mirror of
https://github.com/apache/httpd.git
synced 2025-10-28 20:34:59 +03:00
681f8e5fec
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@82066 13f79535-47bb-0310-9956-ffa450edef68
178 lines
5.3 KiB
Plaintext
178 lines
5.3 KiB
Plaintext
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<TITLE>Custom error responses</TITLE>
|
|
</HEAD>
|
|
|
|
<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
|
|
<BODY
|
|
BGCOLOR="#FFFFFF"
|
|
TEXT="#000000"
|
|
LINK="#0000FF"
|
|
VLINK="#000080"
|
|
ALINK="#FF0000"
|
|
>
|
|
<!--#include virtual="header.html" -->
|
|
<H1 ALIGN="CENTER">Custom error responses</H1>
|
|
|
|
<DL>
|
|
|
|
<DT>Purpose
|
|
|
|
<DD>Additional functionality. Allows webmasters to configure the response of
|
|
Apache to some error or problem.
|
|
|
|
<P>Customizable responses can be defined to be activated in the
|
|
event of a server detected error or problem.
|
|
|
|
<P>e.g. if a script crashes and produces a "500 Server Error"
|
|
response, then this response can be replaced with either some
|
|
friendlier text or by a redirection to another URL (local or
|
|
external).
|
|
<P>
|
|
|
|
<DT>Old behavior
|
|
|
|
<DD>NCSA httpd 1.3 would return some boring old error/problem message
|
|
which would often be meaningless to the user, and would provide no
|
|
means of logging the symptoms which caused it.<BR>
|
|
|
|
<P>
|
|
|
|
<DT>New behavior
|
|
|
|
<DD>The server can be asked to;
|
|
<OL>
|
|
<LI>Display some other text, instead of the NCSA hard coded messages, or
|
|
<LI>redirect to a local URL, or
|
|
<LI>redirect to an external URL.
|
|
</OL>
|
|
|
|
<P>Redirecting to another URL can be useful, but only if some information
|
|
can be passed which can then be used to explain and/or log the
|
|
error/problem
|
|
more clearly.
|
|
|
|
<P>To achieve this, Apache will define new CGI-like environment
|
|
variables, <EM>e.g.</EM>
|
|
|
|
<BLOCKQUOTE><CODE>
|
|
REDIRECT_HTTP_ACCEPT=*/*, image/gif, image/x-xbitmap, image/jpeg <BR>
|
|
REDIRECT_HTTP_USER_AGENT=Mozilla/1.1b2 (X11; I; HP-UX A.09.05 9000/712) <BR>
|
|
REDIRECT_PATH=.:/bin:/usr/local/bin:/etc <BR>
|
|
REDIRECT_QUERY_STRING= <BR>
|
|
REDIRECT_REMOTE_ADDR=121.345.78.123 <BR>
|
|
REDIRECT_REMOTE_HOST=ooh.ahhh.com <BR>
|
|
REDIRECT_SERVER_NAME=crash.bang.edu <BR>
|
|
REDIRECT_SERVER_PORT=80 <BR>
|
|
REDIRECT_SERVER_SOFTWARE=Apache/0.8.15 <BR>
|
|
REDIRECT_URL=/cgi-bin/buggy.pl <BR>
|
|
</CODE></BLOCKQUOTE>
|
|
|
|
<P>note the <CODE>REDIRECT_</CODE> prefix.
|
|
|
|
<P>At least <CODE>REDIRECT_URL</CODE> and <CODE>REDIRECT_QUERY_STRING</CODE>
|
|
will
|
|
be passed to the new URL (assuming it's a cgi-script or a cgi-include).
|
|
The
|
|
other variables will exist only if they existed prior to the
|
|
error/problem.
