Add some safety checks to PMs

lib/channel.js

@@ -2878,6 +2878,20 @@ Channel.prototype.handlePm = function (user, data) {
         return;
     }
 
+    if (data.to === user.name) {
+        user.socket.emit("errorMsg", {
+            msg: "You can't PM yourself!"
+        });
+        return;
+    }
+
+    if (!util.isValidUserName(data.to)) {
+        user.socket.emit("errorMsg", {
+            msg: data.to + " isn't a valid username."
+        });
+        return;
+    }
+
     var msg = data.msg.substring(0, 240);
     var to = null;
     for (var i = 0; i < this.users.length; i++) {
@@ -2888,6 +2902,9 @@ Channel.prototype.handlePm = function (user, data) {
     }
 
     if (!to) {
+        user.socket.emit("errorMsg", {
+            msg: data.to + " is not on this channel."
+        });
         return;
     }