Incorrect / missing display of received messages

Both the CAN Example and the canutil have problems displaying incoming frames.

• CAN Example
  • Silently drops messages with DLC = 0
  • Does not distinguish between messages with Std. (11 bit) and Ext. ID (29 bit)

• canutil
  • Does not distinguish between messages with Std. (11 bit) and Ext. ID (29 bit)

Technical background: CAN-Messages with the "Extended" flag are transmitted with 29 bit identifier, even if the ID would fit into a Standard frame. This is how candump and canutils displays the message:

candump: fills with zeros to show this is an extended frame
  can0  000007FF   [0]

canutil: the information about extended ID is gone
  Id: 7ff bytes: 0 data:

Expeced behavior:

• Messages with Extended ID should be marked so
• Messages with DLC = 0 should be displayed
• Remote request could be displayed like candump does:

   can0       123   [0]  remote request
   can0  000007FF   [8]  remote request
  

• canutil displays remote requests with DLC > 0 like this, which is wrong as the message does not contain data:

   RTR: Id: 7ff bytes: 8 data: 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0
  

• candump also pretty aligns the messages in a table:

    can0  00000800   [8]  11 22 33 44 55 66 77 88
    can0       004   [1]  C8
    can0       004   [1]  CC
    can0       123   [0]  remote request
    can0       123   [0] 
    can0  000007FF   [0] 
    can0  000007FF   [8]  remote request