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Network Working Group                                          G. MalkinRequest for Comments: 1784                                Xylogics, Inc.Updates:1350                                                  A. HarkinCategory: Standards Track                            Hewlett Packard Co.                                                              March 1995TFTP Timeout Interval and Transfer Size OptionsStatus of this Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Abstract   The Trivial File Transfer Protocol [1] is a simple, lock-step, file   transfer protocol which allows a client to get or put a file onto a   remote host.   This document describes two TFTP options. The first allows the client   and server to negotiate the Timeout Interval.  The second allows the   side receiving the file to determine the ultimate size of the   transfer before it begins.  The TFTP Option Extension mechanism is   described in [2].   This document assumes that the reader is familiar with the   terminology and notation of both [1] and [2].Timeout Interval Option Specification   The TFTP Read Request or Write Request packet is modified to include   the timeout option as follows:      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      |  opc  |filename| 0 |  mode  | 0 | timeout| 0 |  #secs | 0 |      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      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.Malkin & Harkin                                                 [Page 1]

RFC 1784                      TFTP Options                    March 1995      mode         The mode of the file transfer: "netascii", "octet", or "mail",         as defined in [1].  This is a NULL-terminated field.      timeout         The Timeout Interval option, "timeout" (case insensitive).         This is a NULL-terminated field.      #secs         The number of seconds to wait before retransmitting, specified         in ASCII.  Valid values range between "1" and "255" octets,         inclusive.  This is a NULL-terminated field.   For example:      +-------+--------+---+--------+---+--------+---+--------+---+      |   1   | foobar | 0 | binary | 0 | timeout| 0 |    1   | 0 |      +-------+--------+---+--------+---+--------+---+--------+---+   is a Read Request, for the file named "foobar", in binary transfer   mode, with a timeout interval of 1 second.   If the server is willing to accept the timeout option, it sends an   Option Acknowledgment (OACK) to the client.  The specified timeout   value must match the value specified by the client.Transfer Size Option Specification   The TFTP Read Request or Write Request packet is modified to include   the tsize option as follows:      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      |  opc  |filename| 0 |  mode  | 0 | tsize  | 0 |  size  | 0 |      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      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.Malkin & Harkin                                                 [Page 2]

RFC 1784                      TFTP Options                    March 1995      tsize         The Transfer Size option, "tsize" (case insensitive).  This is         a NULL-terminated field.      size         The size of the file to be transfered, specified as a         NULL-terminated ASCII string.   For example:      +-------+--------+---+--------+---+--------+---+--------+---+      |   2   | foobar | 0 | binary | 0 | tsize  | 0 | 673312 | 0 |      +-------+--------+---+--------+---+--------+---+--------+---+   is a Write Request, with the 673312-octet file named "foobar", in   binary transfer mode.   In Read Request packets, a size of "0" is specified in the request   and the size of the file, in octets, is returned in the OACK.  If the   file is too large for the client to handle, it may abort the transfer   with an Error packet (error code 3).  In Write Request packets, the   size of the file, in octets, is specified in the request and echoed   back in the OACK.  If the file is too large for the server to handle,   it may abort the transfer with an Error packet (error code 3).Security Considerations   Security issues are not discussed in this memo.References   [1] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33,RFC 1350,       MIT, July 1992.   [2] Malkin, G., and A. Harkin, "TFTP Option Extension",RFC 1782,       Xylogics, Inc., Hewlett Packard Co., March 1995.Malkin & Harkin                                                 [Page 3]

RFC 1784                      TFTP Options                    March 1995Authors' Addresses       Gary Scott Malkin       Xylogics, Inc.       53 Third Avenue       Burlington, MA  01803       Phone:  (617) 272-8140       EMail:  gmalkin@xylogics.com       Art Harkin       Internet Services Project       Information Networks Division       19420 Homestead Road MS 43LN       Cupertino, CA  95014       Phone: (408) 447-3755       EMail: ash@cup.hp.comMalkin & Harkin                                                 [Page 4]