Twitter Streaming 401 Unauthorized OAuth - php

Question

I'm trying to create a script that uses the twitter streaming api to keep a tab on tweets with a certain hash-tag.
Whenever I try creating a request though, I always get a 401 Unauthorized return. Can anyone help me figure out what I'm doing incorrectly?
I tried to follow twitter's api to the dot, but apparently I'm doing something wrong. The code I have is below.
$base_url_string = urlencode($base_url);
$parameter_string = urlencode('oauth_consumer_key') . '=' . urlencode($consumer_key) . '&'
. urlencode('oauth_nonce') . '=' . urlencode($nonce) . '&'
. urlencode('oauth_signature_method') . '=' . urlencode($signature_method) . '&'
. urlencode('oauth_timestamp') . '=' . urlencode($timestamp) . '&'
. urlencode('oauth_token') . '=' . urlencode($token) . '&'
. urlencode('oauth_version') . '=' . urlencode($version) . '&'
. urlencode('track') . '=' . urlencode('#kitten');
$signature_base_string = $method . "&" . $base_url_string . "&" . urlencode($parameter_string);
$signature = base64_encode(hash_hmac('sha1', $signature_base_string, $secret, true));
$fp = fsockopen("ssl://stream.twitter.com", 443, $errno, $errstr, 30);
if (!$fp) {
print "$errstr ($errno)\n";
} else {
$request = $method . " /1.1/statuses/filter.json?" . urlencode("track") . "=" . urlencode("#kitten") . " HTTP/1.1\r\n";
$request .= "Host: stream.twitter.com\r\n";
$request .= 'Authorization: OAuth'
. ' oauth_consumer_key="' . $consumer_key . '",'
. ' oauth_nonce="' . $nonce . '",'
. ' oauth_signature="' . $signature . '",'
. ' oauth_signature_method="' . $signature_method . '",'
. ' oauth_timestamp="' . $timestamp . '",'
. ' oauth_token="' . $token . '",'
. ' oauth_version="' . $version . '"'
. "\r\n\r\n";
print $request . "</br>";
fwrite($fp, $request);
while (!feof($fp)) {
$json = fgets($fp);
echo $json;
$data = json_decode($json, true);
if ($data) {
print $data;
}
}
print 'exiting...';
fclose($fp);
}

Answer 1

Ok so I figured this all out. It was a combination of poor string manipulation and not Percent Encoding everything. Both the keys and values of the OAuth string must be Percent encoded. I had done that in the signature, but not in the actual request. Once I fixed that, the request got through and I was connected to the Twitter Streaming API.