diff --git a/addons/website/models/ir_http.py b/addons/website/models/ir_http.py
index 80d7f5e52b6..75433da2b27 100644
--- a/addons/website/models/ir_http.py
+++ b/addons/website/models/ir_http.py
@@ -80,7 +80,7 @@ class ir_http(orm.AbstractModel):
             if self.geo_ip_resolver and request.httprequest.remote_addr:
                 record = self.geo_ip_resolver.record_by_addr(request.httprequest.remote_addr) or {}
             request.session['geoip'] = record
-            
+
         if request.website_enabled:
             try:
                 if func:
@@ -170,38 +170,8 @@ class ir_http(orm.AbstractModel):
                     path += '?' + request.httprequest.query_string
                 return werkzeug.utils.redirect(path, code=301)
 
-    def _serve_attachment(self):
-        domain = [('type', '=', 'binary'), ('url', '=', request.httprequest.path)]
-        attach = self.pool['ir.attachment'].search_read(request.cr, openerp.SUPERUSER_ID, domain, ['__last_update', 'datas', 'mimetype'], context=request.context)
-        if attach:
-            wdate = attach[0]['__last_update']
-            datas = attach[0]['datas']
-            response = werkzeug.wrappers.Response()
-            server_format = openerp.tools.misc.DEFAULT_SERVER_DATETIME_FORMAT
-            try:
-                response.last_modified = datetime.datetime.strptime(wdate, server_format + '.%f')
-            except ValueError:
-                # just in case we have a timestamp without microseconds
-                response.last_modified = datetime.datetime.strptime(wdate, server_format)
-
-            response.set_etag(hashlib.sha1(datas).hexdigest())
-            response.make_conditional(request.httprequest)
-
-            if response.status_code == 304:
-                return response
-
-            response.mimetype = attach[0]['mimetype'] or 'application/octet-stream'
-            response.data = datas.decode('base64')
-            return response
 
     def _handle_exception(self, exception, code=500):
-        # This is done first as the attachment path may
-        # not match any HTTP controller, so the request
-        # may not be website-enabled.
-        attach = self._serve_attachment()
-        if attach:
-            return attach
-
         is_website_request = bool(getattr(request, 'website_enabled', False) and request.website)
         if not is_website_request:
             # Don't touch non website requests exception handling
diff --git a/openerp/addons/base/ir/ir_http.py b/openerp/addons/base/ir/ir_http.py
index beb337b478f..f29a713669d 100644
--- a/openerp/addons/base/ir/ir_http.py
+++ b/openerp/addons/base/ir/ir_http.py
@@ -1,6 +1,9 @@
+# -*- coding: utf-8 -*-
 #----------------------------------------------------------
 # ir_http modular http routing
 #----------------------------------------------------------
+import datetime
+import hashlib
 import logging
 import re
 import sys
@@ -94,9 +97,39 @@ class ir_http(osv.AbstractModel):
             raise openerp.exceptions.AccessDenied()
         return auth_method
 
+    def _serve_attachment(self):
+        domain = [('type', '=', 'binary'), ('url', '=', request.httprequest.path)]
+        attach = self.pool['ir.attachment'].search_read(request.cr, openerp.SUPERUSER_ID, domain, ['__last_update', 'datas', 'mimetype', 'checksum'], context=request.context)
+        if attach:
+            wdate = attach[0]['__last_update']
+            datas = attach[0]['datas'] or '' # support empty ir_attachment
+            response = werkzeug.wrappers.Response()
+            server_format = openerp.tools.misc.DEFAULT_SERVER_DATETIME_FORMAT
+            try:
+                response.last_modified = datetime.datetime.strptime(wdate, server_format + '.%f')
+            except ValueError:
+                # just in case we have a timestamp without microseconds
+                response.last_modified = datetime.datetime.strptime(wdate, server_format)
+
+            response.set_etag(attach[0]['checksum'])
+            response.make_conditional(request.httprequest)
+
+            if response.status_code == 304:
+                return response
+
+            response.mimetype = attach[0]['mimetype'] or 'application/octet-stream'
+            response.data = datas.decode('base64')
+            return response
+
     def _handle_exception(self, exception):
         # If handle_exception returns something different than None, it will be used as a response
 
+        # This is done first as the attachment path may
+        # not match any HTTP controller
+        attach = self._serve_attachment()
+        if attach:
+            return attach
+
         # Don't handle exception but use werkeug debugger if server in --dev mode
         if openerp.tools.config['dev_mode']:
             raise