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

[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. : +33 (0)4-67-87-61-10 
Fax. : +33 (0)4-67-70-85-44 
Email : address@hidden 
Web Site : http://www.hymatom.fr 
====================================
P Avant d'imprimer, penser à l'environnement
 


-----Message d'origine-----
De : address@hidden [mailto:address@hidden De la part de Lubomir Toshev
Envoyé : lundi 10 septembre 2007 12:35
À : address@hidden
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:

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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 <address@hidden>
lurno> Subject: [lwip-users] Incorrect RequestID field in SNMP response
lurno>  message
lurno> To: address@hidden
lurno> Message-ID: <address@hidden>
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|




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