freebsd-nq/lib/libfetch/fetch.3
Dag-Erling Smørgrav 4ca1ab9434 Imported libfetch into the tree. It compiles, but there's still some
work to do. I especially need help with the man page.
1998-07-09 16:52:44 +00:00

234 lines
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.\" Copyright (c) 1998 Dag-Erling Coïdan Smørgrav
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.Dd July 1, 1998
.Dt FETCH 3
.Os
.Sh NAME
.Nm fetchParseURL ,
.Nm fetchFreeURL ,
.Nm fetchGetURL ,
.Nm fetchPutURL ,
.Nm fetchGetFile ,
.Nm fetchPutFile ,
.Nm fetchGetHTTP ,
.Nm fetchPutHTTP ,
.Nm fetchGetFTP ,
.Nm fetchPutFTP
.Nd file transfer library
.Sh SYNOPSIS
.Fd #include <fetch.h>
.Ft url_t *
.Fn fetchParseURL "char *URL" "char *flags"
.Ft void
.Fn fetchFreeURL "url_t *u"
.Ft FILE *
.Fn fetchGetFile "url_t *u" "char *flags"
.Ft FILE *
.Fn fetchPutFile "url_t *u" "char *flags"
.Ft FILE *
.Fn fetchGetHTTP "url_t *u" "char *flags"
.Ft FILE *
.Fn fetchPutHTTP "url_t *u" "char *flags"
.Ft FILE *
.Fn fetchGetFTP "url_t *u" "char *flags"
.Ft FILE *
.Fn fetchPutFTP "url_t *u" "char *flags"
.Sh DESCRIPTION
These functions implement a high-level library for retrieving and
uploading files using Uniform Resource Locators (URLs).
.Pp
.Fn fetchParseURL
takes a URL in the form of a null-terminated string and splits it into
its components function according to the Common Internet Scheme Syntax
detailed in RFC1738. A regular expression which produces this syntax
is:
.Bd -literal
<scheme>:(//(<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
.Ed
.Pp
Note that some components of the URL are not necessarily relevant to
all URL schemes. For instance, the file scheme only needs the <scheme>
and <document> components.
.Pp
The pointer returned by
.Fn fetchParseURL
should be freed using
.Fn fetchFreeURL .
.Pp
.Fn fetchGetURL
and
.Fn fetchPutURL
constitute the recommended interface to the
.Nm fetch
library. They examine the URL passed to them to determine the transfer
method, and call the appropriate lower-level functions to perform the
actual transfer. The
.Fa flags
argument is a string of characters which specify transfer options. The
meaning of the individual flags is scheme-dependent, and is detailed
in the appropriate section below.
.Pp
All of the
.Fn fetchGetXXX
and
.Fn fetchPutXXX
functions return a pointer to a stream which can be used to read or
write data from or to the requested document, respectively. Not that
although the implementation details of the individual access methods
vary, it can generally be assumed that a stream returned by one of the
.Fn fetchGetXXX
functions is read-only, and that a stream returned by one of the
.Fn fetchPutXXX
functions is write-only.
.Sh FILE SCHEME
.Fn fetchGetFile
and
.Fn fetchPutFile
provide access to documents which are files in a locally mounted file
system. Only the <document> component of the URL is used.
.Pp
.Fn fetchGetFile
does not accept any flags.
.Pp
.Fn fetchPutFile
accepts the
.Fa a
(append to file) flag. If that flag is specified, the data written to
the stream returned by
.Fn fetchPutFile
will be appended to the previous contents of the file, instead of
replacing them.
.Sh FTP SCHEME
.Fn fetchGetFTP
and
.Fn fetchPutFTP
implement the FTP protocol as described in RFC959.
.Pp
If the
.Fa p
(passive) flag is specified, a passive (rather than active) connection
will be attempted.
.Pp
If no user name or password is given, the
.Nm fetch
library will attempt an anonymous login, with user name "ftp" and
password "ftp".
.Sh HTTP SCHEME
The
.Fn fetchGetHTTP
and
.Fn fetchPutHTTP
functions implement the HTTP/1.1 protocol. With a little luck, there's
even a chance that they comply with RFC2068.
.Pp
Since there seems to be no good way of implementing the HTTP PUT
method in a manner consistent with the rest of the
.Nm fetch
library,
.Fn fetchPutHTTP
is currently unimplemented.
.Sh RETURN VALUES
.Fn fetchParseURL
returns a pointer to a
.Fa url_t
structure containing the individual components of the URL. If it is
unable to allocate memory, or the URL is syntactically incorrect,
.Fn fetchParseURL
returns a NULL pointer.
.Pp
.Fn fetchFreeURL
does not return any value.
.Pp
All other functions return a stream pointer which may be used to
access the requested document. Upon failure of any kind, they return a
NULL pointer.
.Sh ENVIRONMENT
The FTP and HTTP functions use the
.Ev HTTP_PROXY
and
.Ev FTP_PROXY
environment variables, respectively, as the address of a proxy server
to use for transferring files.
.Sh SEE ALSO
.Xr fetch 1 ,
.Xr ftpio 3 ,
.Xr lots_of_other_stuff
.Rs
.%A T. Berners-Lee, L. Masinter & M. McCahill
.%D December 1994
.%T Uniform Resource Locators (URL)
.%O RFC1738
.Re
.Rs
.%A R. Fielding, J. Gettys, J. Mogul, H. Frystyk, T. Berners-Lee
.%D Januray 1997
.%B Hypertext Transfer Protocol -- HTTP/1.1
.%O RFC2068
.Re
.Rs
.%A J. Postel, J. K. Reynolds
.%D October 1985
.%B File Transfer Protocol
.%O RFC959
.Re
.Sh DIAGNOSTICS
Add later.
.Sh NOTES
Some parts of the library are not yet implemented. The most notable
examples of this are
.Fn fetchPutHTTP
and proxy support for the FTP access method.
.Pp
I hate HTTP.
.Pp
Why does the \.Pp macro sometimes insert two blank lines instead of
one?
.Sh HISTORY
The
.Nm fetch
library first appeared in
.Fx 3.0 .
.Sh AUTHORS
The
.Nm fetch
library was mostly written by
.An Dag-Erling Coïdan Smørgrav Aq des@FreeBSD.org
with numerous suggestions from
.An Jordan K. Hubbard Aq jkh@FreeBSD.org
and other FreeBSD developers.
It incorporates the older
.Nm ftpio
library, which was originally written by
.Nm Poul-Henning Kamp Aq pkh@FreeBSD.org
and later turned inside out by
.An Jordan K. Hubbard Aq jkh@FreeBSD.org .
.Pp
This manual page was written by
.An Dag-Erling Coïdan Smørgrav Aq des@FreeBSD.org
.Sh BUGS
If I knew, I'd have fixed them.