[lwip-users] Incorrect RequestID field in SNMP response message

[Lubomir Toshev]

Hello,

I have ported lwIP 1.2.0 to a proprietary Coldfire system. I do not
use RTOS and I work with a single thread. I use UDP communication as
well as the SNMP agent. UDP communication works fine, but I have some
problems with the SNMP agent.

I noticed a mismatch between the RequestID fields of the request and
response messages in an SNMP communication sequence. Some SNMP
managers (like HostMonitor) succeed to GET values despite this
mismatch. Others however (like Net-SNMP) will reject the response.

It seems the RequetID field generated by my system has reversed byte
order. Other fields of the message are encoded correctly, for example
the specific variable values (sysUpTime, etc.).

I am not sure if this is an issue of lwIP or it is related to my port.
Please, make some comments on the possible reasons. What shall I be
more carefull about?

Two examples of SNMP GET request/response are given below. The first
one is between HostMomitor (manager) and lwIP (agent). The second one
is between Net-SNMP (manager) and lwIP (agent). Network traffic is
captured by WireShark.

1. HostMonitor <-> lwIP (HostMonitor accepts the response)

SNMP GET requet:
RequestID is encoded 02 01 01 which is interpreted as "1"

SNMP GET response:
RequestID is encoded 02 04 01 00 00 00 which is interpreted as "16777216"

SysUpTime value is encoded 43 03 00 9d c7 which is correct

These are the two messages:
+---------+---------------+----------+
04:39:39,029,776 ETHER
|0 |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|44|00|a9|00|00|80|11|b8|
aa|c0|a8|00|02|c0|a8|00|03|0b|e5|00|a1|00|30|3b|79|30|26|02|01|00|04|06|70|75|62|
6c|69|63|a0|19|02|01|01|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|03|
00|05|00|

+---------+---------------+----------+
04:39:39,030,235 ETHER
|0 |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|11|40|00|ff|11|fa|
3b|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e5|00|36|fa|ef|30|2c|02|01|00|04|06|70|75|62|
6c|69|63|a2|1f|02|04|01|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
01|01|03|00|43|03|00|9d|c7|

2. Net-SNMP <-> lwIP (Net-SNMP rejects the response)

SNMP GET requet:
RequestID is encoded 02 02 70 06 which is interpreted as "28678"

SNMP GET response:
RequestID is encoded 02 04 06 00 00 00 which is interpreted as "100663296"

SysUpTime value is encoded 43 03 01 0F 57 which is correct

These are the two messages:
+---------+---------------+----------+
04:44:59,264,042 ETHER
|0 |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|45|00|ae|00|00|80|11|b8|
a4|c0|a8|00|02|c0|a8|00|03|0b|e6|00|a1|00|31|a2|96|30|27|02|01|00|04|06|70|75|62|
6c|69|63|a0|1a|02|02|70|06|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|
03|00|05|00|

+---------+---------------+----------+
04:44:59,264,466 ETHER
|0 |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|12|40|00|ff|11|fa|
3a|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e6|00|36|89|59|30|2c|02|01|00|04|06|70|75|62|
6c|69|63|a2|1f|02|04|06|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
01|01|03|00|43|03|01|0f|57|

[Frédéric BERNON]

Hi Lubo,

Take a look to these links, perhaps it could be the solution

bug #19699 : Bug in SNMP ASN1 decode; submitted patch
https://savannah.nongnu.org/bugs/?19699

patch #5896 : Bug in SNMP ASN1 decode; submitted patch
https://savannah.nongnu.org/patch/?5896

https://savannah.nongnu.org/patch/download.php?file_id=12596


Tell us if this is the solution to your problem. If you see other place where this problem appear, tell us...

bye

----- Original Message -----
From: "Lubomir Toshev" <***@dir.bg>
To: <lwip-***@nongnu.org>
Sent: Sunday, September 09, 2007 9:01 AM
Subject: [lwip-users] Incorrect RequestID field in SNMP response message

