Apache - Perl interface to the Apache server API
SYNOPSIS
use Apache ();
DESCRIPTION
This module provides a Perl interface the Apache API. It
is here mainly for mod_perl, but may be used for other
Apache modules that wish to embed a Perl interpreter. We
suggest that you also consult the description of the
Apache C API at http://www.apache.org/docs/.
THE REQUEST OBJECT
The request object holds all the information that the
server needs to service a request. Apache Perl*Handlers
will be given a reference to the request object as parame
ter and may choose to update or use it in various ways.
Most of the methods described below obtain information
from or update the request object. The perl version of
the request object will be blessed into the Apache pack
age, it is really a `request_rec*' in disguise.
Apache->request([$r])
The Apache->request method will return a reference to
the request object.
Perl*Handlers can obtain a reference to the request
object when it is passed to them via `@_'. However,
scripts that run under Apache::Registry, for example,
need a way to access the request object. Apache::Reg
istry will make a request object available to these
scripts by passing an object reference to
`Apache->request($r)'. If handlers use modules such
as CGI::Apache that need to access `Apache->request',
they too should do this (e.g. Apache::Status).
$r->as_string
Returns a string representation of the request object.
Mainly useful for debugging.
$r->main
If the current request is a sub-request, this method
returns a blessed reference to the main request struc
ture. If the current request is the main request,
then this method returns `undef'.
$r->prev
This method returns a blessed reference to the previ
ous (internal) request structure or `undef' if there
is no previous request.
This method returns a blessed reference to the next
(internal) request structure or `undef' if there is no
next request.
$r->last
This method returns a blessed reference to the last
(internal) request structure. Handy for logging mod
ules.
$r->is_main
Returns true if the current request object is for the
main request. (Should give the same result as
`!$r->main', but will be more efficient.)
$r->is_initial_req
Returns true if the current request is the first
internal request, returns false if the request is a
sub-request or internal redirect.
SUB REQUESTS
Apache provides a sub-request mechanism to lookup a uri or
filename, performing all access checks, etc., without
actually running the response phase of the given request.
Notice, we have dropped the `sub_req_' prefix here. The
`request_rec*' returned by the lookup methods is blessed
into the Apache::SubRequest class. This way,
`destroy_sub_request()' is called automatically during
`Apache::SubRequest->DESTROY' when the object goes out of
scope. The Apache::SubRequest class inherits all the
methods from the Apache class.
$r->lookup_uri($uri)
my $subr = $r->lookup_uri($uri);
my $filename = $subr->filename;
unless(-e $filename) {
warn "can't stat $filename!\n";
}
$r->lookup_file($filename)
my $subr = $r->lookup_file($filename);
$subr->run
if($subr->run != OK) {
$subr->log_error("something went wrong!");
}
CLIENT REQUEST PARAMETERS
In this section we will take a look at various methods
that can be used to retrieve the request parameters sent
request object blessed into the Apache class, obtained by
the first parameter passed to a handler subroutine or
Apache->request
$r->method( [$meth] )
The $r->method method will return the request method.
It will be a string such as "GET", "HEAD" or "POST".
Passing an argument will set the method, mainly used
for internal redirects.
$r->method_number( [$num] )
The $r->method_number method will return the request
method number. The method numbers are defined by the
M_GET, M_POST,... constants available from the
Apache::Constants module. Passing an argument will
set the method_number, mainly used for internal redi
rects and testing authorization restriction masks.
$r->bytes_sent
The number of bytes sent to the client, handy for log
ging, etc.
$r->the_request
The request line sent by the client, handy for log
ging, etc.
$r->proxyreq
Returns true if the request is proxy http. Mainly
used during the filename translation stage of the
request, which may be handled by a `PerlTransHandler'.
$r->header_only
Returns true if the client is asking for headers only,
e.g. if the request method was HEAD.
$r->protocol
The $r->protocol method will return a string identify
ing the protocol that the client speaks. Typical val
ues will be "HTTP/1.0" or "HTTP/1.1".
$r->hostname
Returns the server host name, as set by full URI or
Host: header.
