tftp: add comment, no code changes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 30 insertions, 5 deletions

diff --git a/networking/tftp.c b/networking/tftp.c
index 5c50b8cec..094c3baab 100644
--- a/networking/tftp.c
+++ b/networking/tftp.c
@@ -1,7 +1,5 @@
 /* vi: set sw=4 ts=4: */
-/* -------------------------------------------------------------------------
- * tftp.c
- *
+/*
  * A simple tftp client/server for busybox.
  * Tries to follow RFC1350.
  * Only "octet" mode supported.
@@ -19,8 +17,7 @@
  * tftpd added by Denys Vlasenko & Vladimir Dronnikov
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
- * ------------------------------------------------------------------------- */
-
+ */
 #include "libbb.h"
 
 #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
@@ -232,6 +229,34 @@ static int tftp_protocol(
 #endif
         }
 
+        /* Examples of network traffic.
+         * Note two cases when ACKs with block# of 0 are sent.
+         *
+         * Download without options:
+         * tftp -> "\0\1FILENAME\0octet\0"
+         *         "\0\3\0\1FILEDATA..." <- tftpd
+         * tftp -> "\0\4\0\1"
+         * ...
+         * Download with option of blksize 16384:
+         * tftp -> "\0\1FILENAME\0octet\0blksize\00016384\0"
+         *         "\0\6blksize\00016384\0" <- tftpd
+         * tftp -> "\0\4\0\0"
+         *         "\0\3\0\1FILEDATA..." <- tftpd
+         * tftp -> "\0\4\0\1"
+         * ...
+         * Upload without options:
+         * tftp -> "\0\2FILENAME\0octet\0"
+         *         "\0\4\0\0" <- tftpd
+         * tftp -> "\0\3\0\1FILEDATA..."
+         *         "\0\4\0\1" <- tftpd
+         * ...
+         * Upload with option of blksize 16384:
+         * tftp -> "\0\2FILENAME\0octet\0blksize\00016384\0"
+         *         "\0\6blksize\00016384\0" <- tftpd
+         * tftp -> "\0\3\0\1FILEDATA..."
+         *         "\0\4\0\1" <- tftpd
+         * ...
+         */
         block_nr = 1;
         cp = xbuf + 2;