How do I get the request body?

I am trying to implement a simple JSON-RPC server. The client part is handled by the jquery.jsonrpc. This seems to work fine, sending a JSON-RPC message as the payload of a post message.

My JSON-RPC 'server' currently just wants to echo the data so I can see the result in the FireBug http response.

The code is this:

<?php
class jsonrpc {
    var $requestData;

    function jsonrpc() {
        if (isset($_SERVER["REQUEST_URI"]) && isset($_SERVER["REQUEST_METHOD"])) {
            if (isset($_SERVER["CONTENT_LENGTH"]) && $_SERVER["CONTENT_LENGTH"] > 0) {
                $this->requestData = "";
                $httpContent = fopen("php://input", "r");
                echo "httpcontent=".$httpContent;
                while ($data = fread($httpContent, 1024)) {
                    $this->requestData .= $data;
                }
                fclose($httpContent);
            }
        }
        echo "jsonrpc::jsonrpc()\n";
    }
}
?>

And the Response tab shows:

POST http://api.localhost/index.php?tm=1317246797964    200 OK      6ms 

 <br />
<b>Warning</b>:  fopen("php://input", "r") - No error in <b>C:\Develop\ZeroSumGames\api\htdocs\rpc.php</b> on line <b>9</b><br />
httpcontent=<br />
<b>Warning</b>:  fread(): supplied argument is not a valid File-Handle resource in <b>C:\Develop\ZeroSumGames\api\htdocs\rpc.php</b> on line <b>11</b><br />
<br />
<b>Warning</b>:  fclose(): supplied argument is not a valid File-Handle resource in <b>C:\Develop\ZeroSumGames\api\htdocs\rpc.php</b> on line <b>14</b><br />
jsonrpc::jsonrpc()

Object { error="Internal server error", version="2.0"}

I can see there is data there because on the FireBug request headers tab I can see this:

Host    api.localhost
User-Agent  Mozilla/5.0 (Windows; U; Windows NT 6.1; en-GB; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13
Accept  application/json, text/javascript, */*
Accept-Language en-gb,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive  115
Connection  keep-alive
Content-Type    application/json; 开发者_高级运维charset=UTF-8
X-Requested-With    XMLHttpRequest
Referer http://api.localhost/index.html
Content-Length  72

And also I can see this on the post tab:

{"jsonrpc":"2.0","method":"example.method.name","id":1,"params":[1,2,3]}

My server is too old for file_get_contents (4.2.2) but the replacement functions I have found on the net internally do the same as what I have written above (more or less) and also have the issue regarding opening of php://input.

So my question is why can't I open php://input for reading?

I upgraded my local machine to 4.4.2 and that works fine so I guess it is a bug in 4.2.2. Not quite the fix I was hoping for.