$r->request_time
Returns the time that the request was made. The time
is the local unix time in seconds since the epoch.
$r->uri( [$uri] )
The $r->uri method will return the requested URI minus
optional query string, optionally changing it with the
first argument.
The $r->filename method will return the result of the
URI --> filename translation, optionally changing it
with the first argument if you happen to be doing the
translation.
$r->path_info( [$path_info] )
The $r->path_info method will return what is left in
the path after the URI --> filename translation,
optionally changing it with the first argument if you
happen to be doing the translation.
$r->args( [$query_string] )
The $r->args method will return the contents of the
URI query string. When called in a scalar context,
the entire string is returned. When called in a list
context, a list of parsed key => value pairs are
returned, i.e. it can be used like this:
$query = $r->args;
%in = $r->args;
$r->args can also be used to set the query string.
This can be useful when redirecting a POST request.
$r->headers_in
The $r->headers_in method will return a %hash of
client request headers. This can be used to initial
ize a perl hash, or one could use the $r->header_in()
method (described below) to retrieve a specific header
value directly.
Will return a HASH reference blessed into the
Apache::Table class when called in a scalar context
with no "key" argument. This requires Apache::Table.
$r->header_in( $header_name, [$value] )
Return the value of a client header. Can be used like
this:
$ct = $r->header_in("Content-type");
$r->header_in($key, $val); #set the value of header '$key'
$r->content
The $r->content method will return the entity body
read from the client, but only if the request content
type is `application/x-www-form-urlencoded'. When
called in a scalar context, the entire string is
returned. When called in a list context, a list of
parsed key => value pairs are returned. *NOTE*: you
can only ask for this once, as the entire body is read
from the client.
This method is used to read data from the client,
looping until it gets all of `$bytes_to_read' or a
timeout happens.
An offset may be specified to place the read data at
some other place than the beginning of the string.
In addition, this method sets a timeout before reading
with `$r->soft_timeout'.
$r->get_remote_host
Lookup the client's DNS hostname. If the configuration
directive HostNameLookups is set to off, this returns
the dotted decimal representation of the client's IP
address instead. Might return undef if the hostname is
not known.
$r->get_remote_logname
Lookup the remote user's system name. Might return
undef if the remote system is not running an RFC 1413
server or if the configuration directive IdentityCheck
is not turned on.
More information about the client can be obtained from the
Apache::Connection object, as described below.
$c = $r->connection
The $r->connection method will return a reference to
the request connection object (blessed into the
Apache::Connection package). This is really a
`conn_rec*' in disguise. The following methods can be
used on the connection object:
$c->remote_host
If the configuration directive HostNameLookups is
set to on: then the first time
`$r->get_remote_host' is called the server does a
DNS lookup to get the remote client's host name.
The result is cached in `$c->remote_host' then
returned. If the server was unable to resolve the
remote client's host name this will be set to "".
Subsequent calls to `$r->get_remote_host' return
this cached value.
If the configuration directive HostNameLookups is
set to off: calls to `$r->get_remote_host' return
a string that contains the dotted decimal repre
sentation of the remote client's IP address. How
ever this string is not cached, and
`$c->remote_host' is undefined. So, it's best to
to call `$r->get_remote_host' instead of directly
accessing this variable.
The dotted decimal representation of the remote
client's IP address. This is set by the server
when the connection record is created so is always
defined.
You can also set this value by providing an argu
ment to it. This is helpful if your server is
behind a squid accelerator proxy which adds a X-
Forwarded-For header.
$c->local_addr
A packed SOCKADDR_IN in the same format as
returned by the pack_sockaddr_in entry in the
Socket manpage, containing the port and address on
the local host that the remote client is connected
to. This is set by the server when the connection
record is created so it is always defined.
$c->remote_addr
A packed SOCKADDR_IN in the same format as
returned by the pack_sockaddr_in entry in the
Socket manpage, containing the port and address on
the remote host that the server is connected to.
This is set by the server when the connection
record is created so it is always defined.
Among other things, this can be used, together
with `$c->local_addr', to perform RFC1413 ident
lookups on the remote client even when the config
uration directive IdentityCheck is turned off.
