Retwis ported to modern Redis data types.

The example (and related documentation at redis.io) was not updated for
5 years. Redis had no sorted sets and hashes when the original code was
written (!). An update was really needed.

We also use a modern PHP client now: Predis. A copy is shipped within
this repository to make life easier to newcomers trying Redis for the
first time via this example.

login.php

@@ -0,0 +1,23 @@
+<?
+include("retwis.php");
+
+# Form sanity checks
+if (!gt("username") || !gt("password"))
+    goback("You need to enter both username and password to login.");
+
+# The form is ok, check if the username is available
+$username = gt("username");
+$password = gt("password");
+$r = redisLink();
+$userid = $r->hget("users",$username);
+if (!$userid)
+    goback("Wrong username or password");
+$realpassword = $r->hget("user:$userid","password");
+if ($realpassword != $password)
+    goback("Wrong useranme or password");
+
+# Username / password OK, set the cookie and redirect to index.php
+$authsecret = $r->hget("user:$userid","auth");
+setcookie("auth",$authsecret,time()+3600*24*365);
+header("Location: index.php");
+?>