freebsd-skq/lib/libfetch/fetch.3
Dag-Erling Smørgrav d8acd8dc5c Second of a series of cleanups to libfetch.
This commit introduces the following features:

 a) the fetchStat*() functions, which return meta-information for a
    document, such as size, modification time, etc.

 b) the use of the com_err(3) facilities to report errors.

It also fixes a bunch of style bugs and a few logic bugs and somewhat
improves the man page.

Changed files, in alphabetical order:

 Makefile:
  Don't generate macros in {ftp,http}err.c.

  Generate category fields for the error message lists.

  Compile the error table.

  Install fetch_err.h along with fetch.h.

 common.c:
  Remove the _netdb_errstring() macro, and add FETCH_ERR_NETDB to the
  error code in the _netdb_seterr() macro.

  Add categories to the _netdb_errlist table.

  Report errors through the Common Error library.

 common.h:
  Add the DEBUG macros.

  Add prototype for fetchConnect().

  Remove the prototype for _fetch_errstring(), which is local to common.c

  Add a categroy field to struct fetcherr, and define constants for
  error categories.

  Define macros for _{url,netdb,ftp,http}_seterr().

 errors.et: (new file)
  List error categories.

 fetch.3:
  Document the fetchStat*() functions.

  Move the "unimplemented functionality" comments from NOTES to BUGS.

  Document that applications which use libfetch must also use
  libcom_err, and list existing error codes.

  Undocument fetchLastErr{Code,String}.

  Remove the (empty) DIAGNOSTICS section.

  Mention Eugene Skepner in the AUTHORS section.

 fetch.c:
  Move the DEBUG macros to common.c

  Add fetchStat() and fetchStatURL().

  Generate error messages for URL parser errors, and fix a minor bug
  in the parser.

  Use 'struct url' instead of 'url_t'.

  Remove fetchLastErr{Code,String}.

 fetch.h:
  Use 'struct url' instead of 'url_t', and remove the typedef.

  Define struct url_stat (used by fetchStat()).

  Add prototypes for fetchStat*().

  Remove the declarations for fetchLastErr{Code,String}.

  Include fetch_err.h.

 fetch_err.et: (new file)
  Error table for libfetch.

 file.c:
  Add fetchStatFile().

  Use 'struct url' instead of 'url_t'.

 ftp.c:
  Add fetchStatFTP().

  Use 'struct url' instead of 'url_t'.

  Don't use fetchLastErrCode.

 ftp.errors:
  Add categories to all error messages.

 http.c:
  Add fetchStatHTTP().

  Use 'struct url' instead of 'url_t'.

  Don't use fetchLastErr{Code,Text}.

 http.errors:
  Add categories to all error messages.

Prompted by: jkh and Eugene Skepner
Numerous sugestions from: Garett Wollman and Eugene Skepner
1998-11-06 22:14:08 +00:00