Post by Lubomir Toshev
Hello,
I have ported lwIP 1.2.0 to a proprietary Coldfire system. I do not
use RTOS and I work with a single thread. I use UDP communication as
well as the SNMP agent. UDP communication works fine, but I have some
problems with the SNMP agent.
I noticed a mismatch between the RequestID fields of the request and
response messages in an SNMP communication sequence. Some SNMP
managers (like HostMonitor) succeed to GET values despite this
mismatch. Others however (like Net-SNMP) will reject the response.
It seems the RequetID field generated by my system has reversed byte
order. Other fields of the message are encoded correctly, for example
the specific variable values (sysUpTime, etc.).
I am not sure if this is an issue of lwIP or it is related to my port.
Please, make some comments on the possible reasons. What shall I be
more carefull about?
Two examples of SNMP GET request/response are given below. The first
one is between HostMomitor (manager) and lwIP (agent). The second one
is between Net-SNMP (manager) and lwIP (agent). Network traffic is
captured by WireShark.
1. HostMonitor <-> lwIP (HostMonitor accepts the response)
RequestID is encoded 02 01 01 which is interpreted as "1"
RequestID is encoded 02 04 01 00 00 00 which is interpreted as "16777216"
SysUpTime value is encoded 43 03 00 9d c7 which is correct
+---------+---------------+----------+
04:39:39,029,776 ETHER
|0 |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|44|00|a9|00|00|80|11|b8|
aa|c0|a8|00|02|c0|a8|00|03|0b|e5|00|a1|00|30|3b|79|30|26|02|01|00|04|06|70|75|62|
6c|69|63|a0|19|02|01|01|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|03|
00|05|00|
+---------+---------------+----------+
04:39:39,030,235 ETHER
|0 |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|11|40|00|ff|11|fa|
3b|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e5|00|36|fa|ef|30|2c|02|01|00|04|06|70|75|62|
6c|69|63|a2|1f|02|04|01|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
01|01|03|00|43|03|00|9d|c7|
2. Net-SNMP <-> lwIP (Net-SNMP rejects the response)
RequestID is encoded 02 02 70 06 which is interpreted as "28678"
RequestID is encoded 02 04 06 00 00 00 which is interpreted as "100663296"
SysUpTime value is encoded 43 03 01 0F 57 which is correct
+---------+---------------+----------+
04:44:59,264,042 ETHER
|0 |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|45|00|ae|00|00|80|11|b8|
a4|c0|a8|00|02|c0|a8|00|03|0b|e6|00|a1|00|31|a2|96|30|27|02|01|00|04|06|70|75|62|
6c|69|63|a0|1a|02|02|70|06|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|
03|00|05|00|
+---------+---------------+----------+
04:44:59,264,466 ETHER
|0 |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|12|40|00|ff|11|fa|
3a|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e6|00|36|89|59|30|2c|02|01|00|04|06|70|75|62|
6c|69|63|a2|1f|02|04|06|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
01|01|03|00|43|03|01|0f|57|
--
Best regards,
Lubo
_______________________________________________
lwip-users mailing list
http://lists.nongnu.org/mailman/listinfo/lwip-users

[Lubomir Toshev]

Hello,

I applied patch #5896 and it solved the problem with the RequestID
field. Actually this problem would affect any s32_t value.

Thank you for the reply.

I would like to discuss a few more things related to SNMP and private
MIB usage. I applied for enterprise PEN which is to be released soon.
I used private_mib.c (from the contrib/unix project) as a reference
to build my private MIB. I use it to keep read-only measurement result
values and read-write configuration values. I successfully GET values
from the private MIB and I also successfully send enterprise-specific
TRAP messages. I have a slight problem with the SET requests.

I tried to analyze the code in private_mib.c and mib2.c and I made the
following assumptions about SET requests:

1. sensorentry_get_object_def_a(...) will set the fields of the
obj_def struct according to the specific referenced item.
2. sensorentry_set_test_a(...) will return true or false if the
specific item can be changed and if the value is within the expected
limits. No actual value change is done here.
3. sensorentry_set_value_a(...) will execute the actual value change of
the referenced item.

Are the above assumptions correct?
Do I miss anything important?
What is the purpose of the functions which names end with _pc?

What actually happens in my system is that when the
sensorentry_set_test_a(...) function is called the viod* value
argument is valid and points to the number passed by the SET message,
but when the sensorentry_set_value_a(...) function is called the void*
value argument is NULL and no longer points to the number passed by
the SET message.

