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In addition to the Apache request record, there are also two other important
data structures of which you should be aware—the server record and the
connection record. The Apache server record contains information about the
server itself, such as the values set by the ErrorLog and
ServerAlias directives. The Apache connection record contains
information about the current connection, such as the IP address of the
initiating client and the authentication method for the request. As with the
request record, the server and connection records are both defined in
src/include/httpd.h in the Apache sources.
Access to each of these records is granted through two separate classes,
appropriately named Apache::Server and Apache::Connection.
Through these two classes, the Apache::Log class, and a few methods
provided by the base Apache class, accessing and sometimes modifying
properties logically connected to the server and its operation are possible.
Although many of the following methods are not used frequently, they are all
good to understand and suitable for scribbling on your mental chalkboard for
later use.
Apache::Server ObjectYou want to access various properties of the Apache server, such as the
ServerNameorTimeOutdirectives.
Create an Apache::Server object and use its methods.
package Cookbook::ViewServer;
use Apache::Constants qw(OK);
use Apache::Log;
use strict;
sub handler {
# Get the Apache request object...
my $r = shift;
# ... and the Apache::Server object for this request.
my $s = $r->server;
$r->send_http_header('text/plain');
# Iterate through all the configured servers.
for (my $s = Apache->server; $s; $s = $s->next) {
print "User directive: ", $s->uid, "\n";
print "Group directive: ", $s->gid, "\n";
print "Port directive: ", $s->port, "\n";
print "TimeOut directive: ", $s->timeout, "\n";
print "ErrorLog directive: ", $s->error_fname, "\n";
print "LogLevel directive: ", $s->loglevel, "\n";
print "ServerName directive: ", $s->server_hostname, "\n";
print "ServerAdmin directive: ", $s->server_admin, "\n";
print "ServerAlias directives:\n" if $s->is_virtual;
print "\t$_\n" foreach @{$s->names};
print "-" x 30, "\n";
}
return OK;
}
1;The previous chapter discussed the Apache request record and the various
pieces of per-request data it holds. In addition to those fields already
discussed, the request record holds a pointer to information about the Apache
server responsible for servicing the current request. The
Apache::Server class provides the interface to many of the base server
configuration directives from the Apache server record. An
Apache::Server object can be created in two ways, either by digging it
out from the current request:
my $s = $r->server;or by retrieving it directly through the Apache class:
my $s = Apache->server;The difference between the two methods is that $r->server()
returns the Apache::Server object associated with the current request.
Apache->server(), on the other hand, returns the main
Apache::Server object in Apache's internal list of configured servers.
The convention is to place the Apache::Server object in the $s
variable, which is how it will be presented throughout this book.
In most cases, you will want to retrieve the Apache::Server object
directly from the request object, because that is the server directly involved
in the current request. However, if you are interested in inspecting or altering
any of the properties of the Apache server outside of a request, such as during
module initialization, in <Perl> sections, or in
startup.pl script, you can use Apache->server().
A partial list of Apache::Server methods is given in Table 4.1.
Apache::Server Methods|
Method |
Example Value |
Details |
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Returns the value of the filename specified by the |
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The numeric value of the group specified by the |
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TRUE |
Returns true if the server is a virtual server. |
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Provides access to the numeric value Apache uses to represent the
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array reference |
Returns an array reference containing the names of any configured
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Apache::Server |
Returns the next server in Apache's internal list of configured servers. |
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Returns the value given by the |
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Returns the value of the |
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Returns the value of the |
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Provides access to the |
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Returns the numeric value of the user specified by the |
The very important thing to remember is that even though the
Apache::Server object is available at request time through the Apache
request object, the scope of its attributes outlasts the current request. In
fact, any changes you make to values in the server record are maintained for the
life of the child, and will affect any requests to that same child process.
Thus, it pays to be careful in your manipulation of server attributes and to
know that changes you make will not be localized to the current
request.
Although the Apache::Server class offers a direct hook into the raw
server configuration, the base Apache class has a few methods that dig
out some of the same information but are more applicable to most programming
needs. For instance, the get_server_name() and
get_server_port() methods from the Apache class are both
sensitive to the UseCanonicalName directive, making them preferable
over direct access to the corresponding fields in the server record at request
time.
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Created: March 18, 2002
Revised: March 18, 2002
URL: http://webreference.com/programming/perl/cookbook/chap4/
