1. Simulating Form Input with POST
1.1. Problem
You want to programmatically issue requests that mimic form inputs
by a user.
1.2. Solution
See Example 1.
Example 1. Basic Perl script to submit a form
#!/usr/bin/perl
use LWP::UserAgent;
use HTTP::Request::Common qw(POST);
$URL = "http://www.example.com/login.php";
$UA = LWP::UserAgent->new();
$req = HTTP::Request::Common::POST( "$URL",
Content_Type => 'form-data',
Content => [
USERNAME => 'admin',
PASSWORD => '12345',
Submit => 'Login'
]
);
$resp = $UA->request($req);
# check for error. Print page if it's OK
if ( ( $resp->code() >= 200 ) && ( $resp->code() < 400 ) ) {
print $resp->decoded_content;
} else {
print "Error: " . $resp->status_line . "\n";
}
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1.3. Discussion
Example 1 shows
posting to a simple login page (login.php) with 2 fields: USERNAME and PASSWORD. If you had a list of usernames and
passwords you wanted to try programmatically, you could iteratively
redefine $req and reinvoke the
$UA->request() method to reissue
new login attempts—perhaps in a foreach or while loop.
The Submit item in the form data is simply there for the sake of being
identical to what a real browser would send. Many applications do not
care what the value of the Submit button is, but the browser will send
that value anyways. You could imagine, however, some circumstances where
a form might have multiple Submit buttons, and the value of the Submit
button would be significant. For example, a search page might have Basic
Search and Advanced Search buttons, and your script must change the
value of the Submit button to tell your application which button was
clicked.
2. Capturing and Storing Cookies
2.1. ProblemMost web applications will use cookies, possibly in conjunction
with other techniques, to manage state or maintain session identity. To
login and stay logged in, your Perl script will have to receive these
cookies and send them back throughout its session. Doing this
programmatically allows you to also test various attributes of session
maintenance.
2.2. Solution
See Example 2.
Example 2. Perl script that automatically captures cookies
#!/usr/bin/perl
use LWP::UserAgent;
use HTTP::Cookies;
use HTTP::Request::Common;
$myCookies = HTTP::Cookies−>new(
file => "cookies.txt",
autosave => 1,
);
$URL = "http://www.example.com/login.php";
$UA = LWP::UserAgent->new();
$UA->cookie_jar( $myCookies );
$req = HTTP::Request->new( GET => "http://www.example.com/" );
$resp = $UA->request($req);
# check for error. Print page if it's OK
if ( ( $resp->code() >= 200 ) && ( $resp->code() < 400 ) ) {
print $resp->decoded_content;
} else {
print "Error: " . $resp->status_line . "\n";
}
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2.3. Discussion
The code in Example 2 assumes you want to
store your cookies in a file, perhaps because you want to look at them after your tests run or perhaps
because you have engineered malicious cookies in advance and want to
load them. You can change the invocation of the cookie_jar() method to create an empty cookie
jar (and one that will be lost when the script terminates) by writing
$UA->cookie_jar( {} ).
