Re: [Python-Dev] Can ftp url start with file:// ?
Senthil Kumaran wrote: On Fri, Jul 09, 2010 at 02:32:04PM -0400, Fred Drake wrote: FTP access also more often reflected the actual file hierarchy of the machine, so trying that path as a system path is more likely to work that I'd expect to see for HTTP. I see the reason. But I doubt if this is a reliable approach. Also when the scheme begins with file:// it should not be confused with ftp, so I think, that portion of code in urllib which work that way should be removed. The issue8801 was fixed in a different way so that no regression is introduced. For 3.2 release, shall we do way with relying on ftp for file:// scheme ? Currently for a url like file://somehost.domain//filesys/file.txt the flow control considers it a ftp url! The expected behaviour might be throw an exception saying that file:// url wont make any sense if it not localhost or absolute path. What if 'somehost.domain' is actually hostname of the machine? Should file:// be allowed in that case or is it the reason to rely on ftp? But it still does not make much sense to use ftp, because there is no guarantee that ftp service is running in that machine. My own inclination would be to regard the current treatment of file: as a bug (albeit one not worth fixing on 2.x). RFC 1630 specification lists the file scheme as being for local file access, and RFC 1738 says they are for host-specific file names and points out that The file URL scheme is unusual in that it does not specify an Internet protocol or access method for such files; as such, its utility in network protocols between hosts is limited. Presumably a hostname in such a URI would require that some host-specific protocol be used (but this should be an access protocol like SMB or NFS, not a transfer protocol like FTP). It seems pretty clear that randomly interpreting particular host names to imply a specific remote-access protocol like FTP is bogus. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 DjangoCon US September 7-9, 2010http://djangocon.us/ See Python Video! http://python.mirocommunity.org/ Holden Web LLC http://www.holdenweb.com/ ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Sat, Jul 10, 2010 at 11:56 PM, Senthil Kumaran orsent...@gmail.com wrote: I see the reason. But I doubt if this is a reliable approach. Also when the scheme begins with file:// it should not be confused with ftp, so I think, that portion of code in urllib which work that way should be removed. I'm not trying to defend the current behavior of defaulting to FTP as a good thing; it's definitely surprising. I am trying to rationalize it so I can be sure I understand why it might have been done to start with. My own preference is to kick out any non-local references with an exception that can be detected (possibly derived from ValueError) so that applications that want rewrite (hopefully with user agreement!) can do so. (Checking for non-local file: URLs on input might be better, of course.) -Fred -- Fred L. Drake fdrake at acm.org ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
Fred Drake fdr...@acm.org wrote: On Sat, Jul 10, 2010 at 11:56 PM, Senthil Kumaran orsent...@gmail.com wro= te: I see the reason. But I doubt if this is a reliable approach. =A0Also when the scheme begins with file:// it should not be confused with ftp, so I think, that portion of code in urllib which work that way should be removed. I'm not trying to defend the current behavior of defaulting to FTP as a good thing; it's definitely surprising. I am trying to rationalize it so I can be sure I understand why it might have been done to start with. My own preference is to kick out any non-local references with an exception that can be detected (possibly derived from ValueError) so that applications that want rewrite (hopefully with user agreement!) can do so. (Checking for non-local file: URLs on input might be better, of course.) Sounds like a good plan to me, too. Bill ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Mon, 12 Jul 2010 12:01:07 am Steve Holden wrote: My own inclination would be to regard the current treatment of file: as a bug (albeit one not worth fixing on 2.x). ... Presumably a hostname in such a URI would require that some host-specific protocol be used (but this should be an access protocol like SMB or NFS, not a transfer protocol like FTP). KDE uses SMB for non-local hostnames in file URIs. It seems pretty clear that randomly interpreting particular host names to imply a specific remote-access protocol like FTP is bogus. Agreed. The right behaviour is to raise an exception and let the caller deal with it, or provide a means to register an alternative. -- Steven D'Aprano ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Fri, Jul 09, 2010 at 02:32:04PM -0400, Fred Drake wrote: FTP access also more often reflected the actual file hierarchy of the machine, so trying that path as a system path is more likely to work that I'd expect to see for HTTP. I see the reason. But I doubt if this is a reliable approach. Also when the scheme begins with file:// it should not be confused with ftp, so I think, that portion of code in urllib which work that way should be removed. The issue8801 was fixed in a different way so that no regression is introduced. For 3.2 release, shall we do way with relying on ftp for file:// scheme ? Currently for a url like file://somehost.domain//filesys/file.txt the flow control considers it a ftp url! The expected behaviour might be throw an exception saying that file:// url wont make any sense if it not localhost or absolute path. What if 'somehost.domain' is actually hostname of the machine? Should file:// be allowed in that case or is it the reason to rely on ftp? But it still does not make much sense to use ftp, because there is no guarantee that ftp service is running in that machine. -- Senthil The whole world is a scab. The point is to pick it constructively. -- Peter Beard ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
Senthil Kumaran orsent...@gmail.com wrote: On Fri, Jul 09, 2010 at 02:23:40PM +1000, Steven D'Aprano wrote: Is this is valid ftp url? # file://ftp.example.com/blah.txt (an ftp URL) My answer is no. When we have the scheme specifically mentioned as file:// it is no point in considering it as ftp url (which should start with ftp://). I agree. Just because the host is *called* ftp doesn't mean you should use the ftp protocol to get the file. It was not just for the host being called ftp.example.com It was for a pattern that file:/// is local file (correct) and file://localhost/somepath is again local file (correct again) but file://anyhost.domain/file.txt is actually ftp (pretty weird). RFC 1738 explicitly says that file://host/path is pretty much useless for anything except host=localhost: ``The file URL scheme is unusual in that it does not specify an Internet protocol or access method for such files; as such, its utility in network protocols between hosts is limited.'' So, FTP is *not* the default protocol. On the other hand, if host actually begins with ftp., it's a pretty good guess that FTP will work. Similarly, if host actually begins with www., it's a pretty good guess that HTTP will work. This seems to me like a practicality-vs.-purity consideration. Bill ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Fri, Jul 9, 2010 at 12:41, Bill Janssen jans...@parc.com wrote:
So, FTP is *not* the default protocol. On the other hand, if host
actually begins with ftp., it's a pretty good guess that FTP will
work.
Actually, FTP *is* the default protocol for most URLs with hostnames in
urllib.py.
urllib.open_file() delegates to open_ftp() if there's a any host other than
the exact string localhost, and open_local_file() otherwise.
import urllib
f =urllib.urlopen('file:///foo.txt')
f =urllib.urlopen('file://localhost/foo.txt')
f = urllib.urlopen('file://www.google.com/')
Traceback (most recent call last):
File stdin, line 1, in module
File c:\python25\lib\urllib.py, line 82, in urlopen
return opener.open(url)
File c:\python25\lib\urllib.py, line 190, in open
return getattr(self, name)(url)
File c:\python25\lib\urllib.py, line 457, in open_file
return self.open_ftp(url)
File c:\python25\lib\urllib.py, line 538, in open_ftp
ftpwrapper(user, passwd, host, port, dirs)
File c:\python25\lib\urllib.py, line 844, in __init__
self.init()
File c:\python25\lib\urllib.py, line 850, in init
self.ftp.connect(self.host, self.port)
File c:\python25\lib\ftplib.py, line 129, in connect
raise socket.error, msg
IOError: [Errno ftp error] (10060, 'Operation timed out')
f =urllib.urlopen('file://127.0.0.1/foo.txt')
Traceback (most recent call last):
File stdin, line 1, in module
File c:\python25\lib\urllib.py, line 82, in urlopen
return opener.open(url)
File c:\python25\lib\urllib.py, line 190, in open
return getattr(self, name)(url)
File c:\python25\lib\urllib.py, line 457, in open_file
return self.open_ftp(url)
File c:\python25\lib\urllib.py, line 538, in open_ftp
ftpwrapper(user, passwd, host, port, dirs)
File c:\python25\lib\urllib.py, line 844, in __init__
self.init()
File c:\python25\lib\urllib.py, line 850, in init
self.ftp.connect(self.host, self.port)
File c:\python25\lib\ftplib.py, line 129, in connect
raise socket.error, msg
IOError: [Errno ftp error] (10061, 'Connection refused')
--
Tim Lesher tles...@gmail.com
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Re: [Python-Dev] Can ftp url start with file:// ?
