Adapt send_and_sniff() test function to work under Windows

Thanks @gpotter2

appveyor.yml

@@ -27,7 +27,7 @@ test_script:
   - set PATH="%APPVEYOR_BUILD_FOLDER%;C:\Program Files\Wireshark\;%PATH%"
   
   # Main unit tests
-  - "%PYTHON%\\python -m coverage run -a bin\\UTscapy -f text -t test\\regression.uts -F -K automaton -K mock_read_routes6_bsd -K fork || exit /b 42"
+  - "%PYTHON%\\python -m coverage run -a bin\\UTscapy -f text -t test\\regression.uts -F -K automaton -K mock_read_routes6_bsd || exit /b 42"
   - 'del test\regression.uts'
 
   # Secondary unit tests

test/regression.uts

@@ -689,26 +689,50 @@ conf.route.route("0.0.0.0")[2]
 arping(_+"/24")
 
 = send() and sniff()
-~ netaccess fork
+~ netaccess
 import time
 import os
-def send_and_sniff(pkt, timeout=2, flt=None, iface=None):
-    """Send a packet, sniff, and check the packet has been seen"""
-    pid = os.fork()
+def _send_or_sniff(pkt, timeout, flt, pid, fork, t_other=None):
     assert pid != -1
     if pid == 0:
         time.sleep(1)
-        (sendp if isinstance(pkt, (Ether, Dot3)) else send)(pkt, iface=iface)
-        os._exit(0)
+        (sendp if isinstance(pkt, (Ether, Dot3)) else send)(pkt)
+        if fork:
+            os._exit(0)
+        else:
+            return
     else:
         spkt = str(pkt)
         pkts = sniff(
-            timeout=timeout, iface=iface, filter=flt,
+            timeout=timeout, filter=flt,
             stop_filter=lambda p: pkt.__class__ in p and str(p[pkt.__class__]) == spkt
         )
-        os.waitpid(pid, 0)
+        if fork:
+            os.waitpid(pid, 0)
+        else:
+            t_other.join()
     assert str(pkt) in (str(p[pkt.__class__]) for p in pkts if pkt.__class__ in p)
 
+def send_and_sniff(pkt, timeout=2, flt=None):
+    """Send a packet, sniff, and check the packet has been seen"""
+    if hasattr(os, "fork"):
+        _send_or_sniff(pkt, timeout, flt, os.fork(), True)
+    else:
+        from threading import Thread
+        def run_function(pkt, timeout, flt, pid, thread, results):
+            _send_or_sniff(pkt, timeout, flt, pid, False, thread)
+            results.put(True)
+        results = Queue.Queue()
+        t_parent = Thread(target=run_function, args=(pkt, timeout, flt, 0, None, results))
+        t_child = Thread(target=run_function, args=(pkt, timeout, flt, 1, t_parent, results))
+        t_parent.start()
+        t_child.start()
+        t_parent.join()
+        t_child.join()
+        assert results.qsize() >= 2
+        while not results.empty():
+            assert results.get()
+
 send_and_sniff(IP(dst="secdev.org")/ICMP())
 send_and_sniff(IP(dst="secdev.org")/ICMP(), flt="icmp")
 send_and_sniff(Ether()/IP(dst="secdev.org")/ICMP())