {
 	}
 }
 
-func (agent *SRTManager) process_induction(packet *Packet) (*Packet) {
+func (agent *SRTManager) process_induction(packet *Packet) (*Packet, error) {
 	if packet.packet_type == HANDSHAKE {
 		hs_cif := packet.cif.(*HandshakeCIF)
 		if hs_cif.hs_type == 1 {
 			agent.state = CONCLUSION
 			agent.ctrl_sock_peer = hs_cif.sock_id
-			return agent.create_induction_resp()
+			return agent.create_induction_resp(), nil
 		}
 	}
-	return nil
+	return nil, errors.New("Packet was not handshake")
 }
 
 func (agent *SRTManager) create_conclusion_resp() (*Packet) {
@@ -131,15 +134,42 @@ func (agent *SRTManager) process_conclusion(packet *Packet) (*Packet) {
 	return nil
 }
 
+func (agent *SRTManager) create_ack_report() (*Packet) {
+	return nil
+}
+
+func (agent *SRTManager) process_data(packet *Packet) (*Packet) {
+	switch packet.packet_type {
+	case DATA:
+		agent.handle_data_storage(packet)
+		if agent.storage.main.queued >= 25 {
+			return agent.create_ack_report()
+		}
+	default:
+		return nil
+	}
+	return nil
+}
+
+func (agent *SRTManager) handle_data_storage(packet *Packet) {
+	if agent.storage == nil {
+		agent.storage = NewDatumStorage(packet)
+	} else {
+		agent.storage.NewDatum(packet)
+	}
+	if len(agent.storage.offshoots) != 0 {
+		agent.storage.Relink()
+	}
+}
+
 func (agent *SRTManager) Process(packet *Packet) (*Packet, error) {
 	switch agent.state {
 	case INDUCTION:
-		return agent.process_induction(packet), nil
+		return agent.process_induction(packet)
 	case CONCLUSION:
 		return agent.process_conclusion(packet), nil
 	case DATA_LOOP:
-		fmt.Println(packet)
+		return agent.process_data(packet), nil
-		return nil, nil
 	default:
 		return nil, errors.New("State not implemented")
 	}

srt/server.go

@@ -2,6 +2,7 @@ package srt
 
 import (
 	"net"
+	"fmt"
 )
 
 func NewServer(port string) (error) {
@@ -14,6 +15,11 @@ func NewServer(port string) (error) {
 }
 
 func start(l net.PacketConn) {
+	defer func() {
+		if r := recover(); r != nil {
+			fmt.Println(r)
+		}
+	}()
 	intake := NewIntake(l, 1)
 	for {
 		intake.Read()

srt/tunnel.go

@@ -21,7 +21,6 @@ func (tunnel *Tunnel) Start() {
 		*a = true
 	}(&(tunnel.broken))
 	tunnel.state = NewSRTManager(tunnel.socket)
-	tunnel.state.make_syn_cookie(tunnel.peer)
 	for {
 		packet, err := tunnel.ReadPacket()
 		if err != nil {
@@ -29,6 +28,7 @@ func (tunnel *Tunnel) Start() {
 		}
 		response, err := tunnel.state.Process(packet)
 		if err != nil {
+			fmt.Println(err)
 			tunnel.broken = true
 		}
 		if response != nil {
@@ -37,10 +37,22 @@ func (tunnel *Tunnel) Start() {
 	}
 }
 
+func (tunnel *Tunnel) Shutdown() {
+	if tunnel.state != nil && tunnel.state.state > 1 {
+		packet := tunnel.state.create_basic_header()
+		packet.packet_type = SHUTDOWN
+		info := new(ControlHeader)
+		info.ctrl_type = 5
+		packet.header_info = info
+		tunnel.WritePacket(packet)
+	}
+}
+
 func (tunnel *Tunnel) WritePacket(packet *Packet) {
 	buffer, err := MarshallPacket(packet, tunnel.state)
 	if err != nil {
 		tunnel.broken = true
+		fmt.Println(err)
 		return
 	}
 	tunnel.socket.WriteTo(buffer, tunnel.peer)