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POhandling a callback with ctypes
 

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    <p>I'm attempting to map libpcap using ctypes to python3.2 and I'm having a problem using callbacks with pcap_loop... here is the code ..</p> <pre><code>class c_int_hack: def from_param(self, *args): return ctypes.c_void_p #void got_packet(u_char *args, const struct pcap_pkthdr *header, # const u_char *packet) CALLBACK=ctypes.CFUNCTYPE(ctypes.c_void_p,c_int_hack,ctypes.pointer(pkthdr),ctypes.POINTER(ctypes.c_ubyte)) #int pcap_loop(pcap_t *p, int cnt, pcap_handler callback, u_char *user) def process(user,pkthdr,packet): print("In callback:") print("pkthdr[0:7]:",pkthdr.contents.len) print("packet6:%2x",packet[6]) print("packet7:%2x",packet[7]) print("packet8:%2x",packet[8]) print("packet9:%2x",packet[9]) print("packet10:%2x",packet[10]) print("packet11:%2x",packet[11]) got_packet=CALLBACK(process) if(pcap_loop(handle,ctypes.c_int(10), got_packet,"what") == -1): err = pcap_geterr(handle) print("pcap_loop error: {0}".format(err)) </code></pre> <p>it seems to have a problem with the 2nd parameter which is the "c_int_hack"</p> <pre><code>Got Required netmask Pcap open live worked! Filter Compiled! Filter installed! Traceback (most recent call last): File "./libpcap.py", line 72, in &lt;module&gt; CALLBACK=ctypes.CFUNCTYPE(ctypes.c_void_p,c_int_hack,ctypes.pointer(pkthdr),ctypes.POINTER(ctypes.c_ubyte)) File "/usr/lib/python3.2/ctypes/__init__.py", line 99, in CFUNCTYPE return _c_functype_cache[(restype, argtypes, flags)] TypeError: unhashable type </code></pre> <p>THis is my first time doing work with ctypes so I'm rather confused at this point. </p> <p>...... EDIT..........</p> <p>So the prototype is trying to accept a pointer to a list of arguments. so I tried doing a pointer to a instance that can take a list but now I'm getting a new error..</p> <pre><code>class ListPOINTER(object): '''Just like a POINTER but accept a list of ctype as an argument''' def __init__(self, etype): self.etype = etype def from_param(self, param): if isinstance(param, (list,tuple)): return (self.etype * len(param))(*param) #void got_packet(u_char *args, const struct pcap_pkthdr *header, # const u_char *packet) args=ListPOINTER() CALLBACK = ctypes.CFUNCTYPE(ctypes.c_void_p,args(ctypes.c_char_p),ctypes.pointer(pkthdr),ctypes.POINTER(ctypes.c_ubyte)) </code></pre> <p>and this is the error</p> <pre><code>Got Required netmask Pcap open live worked! Filter Compiled! Filter installed! Traceback (most recent call last): File "./libpcap.py", line 81, in &lt;module&gt; args=ListPOINTER() TypeError: __init__() takes exactly 2 arguments (1 given) </code></pre>
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