Can be used like:
use Net::Ident qw (lookupFromInAddr);
...
my $remoteuser = lookupFromInAddr ($c->local_addr,
$c->remote_addr, 2);
Note that the lookupFromInAddr interface does not
currently exist in the Net::Ident module, but the
author is planning on adding it soon.
$c->remote_logname
If the configuration directive IdentityCheck is
set to on: then the first time
`$r->get_remote_logname' is called the server does
an RFC 1413 (ident) lookup to get the remote users
system name. Generally for UNI* systems this is
their login. The result is cached in
`$c->remote_logname' then returned. Subsequent
calls to `$r->get_remote_host' return the cached
value.
set to off: then `$r->get_remote_logname' does
nothing and `$c->remote_logname' is always unde
fined.
$c->user( [$user] )
If an authentication check was successful, the
authentication handler caches the user name here.
Sets the user name to the optional first argument.
$c->auth_type
Returns the authentication scheme that success
fully authenticate `$c->user', if any.
$c->aborted
Returns true if the client stopped talking to us.
$c->fileno( [$direction] )
Returns the client file descriptor. If $direction
is 0, the input fd is returned. If $direction is
not null or ommitted, the output fd is returned.
This can be used to detect client disconnect with
out doing any I/O, e.g. using IO::Select.
SERVER CONFIGURATION INFORMATION
The following methods are used to obtain information from
server configuration and access control files.
$r->dir_config( $key )
Returns the value of a per-directory variable speci
fied by the `PerlSetVar' directive.
# <Location /foo/bar>
# PerlSetVar Key Value
# </Location>
my $val = $r->dir_config('Key');
Keys are case-insensitive.
Will return a HASH reference blessed into the
Apache::Table class when called in a scalar context
with no "key" argument. See Apache::Table.
$r->requires
Returns an array reference of hash references, con
taining information related to the require directive.
This is normally used for access control, see the
Apache::AuthzAge manpage for an example.
$r->auth_type
Returns a reference to the current value of the per
directory configuration directive AuthType. Normally
tication scheme defined in RFC 1945, Hypertext Trans
fer Protocol -- HTTP/1.0. However, you could set to
something else and implement your own authentication
scheme.
$r->auth_name
Returns a reference to the current value of the per
directory configuration directive AuthName. The Auth
Name directive creates protection realm within the
server document space. To quote RFC 1945 "These realms
allow the protected resources on a server to be parti
tioned into a set of protection spaces, each with its
own authentication scheme and/or authorization
database." The client uses the root URL of the server
to determine which authentication credentials to send
with each HTTP request. These credentials are tagged
with the name of the authentication realm that created
them. Then during the authentication stage the server
uses the current authentication realm, from
`$r->auth_name', to determine which set of credentials
to authenticate.
$r->document_root
Returns a reference to the current value of the per
server configuration directive DocumentRoot. To quote
the Apache server documentation, "Unless matched by a
directive like Alias, the server appends the path from
the requested URL to the document root to make the
path to the document." This same value is passed to
CGI scripts in the `DOCUMENT_ROOT' environment vari
able.
$r->allow_options
The `$r->allow_options' method can be used for check
ing if it is OK to run a perl script. The
Apache::Options module provides the constants to check
against.
if(!($r->allow_options & OPT_EXECCGI)) {
$r->log_reason("Options ExecCGI is off in this directory",
$filename);
}
$r->get_server_port
Returns the port number on which the server is listen
ing.
$s = $r->server
Return a reference to the server info object (blessed
into the Apache::Server package). This is really a
`server_rec*' in disguise. The following methods can
be used on the server object:
Same as above, but only available during server
startup for use in <Perl> sections, PerlScript or
PerlModule.
$s->server_admin
Returns the mail address of the person responsible for
this server.
$s->server_hostname
Returns the hostname used by this server.
$s->port
Returns the port that this servers listens too.
$s->is_virtual
Returns true if this is a virtual server.
$s->names
Returns the wild-carded names for ServerAlias servers.
$s->dir_config( $key )
Alias for Apache::dir_config.
$s->warn
Alias for Apache::warn.
