send xml declaration

source/Network/Xmpp/Monad.hs

@@ -40,6 +40,15 @@ pushElement x = do
 pushStanza :: Stanza -> XmppConMonad Bool
 pushStanza = pushElement . pickleElem xpStanza
 
+-- XML documents and XMPP streams SHOULD be preceeded by an XML declaration.
+-- UTF-8 is the only supported XMPP encoding. The standalone document
+-- declaration (matching "SDDecl" in the XML standard) MUST NOT be included in
+-- XMPP streams. RFC 6120 defines XMPP only in terms of XML 1.0.
+pushXmlDecl :: XmppConMonad Bool
+pushXmlDecl = do
+    sink <- gets sConPushBS
+    liftIO $ sink "<?xml version='1.0' encoding='UTF-8' ?>"
+
 pushOpenElement :: Element -> XmppConMonad Bool
 pushOpenElement e = do
     sink <- gets sConPushBS

source/Network/Xmpp/Stream.hs

@@ -61,8 +61,10 @@ xmppStartStream = runErrorT $ do
     hostname' <- gets sHostname
     case hostname' of
         Nothing -> throwError StreamConnectionError
-        Just hostname -> lift . pushOpenElement $
+        Just hostname -> lift $ do
-            pickleElem pickleStream ("1.0", Nothing, Just hostname)
+            pushXmlDecl
+            pushOpenElement $
+                pickleElem pickleStream ("1.0", Nothing, Just hostname)
     features <- ErrorT . pullToSink $ runErrorT xmppStream
     modify (\s -> s {sFeatures = features})
     return ()