Please, comment the possible reasons.
--
Best regards,
Lubo





Sunday, September 9, 2007, 7:00:08 PM, you wrote:

lurno> Send lwip-users mailing list submissions to
lurno> lwip-***@nongnu.org

lurno> To subscribe or unsubscribe via the World Wide Web, visit
lurno> http://lists.nongnu.org/mailman/listinfo/lwip-users
lurno> or, via email, send a message with subject or body 'help' to
lurno> lwip-users-***@nongnu.org

lurno> You can reach the person managing the list at
lurno> lwip-users-***@nongnu.org

lurno> When replying, please edit your Subject line so it is more specific
lurno> than "Re: Contents of lwip-users digest..."


lurno> Today's Topics:

lurno> 1. Incorrect RequestID field in SNMP response message
lurno> (Lubomir Toshev)
lurno> 2. Re: Incorrect RequestID field in SNMP response message
lurno> (Fr?d?ric BERNON)


lurno> ----------------------------------------------------------------------

lurno> Message: 1
lurno> Date: Sun, 9 Sep 2007 10:01:27 +0300
lurno> From: Lubomir Toshev <***@dir.bg>
lurno> Subject: [lwip-users] Incorrect RequestID field in SNMP response
lurno> message
lurno> To: lwip-***@nongnu.org
lurno> Message-ID: <***@dir.bg>
lurno> Content-Type: text/plain; charset=us-ascii

lurno> Hello,

lurno> I have ported lwIP 1.2.0 to a proprietary Coldfire system. I do not
lurno> use RTOS and I work with a single thread. I use UDP communication as
lurno> well as the SNMP agent. UDP communication works fine, but I have some
lurno> problems with the SNMP agent.

lurno> I noticed a mismatch between the RequestID fields of the request and
lurno> response messages in an SNMP communication sequence. Some SNMP
lurno> managers (like HostMonitor) succeed to GET values despite this
lurno> mismatch. Others however (like Net-SNMP) will reject the response.

lurno> It seems the RequetID field generated by my system has reversed byte
lurno> order. Other fields of the message are encoded correctly, for example
lurno> the specific variable values (sysUpTime, etc.).

lurno> I am not sure if this is an issue of lwIP or it is related to my port.
lurno> Please, make some comments on the possible reasons. What shall I be
lurno> more carefull about?

lurno> Two examples of SNMP GET request/response are given below. The first
lurno> one is between HostMomitor (manager) and lwIP (agent). The second one
lurno> is between Net-SNMP (manager) and lwIP (agent). Network traffic is
lurno> captured by WireShark.

lurno> 1. HostMonitor <-> lwIP (HostMonitor accepts the response)

lurno> SNMP GET requet:
lurno> RequestID is encoded 02 01 01 which is interpreted as "1"

lurno> SNMP GET response:
lurno> RequestID is encoded 02 04 01 00 00 00 which is interpreted as "16777216"

lurno> SysUpTime value is encoded 43 03 00 9d c7 which is correct

lurno> These are the two messages:
lurno> +---------+---------------+----------+
lurno> 04:39:39,029,776 ETHER
lurno> |0
lurno> |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|44|00|a9|00|00|80|11|b8|
lurno> aa|c0|a8|00|02|c0|a8|00|03|0b|e5|00|a1|00|30|3b|79|30|26|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a0|19|02|01|01|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|03|
lurno> 00|05|00|

lurno> +---------+---------------+----------+
lurno> 04:39:39,030,235 ETHER
lurno> |0
lurno> |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|11|40|00|ff|11|fa|
lurno> 3b|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e5|00|36|fa|ef|30|2c|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a2|1f|02|04|01|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
lurno> 01|01|03|00|43|03|00|9d|c7|

lurno> 2. Net-SNMP <-> lwIP (Net-SNMP rejects the response)

lurno> SNMP GET requet:
lurno> RequestID is encoded 02 02 70 06 which is interpreted as "28678"

lurno> SNMP GET response:
lurno> RequestID is encoded 02 04 06 00 00 00 which is interpreted as "100663296"

