As far as I can see the "Sorcerer's Apprentice" bug is still in the TFTP module (tftp.c) of the latest curl (curl-7.21.4). Given that it has existed for so long and is explicitly warned about in the RFC1123 I'm confused as to how it has existed in the source for so long. It looks to me that every time a data packet gets delayed in the network there will be a duplication of all subsequent packets.

I'm trying to work out the best way to fix this in our local curl source. Simply never retransmitting the data packet on receipt of an old ACK does not really fix it. Because by default the retransmission interval is 15 seconds which means that every time a packet gets discarded due to congestion involves a 15+ second delay. It ends up being longer than 15 seconds because the the CURL TFTP implementation restarts the 15 second timer on receipt of each ACK.

So does anybody have a patch for the Sorcerer's Apprentice bug for tftp.c in the curl source?

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Received on 2011-04-04