To be clear, Python 2.x's urllib.urlopen() has this issue; 3.1's urllib.request.urlopen() rejects non-local hosts in a file URL. -- Tim Lesher tles...@gmail.com ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
Tim Lesher tles...@gmail.com wrote:
On Fri, Jul 9, 2010 at 12:41, Bill Janssen jans...@parc.com wrote:
So, FTP is *not* the default protocol. On the other hand, if host
actually begins with ftp., it's a pretty good guess that FTP will
work.
Actually, FTP *is* the default protocol for most URLs with hostnames in
urllib.py.
urllib.open_file() delegates to open_ftp() if there's a any host other than
the exact string localhost, and open_local_file() otherwise.
I just meant to point out that it's not specified that way by any RFC.
And, while FTP might have been a good default choice last century when
urllib.py was originally written, times have changed. I'd suggest that
HTTP is a better (more likely to succeed) default choice in this century.
If we want to perpetuate these guessing heuristics, I'd suggest using
FTP if the hostname starts with ftp., and HTTP if the hostname starts
with www., and raise an error otherwise.
Bill
import urllib
f =urllib.urlopen('file:///foo.txt')
f =urllib.urlopen('file://localhost/foo.txt')
f = urllib.urlopen('file://www.google.com/')
Traceback (most recent call last):
File stdin, line 1, in module
File c:\python25\lib\urllib.py, line 82, in urlopen
return opener.open(url)
File c:\python25\lib\urllib.py, line 190, in open
return getattr(self, name)(url)
File c:\python25\lib\urllib.py, line 457, in open_file
return self.open_ftp(url)
File c:\python25\lib\urllib.py, line 538, in open_ftp
ftpwrapper(user, passwd, host, port, dirs)
File c:\python25\lib\urllib.py, line 844, in __init__
self.init()
File c:\python25\lib\urllib.py, line 850, in init
self.ftp.connect(self.host, self.port)
File c:\python25\lib\ftplib.py, line 129, in connect
raise socket.error, msg
IOError: [Errno ftp error] (10060, 'Operation timed out')
f =urllib.urlopen('file://127.0.0.1/foo.txt')
Traceback (most recent call last):
File stdin, line 1, in module
File c:\python25\lib\urllib.py, line 82, in urlopen
return opener.open(url)
File c:\python25\lib\urllib.py, line 190, in open
return getattr(self, name)(url)
File c:\python25\lib\urllib.py, line 457, in open_file
return self.open_ftp(url)
File c:\python25\lib\urllib.py, line 538, in open_ftp
ftpwrapper(user, passwd, host, port, dirs)
File c:\python25\lib\urllib.py, line 844, in __init__
self.init()
File c:\python25\lib\urllib.py, line 850, in init
self.ftp.connect(self.host, self.port)
File c:\python25\lib\ftplib.py, line 129, in connect
raise socket.error, msg
IOError: [Errno ftp error] (10061, 'Connection refused')
--
Tim Lesher tles...@gmail.com
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Re: [Python-Dev] Can ftp url start with file:// ?