lurno> SysUpTime value is encoded 43 03 01 0F 57 which is correct

lurno> These are the two messages:
lurno> +---------+---------------+----------+
lurno> 04:44:59,264,042 ETHER
lurno> |0
lurno> |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|45|00|ae|00|00|80|11|b8|
lurno> a4|c0|a8|00|02|c0|a8|00|03|0b|e6|00|a1|00|31|a2|96|30|27|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a0|1a|02|02|70|06|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|
lurno> 03|00|05|00|

lurno> +---------+---------------+----------+
lurno> 04:44:59,264,466 ETHER
lurno> |0
lurno> |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|12|40|00|ff|11|fa|
lurno> 3a|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e6|00|36|89|59|30|2c|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a2|1f|02|04|06|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
lurno> 01|01|03|00|43|03|01|0f|57|

[Frédéric BERNON]

Ok, it's goot that patch #5896 fix your problem. If you see anything with the same kind of problem, tell us.

Sorry, I don't have yet test private MIB use, so, I can't answer you for that.

Perhaps Christiaan or another developer could help you?

====================================
Frédéric BERNON
HYMATOM SA
Chef de projet informatique
Microsoft Certified Professional
Tél. : [phone]
Fax. : [phone]
Email : ***@hymatom.fr
Web Site : http://www.hymatom.fr
====================================
P Avant d'imprimer, penser à l'environnement



-----Message d'origine-----
De : lwip-users-bounces+frederic.bernon=***@nongnu.org [mailto:lwip-users-bounces+frederic.bernon=***@nongnu.org] De la part de Lubomir Toshev
Envoyé : lundi 10 septembre 2007 12:35
À : lwip-users-***@nongnu.org
Objet : [lwip-users] Re: Incorrect RequestID field in SNMP response message


Hello,

I applied patch #5896 and it solved the problem with the RequestID field. Actually this problem would affect any s32_t value.

Thank you for the reply.

I would like to discuss a few more things related to SNMP and private MIB usage. I applied for enterprise PEN which is to be released soon. I used private_mib.c (from the contrib/unix project) as a reference to build my private MIB. I use it to keep read-only measurement result values and read-write configuration values. I successfully GET values from the private MIB and I also successfully send enterprise-specific TRAP messages. I have a slight problem with the SET requests.

I tried to analyze the code in private_mib.c and mib2.c and I made the following assumptions about SET requests:

1. sensorentry_get_object_def_a(...) will set the fields of the obj_def struct according to the specific referenced item. 2. sensorentry_set_test_a(...) will return true or false if the specific item can be changed and if the value is within the expected limits. No actual value change is done here. 3. sensorentry_set_value_a(...) will execute the actual value change of the referenced item.

Are the above assumptions correct?
Do I miss anything important?
What is the purpose of the functions which names end with _pc?

What actually happens in my system is that when the
sensorentry_set_test_a(...) function is called the viod* value argument is valid and points to the number passed by the SET message, but when the sensorentry_set_value_a(...) function is called the void* value argument is NULL and no longer points to the number passed by the SET message.

Please, comment the possible reasons.
--
Best regards,
Lubo





Sunday, September 9, 2007, 7:00:08 PM, you wrote:

lurno> Send lwip-users mailing list submissions to
lurno> lwip-***@nongnu.org

lurno> To subscribe or unsubscribe via the World Wide Web, visit
lurno> http://lists.nongnu.org/mailman/listinfo/lwip-users
lurno> or, via email, send a message with subject or body 'help' to
lurno> lwip-users-***@nongnu.org

lurno> You can reach the person managing the list at
lurno> lwip-users-***@nongnu.org

lurno> When replying, please edit your Subject line so it is more
lurno> specific than "Re: Contents of lwip-users digest..."


lurno> Today's Topics:

lurno> 1. Incorrect RequestID field in SNMP response message
lurno> (Lubomir Toshev)
lurno> 2. Re: Incorrect RequestID field in SNMP response message
lurno> (Fr?d?ric BERNON)


lurno> -----------------------------------------------------------------
lurno> -----

lurno> Message: 1
lurno> Date: Sun, 9 Sep 2007 10:01:27 +0300
lurno> From: Lubomir Toshev <***@dir.bg>
lurno> Subject: [lwip-users] Incorrect RequestID field in SNMP response
lurno> message
lurno> To: lwip-***@nongnu.org
lurno> Message-ID: <***@dir.bg>
lurno> Content-Type: text/plain; charset=us-ascii

lurno> Hello,

lurno> I have ported lwIP 1.2.0 to a proprietary Coldfire system. I do
lurno> not use RTOS and I work with a single thread. I use UDP
lurno> communication as well as the SNMP agent. UDP communication works
lurno> fine, but I have some problems with the SNMP agent.

