572 lines
14 KiB
Groff
572 lines
14 KiB
Groff
.\" Copyright (c) 1998 Dag-Erling Coïdan Smørgrav
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 1, 1998
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.Dt FETCH 3
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.Os
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.Sh NAME
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.Nm fetchMakeURL ,
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.Nm fetchParseURL ,
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.Nm fetchFreeURL ,
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.Nm fetchXGetURL ,
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.Nm fetchGetURL ,
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.Nm fetchPutURL ,
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.Nm fetchStatURL ,
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.Nm fetchListURL ,
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.Nm fetchXGet ,
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.Nm fetchGet ,
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.Nm fetchPut ,
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.Nm fetchStat ,
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.Nm fetchList ,
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.Nm fetchXGetFile ,
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.Nm fetchGetFile ,
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.Nm fetchPutFile ,
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.Nm fetchStatFile ,
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.Nm fetchListFile ,
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.Nm fetchXGetHTTP ,
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.Nm fetchGetHTTP ,
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.Nm fetchPutHTTP ,
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.Nm fetchStatHTTP ,
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.Nm fetchListHTTP ,
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.Nm fetchXGetFTP ,
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.Nm fetchGetFTP ,
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.Nm fetchPutFTP ,
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.Nm fetchStatFTP ,
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.Nm fetchListFTP
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.Nd file transfer functions
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.Sh LIBRARY
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.Lb libfetch
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.Sh SYNOPSIS
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.Fd #include <sys/param.h>
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.Fd #include <stdio.h>
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.Fd #include <fetch.h>
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.Ft struct url *
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.Fn fetchMakeURL "char *scheme" "char *host" "int port" "char *doc" "char *user" "char *pwd"
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.Ft struct url *
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.Fn fetchParseURL "char *URL"
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.Ft void
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.Fn fetchFreeURL "struct url *URL"
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.Ft FILE *
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.Fn fetchXGetURL "char *URL" "struct url_stat *us" "char *flags"
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.Ft FILE *
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.Fn fetchGetURL "char *URL" "char *flags"
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.Ft FILE *
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.Fn fetchPutURL "char *URL" "char *flags"
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.Ft int
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.Fn fetchStatURL "char *URL" "struct url_stat *us" "char *flags"
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.Ft struct url_ent *
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.Fn fetchListURL "char *URL" "char *flags"
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.Ft FILE *
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.Fn fetchXGet "struct url *URL" "struct url_stat *us" "char *flags"
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.Ft FILE *
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.Fn fetchGet "struct url *URL" "char *flags"
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.Ft FILE *
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.Fn fetchPut "struct url *URL" "char *flags"
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.Ft int
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.Fn fetchStat "struct url *URL" "struct url_stat *us" "char *flags"
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.Ft struct url_ent *
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.Fn fetchList "struct url *" "char *flags"
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.Ft FILE *
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.Fn fetchXGetFile "struct url *u" "struct url_stat *us" "char *flags"
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.Ft FILE *
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.Fn fetchGetFile "struct url *u" "char *flags"
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.Ft FILE *
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.Fn fetchPutFile "struct url *u" "char *flags"
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.Ft int
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.Fn fetchStatFile "struct url *URL" "struct url_stat *us" "char *flags"
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.Ft struct url_ent *
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.Fn fetchListFile "struct url *" "char *flags"
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.Ft FILE *
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.Fn fetchXGetHTTP "struct url *u" "struct url_stat *us" "char *flags"
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.Ft FILE *
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.Fn fetchGetHTTP "struct url *u" "char *flags"
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.Ft FILE *
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.Fn fetchPutHTTP "struct url *u" "char *flags"
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.Ft int
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.Fn fetchStatHTTP "struct url *URL" "struct url_stat *us" "char *flags"
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.Ft struct url_ent *
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.Fn fetchListHTTP "struct url *" "char *flags"
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.Ft FILE *
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.Fn fetchXGetFTP "struct url *u" "struct url_stat *us" "char *flags"
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.Ft FILE *
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.Fn fetchGetFTP "struct url *u" "char *flags"
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.Ft FILE *
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.Fn fetchPutFTP "struct url *u" "char *flags"
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.Ft int
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.Fn fetchStatFTP "struct url *URL" "struct url_stat *us" "char *flags"
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.Ft struct url_ent *
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.Fn fetchListFTP "struct url *" "char *flags"
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.Sh DESCRIPTION
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.Pp
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These functions implement a high-level library for retrieving and
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uploading files using Uniform Resource Locators (URLs).
