[Freeipmi-users] libipmiconsole: Duplicate data received by target after NACK

[David O'Shea]

Hi all,

I'm hitting another problem with my Python script using IPMI SOL to talk to a 
Dell system via its iDRAC.  Once the Dell system is running Linux, I'm trying 
to write a small script to it.  Initially I had lots of problems where the Dell 
system never received any of the data I sent, and I'm not sure how flow control 
works for SOL (I tried running 'stty crtscts' on the Dell system but it didn't 
help), so I started pacing the output by sending only 8 bytes every 100ms, 
which should be fine at 115200bps.

One time this error appeared whilst sending this small script:

(ipmiconsole_processing.c, _sol_bmc_to_remote_console_packet, 2672): 
hostname=silicon-bmc.adl.quantum.com; protocol_state=9h: SOL packet NACKED: 
accepted_character_count: accepted_character_count = 0,  
c->session.sol_input_character_data_len = 8

The Dell system then appeared to receive one of these 8-byte chunks twice, 
presumably the one that was NACKED.

First, here are two 8-byte chunks that were echoed back normally:

[2014-09-07 22:15:27,095] DEBUG - Send chunk to target: 'on" in\n '
[2014-09-07 22:15:27,129] DEBUG - Raw input from target: 'on" in\r\n '
[2014-09-07 22:15:27,195] DEBUG - Send chunk to target: '   PREIN'
[2014-09-07 22:15:27,229] DEBUG - Raw input from target: '   PREIN'

so it looks like I normally get a response in 35ms, but then this happened:

[2014-09-07 22:15:27,296] DEBUG - Send chunk to target: 'IT)\n    '
[2014-09-07 22:15:27,396] DEBUG - Send chunk to target: '    # Th'
[2014-09-07 22:15:27,497] DEBUG - Send chunk to target: 'is is us'
[2014-09-07 22:15:27,597] DEBUG - Send chunk to target: 'ed to pr'
[2014-09-07 22:15:27,698] DEBUG - Send chunk to target: 'epare th'
[2014-09-07 22:15:27,798] DEBUG - Send chunk to target: 'e interf'
[2014-09-07 22:15:27,819] DEBUG - Raw input from target: 'IT)\r\n    '
[2014-09-07 22:15:27,869] DEBUG - Raw input from target: 'IT)\r\n        # This 
is used to prepare the interf'

No responses received for over 500ms, then one of the 8-byte chunks is echoed 
back twice.

I verified that "IT)\r\n    " was written to the file on the target twice.

There is no retry mechanism in my script so I assume that libipmiconsole is 
resending when it receives a NACK.

Do I need a full verbose log in order to debug this properly?

I went back through my logs and found another instance of one of these "NACKED" 
messages, it was for 31 characters but those characters didn't seem to get 
duplicated.

Thanks in advance,
David