How to mimic an HTML form submission in a POST request?

Question

I have HTML form that is used for sending bugreports from application to server. I need to mimic this behavior programmatically. What will the corresponding POST request (or series of requests) look like?

<form name="bugreport" method="post" enctype="multipart/form-data" action="http://my-server.com/bugreport.php">
    <div name="SentData">
        <textarea name="logfile" class="UserVisible"></textarea><br>
        <textarea name="configfile" class="UserVisible"></textarea><br>
    </div>
    <textarea name="usercomment" class="invisible"></textarea><br>
    <input name="useremail" type="text" class="invisible">
    <input class="invisible" type="submit" value="Send">
</form> 

Solution

A POST request consists of a number of headers and a request body. When you submit a form, the browser URL encodes names and values of all form fields and then puts them in the request body in this format:

fieldname1=fieldvalue1&fieldname2=fieldvalue2

I.e. the request body looks like a typical query string.

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Here's what the request could look like for your form:

POST /bugreport.php HTTP/1.1
Host: www.example.com
Content-Type: application/x-www-form-urlencoded
Content-Length: [size of the request body]

logfile=blabla&configfile=more+blabla&usercomment=hello&useremail=

---

To make sure your program matches what a browser would do, you can post the form with Firefox and then inspect the request headers and body using Firebug's net panel.