stop panics when signaling messages received by ziffy receiver from z…

…iffy sender

Summary:
Ziffy running in receive mode did not process incoming signaling messages (the tool was assuming Ziffy packets being sent were either SYNC or DELAY_REQ)

```
INFO[0000] listening on port 319 for PTP EVENT packets (SYNC/DELAY_REQ) with ZiffyHexa signature. Sending back the packets as icmp
panic: interface conversion: protocol.Packet is *protocol.Announce, not *protocol.SyncDelayReq
goroutine 54 [running]:
github.com/facebook/time/cmd/ziffy/node.parseSyncPacket({0x2d9910, 0xc000304dc0})
	fbcode/time/cmd/ziffy/node/receiver.go:165 +0x1c5
github.com/facebook/time/cmd/ziffy/node.(*Receiver).handlePacket(0xc0001321b0, {0x2d9910, 0xc000304dc0})
	fbcode/time/cmd/ziffy/node/receiver.go:104 +0x78
created by github.com/facebook/time/cmd/ziffy/node.(*Receiver).Start in goroutine 1
	fbcode/time/cmd/ziffy/node/receiver.go:74 +0x392
[[email protected] ~]# dnf install -y fb-ziffy && systemctl stop sptp && ziffy -mode receiver ; systemctl start sptp
Last metadata expiration check: 0:00:37 ago on Thu 10 Oct 2024 13:36:26.
Package fb-ziffy-20241009-213047.x86_64 is already installed.
Dependencies resolved.
```

Reviewed By: abulimov

Differential Revision: D64358486

fbshipit-source-id: dfaa474a1d7c8b938c1b173bc5d43cc94849b541

cmd/ziffy/node/receiver.go

@@ -148,6 +148,7 @@ func (r *Receiver) sendResponse(sourceIP string, rawPacket gopacket.Packet) erro
 	return nil
 }
 
+// parseSyncPacket parses SYNC/DELAY_REQ packets and returns the packet, source IP and source port
 func parseSyncPacket(packet gopacket.Packet) (*ptp.SyncDelayReq, string, string, error) {
 	ipHeader, ok := packet.NetworkLayer().(*layers.IPv6)
 	if !ok {
@@ -160,7 +161,10 @@ func parseSyncPacket(packet gopacket.Packet) (*ptp.SyncDelayReq, string, string,
 
 	ptpPacket, err := ptp.DecodePacket(packet.ApplicationLayer().Payload())
 	if err != nil {
-		return nil, "", "", fmt.Errorf("unable to decode ptp packet: %w", err)
+		return nil, "", "", fmt.Errorf("unable to decode PTP packet: %w", err)
+	}
+	if ptpPacket.MessageType() != ptp.MessageSync && ptpPacket.MessageType() != ptp.MessageDelayReq {
+		return nil, "", "", fmt.Errorf("not parsing %v: not a SYNC/DELAY_REQ packet", ptpPacket.MessageType().String())
 	}
 	return ptpPacket.(*ptp.SyncDelayReq), ipHeader.SrcIP.String(), strconv.Itoa(int(udpHeader.SrcPort)), nil
 }

cmd/ziffy/node/receiver_test.go

@@ -21,13 +21,14 @@ import (
 	"sync"
 	"testing"
 
+	ptp "github.com/facebook/time/ptp/protocol"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 	"github.com/stretchr/testify/require"
 )
 
-// rawPTP packet received from sender
-var rawPTP = []byte{
+// raw PTP packet (SYNC) received from sender
+var syncPTPPacket = []byte{
 	0xb8, 0xce, 0xf6, 0x61, 0x00, 0x80, 0xc2, 0x18, 0x50, 0x09, 0xca, 0x4e, 0x86, 0xdd, 0x60, 0x00,
 	0x00, 0x00, 0x00, 0x36, 0x11, 0x01, 0xfa, 0xce, 0xdb, 0x00, 0xfa, 0xce, 0x12, 0x02, 0xfa, 0xce,
 	0x00, 0x00, 0xfa, 0xce, 0x00, 0xff, 0xfa, 0xce, 0xdb, 0x00, 0xfa, 0xce, 0x26, 0x08, 0xfa, 0xce,
@@ -37,6 +38,17 @@ var rawPTP = []byte{
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 }
 
+// raw PTP packet (Signaling) received from sender
+var signalPTPPacket = []byte{
+	0xb8, 0xce, 0xf6, 0x61, 0x00, 0x80, 0xc2, 0x18, 0x50, 0x09, 0xca, 0x4e, 0x86, 0xdd, 0x60, 0x00,
+	0x00, 0x00, 0x00, 0x36, 0x11, 0x01, 0xfa, 0xce, 0xdb, 0x00, 0xfa, 0xce, 0x14, 0x20, 0xfa, 0xce,
+	0x00, 0x00, 0xfa, 0xce, 0x00, 0xff, 0xfa, 0xce, 0xdb, 0x00, 0xfa, 0xce, 0x26, 0x08, 0xfa, 0xce,
+	0x00, 0x00, 0xfa, 0xce, 0x00, 0xff, 0xd2, 0xfa, 0x01, 0x3f, 0x00, 0x36, 0x51, 0xeb, 0x0c, 0x02,
+	0x00, 0x2c, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x57, 0x10, 0x05, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd2, 0xfa, 0x00, 0x06, 0xff, 0x7f,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+}
+
 func TestIncRunningHandlers(t *testing.T) {
 	r := Receiver{
 		Config:          &Config{PTPRecvHandlers: 2},
@@ -68,7 +80,7 @@ func TestDecRunningHandlers(t *testing.T) {
 }
 
 func TestHandlePacket(t *testing.T) {
-	packet := gopacket.NewPacket(rawPTP, layers.LinkTypeEthernet, gopacket.DecodeOptions{Lazy: true, NoCopy: true})
+	packet := gopacket.NewPacket(syncPTPPacket, layers.LinkTypeEthernet, gopacket.DecodeOptions{Lazy: true, NoCopy: true})
 
 	r := Receiver{
 		Config:          &Config{PTPRecvHandlers: 3},
@@ -86,13 +98,21 @@ func TestHandlePacket(t *testing.T) {
 	require.Equal(t, true, r.incRunningHandlers())
 }
 
-func TestParseSyncPacket(t *testing.T) {
-	packet := gopacket.NewPacket(rawPTP, layers.LinkTypeEthernet, gopacket.DecodeOptions{Lazy: true, NoCopy: true})
+func TestParseSyncPacketOnSyncPacket(t *testing.T) {
+	packet := gopacket.NewPacket(syncPTPPacket, layers.LinkTypeEthernet, gopacket.DecodeOptions{Lazy: true, NoCopy: true})
 
 	ptpPacket, srcIP, srcPort, err := parseSyncPacket(packet)
 	require.Nil(t, err)
 	require.Equal(t, uint8(ZiffyHexa), ptpPacket.ControlField)
+	require.Equal(t, ptp.MessageSync, ptpPacket.MessageType())
 	require.Equal(t, "face:db00:face:1202:face:0:face:ff", srcIP)
 	require.Equal(t, strconv.Itoa(32770), srcPort)
 	require.Equal(t, uint16(32770), ptpPacket.SourcePortIdentity.PortNumber)
 }
+
+func TestParseSyncPacketOnSignalPacket(t *testing.T) {
+	packet := gopacket.NewPacket(signalPTPPacket, layers.LinkTypeEthernet, gopacket.DecodeOptions{Lazy: true, NoCopy: true})
+
+	_, _, _, err := parseSyncPacket(packet)
+	require.NotNil(t, err)
+}