[Click] ARP problem

Koen Segers koen.segers at edpnet.be
Fri Apr 7 09:41:10 EDT 2006 

I was looking totally wrong. ddd told me the segmentation fault happend 
somewhere else. I find it very strange that valgrind gives an incorrect 
message, but I'm happy I found it, eventually :)

On Wednesday 05 April 2006 16:02, Koen Segers wrote:
> I have changed the arp elements from click-1.4.3 a bit, so that they work
> with my dynamicly generated ip. All that was needed was to change the
> static IPAddress to a pointer to the dynamic IPAddress.
>
> Recently I added merging of manet's to my DDHCP protocol. This implies that
> some nodes reconfigure and get a new ip address.
> The ARP elements become freaky now...
>
> ARPQuerier crashes with a segmentation fault on the following rules of
> insert_entry (function is added as appendix):
> 		if (_age_tail)
> 				ae->age_pprev = &_age_tail->age_next;
> 			else
> 				ae->age_pprev = &_age_head;
> 			_age_tail = *ae->age_pprev = ae;
>
> I tried to clear the arp table by calling clear_map but it gave the same
> problem.
>
> Can somebody explain me what's going on? And how I can overcome this
> problem? I understand the meaning of ARP, but I can't figure out how this
> code works.
>
>
> greetz
>
>
>
>
> Appendix:
> This is what I get from valgrind:
> <snip>
> 00:03:47:70:89:05:      OLSRARPQuerier::there was no entry for 192.168.0.2
> 00:03:47:70:89:05:      OLSRARPQuerier::possible error
> ==32368==
> ==32368== Conditional jump or move depends on uninitialised value(s)
> ==32368==    at 0x8258A94:
> Click::OLSRARPQuerier::insert_entry(Click::IPAddress const&,
> Click::EtherAddress const&) (olsr_arpquerier.cc:303)
> ==32368==    by 0x8257A9A:
> Click::AddARPEntry::simple_action(Click::Packet*) (packet.hh:655)
> ==32368==    by 0x81E6CFA: Click::Element::push(int, Click::Packet*)
> (element.cc:848)
> ==32368==    by 0x825CAF9: Click::OLSRClassifier::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x825C22B: Click::OLSRCheckPacketHeader::push(int,
> Click::Packet*) (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x8241C01: Click::IPFilter::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> 00:03:47:70:89:05:      OLSRARPQuerier::no error occured
> link 192.168.0.1 <--> 192.168.0.2 insert | 31 161050
> 192.168.0.1 adding link to 192.168.0.2
> Adding new neighbor: 192.168.0.2
> No click upcall set!
> 00:03:47:70:89:04:      OLSRARPQuerier::there was no entry for 192.168.0.1
> 00:03:47:70:89:04:      OLSRARPQuerier::possible error
> ==32368==
> ==32368== Use of uninitialised value of size 4
> ==32368==    at 0x8258AA5:
> Click::OLSRARPQuerier::insert_entry(Click::IPAddress const&,
> Click::EtherAddress const&) (olsr_arpquerier.cc:307)
> ==32368==    by 0x8257A9A:
> Click::AddARPEntry::simple_action(Click::Packet*) (packet.hh:655)
> ==32368==    by 0x81E6CFA: Click::Element::push(int, Click::Packet*)
> (element.cc:848)
> ==32368==    by 0x825CAF9: Click::OLSRClassifier::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x825C22B: Click::OLSRCheckPacketHeader::push(int,
> Click::Packet*) (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x8241C01: Click::IPFilter::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==
> ==32368== Invalid write of size 4
> ==32368==    at 0x8258AA5:
> Click::OLSRARPQuerier::insert_entry(Click::IPAddress const&,
> Click::EtherAddress const&) (olsr_arpquerier.cc:307)
> ==32368==    by 0x8257A9A:
> Click::AddARPEntry::simple_action(Click::Packet*) (packet.hh:655)
> ==32368==    by 0x81E6CFA: Click::Element::push(int, Click::Packet*)
> (element.cc:848)
> ==32368==    by 0x825CAF9: Click::OLSRClassifier::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x825C22B: Click::OLSRCheckPacketHeader::push(int,
> Click::Packet*) (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x8241C01: Click::IPFilter::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==  Address 0x59 is not stack'd, malloc'd or (recently) free'd
> ==32368==
> ==32368== Process terminating with default action of signal 11 (SIGSEGV)
> ==32368==  Access not within mapped region at address 0x59
> ==32368==    at 0x8258AA5:
> Click::OLSRARPQuerier::insert_entry(Click::IPAddress const&,
> Click::EtherAddress const&) (olsr_arpquerier.cc:307)
> ==32368==    by 0x8257A9A:
> Click::AddARPEntry::simple_action(Click::Packet*) (packet.hh:655)
> ==32368==    by 0x81E6CFA: Click::Element::push(int, Click::Packet*)
> (element.cc:848)
> ==32368==    by 0x825CAF9: Click::OLSRClassifier::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x825C22B: Click::OLSRCheckPacketHeader::push(int,
> Click::Packet*) (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x8241C01: Click::IPFilter::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
> ==32368==    by 0x81E6D25: Click::Element::push(int, Click::Packet*)
> (element.hh:314)
>
>
>
> void OLSRARPQuerier::insert_entry(const IPAddress &ip, const EtherAddress
> &ether)
> {
> 	int bucket = ip_bucket(ip);
> 	//click_chatter("OLSRARPQuerier::insert_entry met ip %s en ethernet %s",
> ip.s().cc(), ether.s().cc());
>
> 	_lock.acquire_read();
>
> 	ARPEntry *ae = _map[bucket];
>
> 	while (ae && ae->ip != ip)
> 		ae = ae->next;
>
> 	if (ae)
> 	{
> 		//click_chatter("%s:\t:OLSRARPQuerier::there was allready an entry for
> %s", _info->get_hw_addr().s().cc(), ip.s().cc());
> 		if (ae->ok && ae->en != ether)
> 			click_chatter("OLSRARPQuerier overwriting an entry");
> 		ae->en = ether;
> 		ae->last_response_jiffies = click_jiffies();
> 		_lock.release_read();
> 	}
> 	else
> 	{
> 		click_chatter("%s:\tOLSRARPQuerier::there was no entry for %s",
> _info->get_hw_addr().s().cc(), ip.s().cc());
> 		_lock.release_read();
> 		_lock.acquire_write();
> 		if (_cache_size >= _capacity)
> 			expire_hook(0, this);
> 		if (ARPEntry *ae = new ARPEntry)
> 		{
> 			ae->ip = ip;
> 			ae->en = ether;
> 			ae->ok = 1;				// the entry is automatically ok, since we are setting
> the mac address
> 			ae->polling = 0;			// don't know what polling does ..
> 			ae->head = ae->tail = 0;		// no buffered packets
> 			ae->last_response_jiffies = click_jiffies();
> 			ae->pprev = &_map[bucket];
> 			if ((ae->next = _map[bucket]))
> 				ae->next->pprev = &ae->next;
> 			_map[bucket] = ae;
>
> 			click_chatter("%s:\tOLSRARPQuerier::possible error",
> _info->get_hw_addr().s().cc());
> 			if (_age_tail)
> 				ae->age_pprev = &_age_tail->age_next;
> 			else
> 				ae->age_pprev = &_age_head;
> 			_age_tail = *ae->age_pprev = ae;
> 			click_chatter("%s:\tOLSRARPQuerier::no error occured",
> _info->get_hw_addr().s().cc());
> 			ae->age_next = 0;
> 		}
> 		_lock.release_write();
> 	}
> }

-- 

Koen Segers
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