ceph: add auth buf in prepare_write_connect()

Move the addition of the authorizer buffer to a connection's
out_kvec out of get_connect_authorizer() and into its caller.  This
way, the caller--prepare_write_connect()--can avoid adding the
connect header to out_kvec before it has been fully initialized.

Prior to this patch, it was possible for a connect header to be
sent over the wire before the authorizer protocol or buffer length
fields were initialized.  An authorizer buffer associated with that
header could also be queued to send only after the connection header
that describes it was on the wire.

Fixes http://tracker.newdream.net/issues/2424

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -656,8 +656,6 @@ static void prepare_write_keepalive(struct ceph_connection *con)
 static struct ceph_auth_handshake *get_connect_authorizer(struct ceph_connection *con,
 						int *auth_proto)
 {
-	void *auth_buf;
-	int auth_len;
 	struct ceph_auth_handshake *auth;
 
 	if (!con->ops->get_authorizer) {
@@ -680,15 +678,9 @@ static struct ceph_auth_handshake *get_connect_authorizer(struct ceph_connection
 	if (test_bit(CLOSED, &con->state) || test_bit(OPENING, &con->state))
 		return ERR_PTR(-EAGAIN);
 
-	auth_buf = auth->authorizer_buf;
-	auth_len = auth->authorizer_buf_len;
 	con->auth_reply_buf = auth->authorizer_reply_buf;
 	con->auth_reply_buf_len = auth->authorizer_reply_buf_len;
 
-	con->out_connect.authorizer_len = cpu_to_le32(auth_len);
-
-	if (auth_len)
-		ceph_con_out_kvec_add(con, auth_len, auth_buf);
 
 	return auth;
 }
@@ -737,12 +729,20 @@ static int prepare_write_connect(struct ceph_connection *con)
 	con->out_connect.protocol_version = cpu_to_le32(proto);
 	con->out_connect.flags = 0;
 
-	ceph_con_out_kvec_add(con, sizeof (con->out_connect), &con->out_connect);
 	auth_proto = CEPH_AUTH_UNKNOWN;
 	auth = get_connect_authorizer(con, &auth_proto);
 	if (IS_ERR(auth))
 		return PTR_ERR(auth);
+
 	con->out_connect.authorizer_protocol = cpu_to_le32(auth_proto);
+	con->out_connect.authorizer_len = auth ?
+		cpu_to_le32(auth->authorizer_buf_len) : 0;
+
+	ceph_con_out_kvec_add(con, sizeof (con->out_connect),
+					&con->out_connect);
+	if (auth && auth->authorizer_buf_len)
+		ceph_con_out_kvec_add(con, auth->authorizer_buf_len,
+					auth->authorizer_buf);
 
 	con->out_more = 0;
 	set_bit(WRITE_PENDING, &con->state);