Why is my cURL POST data not populating fields?

StackOverflow https://stackoverflow.com/questions/22179239

  •  05-06-2023
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Question

I have searched through previous posts, but cannot find an example of the same issue using a similar code approach.

I am submitting data via cURL to a remote URL, before sending the user to a 'thanks' confirmation page.

When I submit the form (full code below), the remote URL fields are not populated and every form field remains empty:

<?php
// Setup empty fields
$SubmitForm_first_name = $SubmitForm_last_name = $SubmitForm_job_title = "";
$SubmitForm_first_nameError = $SubmitForm_last_nameError = $SubmitForm_job_titleError = "";

// Validate Field Entry
if ($_SERVER["REQUEST_METHOD"] == "POST")
{
    $valid = true; // Redirect if valid

    if (empty($_POST["SubmitForm_first_name"]))
    {$valid = false; $SubmitForm_first_nameError = "First name required";}
        else
        {$SubmitForm_first_name = htmlspecialchars($_POST["SubmitForm_first_name"]);}

    if (empty($_POST["SubmitForm_last_name"]))
    {$valid = false; $SubmitForm_last_nameError = "Surname required";}
        else
        {$SubmitForm_last_name = htmlspecialchars($_POST["SubmitForm_last_name"]);}

    if (empty($_POST["SubmitForm_job_title"]))
    {$valid = false; $SubmitForm_job_titleError = "Job title required";}
        else
        {$SubmitForm_job_title = htmlspecialchars($_POST["SubmitForm_job_title"]);}

// Start session
session_start();

// Register
session_register('SubmitForm_first_name');
session_register('SubmitForm_last_name');
session_register('SubmitForm_job_title');

// Populate
$_SESSION['SubmitForm_first_name'] = $SubmitForm_first_name;
$_SESSION['SubmitForm_last_name'] = $SubmitForm_last_name;
$_SESSION['SubmitForm_job_title'] = $SubmitForm_job_title; 

// Redirect valid form to process
if($valid)
    //set POST variables
    { $url = 'http://www.example.com/submit.php';
    $fields = array(
                        'SubmitForm[first_name]' => urlencode($SubmitForm_first_name),
                        'SubmitForm[last_name]' => urlencode($SubmitForm_last_name),
                        'SubmitForm[job_title]' => urlencode($SubmitForm_job_title)
                    );

    //url-ify the data for the POST
    foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; }
    rtrim($fields_string, '&');

    //open connection
    $ch = curl_init();

    //set the url, number of POST vars, POST data
    curl_setopt($ch,CURLOPT_URL, $url);
    curl_setopt($ch,CURLOPT_POST, count($fields));
    curl_setopt($ch,CURLOPT_POSTFIELDS, $fields_string);

    //execute post
    $result = curl_exec($ch);

    //close connection
    curl_close($ch);

    // redirect to thank you page
    header('Location: http://www.example.com/thanks.php');
}
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
    </head>
    <body>
        <div>

        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" name="submit_data" method="POST" id="submit_data">

            <fieldset>
                <legend>Your Details</legend>
                    <p><label for="SubmitForm_first_name">First Name</label><input type="text" id="SubmitForm_first_name" size="20" maxlength="50" value="<?php echo $SubmitForm_first_name;?>" name="SubmitForm_first_name" /><br /><span class="error"> <?php echo $SubmitForm_first_nameError;?></span></p>
                    <p><label for="SubmitForm_last_name">Surname</label><input type="text" id="SubmitForm_last_name" size="20" maxlength="50" value="<?php echo $SubmitForm_last_name;?>" name="SubmitForm_last_name" /><br /><span class="error"> <?php echo $SubmitForm_last_nameError;?></span></p>
                    <p><label for="SubmitForm_job_title">Job Title</label><input type="text" id="SubmitForm_job_title" size="30" maxlength="30" value="<?php echo $SubmitForm_job_title;?>" name="SubmitForm_job_title" /><br /><span class="error"> <?php echo $SubmitForm_job_titleError;?></span></p>
            </fieldset>

            <input type="submit" value="Submit" />
        </form>
        </div>
    </body>
</html>

However, if I do a direct HTTP post (code example below), every field populates correctly:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
    </head>
    <body>
        <div>

    <form action="http://www.example.com/submit.php" name="inputData" method="POST" id="inputData">

            <fieldset>
                <legend>Your Details</legend>
                    <p><label for="SubmitForm_first_name">First Name</label><input type="text" id="SubmitForm[first_name]" size="20" maxlength="50" value="<?php echo $SubmitForm_first_name;?>" name="SubmitForm[first_name]" /><br /><span class="error"> <?php echo $SubmitForm_first_nameError;?></span></p>
                    <p><label for="SubmitForm_last_name">Surname</label><input type="text" id="SubmitForm[last_name]" size="20" maxlength="50" value="<?php echo $SubmitForm_last_name;?>" name="SubmitForm[last_name]" /><br /><span class="error"> <?php echo $SubmitForm_last_nameError;?></span></p>
                    <p><label for="SubmitForm_job_title">Job Title</label><input type="text" id="SubmitForm[job_title]" size="30" maxlength="30" value="<?php echo $SubmitForm_job_title;?>" name="SubmitForm[job_title]" /><br /><span class="error"> <?php echo $SubmitForm_job_titleError;?></span></p>
            </fieldset>

            <input type="submit" value="Submit" />
        </form>
        </div>
    </body>
</html>

The third-party URL is expecting the following fields:

"SubmitForm[first_name]", "SubmitForm[last_name]" and "SubmitForm[job_title]"

Please can anybody spot why the cURL example would result in empty fields on the remote form?

