On Thu, Sep 10, 2020 at 05:17:57PM +0200, Javier Martinez Canillas wrote: > Commit 781b3e5efc3 (tftp: Do not use priority queue) caused a regression > when fetching files over TFTP whose size is bigger than 65535 * block size. > > grub> linux /images/pxeboot/vmlinuz > grub> echo $? > 0 > grub> initrd /images/pxeboot/initrd.img > error: timeout reading '/images/pxeboot/initrd.img'. > grub> echo $? > 28 > > It is caused by the block number counter being a 16-bit field, which leads > to a maximum file size of ((1 << 16) - 1) * block size. Because GRUB sets > the block size to 1024 octets (by using the TFTP Blocksize Option from RFC > 2348 [0]), the maximum file size that can be transferred is 67107840 bytes. > > The TFTP PROTOCOL (REVISION 2) RFC 1350 [1] does not mention what a client > should do when a file size is bigger than the maximum, but most TFTP hosts > support the block number counter to be rolled over. That is, acking a data > packet with a block number of 0 is taken as if the 65356th block was acked. > > It was working before because the block counter roll-over was happening due > an overflow. But that got fixed by the mentioned commit, which led to the > regression when attempting to fetch files larger than the maximum size. > > To allow TFTP file transfers of unlimited size again, re-introduce a block > counter roll-over so the data packets are acked preventing the timeouts. > > [0]: https://tools.ietf.org/html/rfc2348 > [1]: https://tools.ietf.org/html/rfc1350 > > Fixes: 781b3e5efc3 (tftp: Do not use priority queue) > Suggested-by: Peter Jones <pjo...@redhat.com> > Signed-off-by: Javier Martinez Canillas <javi...@redhat.com>
Reviewed-by: Daniel Kiper <daniel.ki...@oracle.com> Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