366 lines
10 KiB
Groff

.\" Copyright (c) 1998 Dag-Erling Coïdan Smørgrav
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $Id: fetch.3,v 1.3 1998/11/05 19:48:16 des Exp $
.\"
.Dd July 1, 1998
.Dt FETCH 3
.Os
.Sh NAME
.Nm fetchGetURL ,
.Nm fetchPutURL ,
.Nm fetchStatURL ,
.Nm fetchParseURL ,
.Nm fetchGet ,
.Nm fetchPut ,
.Nm fetchStat ,
.Nm fetchGetFile ,
.Nm fetchPutFile ,
.Nm fetchStatFile ,
.Nm fetchGetHTTP ,
.Nm fetchPutHTTP ,
.Nm fetchStatHTTP ,
.Nm fetchGetFTP ,
.Nm fetchPutFTP
.Nm fetchStatFTP
.Nd file transfer library
.Sh SYNOPSIS
.Fd #include <fetch.h>
.Ft FILE *
.Fn fetchGetURL "char *URL" "char *flags"
.Ft FILE *
.Fn fetchPutURL "char *URL" "char *flags"
.Ft int
.Fn fetchStatURL "char *URL" "struct url_stat *us" "char *flags"
.Ft struct url *
.Fn fetchParseURL "char *URL" "char *flags"
.Ft FILE *
.Fn fetchGet "struct url *URL" "char *flags"
.Ft FILE *
.Fn fetchPut "struct url *URL" "char *flags"
.Ft int
.Fn fetchStat "struct url *URL" "struct url_stat *us" "char *flags"
.Ft FILE *
.Fn fetchGetFile "struct url *u" "char *flags"
.Ft FILE *
.Fn fetchPutFile "struct url *u" "char *flags"
.Ft int
.Fn fetchStatFile "struct url *URL" "struct url_stat *us" "char *flags"
.Ft FILE *
.Fn fetchGetHTTP "struct url *u" "char *flags"
.Ft FILE *
.Fn fetchPutHTTP "struct url *u" "char *flags"
.Ft int
.Fn fetchStatHTTP "struct url *URL" "struct url_stat *us" "char *flags"
.Ft FILE *
.Fn fetchGetFTP "struct url *u" "char *flags"
.Ft FILE *
.Fn fetchPutFTP "struct url *u" "char *flags"
.Ft int
.Fn fetchStatFTP "struct url *URL" "struct url_stat *us" "char *flags"
.Sh DESCRIPTION
.Pp
These functions implement a high-level library for retrieving and
uploading files using Uniform Resource Locators (URLs).
.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
.Fn fetchStatURL
attempts to obtain the requested document's metadata and fill in the
structure pointed to by it's second argument. The
.Fa url_stat
structure is defined as follows in
.Aq Pa fetch.h :
.Bd -literal
struct url_stat {
off_t size;
time_t time;
};
.Ed
.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 free .
.Pp
.Fn fetchGet ,
.Fn fetchPut
and
.Fn fetchStat
are similar to
.Fn fetchGetURL ,
.Fn fetchPutURL
and
.Fn fetchStatURL ,
except that they expect a pre-parsed URL in the form of a pointer to
a
.Fa struct url
rather than a string.
.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. Note 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 struct url
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
The
.Fn fetchStat
functions return 0 on success and -1 on failure.
.Pp
All other functions return a stream pointer which may be used to
access the requested document, or NULL if an error occurred.
.Pp
.Nm Libfetch
uses the Common Error Library
.Nm ( libcom_err )
to report errors. The error code passed to
.Fn com_err
is one of:
.Bl -tag -width Er
.It Bq Er FETCH_ABORT
Operation aborted
.It Bq Er FETCH_AUTH
Authentication failed
.It Bq Er FETCH_DOWN
Service unavailable
.It Bq Er FETCH_EXISTS
File exists
.It Bq Er FETCH_FULL
File system full
.It Bq Er FETCH_INFO
Informational response
.It Bq Er FETCH_MEMORY
Insufficient memory
.It Bq Er FETCH_MOVED
File has moved
.It Bq Er FETCH_NETWORK
Network error
.It Bq Er FETCH_OK
No error
.It Bq Er FETCH_PROTO
Protocol error
.It Bq Er FETCH_RESOLV
Resolver error
.It Bq Er FETCH_SERVER
Server error
.It Bq Er FETCH_TEMP
Temporary error
.It Bq Er FETCH_TIMEOUT
Operation timed out
.It Bq Er FETCH_UNAVAIL
File is not available
.It Bq Er FETCH_UNKNOWN
Unknown error
.It Bq Er FETCH_URL
Invalid URL
.El
.Pp
The accompanying error message includes a protocol-specific error code
and message, e.g. "File is not available (404 Not Found)"
.Sh ENVIRONMENT
The FTP and HTTP related 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 com_err 3 ,
.Xr fetch 1 ,
.Xr ftpio 3
.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 NOTES
The
.Nm fetch
library uses the Common Error library, and applications which link
with
.Nm libfetch
must therefore also link with
.Nm libcom_err .
.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 ,
.An Eugene Skepner Aq eu@qub.com
and other FreeBSD developers.
It replaces the older
.Nm ftpio
library written by
.An Poul-Henning Kamp Aq pkh@FreeBSD.org
and
.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
Some parts of the library are not yet implemented. The most notable
examples of this are
.Fn fetchPutHTTP ,
.Fn fetchStatFTP ,
.Fn fetchStatHTTP
and FTP proxy support.
.Pp
There's no way to select a proxy at run-time other than setting the
.Ev HTTP_PROXY
or
.Ev FTP_PROXY
environment variables as appropriate. There is also no way to stop the
FTP and HTTP functions from trying to use a proxy if these variables
are set.
.Pp
HTTP authentication doesn't work. I'm not sure that's a bug in my
code; as far as I can determine,
.Nm libfetch
handles HTTP/1.1 basic authentication correctly as outlined in
RFC2068, but I haven't been able to find an HTTP server that honors
the Authentication: header field. Also,
.Nm libfetch
does not attempt to interpret and respond to authentication requests
from the HTTP server.
.Pp
No attempt is made to encode spaces etc. within URLs. Spaces in the
document part of an URLshould be replaced with "%20" in HTTP URLs and
"\\ " in FTP URLs.
.Pp
Error numbers are unique only within a certain context; the error
codes used for FTP and HTTP overlap, as do those used for resolver and
system errors. For instance, error code 202 means "Command not
implemented, superfluous at this site" in an FTP context and
"Accepted" in an HTTP context.
.Pp
The man page is poorly written and produces badly formatted text.
.Pp
Tons of other stuff.