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.Pp
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.Fn fetchParseURL
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takes a URL in the form of a null-terminated string and splits it into
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its components function according to the Common Internet Scheme Syntax
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detailed in RFC1738.
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A regular expression which produces this syntax is:
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.Bd -literal
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<scheme>:(//(<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
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.Ed
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.Pp
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If the URL does not seem to begin with a scheme name, the following
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syntax is assumed:
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.Bd -literal
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((<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
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.Ed
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.Pp
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Note that some components of the URL are not necessarily relevant to
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all URL schemes.
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For instance, the file scheme only needs the <scheme> and <document>
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components.
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.Pp
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.Fn fetchMakeURL
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and
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.Fn fetchParseURL
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return a pointer to a
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.Fa url
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structure, which is defined as follows in
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.Aq Pa fetch.h :
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.Bd -literal
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#define URL_SCHEMELEN 16
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#define URL_USERLEN 256
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#define URL_PWDLEN 256
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struct url {
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char scheme[URL_SCHEMELEN+1];
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char user[URL_USERLEN+1];
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char pwd[URL_PWDLEN+1];
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char host[MAXHOSTNAMELEN+1];
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int port;
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char *doc;
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off_t offset;
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size_t length;
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};
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.Ed
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.Pp
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The pointer returned by
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.Fn fetchMakeURL
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or
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.Fn fetchParseURL
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should be freed using
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.Fn fetchFreeURL .
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.Pp
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.Fn fetchXGetURL ,
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.Fn fetchGetURL ,
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and
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.Fn fetchPutURL
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constitute the recommended interface to the
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.Nm fetch
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library.
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They examine the URL passed to them to determine the transfer
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method, and call the appropriate lower-level functions to perform the
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actual transfer.
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.Fn fetchXGetURL
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also returns the remote document's metadata in the
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.Fa url_stat
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structure pointed to by the
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.Fa us
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argument.
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.Pp
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The
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.Fa flags
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argument is a string of characters which specify transfer options.
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The
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meaning of the individual flags is scheme-dependent, and is detailed
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in the appropriate section below.
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.Pp
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.Fn fetchStatURL
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attempts to obtain the requested document's metadata and fill in the
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structure pointed to by it's second argument.
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The
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.Fa url_stat
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structure is defined as follows in
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.Aq Pa fetch.h :
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.Bd -literal
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struct url_stat {
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off_t size;
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time_t atime;
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time_t mtime;
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};
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.Ed
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.Pp
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If the size could not be obtained from the server, the
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.Fa size
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field is set to -1.
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If the modification time could not be obtained from the server, the
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.Fa mtime
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field is set to the epoch.
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If the access time could not be obtained from the server, the
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.Fa atime
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field is set to the modification time.
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.Pp
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.Fn fetchListURL
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attempts to list the contents of the directory pointed to by the URL
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provided.
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If successful, it returns a malloced array of
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.Fa url_ent
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structures.
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The
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.Fa url_ent
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structure is defined as follows in
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.Aq Pa fetch.h :
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.Bd -literal
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struct url_ent {
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char name[MAXPATHLEN];
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struct url_stat stat;
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};
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.Ed
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.Pp
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The list is terminated by an entry with an empty name.
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.Pp
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The pointer returned by
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.Fn fetchListURL
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should be freed using
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.Fn free .
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.Pp
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.Fn fetchXGet ,
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.Fn fetchGet ,
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.Fn fetchPut
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and
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.Fn fetchStat
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are similar to
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.Fn fetchXGetURL ,
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.Fn fetchGetURL ,
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.Fn fetchPutURL
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and
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.Fn fetchStatURL ,
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except that they expect a pre-parsed URL in the form of a pointer to
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a
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.Fa struct url
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rather than a string.
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.Pp
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All of the
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.Fn fetchXGetXXX ,
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.Fn fetchGetXXX
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and
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.Fn fetchPutXXX
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functions return a pointer to a stream which can be used to read or
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write data from or to the requested document, respectively.
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Note that
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although the implementation details of the individual access methods
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vary, it can generally be assumed that a stream returned by one of the
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.Fn fetchXGetXXX
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or
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.Fn fetchGetXXX
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functions is read-only, and that a stream returned by one of the
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.Fn fetchPutXXX
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functions is write-only.