|
|
<STRONG>None</STRONG> of these will be set if your ErrorDocument is an
|
|
<EM>external</EM> redirect (<EM>i.e.</EM>, anything starting with a
|
|
scheme name
|
|
like <CODE>http:</CODE>, even if it refers to the same host as the
|
|
server).<P>
|
|
|
|
<DT>Configuration
|
|
|
|
<DD> Use of "ErrorDocument" is enabled for .htaccess files when the
|
|
<A HREF="mod/core.html#allowoverride">"FileInfo" override</A> is
|
|
allowed.
|
|
|
|
<P>Here are some examples...
|
|
|
|
<BLOCKQUOTE><CODE>
|
|
ErrorDocument 500 /cgi-bin/crash-recover <BR>
|
|
ErrorDocument 500 "Sorry, our script crashed. Oh dear<BR>
|
|
ErrorDocument 500 http://xxx/ <BR>
|
|
ErrorDocument 404 /Lame_excuses/not_found.html <BR>
|
|
ErrorDocument 401 /Subscription/how_to_subscribe.html
|
|
</CODE></BLOCKQUOTE>
|
|
|
|
<P>The syntax is,
|
|
|
|
<P><CODE><A HREF="mod/core.html#errordocument">ErrorDocument</A></CODE>
|
|
<3-digit-code> action
|
|
|
|
<P>where the action can be,
|
|
|
|
<OL>
|
|
<LI>Text to be displayed. Prefix the text with a quote ("). Whatever
|
|
follows the quote is displayed. <EM>Note: the (") prefix isn't
|
|
displayed.</EM>
|
|
|
|
<LI>An external URL to redirect to.
|
|
|
|
<LI>A local URL to redirect to.
|
|
|
|
</OL>
|
|
</DL>
|
|
|
|
<P><HR><P>
|
|
|
|
<H2>Custom error responses and redirects</H2>
|
|
|
|
<DL>
|
|
|
|
<DT>Purpose
|
|
|
|
<DD>Apache's behavior to redirected URLs has been modified so that additional
|
|
environment variables are available to a script/server-include.<P>
|
|
|
|
<DT>Old behavior
|
|
|
|
<DD>Standard CGI vars were made available to a script which has been
|
|
redirected to. No indication of where the redirection came from was
|
|
provided.
|
|
|
|
<P>
|
|
|
|
<DT>New behavior
|
|
<DD>
|
|
|
|
A new batch of environment variables will be initialized for use by a
|
|
script which has been redirected to. Each new variable will have the
|
|
prefix <CODE>REDIRECT_</CODE>. <CODE>REDIRECT_</CODE> environment
|
|
variables are created from the CGI environment variables which existed
|
|
prior to the redirect, they are renamed with a <CODE>REDIRECT_</CODE>
|
|
prefix, <EM>i.e.</EM>, <CODE>HTTP_USER_AGENT</CODE> becomes
|
|
<CODE>REDIRECT_HTTP_USER_AGENT</CODE>. In addition to these new
|
|
variables, Apache will define <CODE>REDIRECT_URL</CODE> and
|
|
<CODE>REDIRECT_STATUS</CODE> to help the script trace its origin.
|
|
Both the original URL and the URL being redirected to can be logged in
|
|
the access log.
|
|
|
|
</DL>
|
|
<P>
|
|
If the ErrorDocument specifies a local redirect to a CGI script, the script
|
|
should include a "<SAMP>Status:</SAMP>" header field in its output
|
|
in order to ensure the propagation all the way back to the client
|
|
of the error condition that caused it to be invoked. For instance, a Perl
|
|
ErrorDocument script might include the following:
|
|
</P>
|
|
<PRE>
|
|
:
|
|
print "Content-type: text/html\n";
|
|
printf "Status: %s Condition Intercepted\n", $ENV{"REDIRECT_STATUS"};
|
|
:
|
|
</PRE>
|
|
<P>
|
|
If the script is dedicated to handling a particular error condition, such as
|
|
<SAMP>404 Not Found</SAMP>, it can use the specific code and
|
|
error text instead.
|
|
</P>
|
|
|
|
<!--#include virtual="footer.html" -->
|
|
</BODY>
|
|
</HTML>
|