[Qemu-devel] Qemu's internal TFTP server breaks lock-step-iness of TFTP

[Milan Plzik <milan.plzik@gmail.com>]

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  Hello,

  according to RFC 1350 and RFC 2347, TFTP server should answer RRQ by
either OACK or DATA packet. Qemu's internal TFTP server answers RRQ with
additional options by sending both OACK and DATA packet, thus breaking
the "lock-step" feature of the protocol, and also confuses client.

  Proposed solution would be to, in case of OACK packet, wait for ACK
from client and just then start sending data. Attached patch implements
this.

  I would like to thank to mbc and th1 (who is the rightful author of
the patch) from #gpxe for their time, effort and patience with me :)

	Milan Plzik

[-- Attachment #2: qemu_tftp_handle_oack_correctly.patch --]
[-- Type: text/x-patch, Size: 283 bytes --]

diff --git a/slirp/tftp.c b/slirp/tftp.c
index 082f5d0..db869fc 100644
--- a/slirp/tftp.c
+++ b/slirp/tftp.c
@@ -362,6 +362,7 @@ static void tftp_handle_rrq(Slirp *slirp, struct tftp_t *tp, int pktlen)
 	  }
 
 	  tftp_send_oack(spt, "tsize", tsize, tp);
+	  return;
       }
   }