lurno> I noticed a mismatch between the RequestID fields of the request
lurno> and response messages in an SNMP communication sequence. Some
lurno> SNMP managers (like HostMonitor) succeed to GET values despite
lurno> this mismatch. Others however (like Net-SNMP) will reject the
lurno> response.

lurno> It seems the RequetID field generated by my system has reversed
lurno> byte order. Other fields of the message are encoded correctly,
lurno> for example the specific variable values (sysUpTime, etc.).

lurno> I am not sure if this is an issue of lwIP or it is related to my
lurno> port. Please, make some comments on the possible reasons. What
lurno> shall I be more carefull about?

lurno> Two examples of SNMP GET request/response are given below. The
lurno> first one is between HostMomitor (manager) and lwIP (agent). The
lurno> second one is between Net-SNMP (manager) and lwIP (agent).
lurno> Network traffic is captured by WireShark.

lurno> 1. HostMonitor <-> lwIP (HostMonitor accepts the response)

lurno> SNMP GET requet:
lurno> RequestID is encoded 02 01 01 which is interpreted as "1"

lurno> SNMP GET response:
lurno> RequestID is encoded 02 04 01 00 00 00 which is interpreted as
lurno> "16777216"

lurno> SysUpTime value is encoded 43 03 00 9d c7 which is correct

lurno> These are the two messages:
lurno> +---------+---------------+----------+
lurno> 04:39:39,029,776 ETHER
lurno> |0
lurno> |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|44|00|a9|00|00|80|11|b8|
lurno> aa|c0|a8|00|02|c0|a8|00|03|0b|e5|00|a1|00|30|3b|79|30|26|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a0|19|02|01|01|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|03|
lurno> 00|05|00|

lurno> +---------+---------------+----------+
lurno> 04:39:39,030,235 ETHER
lurno> |0
lurno> |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|11|40|00|ff|11|fa|
lurno> 3b|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e5|00|36|fa|ef|30|2c|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a2|1f|02|04|01|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
lurno> 01|01|03|00|43|03|00|9d|c7|

lurno> 2. Net-SNMP <-> lwIP (Net-SNMP rejects the response)

lurno> SNMP GET requet:
lurno> RequestID is encoded 02 02 70 06 which is interpreted as "28678"

lurno> SNMP GET response:
lurno> RequestID is encoded 02 04 06 00 00 00 which is interpreted as
lurno> "100663296"

lurno> SysUpTime value is encoded 43 03 01 0F 57 which is correct

lurno> These are the two messages:
lurno> +---------+---------------+----------+
lurno> 04:44:59,264,042 ETHER
lurno> |0
lurno> |00|06|70|00|00|01|00|c0|9f|16|ba|a3|08|00|45|00|00|45|00|ae|00|00|80|11|b8|
lurno> a4|c0|a8|00|02|c0|a8|00|03|0b|e6|00|a1|00|31|a2|96|30|27|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a0|1a|02|02|70|06|02|01|00|02|01|00|30|0e|30|0c|06|08|2b|06|01|02|01|01|
lurno> 03|00|05|00|

lurno> +---------+---------------+----------+
lurno> 04:44:59,264,466 ETHER
lurno> |0
lurno> |00|c0|9f|16|ba|a3|00|06|70|00|00|01|08|00|45|00|00|4a|00|12|40|00|ff|11|fa|
lurno> 3a|c0|a8|00|03|c0|a8|00|02|00|a1|0b|e6|00|36|89|59|30|2c|02|01|00|04|06|70|75|62|
lurno> 6c|69|63|a2|1f|02|04|06|00|00|00|02|01|00|02|01|00|30|11|30|0f|06|08|2b|06|01|02|
lurno> 01|01|03|00|43|03|01|0f|57|