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659fe5d24825b160cae512538088020d97a60239Timo Sirainen<TITLE>Custom error responses</TITLE>
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16c89b1260c9d07c01c83a9219424d3727069b2eTimo Sirainen<H1 ALIGN="CENTER">Custom error responses</H1>
024815ea2ffdda9ea79919f18e865663977f73eaTimo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen<DL>
7c95b03620a03a43dd72d39608cea5fc77393ad6Timo Sirainen
7c95b03620a03a43dd72d39608cea5fc77393ad6Timo Sirainen<DT>Purpose
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen <DD>Additional functionality. Allows webmasters to configure the response of
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen Apache to some error or problem.
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen <P>Customizable responses can be defined to be activated in the
e8acc691a14a6d0884c5ca9aa4d8507f1e082040Timo Sirainen event of a server detected error or problem.
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen <P>e.g. if a script crashes and produces a "500 Server Error"
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen response, then this response can be replaced with either some
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen friendlier text or by a redirection to another URL (local or
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen external).
7c95b03620a03a43dd72d39608cea5fc77393ad6Timo Sirainen
df4018ae2f0a95be602f724ca70df7e0e3bd6a7dTimo Sirainen <P>
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen<DT>Old behavior
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen <DD>NCSA httpd 1.3 would return some boring old error/problem message
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen which would often be meaningless to the user, and would provide no
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen means of logging the symptoms which caused it.<BR>
1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen <P>
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen<DT>New behavior
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen <DD>The server can be asked to;
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <OL>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <LI>Display some other text, instead of the NCSA hard coded messages, or
1175f27441385a7011629f295f42708f9a3a4ffcTimo Sirainen <LI>redirect to a local URL, or
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <LI>redirect to an external URL.
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen </OL>
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <P>Redirecting to another URL can be useful, but only if some information
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen can be passed which can then be used to explain and/or log the error/problem
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen more clearly.
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <P>To achieve this, Apache will define new CGI-like environment
1175f27441385a7011629f295f42708f9a3a4ffcTimo Sirainen variables, e.g.
1175f27441385a7011629f295f42708f9a3a4ffcTimo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <blockquote><code>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_HTTP_ACCEPT=*/*, image/gif, image/x-xbitmap, image/jpeg <br>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_HTTP_USER_AGENT=Mozilla/1.1b2 (X11; I; HP-UX A.09.05 9000/712) <br>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_PATH=.:/bin:/usr/local/bin:/etc <br>
16c89b1260c9d07c01c83a9219424d3727069b2eTimo SirainenREDIRECT_QUERY_STRING= <br>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo SirainenREDIRECT_REMOTE_ADDR=121.345.78.123 <br>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_REMOTE_HOST=ooh.ahhh.com <br>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_SERVER_NAME=crash.bang.edu <br>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_SERVER_PORT=80 <br>
bb10ebcf076c959c752f583746d83805d7686df8Timo SirainenREDIRECT_SERVER_SOFTWARE=Apache/0.8.15 <br>
faed8babca9914257f34fb2e603d74016d563b2dTimo SirainenREDIRECT_URL=/cgi-bin/buggy.pl <br>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen </code></blockquote>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <P>note the <code>REDIRECT_</code> prefix.
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <P>At least <code>REDIRECT_URL</code> and <code>REDIRECT_QUERY_STRING</code> will
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen be passed to the new URL (assuming it's a cgi-script or a cgi-include). The
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen other variables will exist only if they existed prior to the error/problem.
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <b>None</b> of these will be set if your ErrorDocument is an
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <i>external</i> redirect (i.e. anything starting with a protocol name
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen like <code>http:</code>, even if it refers to the same host as the
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen server).<p>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen<DT>Configuration
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <DD> Use of "ErrorDocument" is enabled for .htaccess files when the
e8acc691a14a6d0884c5ca9aa4d8507f1e082040Timo Sirainen <A HREF="mod/core.html#allowoverride">"FileInfo" override</A> is allowed.
e8acc691a14a6d0884c5ca9aa4d8507f1e082040Timo Sirainen
e8acc691a14a6d0884c5ca9aa4d8507f1e082040Timo Sirainen <P>Here are some examples...
