Re: M3UA: Message Length
"David Laight" <[email protected]> Mon, 14 Oct 2013 10:20:28 +0100
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Message-ID | <[email protected]> |
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I=92ve NFI what you used to take that trace =96 Wireshark will only give =
me a hexdump.
Anyway the packet decodes as:
=20
Pad, MAC addresses, ethertype
0000 00 00 00 01 00 06 00 1a 30 2b 4b c0 00 00 08 00
IP header
0010 45 02 00 ac 13 31 00 00 fe 84 3f ca 0a 3a 70 c8
0020 0a 3a e3 94
SCTP
ports: 0f 53 0f 59
tag: 49 33 5f c5
cksum: 7f 3e b6 8d
0030 chunk type: 00
flags: 03
length: 00 8a
TSN: da 58 6c 93
Stream id: 00 01
Stream-seq: 00 08
Payload-id: 00 00 00 03
=20
M3UA data, length 0x7c
0040 01 00 01 01 00 00 00 7c
02 00 00 08
00 00 00 02
0050 00 06 00 08
00 00 00 08
02 10 00 62
00 00 0b ba
0060 00 00 13 8b 03 03 01 00 11 01 03 04 08 0c 45 04
0070 43 8b 13 07 04 43 ba 0b 07 39 00 00 00 00 00 00
0080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04 04
0090 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04
00a0 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04
00b0 04 04 04 10 04 40 00 00 00 00
=20
Inter-chunk pad: 00 00
=20
The problem is that the length of the M3UA message (0x7c) is larger =
than the payload
part of the SCTP message (0x8a =96 0x10 =3D 0x7a).
The RFC might let you send that if the M3UA length were 0x7a, but I know =
that
all implementations will not be able to receive such messages =96 so it =
is best not
to send them.
=20
David
=20
=20
From: santosh nayak [mailto:[email protected]]=20
Sent: 14 October 2013 05:47
To: David Laight
Subject: Re: [Sigtran] M3UA: Message Length
=20
Hi,
=20
Thanks for the response...
=20
I am attaching the pcap... packet number 85
Could you explain what MUST is violated???
=20
Thanks,
Santosh
=20
=20
On Thu, Oct 10, 2013 at 5:57 PM, David Laight <[email protected]> =
wrote:
> From: [email protected] [mailto:[email protected]] On =
Behalf Of Michael Tuexen
> On Oct 10, 2013, at 11:40 AM, santosh nayak =
<[email protected]> wrote:
>
> > Hi,
> >
> > We have a situation where message is being rejected at M3UA layer =
due to
> > buffer length is not equal to message length.
> >
> > What is the significance of Message Length and its importance with =
padding...
> >
> > in the current issue M3UA peer is sending the data buffer of size =
122 bytes
> > to KSCTP. But message length parameter of M3UA common header =
contains a value
> > of 124 and KSCTP is doing the padding at its level of 2 bytes which =
is
> > observed from the wireshark traces.
Are you sure that pad isn't just from SCTP aligning it's chunks?
> > Now at DUT message droped with reason (message length parameter is =
greater
> > than actual M3UA data buffer size)
> >
> > Is this expected??? Please comment on this...
>
> At least the behaviour of the sender is not expected, since the sender
> violates a MUST.
I'm not sure what the note in section 3.1.4 is trying to allow, but
I think the message you are describing is definitely illegal.
I believe that the overall length in the 'common' header should always
match that of the SCTP data chunk.
This allows M3UA data to be separated into messages when sent using =
(say)
TCP rather than SCTP.
I suspect the note allows an implementation to add the pad (following a
parameter) when it adds a new one, rather than when it adds a parameter
that isn't a multiple of 4 bytes.
In any case I'd change your sending end.
