From 8fcef413a2c9d600dcd0f9125727ab29f4b5bf49 Mon Sep 17 00:00:00 2001
From: Nils Weiss <nils@dissecto.com>
Date: Wed, 13 Dec 2023 21:39:50 +0100
Subject: [PATCH 1/3] Use aux data in NativeCANSocket to determine timestamp of
 packet

---
 scapy/contrib/cansocket_native.py          | 33 ++++++++++++++++++----
 scapy/contrib/isotp/isotp_native_socket.py |  2 +-
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/scapy/contrib/cansocket_native.py b/scapy/contrib/cansocket_native.py
index ba9ef0ff440..49efacd457c 100644
--- a/scapy/contrib/cansocket_native.py
+++ b/scapy/contrib/cansocket_native.py
@@ -15,11 +15,11 @@
 import time
 
 from scapy.config import conf
+from scapy.data import SO_TIMESTAMPNS
 from scapy.supersocket import SuperSocket
-from scapy.error import Scapy_Exception, warning
+from scapy.error import Scapy_Exception, warning, log_runtime
 from scapy.packet import Packet
 from scapy.layers.can import CAN, CAN_MTU, CAN_FD_MTU
-from scapy.arch.linux import get_last_packet_timestamp
 from scapy.compat import raw
 
 from typing import (
@@ -84,6 +84,20 @@ def __init__(self,
                 "Could not modify receive own messages (%s)", exception
             )
 
+        try:
+            # Receive Auxiliary Data (Timestamps)
+            self.ins.setsockopt(
+                socket.SOL_SOCKET,
+                SO_TIMESTAMPNS,
+                1
+            )
+            self.auxdata_available = True
+        except OSError:
+            # Note: Auxiliary Data is only supported since
+            #       Linux 2.6.21
+            msg = "Your Linux Kernel does not support Auxiliary Data!"
+            log_runtime.info(msg)
+
         if self.fd:
             try:
                 self.ins.setsockopt(socket.SOL_CAN_RAW,
@@ -118,8 +132,9 @@ def recv_raw(self, x=CAN_MTU):
         # type: (int) -> Tuple[Optional[Type[Packet]], Optional[bytes], Optional[float]]  # noqa: E501
         """Returns a tuple containing (cls, pkt_data, time)"""
         pkt = None
+        ts = None
         try:
-            pkt = self.ins.recv(self.MTU)
+            pkt, _, ts = self._recv_raw(self.ins, self.MTU)
         except BlockingIOError:  # noqa: F821
             warning("Captured no data, socket in non-blocking mode.")
         except socket.timeout:
@@ -130,14 +145,22 @@ def recv_raw(self, x=CAN_MTU):
 
         # need to change the byte order of the first four bytes,
         # required by the underlying Linux SocketCAN frame format
-        if not conf.contribs['CAN']['swap-bytes'] and pkt is not None:
+        if not conf.contribs['CAN']['swap-bytes'] and pkt:
             pack_fmt = "<I%ds" % (len(pkt) - 4)
             unpack_fmt = ">I%ds" % (len(pkt) - 4)
             pkt = struct.pack(pack_fmt, *struct.unpack(unpack_fmt, pkt))
-        return self.basecls, pkt, get_last_packet_timestamp(self.ins)
+
+        if pkt and ts is None:
+            from scapy.arch.linux import get_last_packet_timestamp
+            ts = get_last_packet_timestamp(self.ins)
+
+        return self.basecls, pkt, ts
 
     def send(self, x):
         # type: (Packet) -> int
+        if x is None:
+            return 0
+
         try:
             x.sent_time = time.time()
         except AttributeError:
diff --git a/scapy/contrib/isotp/isotp_native_socket.py b/scapy/contrib/isotp/isotp_native_socket.py
index 7718365c954..127e91f6d0e 100644
--- a/scapy/contrib/isotp/isotp_native_socket.py
+++ b/scapy/contrib/isotp/isotp_native_socket.py
@@ -390,7 +390,7 @@ def recv_raw(self, x=0xffff):
                 self.close()
             return None, None, None
 
-        if ts is None:
+        if pkt and ts is None:
             ts = get_last_packet_timestamp(self.ins)
         return self.basecls, pkt, ts
 

From 8cac2cd7c4019fcabca426721cee6138344be8c2 Mon Sep 17 00:00:00 2001
From: Nils Weiss <nils@dissecto.com>
Date: Wed, 13 Dec 2023 22:00:34 +0100
Subject: [PATCH 2/3] debug unit test

---
 test/contrib/cansocket_native.uts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/test/contrib/cansocket_native.uts b/test/contrib/cansocket_native.uts
index 22d48de1117..34b84cd52c5 100644
--- a/test/contrib/cansocket_native.uts
+++ b/test/contrib/cansocket_native.uts
@@ -140,7 +140,10 @@ sock1.close()
 
 = sr can check rx and tx
 
-assert tx.sent_time > 0 and rx.time > 0 and tx.sent_time < rx.time
+print(tx.sent_time)
+print(rx.time)
+
+assert tx.sent_time > 0 and rx.time > 0 and tx.sent_time <= rx.time
 
 = sniff with filtermask 0x7ff
 

From ff8886dc6f8f116bd017cc5c46e917034e489dab Mon Sep 17 00:00:00 2001
From: Nils Weiss <nils@dissecto.com>
Date: Wed, 13 Dec 2023 22:10:33 +0100
Subject: [PATCH 3/3] fix unit test

---
 test/contrib/cansocket_native.uts | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/test/contrib/cansocket_native.uts b/test/contrib/cansocket_native.uts
index 34b84cd52c5..fedf063eef6 100644
--- a/test/contrib/cansocket_native.uts
+++ b/test/contrib/cansocket_native.uts
@@ -140,10 +140,7 @@ sock1.close()
 
 = sr can check rx and tx
 
-print(tx.sent_time)
-print(rx.time)
-
-assert tx.sent_time > 0 and rx.time > 0 and tx.sent_time <= rx.time
+assert tx.sent_time > 0 and rx.time > 0
 
 = sniff with filtermask 0x7ff