Enrolment

I don't know what version you're using but I had that problem in 1.9 and adding this bit of code to the ipn.php worked for me: 

<?php // $Id: ipn.php,v 1.22.2.1 2009/09/22 01:51:19 moodler Exp $
//Revised JEL 11/18/09
/**
* Listens for Instant Payment Notification from PayPal
*
* This script waits for Payment notification from PayPal,
* then double checks that data by sending it back to PayPal.
* If PayPal verifies this then it sets up the enrolment for that
*
* Set the $user->timeaccess course array
*
* @param user referenced object, must contain $user->id already set
*/
require("../../config.php");
require("enrol.php");

/// Keep out casual intruders
if (empty($_POST) or !empty($_GET)) {
error("Sorry, you can not use the script that way.");
}

/// Read all the data from PayPal and get it ready for later;
/// we expect only valid UTF-8 encoding, it is the responsibility
/// of user to set it up properly in PayPal business acount,
/// it is documented in docs wiki.

$req = 'cmd=_notify-validate';

$data = new object();

foreach ($_POST as $key => $value) {
$value = stripslashes($value);
$req .= "&$key=".urlencode($value);
$data->$key = $value;
}

$custom = explode('-', $data->custom);
$data->userid = (int)$custom[0];
$data->courseid = (int)$custom[1];
$data->payment_gross = $data->mc_gross;
$data->payment_currency = $data->mc_currency;
$data->timeupdated = time();

/// get the user and course records

if (! $user = get_record("user", "id", $data->userid) ) {
email_paypal_error_to_admin("Not a valid user id", $data);
die;
}

if (! $course = get_record("course", "id", $data->courseid) ) {
email_paypal_error_to_admin("Not a valid course id", $data);
die;
}

if (! $context = get_context_instance(CONTEXT_COURSE, $course->id)) {
email_paypal_error_to_admin("Not a valid context id", $data);
die;
}

/// write a log to prove we got this far. Look for it in the enrol/paypal folder.
// While there check for any error logs.

//Uncomment below to see the raw data before processing
//email_paypal_error_to_admin("In ipn.php Before log line 67", $data);

$log = fopen("moodle_ipn.log", "a");
fwrite($log, "\n\nipn - " . gmstrftime ("%b %d %Y %H:%M:%S", time()) . "\n");

//echo "key is $key and value is $value"."<br/>";

//Write the transaction details to the log file.
//The log file is useful for debugging problems. You'll ideally never lose any details, and if the database is down for any //reason, you need a backup..
//If the log is empty then $req did not get built
//---------------------------------------------
fwrite($log,$req."\ n");

// post back to PayPal system to validate
// If you are not getting back a VERIFIED or INVALID immediately from PayPal, the problem is probably in the
// header buildup or the ports used for confirmation
// This worked in both the sandbox and live site.

$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";

If(empty($CFG->usepaypalsandbox)){
$fp = fsockopen ('www.paypal.com', 80, $errno, $errstr, 30); // <- Use this line for real use
}else{
$fp = fsockopen ('www.sandbox.paypal.com', 80, $errno, $errstr, 30); // <- Use this line when testing in SandBox
}

if (!$fp) { /// Could not open a socket to PayPal - FAIL
echo "<p>Error: could not access paypal.com</p>";
email_paypal_error_to_admin("Could not access paypal.com to verify payment", $data);
die;
}

//JEL Foggy Bottom Web Design

if (!$fp) {
echo "$errstr ($errno)";
fwrite($log, "Failed to open HTTP connection!");
$res = "FAILED to open FP";
}
else {
fputs ($fp, $header . $req);

//uncomment the two lines below to receive an email of the information sent TO PayPal for verification
//$admin = get_admin();
//email_to_user($admin, $admin, "We put this to IPN", $req);
}

/// Now read the response and check if everything is OK.

while (!feof($fp)) {
$result = fgets($fp, 1024);

//uncomment the two lines below to receive an email of the information RECEIVED from PayPal for verification
//$admin = get_admin();
//email_to_user($admin, $admin, "We got this back line 117", $res);

if (strcmp($result, "VERIFIED") == 0) { // VALID PAYMENT!