$s->log_error
Alias for Apache::log_error.
$s->uid
Returns the numeric user id under which the server
answers requests. This is the value of the User
directive.
$s->gid
Returns the numeric group id under which the server
answers requests. This is the value of the Group
directive.
$s->loglevel
Returns the value of the current LogLevel. This method
is added by the Apache::Log module, which needs to be
pulled in.
use Apache::Log;
print "LogLevel = ", $s->loglevel;
If using Perl 5.005+, the following constants are
defined (but not exported):
Apache::Log::ALERT
Apache::Log::CRIT
Apache::Log::ERR
Apache::Log::WARNING
Apache::Log::NOTICE
Apache::Log::INFO
Apache::Log::DEBUG
$r->get_handlers( $hook )
Returns a reference to a list of handlers enabled for
$hook. $hook is a string representing the phase to
handle. The returned list is a list of references to
the handler subroutines.
$list = $r->get_handlers( 'PerlHandler' );
$r->set_handlers( $hook, [\&handler, ... ] )
Sets the list if handlers to be called for $hook.
$hook is a string representing the phase to handle.
The list of handlers is an anonymous array of code
references to the handlers to install for this request
phase. The special list [ \&OK ] can be used to dis
able a particular phase.
$r->set_handlers( PerlLogHandler => [ \&myhandler1, \&myhandler2 ] );
$r->set_handlers( PerlAuthenHandler => [ \&OK ] );
$r->push_handlers( $hook, \&handler )
Pushes a new handler to be called for $hook. $hook is
a string representing the phase to handle. The handler
is a reference to a subroutine to install for this
request phase. This handler will be called before any
configured handlers.
$r->push_handlers( PerlHandler => \&footer);
SETTING UP THE RESPONSE
The following methods are used to set up and return the
response back to the client. This typically involves set
ting up $r->status(), the various content attributes and
optionally some additional $r->header_out() calls before
calling $r->send_http_header() which will actually send
the headers to the client. After this a typical applica
tion will call the $r->print() method to send the response
content to the client.
$r->send_http_header
Send the response line and all headers to the client.
tent_xxx() and $r->no_cache() attributes (described
below) and then append the headers defined by
$r->header_out (or $r->err_header_out if status indi
cates an error).
$r->get_basic_auth_pw
If the current request is protected by Basic authenti
cation, this method will return 0, otherwise -1. The
second return value will be the decoded password sent
by the client.
($ret, $sent_pw) = $r->get_basic_auth_pw;
$r->note_basic_auth_failure
Prior to requiring Basic authentication from the
client, this method will set the outgoing HTTP headers
asking the client to authenticate for the realm
defined by the configuration directive `AuthName'.
$r->handler( [$meth] )
Set the handler for a request. Normally set by the
configuration directive `AddHandler'.
$r->handler( "perl-script" );
$r->notes( $key, [$value] )
Return the value of a named entry in the Apache
`notes' table, or optionally set the value of a named
entry. This table is used by Apache modules to pass
messages amongst themselves. Generally if you are
writing handlers in mod_perl you can use Perl vari
ables for this.
$r->notes("MY_HANDLER" => OK);
$val = $r->notes("MY_HANDLER");
Will return a HASH reference blessed into the
Apache::Table class when called in a scalar context
with no "key" argument. This requires Apache::Table.
$r->pnotes( $key, [$value] )
Like $r->notes, but takes any scalar as an value.
$r->pnotes("MY_HANDLER" => [qw(one two)]);
my $val = $r->pnotes("MY_HANDLER");
print $val->[0]; # prints "one"
Advantage over just using a Perl variable is that
$r->pnotes gets cleaned up after every request.
Return the value of a named entry in the Apache `sub
process_env' table, or optionally set the value of a
named entry. This table is used by mod_include. By
setting some custom variables inside a perl handler it
is possible to combine perl with mod_include nicely.
If you say, e.g. in a PerlHeaderParserHandler
$r->subprocess_env(MyLanguage => "de");
you can then write in your .shtml document:
<!--#if expr="$MyLanguage = en" -->
English
<!--#elif expr="$MyLanguage = de" -->
Deutsch
<!--#else -->
Sorry
<!--#endif -->
Will return a HASH reference blessed into the
Apache::Table class when called in a scalar context
with no "key" argument. This requires Apache::Table.
