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Javier Martinez Canillas a6838bbc67 tftp: Roll-over block counter to prevent data packets timeouts 
Commit 781b3e5efc (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: 781b3e5efc (tftp: Do not use priority queue)

Suggested-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-09-11 15:52:07 +02:00
asm-tests asm-tests/i386-pc: Check that movl is 5 bytes. 2016-09-28 20:31:04 +03:00
conf gettext: Restore patches to po/Makefile.in.in 2020-03-10 21:17:54 +01:00
docs docs/grub: Support for probing partition UUID on MSDOS disks 2020-05-15 15:27:58 +02:00
grub-core tftp: Roll-over block counter to prevent data packets timeouts 2020-09-11 15:52:07 +02:00
include cryptodisk: Fix incorrect calculation of start sector 2020-09-11 15:51:04 +02:00
po po: Fix replacement of %m in sed programs 2020-03-10 21:32:09 +01:00
tests syslinux: Fix syslinux_test in out-of-tree builds 2019-03-05 10:27:53 +01:00
themes/starfield Starfield theme. 2012-02-23 17:21:38 +01:00
unicode * unicode: Import Unicode 6.0 data. 2011-12-25 16:17:25 +01:00
util templates: Remove unnecessary trailing semicolon 2020-09-11 15:51:25 +02:00
.gitattributes gitattributes: Mark po/exclude.pot as binary so git won't try to diff nonprintables 2019-09-23 13:17:15 +02:00
.gitignore gitignore: Add a few forgotten file patterns 2020-05-15 15:06:21 +02:00
.travis.yml travis: Add Travis CI config file 2019-02-25 14:02:06 +01:00
acinclude.m4 Fix -nopie/-nopie check. 2017-01-30 19:38:55 +01:00
AUTHORS 2005-09-03 Yoshinori K. Okuji <okuji@enbug.org> 2005-09-03 16:54:27 +00:00
autogen.sh autogen: Replace -iname with -ipath in find command 2020-05-15 15:35:59 +02:00
bootstrap gnulib: Upgrade Gnulib and switch to bootstrap tool 2019-03-05 10:48:12 +01:00
bootstrap.conf gettext: Restore patches to po/Makefile.in.in 2020-03-10 21:17:54 +01:00
BUGS * BUGS: New file. 2011-01-11 00:06:01 +01:00
ChangeLog-2015 Autogenerate ChangeLog from git changelog. 2015-01-24 17:29:50 +01:00
config.h.in Remove libgcc dependency. 2015-03-03 20:50:37 +01:00
configure.ac INSTALL/configure: Update install doc and configure comment 2020-05-25 14:49:53 +02:00
COPYING 2007-07-22 Yoshinori K. Okuji <okuji@enbug.org> 2007-07-21 23:32:33 +00:00
coreboot.cfg * coreboot.cfg: Add missing file. 2013-11-20 00:52:23 +01:00
geninit.sh automake commit without merge history 2010-05-06 11:34:04 +05:30
gentpl.py build: Fix GRUB i386-pc build with Ubuntu gcc 2020-03-31 12:17:02 +02:00
INSTALL safemath: Add some arithmetic primitives that check for overflow 2020-07-29 16:55:47 +02:00
linguas.sh linguas: Don't skip ko.po. 2017-02-04 00:06:57 +01:00
Makefile.am Makefile: Make libgrub.pp depend on config-util.h 2020-03-10 21:39:53 +01:00
Makefile.util.def templates: Output a menu entry for firmware setup on UEFI FastBoot systems 2020-04-21 22:14:12 +02:00
NEWS Release 2.04 2019-07-04 15:57:30 +02:00
README README: Remove dead link to the wiki 2015-11-06 04:31:23 +01:00
THANKS 2009-12-11 Robert Millan <rmh.grub@aybabtu.com> 2009-12-11 22:44:47 +00:00
TODO TODO: Remove obsolete link 2016-02-12 17:51:52 +01:00

README 

This is GRUB 2, the second version of the GRand Unified Bootloader.
GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more
robust, more powerful, and more portable.

See the file NEWS for a description of recent changes to GRUB 2.

See the file INSTALL for instructions on how to build and install the
GRUB 2 data and program files.

Please visit the official web page of GRUB 2, for more information.
The URL is <http://www.gnu.org/software/grub/grub.html>.

More extensive documentation is available in the Info manual,
accessible using 'info grub' after building and installing GRUB 2.

There are a number of important user-visible differences from the
first version of GRUB, now known as GRUB Legacy. For a summary, please
see:

  info grub Introduction 'Changes from GRUB Legacy'