// check the payment_status and payment_reason

// If status is not completed or pending then unenrol the student if already enrolled
// and notify admin

if ($data->payment_status != "Completed" and $data->payment_status != "Pending") {
role_unassign(0, $data->userid, 0, $context->id);
email_paypal_error_to_admin("Status not completed or pending. User unenrolled from course", $data);
die;
}

// If currency is incorrectly set then someone maybe trying to cheat the system

if ($data->mc_currency != $course->currency) {
email_paypal_error_to_admin("Currency does not match course settings, received: ".addslashes($data->mc_currency), $data);
die;
}

// If status is pending and reason is other than echeck then we are on hold until further notice
// Email user to let them know. Email admin.

if ($data->payment_status == "Pending" and $data->pending_reason != "echeck") {
email_to_user($user, get_admin(), "Moodle: PayPal payment", "Your PayPal payment is pending.");
email_paypal_error_to_admin("Payment pending", $data);
die;
}

// If our status is not completed or not pending on an echeck clearance then ignore and die
// This check is redundant at present but may be useful if paypal extend the return codes in the future

if (! ( $data->payment_status == "Completed" or
($data->payment_status == "Pending" and $data->pending_reason == "echeck") ) ) {
die;
}

// At this point we only proceed with a status of completed or pending with a reason of echeck

if ($existing = get_record("enrol_paypal", "txn_id", addslashes($data->txn_id))) { // Make sure this transaction doesn't exist already
email_paypal_error_to_admin("Transaction $data->txn_id is being repeated!", $data);
die;

}

if ($data->business != $CFG->enrol_paypalbusiness) { // Check that the email is the one we want it to be
email_paypal_error_to_admin("Business email is $data->business (not $CFG->enrol_paypalbusiness)", $data);
die;

}

if (!$user = get_record('user', 'id', $data->userid)) { // Check that user exists
email_paypal_error_to_admin("User $data->userid doesn't exist", $data);
die;
}

if (!$course = get_record('course', 'id', $data->courseid)) { // Check that course exists
email_paypal_error_to_admin("Course $data->courseid doesn't exist", $data);;
die;
}

// Check that amount paid is the correct amount
if ( (float) $course->cost < 0 ) {
$cost = (float) $CFG->enrol_cost;
} else {
$cost = (float) $course->cost;
}

if ($data->payment_gross < $cost) {
$cost = format_float($cost, 2);
email_paypal_error_to_admin("Amount paid is not enough ($data->payment_gross < $cost))", $data);
die;

}
// ALL CLEAR !

if (!insert_record("enrol_paypal", addslashes_object($data))) { // Insert a transaction record
email_paypal_error_to_admin("Error while trying to insert valid transaction", $data);
}

if (!enrol_into_course($course, $user, 'paypal')) {
email_paypal_error_to_admin("Error while trying to enrol ".fullname($user)." in '$course->fullname'", $data);
die;
} else {
$teacher = get_teacher($course->id);

if (!empty($CFG->enrol_mailstudents)) {
$a->coursename = $course->fullname;
$a->profileurl = "$CFG->wwwroot/user/view.php?id=$user->id";
email_to_user($user, $teacher, get_string("enrolmentnew", '', $course->shortname),
get_string('welcometocoursetext', '', $a));
}

if (!empty($CFG->enrol_mailteachers)) {
$a->course = $course->fullname;
$a->user = fullname($user);
email_to_user($teacher, $user, get_string("enrolmentnew", '', $course->shortname),
get_string('enrolmentnewuser', '', $a));
}

if (!empty($CFG->enrol_mailadmins)) {
$a->course = $course->fullname;
$a->user = fullname($user);
$admins = get_admins();
foreach ($admins as $admin) {
email_to_user($admin, $user, get_string("enrolmentnew", '', $course->shortname),
get_string('enrolmentnewuser', '', $a));
}
}

}

} else if (strcmp ($result, "INVALID") == 0) { // ERROR
insert_record("enrol_paypal", addslashes_object($data), false);
email_paypal_error_to_admin("Received an invalid payment notification!! (Fake payment?)", $data);
}
}

fclose($fp);
flcose($log);
exit;

/// FUNCTIONS //////////////////////////////////////////////////////////////////

function email_paypal_error_to_admin($subject, $data) {
$admin = get_admin();
$site = get_site();

$message = "$site->fullname: Transaction failed.\n\n$subject\n\n";

foreach ($data as $key => $value) {
$message .= "$key => $value\n";
}

email_to_user($admin, $admin, "PAYPAL ERROR: ".$subject, $message);

}
?>