David
=20
=0D=0A
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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-GB link=3Dblue =
vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>I=92ve NFI what you used to take that trace =96 Wireshark will only =
give me a hexdump.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>Anyway the packet decodes as:<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'><o:p> </o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>Pad, MAC =
addresses, ethertype<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>0000=A0 00 00 00 =
01 00 06 00 1a=A0 30 2b 4b c0 00 00 08 00<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>IP =
header<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>0010=A0 45 02 00 =
ac 13 31 00 00=A0 fe 84 3f ca 0a 3a 70 c8<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>0020=A0 0a 3a e3 =
94<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>SCTP<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
ports: 0f 53 0f 59<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
tag:=A0=A0 49 33 5f c5<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
cksum: 7f 3e b6 8d<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>0030=A0 chunk =
type: 00<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
flags:=A0=A0=A0=A0=A0 03<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
length:=A0=A0=A0=A0 00 8a<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
TSN:=A0=A0=A0=A0=A0=A0=A0 da 58 6c 93<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
Stream id:=A0 00 01<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
Stream-seq: 00 08<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>=A0=A0=A0=A0=A0 =
Payload-id: 00 00 00 03<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'><o:p> </o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>M3UA data, length =
0x7c<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>0040=A0 01 00 01 =
01 00 00 00 7c<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 02 00 00 =
08<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 00 00 00 =
02<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>0050=A0=A0=A0=A0=A0=A0=A0 00 06 00 08<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 00 00 00 =
08<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 02 10 00 =
62<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 00 00 0b =
ba<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>0060=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 00 00 13 8b 03 03 =
01 00=A0 11 01 03 04 08 0c 45 04<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>0070=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 43 8b 13 07 04 43 =
ba 0b=A0 07 39 00 00 00 00 00 00<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>0080=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 00 00 00 00 00 00 =
00 00=A0 00 00 00 00 00 00 04 04<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>0090=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 04 04 04 04 04 04 =
04 04=A0 04 04 04 04 04 04 04 04<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>00a0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 04 04 04 04 04 04 =
04 04=A0 04 04 04 04 04 04 04 04<o:p></o:p></span></p><p =
class=3DMsoNormal style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'>00b0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 04 04 04 10 04 40 =
00 00=A0 00 00<o:p></o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida =
Console"'><o:p> </o:p></span></p><p class=3DMsoNormal =
style=3D'text-autospace:none'><span =
style=3D'font-size:9.0pt;font-family:"Lucida Console"'>Inter-chunk pad: =
00 00<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>The problem is that the length of the M3UA message (0x7c)=A0 is =
larger than the payload<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>part of the SCTP message (0x8a =96 0x10 =3D =
0x7a).<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>The RFC might let you send that if the M3UA length were 0x7a, but I =
know that<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>all implementations will not be able to receive such messages =96 so =
it is best not<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>to send them.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =
David<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'><o:p> </o:p></span></p><div =
style=3D'border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm =
4.0pt'><div><div style=3D'border:none;border-top:solid #B5C4DF =
1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=3DMsoNormal><b><span =
lang=3DEN-US =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span>=
</b><span lang=3DEN-US =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> santosh =
nayak [mailto:[email protected]] <br><b>Sent:</b> 14 October =
2013 05:47<br><b>To:</b> David Laight<br><b>Subject:</b> Re: [Sigtran] =
M3UA: Message Length<o:p></o:p></span></p></div></div><p =
class=3DMsoNormal><o:p> </o:p></p><div><p =
class=3DMsoNormal>Hi,<o:p></o:p></p><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>Thanks for the response...<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p class=3DMsoNormal>I =
am attaching the pcap... packet number 85<o:p></o:p></p></div><div><p =
class=3DMsoNormal>Could you explain what MUST is =
violated???<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>Thanks,<o:p></o:p></p></div><div><p =
class=3DMsoNormal>Santosh<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div></div><div><p =
class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'><o:p> </o:p></p><div><p =
class=3DMsoNormal>On Thu, Oct 10, 2013 at 5:57 PM, David Laight <<a =
href=3D"mailto:[email protected]" =
target=3D"_blank">[email protected]</a>> =
wrote:<o:p></o:p></p><p class=3DMsoNormal>> From: <a =
href=3D"mailto:[email protected]">[email protected]</a> =
[mailto:<a =
href=3D"mailto:[email protected]">[email protected]</a>] =
On Behalf Of Michael Tuexen<o:p></o:p></p><div><p class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'>> On Oct 10, 2013, at 11:40 AM, =
santosh nayak <<a =
href=3D"mailto:[email protected]">[email protected]</a>&g=
t; wrote:<br>><br>> > Hi,<br>> ><br>> > We have a =
situation where message is being rejected at M3UA layer due to<br>> =
> buffer length is not equal to message length.<br>> ><br>> =
> What is the significance of Message Length and its importance with =
padding...<br>> ><br>> > in the current issue M3UA peer is =
sending the data buffer of size 122 bytes<br>> > to KSCTP. But =
message length parameter of M3UA common header contains a value<br>> =
> of 124 and KSCTP is doing the padding at its level of 2 bytes which =
is<br>> > observed from the wireshark =
traces.<o:p></o:p></p></div><p class=3DMsoNormal>Are you sure that pad =
isn't just from SCTP aligning it's chunks?<o:p></o:p></p><div><p =
class=3DMsoNormal style=3D'margin-bottom:12.0pt'><br>> > Now at =
DUT message droped with reason (message length parameter is =
greater<br>> > than actual M3UA data buffer size)<br>> =
><br>> > Is this expected??? Please comment on =
this...<br>><br>> At least the behaviour of the sender is not =
expected, since the sender<br>> violates a =
MUST.<o:p></o:p></p></div><p class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'>I'm not sure what the note in section =
3.1.4 is trying to allow, but<br>I think the message you are describing =
is definitely illegal.<br><br>I believe that the overall length in the =
'common' header should always<br>match that of the SCTP data =
chunk.<br>This allows M3UA data to be separated into messages when sent =
using (say)<br>TCP rather than SCTP.<br><br>I suspect the note allows an =
implementation to add the pad (following a<br>parameter) when it adds a =
new one, rather than when it adds a parameter<br>that isn't a multiple =
of 4 bytes.<br><br>In any case I'd change your sending end.<br><span =
style=3D'color:#888888'><br><span class=3Dhoenzb> =
David</span><br><br><br></span><o:p></o:p></p></div><p =
class=3DMsoNormal><o:p> </o:p></p></div></div></div>
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