Tue 07 May 2013 11:51:19 PM UTC, comment #6:
Just so you are aware, the still-existing code in ipmi_lan_sendto() is still incorrect for IPMI 1.5 compatibility:
/*
Note from Table 12-8, RMCP Packet for IPMI via Ethernet footnote
Some LAN adapter chips may have a problem where packets of overall
lengths 56, 84, 112, 128, or 156 are not handled correctly. The
PAD byte is added as necessary to avoid these overall
lengths. Remote console software must use the PAD byte when
formatting packets to any 10/100 Ethernet device that accepts RMCP
packets. -- Anand Babu
*/
_len = len;
if (_len == 56
|| _len == 84
|| _len == 112
|| _len == 128
|| _len == 156)
pad_len += IPMI_LAN_PKT_PAD_SIZE;
Note the words "overall length" are used here in the comment (and in the specification), yet the length value being compared here is only the UDP payload length (not the "overall length").
If you really want this code to be correct, you would need to calculate the "overall length" of the Ethernet frame, which includes Ethernet frame header and CRC, IP header, and UDP header. Or perhaps the "overall length" only includes the UDP/IP portion - the specification just says "packets of overall lengths", so that's a little bit vague.
My guess is that this "Legacy PAD" probably isn't needed by whatever broken network controllers required it 10+ years ago and since FreeIPMI isn't padding the correct packets anyway, I suggest just removing this code. It's wrong.
-Rob
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