Fix encoding and do escaping in authorize.net xml

- Escapes &, <, and > except in extraOptions tags, which need to allow special
    characters
- Encodes string as UTF-8 before sending it over the wire
- Replaces xml entities in responses with the correct chars

This change should fix some of the 500 server errors people were getting when
they had unusual characters in their payment info.

r2/r2/lib/authorize/api.py

@@ -37,6 +37,8 @@
 from r2.models import NotFound
 from r2.models.bidding import CustomerID, PayID, ShippingAddress
 
+from xml.sax.saxutils import escape
+
 # list of the most common errors.
 Errors = Storage(TESTMODE = "E00009",
                  TRANSACTION_FAIL = "E00027",
@@ -49,6 +51,9 @@ class AuthorizeNetException(Exception):
     pass
 
 
+# xml tags whose content shouldn't be escaped 
+_no_escape_list = ["extraOptions"]
+
 class SimpleXMLObject(object):
     """
     All API transactions are done with authorize.net using XML, so
@@ -74,6 +79,10 @@ def toXML(self):
         def process(k, v):
             if isinstance(v, SimpleXMLObject):
                 v = v.toXML()
+            elif v is not None:
+                v = unicode(v)
+                if k not in _no_escape_list:
+                    v = escape(v) # escape &, <, and >
             if v is not None:
                 content.append(self.simple_tag(k, v))
 
@@ -213,7 +222,7 @@ def make_request(self):
         u = urlparse(g.authorizenetapi)
         try:
             conn = HTTPSConnection(u.hostname, u.port)
-            conn.request("POST", u.path, self.toXML(),
+            conn.request("POST", u.path, self.toXML().encode('utf-8'),
                          {"Content-type": "text/xml"})
             res = conn.getresponse()
             res = self.handle_response(res.read())
@@ -237,7 +246,9 @@ def _autoclose_handler(self, m):
 
     def handle_response(self, res):
         res = self._autoclose_re.sub(self._autoclose_handler, res)
-        res = BeautifulStoneSoup(res, markupMassage=False)
+        res = BeautifulStoneSoup(res, 
+                                 markupMassage=False, 
+                                 convertEntities=BeautifulStoneSoup.XML_ENTITIES)
         if res.resultcode.contents[0] == u"Ok":
             return self.process_response(res)
         else: