Re: truncated-ip 4.1.32_rc5 (wrong IP header byte swapping?)

You could have warned that I'd get thousands of lines per
second. Luckily, I sent them to a file for further review ;)

I improved on your suggested filter by also printing the
protocol number:

dtrace -n 'fbt::fr_check:return{trace(arg1);}' \
   -n 'fbt::ipf_hook:return{trace(arg1);}' \
   -n 'fbt::ipf_hook:entry{self->hdr =
((hook_pkt_event_t *)arg1)->hpe_hdr;}' \
   -n 'fbt::fr_check:entry{printf("len %d\tprot %d",
((struct ip *)self->hdr)->ip_len, ((struct ip *)self->hdr)->ip_p);}' \
   > /pool/test4

Lengths seem quite reasonable (<= 112), all return codes
are zero:

Raw outputs are not very entertaining and look like this:

# ggrep -A2 -w 'prot 1' /pool/test4 | less
CPU     ID                    FUNCTION:NAME
   0   1282                   fr_check:entry len 84      prot 1
   0   1283                  fr_check:return                 0
   0   2199                  ipf_hook:return                 0
   0   1282                   fr_check:entry len 84      prot 1
   0   1283                  fr_check:return                 0
   0   2199                  ipf_hook:return                 0
   0   1282                   fr_check:entry len 84      prot 1
   0   1283                  fr_check:return                 0
   0   2199                  ipf_hook:return                 0
...
--
   0   1282                   fr_check:entry len 106     prot 1
   0   1283                  fr_check:return                 0
   0   2199                  ipf_hook:return                 0
--
   0   1282                   fr_check:entry len 40      prot 1
   0   1283                  fr_check:return                 0
   0   2199                  ipf_hook:return                 0
   0   1282                   fr_check:entry len 68      prot 1
   0   1283                  fr_check:return                 0
   0   2199                  ipf_hook:return                 0
--

"Stats" are like this:

# ggrep -A2 -w 'prot 1' /pool/test4  | sort | uniq -c
   10   0   1282                   fr_check:entry len 106        prot 1
    3   0   1282                   fr_check:entry len 112        prot 1
   45   0   1282                   fr_check:entry len 40 prot 1
   24   0   1282                   fr_check:entry len 56 prot 1
   16   0   1282                   fr_check:entry len 64 prot 1
    3   0   1282                   fr_check:entry len 68 prot 1
    2   0   1282                   fr_check:entry len 76 prot 1
  112   0   1282                   fr_check:entry len 84 prot 1
  215   0   1283                  fr_check:return                 0
  215   0   2199                  ipf_hook:return                 0

The gateway does not appear in traceroutes.

//Jim

Darren Reed wrote:
> Jim Klimov wrote:
>> ...
>>
>> Just for kicks, I tried to comment away the whole block
>> of these 2-4 lines you patched, to see what happens.
>>
>> I found that with without these lines our new gateway
>> appears in the traces, as well as our next-hop cisco.
>> Further hosts on the route thru internet do not respond,
>> except for the destination host ("www.ru" = 194.87.0.50,
>> a popular network-checking target here in Russia).
>>
>> During the previous tests it sometimes replied to the
>> traceroutes, but sometimes it didn't. With htons/ntohs
>> lines commented, it always replied.
> 
> Ok... so those lines need to be there...
> 
> With them there, what do you see from this when you try to traceroute:
> 
> dtrace -n 'fbt::fr_check:return{trace(arg1);}' -n
> 'fbt::ipf_hook:return{trace(arg1);}' -n 'fbt::ipf_hook:entry{self->hdr =
> ((hook_pkt_event_t *)arg1)->hpe_hdr;}' -n
> 'fbt::fr_check:entry{printf("len %d", ((struct ip *)self->hdr)->ip_len);}'
> 
> Darren
> 


-- 


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| Климов Евгений,                                 Jim Klimov |
| технический директор                                   CTO |
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