RFC 1782 (rfc1782) - Page 2 of 6
TFTP Option Extension
Alternative Format: Original Text Document
RFC 1782 TFTP Option Extension March 1995
Options are appended to a TFTP Read Request or Write Request packet
as follows:
+-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+-->
| opc |filename| 0 | mode | 0 | opt1 | 0 | value1 | 0 |
>-------+---+---~~---+---+
-------+---+---~~---+---+
The "0"s shown in these illustrations and the ones below are all
all zero octets, i.e., NULL terminators for the preceeding
fields.
opc
The opcode field contains either a 1, for Read Requests, or 2,
for Write Requests, as defined in [1].
filename
The name of the file to be read or written, as defined in [1].
This is a NULL-terminated field.
mode
The mode of the file transfer: "netascii", "octet", or "mail",
as defined in [1]. This is a NULL-terminated field.
opt1
The first option, in case-insensitive ASCII (e.g., "blksize").
This is a NULL-terminated ASCII field.
value1
The value associated with the first option, in case-insensitive
ASCII. This is a NULL-terminated field.
optN, valueN
The final option/value pair. Each NULL-terminated field is
specified in case-insensitive ASCII.
The options and values are all NULL-terminated, in keeping with the
original request format. If multiple options are to be negotiated,
they are appended to each other. The order in which options are
specified is not significant. The maximum size of a request packet
is 512 octets.
Malkin & Harkin