Many thanks

UPDATE

<?php
// Setup empty fields
$SubmitForm_first_name = $SubmitForm_last_name = $SubmitForm_job_title = "";
$SubmitForm_first_nameError = $SubmitForm_last_nameError = $SubmitForm_job_titleError = "";

// Validate Field Entry
if ($_SERVER["REQUEST_METHOD"] == "POST")
{
    $valid = true; // Redirect if valid

    if (empty($_POST["SubmitForm_first_name"]))
    {$valid = false; $SubmitForm_first_nameError = "First name required";}
        else
        {$SubmitForm_first_name = htmlspecialchars($_POST["SubmitForm_first_name"]);}

    if (empty($_POST["SubmitForm_last_name"]))
    {$valid = false; $SubmitForm_last_nameError = "Surname required";}
        else
        {$SubmitForm_last_name = htmlspecialchars($_POST["SubmitForm_last_name"]);}

    if (empty($_POST["SubmitForm_job_title"]))
    {$valid = false; $SubmitForm_job_titleError = "Job title required";}
        else
        {$SubmitForm_job_title = htmlspecialchars($_POST["SubmitForm_job_title"]);}

// Start session
session_start();

// Register
session_register('SubmitForm_first_name');
session_register('SubmitForm_last_name');
session_register('SubmitForm_job_title');

// Populate
$_SESSION['SubmitForm_first_name'] = $SubmitForm_first_name;
$_SESSION['SubmitForm_last_name'] = $SubmitForm_last_name;
$_SESSION['SubmitForm_job_title'] = $SubmitForm_job_title; 

// Redirect valid form to process
if($valid)
    //set POST variables
    { $url = 'http://www.example.com/submit.php';
    $fields = array(
                        'SubmitForm[first_name]' => $SubmitForm_first_name,
                        'SubmitForm[last_name]' => $SubmitForm_last_name,
                        'SubmitForm[job_title]' => $SubmitForm_job_title
                    );

    //open connection
    $ch = curl_init();

    //set the url, number of POST vars, POST data
    curl_setopt($ch,CURLOPT_URL, $url);
    curl_setopt($ch,CURLOPT_POST, count($fields));
    curl_setopt($ch,CURLOPT_POSTFIELDS, $fields);

    //execute post
    $result = curl_exec($ch);

    //close connection
    curl_close($ch);

    // redirect to thank you page
    header('Location: http://www.example.com/thanks.php');
}
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
    </head>
    <body>
        <div>

        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" name="submit_data" method="POST" id="submit_data">

            <fieldset>
                <legend>Your Details</legend>
                    <p><label for="SubmitForm_first_name">First Name</label><input type="text" id="SubmitForm_first_name" size="20" maxlength="50" value="<?php echo $SubmitForm_first_name;?>" name="SubmitForm_first_name" /><br /><span class="error"> <?php echo $SubmitForm_first_nameError;?></span></p>
                    <p><label for="SubmitForm_last_name">Surname</label><input type="text" id="SubmitForm_last_name" size="20" maxlength="50" value="<?php echo $SubmitForm_last_name;?>" name="SubmitForm_last_name" /><br /><span class="error"> <?php echo $SubmitForm_last_nameError;?></span></p>
                    <p><label for="SubmitForm_job_title">Job Title</label><input type="text" id="SubmitForm_job_title" size="30" maxlength="30" value="<?php echo $SubmitForm_job_title;?>" name="SubmitForm_job_title" /><br /><span class="error"> <?php echo $SubmitForm_job_titleError;?></span></p>
            </fieldset>

            <input type="submit" value="Submit" />
        </form>
        </div>
    </body>
</html>
Was it helpful?

Solution 2

Thanks to @Quixrick and @Wrikken for the very helpful pointers.

It turned out that the third-party needed an addition specific "submit" field posting with the other fields. Adding that in posted data fine.

OTHER TIPS

When I ran your code, I got a notice Notice: Undefined variable: fields_string. I doubt this has anything to do with it - the script ran just fine.

For some reason, rtrim does not seem to be chopping off that last & if I print out the string. This also doesn't seem to make a difference for me. Again, the script ran just fine.

rtrim($fields_string, '&');
print $fields_string;

// OUTPUTS:
// SubmitForm[first_name]=XXXXX&SubmitForm[last_name]=YYYYY&SubmitForm[job_title]=Rock+Star&

The script cURL calls just does a dump of $_POST and everything comes through just fine.

Array
(
    [SubmitForm] => Array
    (
        [first_name] => XXXXX
        [last_name] => YYYYY
        [job_title] => Rock Star
    )

)

So maybe try doing a dump of $_POST on your destination script and see if you get the same thing. If not, then I suspect it's an error with cURL. Try adding in some error checking to your cURL request.

$result = curl_exec($ch);

if(curl_errno($ch)) {
    print 'CURL Error: '.curl_error($ch);
}

See if that gives you an error of some sort. A common problem is to be connecting to an https URL and it can't verify the SSL certificate.

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