Bug 355337 – net-misc/iputils-20100418-r1 - tracepath claims that ! 28 >= 28

• Status: RESOLVED FIXED
• Product: Gentoo Linux

[Description Mike Fied 2011-02-17 16:24:38 UTC]

tracepath with specified pktlen=28 bytes fails with the following errmsg:

# tracepath -l 28 10.100.100.4
Error: length must be >= 28


 

Reproducible: Always

Steps to Reproduce:
1. # tracepath -l 28 10.100.100.4
Actual Results:  
Error: length must be >= 28

Expected Results:  
28 >= 28

results positive after changing the pktlen to 29 bytes: 

# tracepath -l 29 10.100.100.4
1: 10.0.0.1 0.464ms
2: 10.100.100.1 9.557ms
3: somehost.com 15.503ms reached
Resume: pmtu 29 hops 3 back 62

[Comment 1 Mike Fied 2011-02-17 16:28:22 UTC]

iputils-sss20100418
2.6.36-gentoo-r1
x86_64

[Comment 2 Jeroen Roovers (RETIRED) 2011-02-17 21:51:08 UTC]

Created attachment 262879 [details, diff]
Correct the error message.

[Comment 3 Jeroen Roovers (RETIRED) 2011-02-17 21:56:11 UTC]

Actually, if you try to patch it the other way, you get this:
bastiaan ~ # /var/tmp/portage/net-misc/iputils-20100418-r1/work/iputils-s20100418/tracepath -l 28 www.gentoo.org
 1:  send failed
     Resume: pmtu 28
bastiaan ~ # [blink]

[Comment 4 Mike Fied 2011-02-18 13:19:10 UTC]

Thank you Jeroen,

The ip plus the icmp header is 28 so ">" is the only way to go... i thought it could be possible to send no payload.. just headers in the packet.

Thanks again!

Mike



(In reply to comment #3)
> Actually, if you try to patch it the other way, you get this:
> bastiaan ~ #
> /var/tmp/portage/net-misc/iputils-20100418-r1/work/iputils-s20100418/tracepath
> -l 28 www.gentoo.org
>  1:  send failed
>      Resume: pmtu 28
> bastiaan ~ # [blink]
> 

[Comment 5 Mike Fied 2011-02-18 13:24:45 UTC]

Hello again,

well, it is possible to send 0 bytes in the payload using ICMP... just the IP and icmp header, so via tracepath it also should be possible to specify 28 bytes... am I missing something here?

Thanks!

Mike

[Comment 6 Jeroen Roovers (RETIRED) 2011-02-18 13:39:39 UTC]

Ideally the command line switch shouldn't set the packet length but the payload length.

[Comment 7 Mike Fied 2011-02-18 14:11:33 UTC]

# ping -s 0 [host]
sends no payload, only headers

tracepath, also icmp, requires payload ( in our case )
so if it would require payload size instead of packet size it still would have to still requre payload_length > 0

[Comment 8 SpanKY 2011-02-19 18:06:11 UTC]

ive added the error message fix to iputils-20101006.  as for improving the behavior in general, take it upstream -> [e-mail].