Re: [RFC 959] FTP in ASCII mode
"Sandeep Srivastava" <sandeep.kumar.srivastava@gmail.com> Tue, 21 February 2006 07:23 UTC
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Date: Tue, 21 Feb 2006 12:53:32 +0530
From: Sandeep Srivastava <sandeep.kumar.srivastava@gmail.com>
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Subject: Re: [RFC 959] FTP in ASCII mode
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First of all thanks to everybody for the response. I knew that a FTP transfer in ASCII mode does EOL and EOF conversions based on the OS of the receiving system. And I very much expected my UTF-8 encoded file to get garbled when I FTPied it in ASCII mode. But guess what, it was not garbled on the receiving system. Maybe I was lucky, or maybe its because UTF-8 is backward compatible with ASCII. But then, as ASCII is purely 7-bits, the FTP in ASCII mode should have corrupted the UTF-8 encoded file, because UTF-8 is 8-bits. Moreover, in ASCII code page, code point 13=CR and code point 10=LF, but that might not be the case in every other code page. Hence the EOL conversion (in FTP ASCII mode) might corrupt that text file if it is encoded using a non-ASCII encoding. And what about handling the Unicode NewLine characters? Anyway... After reading all the wonderful replies, my conclusion is, even though my FTP client/server handled the UTF-8 encoded text file (which BTW contained Devanagri characters) correctly, there is a possibility that a text file, encoded in an encoding other than ASCII runs a risk of being corrupted when FTPied in ASCII mode. Therefore, always use ASCII mode to transfer only ASCII encoded files, and Binary mode to transfer non-ASCII encoded files. I was wondering why isn't there something like a "Text" mode for FTPing text files, which could handle text files encoded using any encoding available in this world, and then, the FTP client/server still does the EOL and EOF conversions properly? Thanks, Sandeep. On 2/21/06, Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp> wrote: > > John C Klensin wrote: > > > Sandeep's question raises another interesting issue. I just > > went back and reread RFC 2640. It does not seem to address the > > "TYPE A" issue at all. It does say (Section 2, paragraph 1) > > "Clients and servers are, however, under no obligation to > > perform any conversion on the contents of a file for operations > > such as STOR or RETR", which I would take to imply that it > > anticipates I18N FTP operations to be entirely binary ("TYPE I") > > although that is not explicit. > > As for Japanese processing, UTF-8 is not visible by users and on > the network, because UTF-8 is not only useless but also harmful. > > Instead, ISO-2022-JP, ShiftJIS and EUC are the major character sets. > Some ftp implementations does assume (sometimes depending on environment > variables) network character code ShiftJIS or EUC and perform appropriate > conversions, which garbles UTF-8. > > On the other hand, if you use ISO-2022-JP, which is 7 bit pure and ASCII > compatible (in a sense, it is pure ASCII), we can safely use ASCII mode > of vanilla ftp and there is no confusion as long as we are in ASCII > environment. > > Similar encoding can be profiled using ISO 2022 to obtain a fully > internationalized, 7 bit pure, ASII compatible character encoding. > > The only problem for RFC2460 was that it does not need MIME for > charset and 8bit extension that it makes it clear that MIME is > useless. > > Note that long term state maintainance of full ISO 2022 is not > more complex than that of UTF-8. Note also that, carefully profiled > ISO 2022, such as ISO-2022-JP, requires state maintainance a lot > simpler than that of UTF-8. > > > Whether the characters in use are UTF-8 or not, we've still got > > that issue with line-endings. > > Line-ending issues of any ISO 2022 based encoding are just as simple > as those of ASCII. > > Masataka Ohta > > > > _______________________________________________ > Ietf mailing list > Ietf@ietf.org > https://www1.ietf.org/mailman/listinfo/ietf >
_______________________________________________ Ietf mailing list Ietf@ietf.org https://www1.ietf.org/mailman/listinfo/ietf
- [RFC 959] FTP in ASCII mode Sandeep Srivastava
- Re: [RFC 959] FTP in ASCII mode Peter Dambier
- Re: [RFC 959] FTP in ASCII mode John C Klensin
- Re: [RFC 959] FTP in ASCII mode John C Klensin
- Re: [RFC 959] FTP in ASCII mode Masataka Ohta
- Re: [RFC 959] FTP in ASCII mode Sandeep Srivastava
- Re: [RFC 959] FTP in ASCII mode John C Klensin
- Re: [RFC 959] FTP in ASCII mode Frank Ellermann
- Re: [RFC 959] FTP in ASCII mode Sandeep Srivastava
- Re: [RFC 959] FTP in ASCII mode Peter Dambier