$r->content_type( [$newval] )
Get or set the content type being sent to the client.
Content types are strings like "text/plain",
"text/html" or "image/gif". This corresponds to the
"Content-Type" header in the HTTP protocol. Example
of usage is:
$previous_type = $r->content_type;
$r->content_type("text/plain");
$r->content_encoding( [$newval] )
Get or set the content encoding. Content encodings
are string like "gzip" or "compress". This correspond
to the "Content-Encoding" header in the HTTP protocol.
$r->content_languages( [$array_ref] )
Get or set the content languages. The content lan
guage corresponds to the "Content-Language" HTTP
header and is an array reference containing strings
such as "en" or "no".
$r->status( $integer )
Get or set the reply status for the client request.
The Apache::Constants module provide mnemonic names
for the status codes.
$r->status_line( $string )
Get or set the response status line. The status line
is a string like "200 Document follows" and it will
$r->status() described above.
$r->headers_out
The $r->headers_out method will return a %hash of
server response headers. This can be used to initial
ize a perl hash, or one could use the $r->header_out()
method (described below) to retrieve or set a specific
header value directly.
Will return a HASH reference blessed into the
Apache::Table class when called in a scalar context
with no "key" argument. This requires Apache::Table.
$r->header_out( $header, $value )
Change the value of a response header, or create a new
one. You should not define any "Content-XXX" headers
by calling this method, because these headers use
their own specific methods. Example of use:
$r->header_out("WWW-Authenticate" => "Basic");
$val = $r->header_out($key);
$r->err_headers_out
The $r->err_headers_out method will return a %hash of
server response headers. This can be used to initial
ize a perl hash, or one could use the
$r->err_header_out() method (described below) to
retrieve or set a specific header value directly.
The difference between headers_out and err_headers_out
is that the latter are printed even on error, and per
sist across internal redirects (so the headers printed
for ErrorDocument handlers will have them).
Will return a HASH reference blessed into the
Apache::Table class when called in a scalar context
with no "key" argument. This requires Apache::Table.
$r->err_header_out( $header, [$value] )
Change the value of an error response header, or cre
ate a new one. These headers are used if the status
indicates an error.
$r->err_header_out("Warning" => "Bad luck");
$val = $r->err_header_out($key);
$r->no_cache( $boolean )
This is a flag that indicates that the data being
returned is volatile and the client should be told not
to cache it.
This method sends data to the client with
`$r->write_client', but first sets a timeout before
sending with `$r->soft_timeout'. This method is called
instead of CORE::print when you use print() in your
mod_perl programs.
This method treats scalar references specially. If an
item in @list is a scalar reference, it will be deref
erenced before printing. This is a performance opti
mization which prevents unneeded copying of large
strings, and it is subtly different from Perl's stan
dard print() behavior.
Example:
$foo = \"bar"; print($foo);
The result is "bar", not the "SCALAR(0xDEADBEEF)" you
might have expected. If you really want the reference
to be printed out, force it into a scalar context by
using `print(scalar($foo))'.
$r->send_fd( $filehandle )
Send the contents of a file to the client. Can for
instance be used like this:
open(FILE, $r->filename) || return 404;
$r->send_fd(FILE);
close(FILE);
$r->internal_redirect( $newplace )
Redirect to a location in the server namespace without
telling the client. For instance:
$r->internal_redirect("/home/sweet/home.html");
$r->internal_redirect_handler( $newplace )
Same as internal_redirect, but the handler from `$r'
is preserved.
$r->custom_response($code, $uri)
This method provides a hook into the ErrorDocument
mechanism, allowing you to configure a custom response
for a given response code at request-time.
