custom 404 doesn't work properly - php

Question

I am using this code on my website (It is included in 404.php):
<?php
if (isset($_POST["op"]) && ($_POST["op"]=="send")) {
/******** START OF CONFIG SECTION *******/
$sendto = "myemail#gmail.com";
$subject = "Website Contact Enquiry";
/******** END OF CONFIG SECTION *******/
$message = $HTTP_POST_VARS['message'];
$headers = "From: $email\n";
$headers . "MIME-Version: 1.0\n"
. "Content-Transfer-Encoding: 7bit\n"
. "Content-type: text/html; charset = \"iso-8859-1\";\n\n";
$request = $_SERVER["REQUEST_URI"];
$self = $_SERVER["PHP_SELF"];
// Build the email body text
$emailcontent = "
-----------------------------------------------------------------------------
WEBSITE CONTACT ENQUIRY
-----------------------------------------------------------------------------
$request
$self
$message
";
if (!trim($message)) {
echo "<p>Please go back and type a Message</p><p><a href='javascript: history.go(-1)'>Click here to go back</a>.</p>";
}
// Sends out the email or will output the error message
elseif (mail($sendto, $subject, $emailcontent, $headers)) {
echo "<br><br><p><b>Thank You </b></p><p>We will be in touch as soon as possible.</p>";
}
}
else {
?>
And this is my form
<form action="http://www.ahornblume.ch/404.php" method="post">
<INPUT NAME="op" TYPE="hidden" VALUE="send">
<textarea name="message" cols="25" rows="4" placeholder="Wenn Sie eine Antwort wünschen, vergessen Sie bitte ihre email Adresse nicht."></textarea><br>
<input name="submit" type="submit" value="Send Message">
</form>
I am redirecting all 404 errors in my htaccess file like so:
ErrorDocument 404 /404.php
If I go to ahornblume.ch/404.php everything works and I can use the form to send emails.
But, if I go to ahornblume.ch/something the contact form doesn't work.

Answer 1

Your form does not have an action specified so it will submit to the URL that was used to display the form.
In case of ahornblume.ch/404.php it will submit to 404.php and it will work.
In case of ahornblume.ch/something it will result in a 404 error that will just display the 404.php page, but the form post will have been discarded.
To fix, specify an action with an absolute path/404.php

Answer 2

If you are including the contact form you might want to check the links first! It's probably just a wrong link. Avoid using stuff like action="../php/contact_form.php". With include/require/require_once, I always opt for $root = realpath($_SERVER["DOCUMENT_ROOT"]);require_once($root."/path/to/file/myfile.php");
So if the contact form is displaying but when you click submit nothing happens, the cause is most likely that the server cannot locate the "action" php file. You have two options:
1: instead of <form action="../your_file.php" use the full link. <form action="http://yoursite.com/path/to/your/file/yourfile.php"
2. Always make use of root for include, require and require_once and use an additional variable like $url=http://www.yoursite.com and whenever you need to insert links, use PHP, as follows:This is a link. It may look like a lot of trouble, but it will make your life much much easier in some cases. Switching to https or any kind of global modification will mean that you only have to change 1 variable, $url. Every single link will then automatically be updated. If you know for a fact that you don't need this, option number 1 will do.

Answer 3

Are you using javascript/ajax/jquery for the form submission? If you are send a post request like that, check the link in the .js file or wherever you have the code and use an absolute path for the post request.