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.Sh FILE SCHEME
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.Fn fetchXGetFile ,
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.Fn fetchGetFile
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and
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.Fn fetchPutFile
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provide access to documents which are files in a locally mounted file
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system.
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Only the <document> component of the URL is used.
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.Pp
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.Fn fetchXGetFile
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and
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.Fn fetchGetFile
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do not accept any flags.
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.Pp
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.Fn fetchPutFile
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accepts the
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.Fa a
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(append to file) flag.
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If that flag is specified, the data written to
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the stream returned by
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.Fn fetchPutFile
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will be appended to the previous contents of the file, instead of
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replacing them.
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.Sh FTP SCHEME
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.Fn fetchXGetFTP ,
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.Fn fetchGetFTP
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and
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.Fn fetchPutFTP
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implement the FTP protocol as described in RFC959.
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.Pp
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If the
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.Fa p
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(passive) flag is specified, a passive (rather than active) connection
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will be attempted.
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.Pp
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If the
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.Fa h
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(high) flag is specified, data sockets will be allocated in the high
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port range (see
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.Xr ip 4 ).
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.Pp
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If the
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.Fa d
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(direct) flag is specified,
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.Fn fetchXGetFTP ,
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.Fn fetchGetFTP
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and
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.Fn fetchPutFTP
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will use a direct connection even if a proxy server is defined.
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.Pp
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If no user name or password is given, the
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.Nm fetch
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library will attempt an anonymous login, with user name "ftp" and
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password "ftp".
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.Sh HTTP SCHEME
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The
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.Fn fetchXGetHTTP ,
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.Fn fetchGetHTTP
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and
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.Fn fetchPutHTTP
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functions implement the HTTP/1.1 protocol.
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With a little luck, there's
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even a chance that they comply with RFC2068.
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.Pp
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If the
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.Fa d
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(direct) flag is specified,
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.Fn fetchXGetHTTP ,
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.Fn fetchGetHTTP
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and
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.Fn fetchPutHTTP
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will use a direct connection even if a proxy server is defined.
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.Pp
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Since there seems to be no good way of implementing the HTTP PUT
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method in a manner consistent with the rest of the
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.Nm fetch
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library,
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.Fn fetchPutHTTP
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is currently unimplemented.
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.Sh RETURN VALUES
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.Fn fetchParseURL
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returns a pointer to a
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.Fa struct url
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containing the individual components of the URL.
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If it is
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unable to allocate memory, or the URL is syntactically incorrect,
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.Fn fetchParseURL
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returns a NULL pointer.
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.Pp
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The
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.Fn fetchStat
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functions return 0 on success and -1 on failure.
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.Pp
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All other functions return a stream pointer which may be used to
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access the requested document, or NULL if an error occurred.
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.Pp
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The following error codes are defined in
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.Aq Pa fetch.h :
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.Bl -tag -width 18n
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.It Bq Er FETCH_ABORT
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Operation aborted
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.It Bq Er FETCH_AUTH
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Authentication failed
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.It Bq Er FETCH_DOWN
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Service unavailable
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.It Bq Er FETCH_EXISTS
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File exists
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.It Bq Er FETCH_FULL
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File system full
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.It Bq Er FETCH_INFO
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Informational response
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.It Bq Er FETCH_MEMORY
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Insufficient memory
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.It Bq Er FETCH_MOVED
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File has moved
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.It Bq Er FETCH_NETWORK
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Network error
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.It Bq Er FETCH_OK
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No error
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.It Bq Er FETCH_PROTO
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Protocol error
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.It Bq Er FETCH_RESOLV
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Resolver error
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.It Bq Er FETCH_SERVER
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Server error
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.It Bq Er FETCH_TEMP
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Temporary error
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.It Bq Er FETCH_TIMEOUT
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Operation timed out
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.It Bq Er FETCH_UNAVAIL
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File is not available
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.It Bq Er FETCH_UNKNOWN
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Unknown error
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.It Bq Er FETCH_URL
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Invalid URL
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.El
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.Pp
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The accompanying error message includes a protocol-specific error code
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and message, e.g. "File is not available (404 Not Found)"
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.Sh ENVIRONMENT
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.Bl -tag -width FTP_PASSIVE_MODE
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.It Ev FTP_LOGIN
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Default FTP login if none was provided in the URL.
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.It Ev FTP_PASSIVE_MODE
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If set to anything but
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.Ql no ,
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forces the FTP code to use passive mode.
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.It Ev FTP_PASSWORD
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Default FTP password if the remote server requests one and none was
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provided in the URL.
