Пункт 135. Apache Module mod_dir
| Description: | Provides for "trailing slash" redirects and
serving directory index files |
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| Status: | Base |
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| Module Identifier: | dir_module |
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| Source File: | mod_dir.c |
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Summary
The index of a directory can come from one of two sources:
- A file written by the user, typically called
index.html . The DirectoryIndex directive sets the
name of this file. This is controlled by
mod_dir .
- Otherwise, a listing generated by the server. This is
provided by
mod_autoindex .
The two functions are separated so that you can completely
remove (or replace) automatic index generation should you want
to.
A "trailing slash" redirect is issued when the server
receives a request for a URL
http://servername/foo/dirname where
dirname is a directory. Directories require a
trailing slash, so mod_dir issues a redirect to
http://servername/foo/dirname/ .
DirectoryCheckHandler Directive
| Description: | Toggle how this module responds when another handler is configured |
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| Syntax: | DirectoryCheckHandler On|Off |
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| Default: | DirectoryCheckHandler Off |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | Indexes |
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| Status: | Base |
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| Module: | mod_dir |
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| Compatibility: | Available in 2.4.8 and later. Releases prior to 2.4 implicitly
act as if "DirectoryCheckHandler ON" was specified. |
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The DirectoryCheckHandler directive determines
whether mod_dir should check for directory indexes or
add trailing slashes when some other handler has been configured for
the current URL. Handlers can be set by directives such as
SetHandler or by other modules,
such as mod_rewrite during per-directory substitutions.
In releases prior to 2.4, this module did not take any action if any
other handler was configured for a URL. This allows directory indexes to
be served even when a SetHandler directive is
specified for an entire directory, but it can also result in some conflicts
with modules such as mod_rewrite .
DirectoryIndex Directive
| Description: | List of resources to look for when the client requests
a directory |
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| Syntax: | DirectoryIndex
disabled | local-url [local-url] ... |
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| Default: | DirectoryIndex index.html |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | Indexes |
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| Status: | Base |
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| Module: | mod_dir |
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The DirectoryIndex directive sets the
list of resources to look for, when the client requests an index
of the directory by specifying a / at the end of the directory
name. Local-url is the (%-encoded) URL of a document on
the server relative to the requested directory; it is usually the
name of a file in the directory. Several URLs may be given, in
which case the server will return the first one that it finds. If
none of the resources exist and the Indexes option is
set, the server will generate its own listing of the
directory.
Example
DirectoryIndex index.html
then a request for http://example.com/docs/ would
return http://example.com/docs/index.html if it
exists, or would list the directory if it did not.
Note that the documents do not need to be relative to the
directory;
DirectoryIndex index.html index.txt /cgi-bin/index.pl
would cause the CGI script /cgi-bin/index.pl to be
executed if neither index.html or index.txt
existed in a directory.
A single argument of "disabled" prevents mod_dir from
searching for an index. An argument of "disabled" will be interpreted
literally if it has any arguments before or after it, even if they are "disabled"
as well.
Note: Multiple DirectoryIndex
directives within the same context will add
to the list of resources to look for rather than replace:
# Example A: Set index.html as an index page, then add index.php to that list as well.
<Directory "/foo">
DirectoryIndex index.html
DirectoryIndex index.php
</Directory>
# Example B: This is identical to example A, except it's done with a single directive.
<Directory "/foo">
DirectoryIndex index.html index.php
</Directory>
# Example C: To replace the list, you must explicitly reset it first:
# In this example, only index.php will remain as an index resource.
<Directory "/foo">
DirectoryIndex index.html
DirectoryIndex disabled
DirectoryIndex index.php
</Directory>
DirectoryIndexRedirect Directive
| Description: | Configures an external redirect for directory indexes.
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| Syntax: | DirectoryIndexRedirect on | off | permanent | temp | seeother |
3xx-code
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| Default: | DirectoryIndexRedirect off |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | Indexes |
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| Status: | Base |
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| Module: | mod_dir |
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| Compatibility: | Available in version 2.3.14 and later |
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By default, the DirectoryIndex is selected
and returned transparently to the client. DirectoryIndexRedirect causes an external redirect
to instead be issued.
The argument can be:
-
on : issues a 302 redirection to the index resource.
-
off : does not issue a redirection. This is the legacy behaviour of mod_dir.
-
permanent : issues a 301 (permanent) redirection to the index resource.
-
temp : this has the same effect as on
-
seeother : issues a 303 redirection (also known as "See Other") to the index resource.
- 3xx-code: issues a redirection marked by the chosen 3xx code.
Example
DirectoryIndexRedirect on
A request for http://example.com/docs/ would
return a temporary redirect to http://example.com/docs/index.html
if it exists.
DirectorySlash Directive
| Description: | Toggle trailing slash redirects on or off |
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| Syntax: | DirectorySlash On|Off |
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| Default: | DirectorySlash On |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | Indexes |
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| Status: | Base |
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| Module: | mod_dir |
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The DirectorySlash directive determines whether
mod_dir should fixup URLs pointing to a directory or
not.
Typically if a user requests a resource without a trailing slash, which
points to a directory, mod_dir redirects him to the same
resource, but with trailing slash for some good reasons:
- The user is finally requesting the canonical URL of the resource
-
mod_autoindex works correctly. Since it doesn't emit
the path in the link, it would point to the wrong path.
-
DirectoryIndex will be evaluated
only for directories requested with trailing slash.
- Relative URL references inside html pages will work correctly.
If you don't want this effect and the reasons above don't
apply to you, you can turn off the redirect as shown below. However,
be aware that there are possible security implications to doing
this.
# see security warning below!
<Location "/some/path">
DirectorySlash Off
SetHandler some-handler
</Location>
Security Warning
Turning off the trailing slash redirect may result in an information
disclosure. Consider a situation where mod_autoindex is
active ( Options +Indexes ) and DirectoryIndex is set to a valid resource (say,
index.html ) and there's no other special handler defined for
that URL. In this case a request with a trailing slash would show the
index.html file. But a request without trailing slash
would list the directory contents.
Also note that some browsers may erroneously change POST requests into GET
(thus discarding POST data) when a redirect is issued.
FallbackResource Directive
| Description: | Define a default URL for requests that don't map to a file |
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| Syntax: | FallbackResource disabled | local-url |
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| Default: | disabled - httpd will return 404 (Not Found) |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | Indexes |
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| Status: | Base |
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| Module: | mod_dir |
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| Compatibility: | The disabled argument is available in version 2.4.4 and
later |
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Use this to set a handler for any URL that doesn't map to anything
in your filesystem, and would otherwise return HTTP 404 (Not Found).
For example
FallbackResource /not-404.php
will cause requests for non-existent files to be handled by
not-404.php , while requests for files that exist
are unaffected.
It is frequently desirable to have a single file or resource
handle all requests to a particular directory, except those requests
that correspond to an existing file or script. This is often
referred to as a 'front controller.'
In earlier versions of httpd, this effect typically required
mod_rewrite , and the use of the -f and
-d tests for file and directory existence. This now
requires only one line of configuration.
FallbackResource /index.php
Existing files, such as images, css files, and so on, will be
served normally.
Use the disabled argument to disable that feature
if inheritance from a parent directory is not desired.
In a sub-URI, such as http://example.com/blog/ this
sub-URI has to be supplied as local-url:
<Directory "/web/example.com/htdocs/blog">
FallbackResource /blog/index.php
</Directory>
<Directory "/web/example.com/htdocs/blog/images">
FallbackResource disabled
</Directory>