Example:
use Apache::Constants ':common';
sub handler {
my($r) = @_;
return OK;
}
#<Location $r->uri>
#ErrorDocument 401 /error.html
#</Location>
$r->custom_response(AUTH_REQUIRED, "/error.html");
#can send a string too
#<Location $r->uri>
#ErrorDocument 401 "sorry, go away"
#</Location>
#$r->custom_response(AUTH_REQUIRED, "sorry, go away");
return AUTH_REQUIRED;
}
SERVER CORE FUNCTIONS
$r->soft_timeout($message)
$r->hard_timeout($message)
$r->kill_timeout
$r->reset_timeout
(Documentation borrowed from http_main.h)
There are two functions which modules can call to
trigger a timeout (with the per-virtual-server timeout
duration); these are hard_timeout and soft_timeout.
The difference between the two is what happens when
the timeout expires (or earlier than that, if the
client connection aborts) --- a soft_timeout just puts
the connection to the client in an "aborted" state,
which will cause http_protocol.c to stop trying to
talk to the client, but otherwise allows the code to
continue normally. hard_timeout(), by contrast, logs
the request, and then aborts it completely ---
longjmp()ing out to the accept() loop in http_main.
Any resources tied into the request resource pool will
be cleaned up; everything that is not will leak.
soft_timeout() is recommended as a general rule,
because it gives your code a chance to clean up. How
ever, hard_timeout() may be the most convenient way of
dealing with timeouts waiting for some external
resource other than the client, if you can live with
the restrictions.
be guarded with block_alarms() and unblock_alarms()
--- these are declared in alloc.c because they are
most often used in conjunction with routines to allo
cate something or other, to make sure that the cleanup
does get registered before any alarm is allowed to
happen which might require it to be cleaned up; they *
are, however, implemented in http_main.c.
kill_timeout() will disarm either variety of timeout.
reset_timeout() resets the timeout in progress.
$r->post_connection($code_ref)
$r->register_cleanup($code_ref)
Register a cleanup function which is called just
before $r->pool is destroyed.
$r->register_cleanup(sub {
my $r = shift;
warn "registered cleanup called for ", $r->uri, "\n";
});
The post_connection method is simply an alias for reg
ister_cleanup, as this method may be used to run code
after the client connection is closed, which may not
be a cleanup.
CGI SUPPORT
We also provide some methods that make it easier to sup
port the CGI type of interface.
$r->send_cgi_header()
Take action on certain headers including Status:,
Location: and Content-type: just as mod_cgi does, then
calls $r->send_http_header(). Example of use:
$r->send_cgi_header(<<EOT);
Location: /foo/bar
Content-type: text/html
EOT
ERROR LOGGING
The following methods can be used to log errors.
$r->log_reason($message, $file)
The request failed, why?? Write a message to the
server errorlog.
$r->log_reason("Because I felt like it", $r->filename);
Uh, oh. Write a message to the server errorlog.
$r->log_error("Some text that goes in the error_log");
$r->warn($message)
For pre-1.3 versions of apache, this is just an alias
for `log_error'. With 1.3+ versions of apache, this
message will only be send to the error_log if LogLevel
is set to warn or higher.
UTILITY FUNCTIONS
Apache::unescape_url($string)
Handy function for unescapes. Use this one for file
names/paths. Use unescape_url_info for the result of
submitted form data.
Apache::unescape_url_info($string)
Handy function for unescapes submitted form data. In
opposite to unescape_url it translates the plus sign
to space.
Apache::perl_hook($hook)
Returns true if the specified callback hook is
enabled:
for (qw(Access Authen Authz ChildInit Cleanup Fixup
HeaderParser Init Log Trans Type))
{
print "$_ hook enabled\n" if Apache::perl_hook($_);
}
GLOBAL VARIABLES
$Apache::Server::Starting
Set to true when the server is starting.
$Apache::Server::ReStarting
Set to true when the server is starting.
SEE ALSO
perl(1), Apache::Constants(3), Apache::Registry(3),
Apache::Debug(3), Apache::Options(3), CGI:\fIs0:Apache(3)
Apache C API notes at `http://www.apache.org/docs/'
AUTHORS
Perl interface to the Apache C API written by Doug
MacEachern with contributions from Gisle Aas, Andreas
Koenig, Eric Bartley, Rob Hartill, Gerald Richter, Sal
vador Ortiz and others.
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