On 9 July 2010 19:04, Bill Janssen jans...@parc.com wrote: If we want to perpetuate these guessing heuristics, I'd suggest using FTP if the hostname starts with ftp., and HTTP if the hostname starts with www., and raise an error otherwise. From what Tim says, it sounds like guessing is only in 2.x. Removing the guessing clearly isn't a bug fix, so there's nothing to do in the 2.x line (as there won't be a 2.8). 3.1 already has the stricter (and in my view correct) behaviour, and I see no reason to introduce the 2.x behaviour into Python 3. So I'd say there's nothing to do. Paul. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Fri, Jul 9, 2010 at 2:04 PM, Bill Janssen jans...@parc.com wrote: I'd suggest that HTTP is a better (more likely to succeed) default choice in this century. FTP access also more often reflected the actual file hierarchy of the machine, so trying that path as a system path is more likely to work that I'd expect to see for HTTP. Really, I'd expect any non-local file: URLs to be kicked back to the application, and let it decide to re-write if it wants to. -Fred -- Fred L. Drake, Jr.fdrake at gmail.com A storm broke loose in my mind. --Albert Einstein ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
Paul Moore wrote: On 9 July 2010 19:04, Bill Janssen jans...@parc.com wrote: If we want to perpetuate these guessing heuristics, I'd suggest using FTP if the hostname starts with ftp., and HTTP if the hostname starts with www., and raise an error otherwise. From what Tim says, it sounds like guessing is only in 2.x. Removing the guessing clearly isn't a bug fix, so there's nothing to do in the 2.x line (as there won't be a 2.8). 3.1 already has the stricter (and in my view correct) behaviour, and I see no reason to introduce the 2.x behaviour into Python 3. So I'd say there's nothing to do. Paul. This /could/ become a bugfix in 2.7.x if people thought it was a sufficiently egregious bug to need fixing. Given that the matter is only now coming to light it's probably bets to let sleeping dogs lie. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 DjangoCon US September 7-9, 2010http://djangocon.us/ See Python Video! http://python.mirocommunity.org/ Holden Web LLC http://www.holdenweb.com/ ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] Can ftp url start with file:// ?
Strictly not a Python question, but I wanted to know from the experience of others in this list. Is this is valid ftp url? # file://ftp.example.com/blah.txt (an ftp URL) My answer is no. When we have the scheme specifically mentioned as file:// it is no point in considering it as ftp url (which should start with ftp://). If I go ahead with this assumption and fix a bug in stdlib, I am introducing a regression because at the moment the above is considered a ftp url. -- Senthil A real diplomat is one who can cut his neighbor's throat without having his neighbour notice it. -- Trygve Lie ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Fri, 9 Jul 2010 01:52:32 pm Senthil Kumaran wrote: Strictly not a Python question, but I wanted to know from the experience of others in this list. Is this is valid ftp url? # file://ftp.example.com/blah.txt (an ftp URL) My answer is no. When we have the scheme specifically mentioned as file:// it is no point in considering it as ftp url (which should start with ftp://). I agree. Just because the host is *called* ftp doesn't mean you should use the ftp protocol to get the file. http://en.wikipedia.org/wiki/File_URI_scheme If I go ahead with this assumption and fix a bug in stdlib, I am introducing a regression because at the moment the above is considered a ftp url. Do you have a url for the bug report? -- Steven D'Aprano ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Can ftp url start with file:// ?
On Fri, Jul 09, 2010 at 02:23:40PM +1000, Steven D'Aprano wrote: Is this is valid ftp url? # file://ftp.example.com/blah.txt (an ftp URL) My answer is no. When we have the scheme specifically mentioned as file:// it is no point in considering it as ftp url (which should start with ftp://). I agree. Just because the host is *called* ftp doesn't mean you should use the ftp protocol to get the file. It was not just for the host being called ftp.example.com It was for a pattern that file:/// is local file (correct) and file://localhost/somepath is again local file (correct again) but file://anyhost.domain/file.txt is actually ftp (pretty weird). Do you have a url for the bug report? http://bugs.python.org/issue8801 Don't go into the suggestion in the report, but just notice that file url lead to an ftp error exception. -- Senthil ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
