Informative error messages, 2

21.08.2005 17:24

Just spent 30 minutes solving another problem that I could fix in 30 seconds if I would only get a proper error message. Whoever wrote OS X printing system obviously thought that error handling is for the weak. I just found out that OS X will simply say "Print job stopped" (in exactly the same way as if someone stopped the job manually) instead of reporting an error if lpd daemon on a remote printer refuses the connection.

After checking all sorts of configuration options in OS X, adding and removing printers I finally run tcpdump to see what exactly is happening on the network. This is what I got:

17:36:01.864288 IP orion.printer > sen.1012: P 1:57(56) ack 5 win 1448 <nop,nop,timestamp 20706385 3602102236>
        0x0000:  4500 006c d2e0 4000 4006 e450 c0a8 0102  E..l..@.@..P....
        0x0010:  c0a8 0108 0203 03f4 983c 26f2 d079 9481  .........<&..y..
        0x0020:  8018 05a8 7bbb 0000 0101 080a 013b f451  ....{........;.Q
        0x0030:  d6b3 b7dc 6f72 696f 6e3a 206c 7064 3a20  ....orion:.lpd:.
        0x0040:  596f 7572 2068 6f73 7420 646f 6573 206e  Your.host.does.n
        0x0050:  6f74 2068 6176 6520 6c69 6e65 2070 7269  ot.have.line.pri
        0x0060:  6e74 6572 2061 6363 6573 730a            nter.access.

Duh. One vi session of the /etc/hosts.lpd later, I could print again from my Powerbook, but how did OS X understand this as "Print job stopped" is beyond my comprehension.

Posted by Tomaž | Categories: Code

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