[Click] IPv6 AddressTranslator - Possible bug

[Eddie Kohler]

Hi Tim,

Sorry no one got back to you earlier -- the AddressTranslator element is 
a bit abandoned.  I just went ahead and checked in your fix.  Thanks!

Eddie


Tim wrote:
> Hello,
> 
> I have just recently learn about click, and after spending just a couple
> of hours with it, I was quite impressed.  I'm currently doing IPv6
> research, and it took me very little time to build myself a basic IPv6
> router, all without touching any code.  Very nice.
> 
> In any case, I've started working with the AddressTranslator, as it
> appears this module could greatly help me in my research.  I've been
> fighting with it for several days now, and I think I may have finally
> tracked down my troubles to a bug.  (It's either that, or my own
> misunderstanding.)
> 
> Here's a snippet of my configuration:
> 
> 
> // Dynamically mapped
> at :: AddressTranslator(0, 1, 0, 1, 2002:c0a8:1302::);
> //...
> 
> // Outward
> rt[1] -> dhl1 :: DecIP6HLIM()
>       -> IP6Print("Outward")
>       -> at
>       -> CheckIP6Header()
>       -> GetIP6Address(24)
>       -> IP6Print("Outward, translated")
>       -> if0Solicitor
>       -> if0out;
> 
> // Inward
> rt[2] -> dhl2 :: DecIP6HLIM()
>       -> IP6Print("Inward")
>       -> [1]at[1]
>       -> CheckIP6Header()
>       -> GetIP6Address(24)
>       -> IP6Print("Inward, translated")
>       -> if1Solicitor
>       -> if1out;
> //...
> 
> 
> My goal is to have a simple IPv6 router with one exception.  I'd like
> to map all incoming packets, regardless of their destination, to the
> internal destination address '2002:c0a8:1302::'.  Then, when the
> responses are sent back over the same connection, the source addresses
> should be re-written based on the original external destination address.
> It seems like the dynamic mapping feature of this module should handle
> this situation. (Though I can't be completely sure... the documentation
> is currently sparse.)
> 
> I got very close to realizing this setup with this configuration.  The
> incoming destination address of ICMPv6 packets was rewritten to my
> internal host, and the response came back into this element.  However,
> the dynamic re-mapping of the source address failed on the way back out.
> It just dropped the packets outright.
> 
> After reading through much code, I made a small change in the way
> lookup() is called in the handle_outward() function, and everything
> started to work.  Based on how handle_inward() is written, it seems like
> this is a good thing to change, but I may be totally wrong.  I have
> attached a patch for the changes I've made (it is very short).  If you
> could let me know if this is the "right thing" to do, I'd appreciate it.
> If it is a good change to make, I'd appreciate it even more if it were
> committed to CVS. =)
> 
> If my changes are misguided, I'd also appreciate some guidance in this
> matter.
> 
> Thanks for a great piece of software,
> tim
> 
> PS- The patch is against the current release version, 1.4.3.  I noticed
>     this file hasn't changed in CVS since, so hopefully that's ok.
> 
> 
> ------------------------------------------------------------------------
> 
> --- addresstranslator.cc	2003-10-10 00:40:25.000000000 -0400
> +++ addresstranslator.cc.new	2006-01-27 20:07:21.000000000 -0500
> @@ -565,7 +565,7 @@
>      {
>  
>        unsigned char * icmp6_start = (unsigned char *)(ip6_new +1);
> -      if (lookup(ip6_src, dport, ip6_msrc, mport, ip6_dst, sport, _dynamic_mapping_allocation_direction))
> +      if (lookup(ip6_src, dport, ip6_msrc, mport, ip6_dst, sport, 0))
>  	{
>  	 
>  	  ip6_new->ip6_src = ip6_msrc;
> @@ -611,7 +611,7 @@
>         sport = ntohs(tcp_new->th_sport);
>         dport = ntohs(tcp_new->th_dport);
>  
> -      if (lookup(ip6_src, sport, ip6_msrc, mport, ip6_dst, dport, _dynamic_mapping_allocation_direction))
> +      if (lookup(ip6_src, sport, ip6_msrc, mport, ip6_dst, dport, 0))
>  	{
>  	  ip6_new->ip6_src = ip6_msrc;
>  	  tcp_new->th_sport = htons(mport);
> @@ -634,7 +634,7 @@
>        sport = ntohs(udp_new->uh_sport);
>        dport = ntohs(udp_new->uh_dport);
>  
> -      if (lookup(ip6_src, sport, ip6_msrc, mport, ip6_dst, dport, _dynamic_mapping_allocation_direction))
> +      if (lookup(ip6_src, sport, ip6_msrc, mport, ip6_dst, dport, 0))
>  	{
>  	  ip6_new->ip6_src = ip6_msrc;
>  	  udp_new->uh_sport = htons(mport);
> 
> 
> ------------------------------------------------------------------------
> 
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