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen <blockquote><code>
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo SirainenErrorDocument 500 /cgi-bin/crash-recover <br>
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo SirainenErrorDocument 500 "Sorry, our script crashed. Oh dear<br>
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo SirainenErrorDocument 500 http://xxx/ <br>
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo SirainenErrorDocument 404 /Lame_excuses/not_found.html <br>
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo SirainenErrorDocument 401 /Subscription/how_to_subscribe.html
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen </code></blockquote>
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen <P>The syntax is,
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen <P><code><A HREF="mod/core.html#errordocument">ErrorDocument</A></code>
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen&lt;3-digit-code&gt; action
09c3a491f4f6ccebe290c7709bdc0d79a187610bTimo Sirainen
659fe5d24825b160cae512538088020d97a60239Timo Sirainen <P>where the action can be,
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen <OL>
659fe5d24825b160cae512538088020d97a60239Timo Sirainen <LI>Text to be displayed. Prefix the text with a quote (&quot;). Whatever
1b84018ce06dba050f1111a2cfa6332595f603fdTimo Sirainen follows the quote is displayed. <em>Note: the (&quot;) prefix isn't
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen displayed.</em>
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
659fe5d24825b160cae512538088020d97a60239Timo Sirainen <LI>An external URL to redirect to.
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen <LI>A local URL to redirect to.
659fe5d24825b160cae512538088020d97a60239Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen </OL>
659fe5d24825b160cae512538088020d97a60239Timo Sirainen</DL>
659fe5d24825b160cae512538088020d97a60239Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen<P><HR><P>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen
053843989f13d9013b265fb401a4bde7e0e6568eTimo Sirainen<h2>Custom error responses and redirects</H2>
659fe5d24825b160cae512538088020d97a60239Timo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen<DL>
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen<DT>Purpose
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen <DD>Apache's behavior to redirected URLs has been modified so that additional
9d8d1efcc1274ef4d8413c3687549b297d81da10Timo Sirainen environment variables are available to a script/server-include.<p>
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen<DT>Old behavior
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen <DD>Standard CGI vars were made available to a script which has been
8e7da21696c9f8a6d5e601243fb6172ec85d47b2Timo Sirainen redirected to. No indication of where the redirection came from was provided.
659fe5d24825b160cae512538088020d97a60239Timo Sirainen
659fe5d24825b160cae512538088020d97a60239Timo Sirainen <p>
659fe5d24825b160cae512538088020d97a60239Timo Sirainen
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen<DT>New behavior
c93f3ab84b317acf4755063ab4856c8fbfd3e064Timo Sirainen <DD>
659fe5d24825b160cae512538088020d97a60239Timo Sirainen
1b84018ce06dba050f1111a2cfa6332595f603fdTimo SirainenA new batch of environment variables will be initialized for use by a
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainenscript which has been redirected to. Each new variable will have the
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainenprefix <code>REDIRECT_</code>. <code>REDIRECT_</code> environment
1175f27441385a7011629f295f42708f9a3a4ffcTimo Sirainenvariables are created from the CGI environment variables which existed
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainenprior to the redirect, they are renamed with a <code>REDIRECT_</code>
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainenprefix, i.e. <code>HTTP_USER_AGENT</code> becomes
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen<code>REDIRECT_HTTP_USER_AGENT</code>. In addition to these new
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainenvariables, Apache will define <code>REDIRECT_URL</code> and
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainen<code>REDIRECT_STATUS</code> to help the script trace its origin.
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo SirainenBoth the original URL and the URL being redirected to can be logged in
287ba82a8da3eaa473b5735d4eeac2fb4c5d8117Timo Sirainenthe access log.
c93f3ab84b317acf4755063ab4856c8fbfd3e064Timo Sirainen
5a07b37a9df398b5189c14872a600384208ab74bTimo Sirainen</DL>
1175f27441385a7011629f295f42708f9a3a4ffcTimo Sirainen
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