non blocking reception works

demo_pcap.py

@@ -0,0 +1,15 @@
+import pcap
+
+
+print("Interfaces:\n" + '\n'.join(pcap.findalldevs()))
+print("ex_name")
+for i in range(0, 10):
+    strInterfaceName = pcap.ex_name("eth"+str(i))
+    if (strInterfaceName == '\\Device\\NPF_{E4B8176C-8516-4D48-88BC-85225ABCF259}'):
+        print("This is the wanted Ethernet adaptor.")
+    print("eth"+ str(i) + " is " + strInterfaceName)
+    
+sniffer = pcap.pcap(name=None, promisc=True, immediate=True, timeout_ms=50)
+addr = lambda pkt, offset: '.'.join(str(pkt[i]) for i in range(offset, offset + 4))
+for ts, pkt in sniffer:
+     print('%d\tSRC %-16s\tDST %-16s' % (ts, addr(pkt, sniffer.dloff + 12), addr(pkt, sniffer.dloff + 16)))

pyPlcHomeplug.py

@@ -127,30 +127,63 @@ class pyPlcHomeplug():
         addToTrace("transmitting test frame...")
         self.composeTestFrame()
         self.sniffer.sendpacket(bytes(self.mytransmitbuffer))
+        
+    def findEthernetAdaptor(self):
+        self.strInterfaceName="eth0" # default, if the real is not found
+        print("Interfaces:\n" + '\n'.join(pcap.findalldevs()))
+        for i in range(0, 10):
+            strInterfaceName = pcap.ex_name("eth"+str(i))
+            if (strInterfaceName == '\\Device\\NPF_{E4B8176C-8516-4D48-88BC-85225ABCF259}'):
+                print("This is the wanted Ethernet adaptor.")
+                self.strInterfaceName="eth"+str(i)
+            print("eth"+ str(i) + " is " + strInterfaceName)
 
     def __init__(self, callbackAddToTrace=None, callbackShowStatus=None):
         self.mytransmitbuffer = bytearray("Hallo das ist ein Test", 'UTF-8')
+        self.nPacketsReceived = 0
         self.callbackAddToTrace = callbackAddToTrace
-        self.callbackShowStatus = callbackShowStatus        #self.sniffer = pcap.pcap(name=None, promisc=True, immediate=True, timeout_ms=50)
-        # eth3 bedeutet: Dritter Eintrag von hinten, in der Liste der Interfaces, die von pcap.findalldevs geliefert wird.
-        #  Verbesserungsbedarf: Interface namensbasiert auswählen.
-        self.sniffer = pcap.pcap(name="eth3", promisc=True, immediate=True, timeout_ms=50)
+        self.callbackShowStatus = callbackShowStatus
+        #self.sniffer = pcap.pcap(name=None, promisc=True, immediate=True, timeout_ms=50)
+        # eth3 means: Third entry from back, in the list of interfaces, which is provided by pcap.findalldevs.
+        #  Improvement necessary: select the interface based on the name.
+        # For debugging of the interface names, we can patch the file
+        # C:\Users\uwemi\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p0\LocalCache\local-packages\Python310\site-packages\pcap\_pcap_ex.py,
+        # in the function
+        #    def name(name: bytes) -> bytes:
+        # in the place after
+        # if i == idx:
+        #           print("index match at " + str(i) + " dev name=" + str(dev.name) + " dev.description=" + str(dev.description))
+        # This will print the description of the used interface.
+        #
+        # Patch for non-blocking read-iteration:
+        #   in _pcap.py, function def __next__(self), in the case of timeout (if n==0), we need to "raise StopIteration" instead of "continue".
+        #
+        self.findEthernetAdaptor()
+        self.sniffer = pcap.pcap(name=self.strInterfaceName, promisc=True, immediate=True, timeout_ms=50)
+        self.sniffer.setnonblock(True)
+        print("sniffer created at " + self.strInterfaceName)
 
     def addToTrace(s):
         self.callbackAddToTrace(s)
+
+    def showStatus(self, s):
+        self.callbackShowStatus(s) 
         
-    def mainfunction(self):
+    def mainfunction(self):  
+        # print("will evaluate self.sniffer")
+        for ts, pkt in self.sniffer: # attention: for using this in non-blocking manner, we need the patch described above.
+            self.nPacketsReceived+=1
+            print('%d' % (ts))
+            #if (self.isHomeplug(pkt)):
+            #    self.showMacAddresses(pkt)
+            #    showAsHex(pkt)
+            #    if (pkt[15]==0x64): #SLAC_Request
+            #        self.sendTestFrame()
+            #    
+            #else:
+            #    addToTrace("(other)")
+        self.showStatus("nPacketsReceived=" + str(self.nPacketsReceived))
         
-        for ts, pkt in self.sniffer:
-            #print('%d' % (ts))
-            if (self.isHomeplug(pkt)):
-                self.showMacAddresses(pkt)
-                showAsHex(pkt)
-                if (pkt[15]==0x64): #SLAC_Request
-                    self.sendTestFrame()
-                
-            else:
-                addToTrace("(other)")
     def close(self):
         self.sniffer.close()
 

pyPlcWorker.py

@@ -6,9 +6,6 @@
 #------------------------------------------------------------
 import pyPlcHomeplug
 
-
-
-
 class pyPlcWorker():
     def __init__(self, callbackAddToTrace=None, callbackShowStatus=None):
         print("initializing pyPlcWorker") 
@@ -27,11 +24,9 @@ class pyPlcWorker():
         
     def mainfunction(self):
         self.nMainFunctionCalls+=1
-        self.showStatus("pyPlcWorker loop " + str(self.nMainFunctionCalls))
-        #self.hp.mainfunction()
+        #self.showStatus("pyPlcWorker loop " + str(self.nMainFunctionCalls))
+        self.hp.mainfunction() # call the lower-level worker
         
-
-
     def handleUserAction(self, strAction):
         self.strUserAction = strAction
         self.addToTrace("UserAction " + strAction)