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.It Ev FTP_PROXY
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URL of the proxy to use for FTP requests.
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The document part is ignored.
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FTP and HTTP proxies are supported; if no scheme is specified, FTP is
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assumed.
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If the proxy is an FTP proxy,
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.Nm libfetch
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will send
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.Ql user@host
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as user name to the proxy, where
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.Ql user
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is the real user name, and
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.Ql host
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is the name of the FTP server.
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.Pp
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If this variable is set to an empty string, no proxy will be used for
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FTP requests, even if the
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.Ev HTTP_PROXY
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variable is set.
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.It Ev HTTP_AUTH
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Specifies HTTP authorization parameters as a colon-separated list of
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items.
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The first and second item are the authorization scheme and realm
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respectively; further items are scheme-dependent.
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Currently, only basic authorization is supported.
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.Pp
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Basic authorization requires two parameters: the user name and
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password, in that order.
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.Pp
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This variable is only used if the server requires authorization and
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no user name or password was specified in the URL.
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.It Ev HTTP_PROXY
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URL of the proxy to use for HTTP requests.
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The document part is ignored.
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Only HTTP proxies are supported for HTTP requests.
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If no port number is specified, the default is 3128.
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.Pp
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Note that this proxy will also be used for FTP documents, unless the
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.Ev FTP_PROXY
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variable is set.
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.It Ev HTTP_PROXY_AUTH
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Specifies authorization parameters for the HTTP proxy in the same
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format as the
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.Ev HTTP_AUTH
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variable.
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.Pp
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This variable is used if and only if connected to an HTTP proxy, and
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is ignored if a user and/or a password were specified in the proxy
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URL.
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.El
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.Sh SEE ALSO
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|
.Xr fetch 1 ,
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.Xr ftpio 3 ,
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.Xr ip 4 .
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.Rs
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.%A T. Berners-Lee
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.%A L. Masinter
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.%A M. McCahill
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.%D December 1994
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.%T Uniform Resource Locators (URL)
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.%O RFC1738
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.Re
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.Rs
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.%A R. Fielding
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.%A J. Gettys
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.%A J. Mogul
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.%A H. Frystyk
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.%A T. Berners-Lee
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.%D Januray 1997
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.%B Hypertext Transfer Protocol -- HTTP/1.1
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.%O RFC2068
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.Re
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.Rs
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.%A J. Postel
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.%A J. K. Reynolds
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.%D October 1985
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.%B File Transfer Protocol
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.%O RFC959
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.Re
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.Sh HISTORY
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The
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.Nm fetch
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library first appeared in
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.Fx 3.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm fetch
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|
library was mostly written by
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.An Dag-Erling Co\(:idan Sm\(/orgrav Aq des@FreeBSD.org
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with numerous suggestions from
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.An Jordan K. Hubbard Aq jkh@FreeBSD.org ,
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.An Eugene Skepner Aq eu@qub.com
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and other
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.Fx
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developers.
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It replaces the older
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.Nm ftpio
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|
library written by
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.An Poul-Henning Kamp Aq pkh@FreeBSD.org
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and
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.An Jordan K. Hubbard Aq jkh@FreeBSD.org .
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.Pp
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This manual page was written by
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.An Dag-Erling Co\(:idan Sm\(/orgrav Aq des@FreeBSD.org .
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.Sh BUGS
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Some parts of the library are not yet implemented.
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The most notable
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examples of this are
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.Fn fetchPutHTTP ,
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.Fn fetchListHTTP ,
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.Fn fetchListFTP
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and FTP proxy support.
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.Pp
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There's no way to select a proxy at run-time other than setting the
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.Ev HTTP_PROXY
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or
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.Ev FTP_PROXY
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environment variables as appropriate.
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.Pp
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.Nm libfetch
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does not understand or obey 305 (Use Proxy) replies.
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.Pp
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Error numbers are unique only within a certain context; the error
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codes used for FTP and HTTP overlap, as do those used for resolver and
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system errors.
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For instance, error code 202 means "Command not
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implemented, superfluous at this site" in an FTP context and
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"Accepted" in an HTTP context.
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.Pp
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.Fn fetchStatFTP
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does not check that the result of an MDTM command is a valid date.
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.Pp
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The man page is incomplete, poorly written and produces badly
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formatted text.
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.Pp
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The error reporting mechanism is unsatisfactory.
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.Pp
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Some parts of the code are not fully reentrant.
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