s4:messaging: make sure only imessaging_client_init() can be used with a wrapper tevent_context wrapper

imessaging_client_init() can be used with a wrapper tevent_context,
but only if a global messaging_dgm_ref() already exist.

All other uses of imessaging_init() and imessaging_client_init()
require a raw tevent_context.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Thu Jul 12 02:23:37 CEST 2018 on sn-devel-144

1 files changed, 26 insertions, 2 deletions

diff --git a/source4/lib/messaging/messaging.c b/source4/lib/messaging/messaging.c
index 8903322bdc7..935951f3fba 100644
--- a/source4/lib/messaging/messaging.c
+++ b/source4/lib/messaging/messaging.c
@@ -319,7 +319,7 @@ NTSTATUS imessaging_reinit_all(void)
 /*
   create the listening socket and setup the dispatcher
 */
-struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
+static struct imessaging_context *imessaging_init_internal(TALLOC_CTX *mem_ctx,
 					   struct loadparm_context *lp_ctx,
 					   struct server_id server_id,
 					   struct tevent_context *ev)
@@ -573,6 +573,30 @@ static void imessaging_dgm_recv(struct tevent_context *ev,
 	}
 }
 
+struct imessaging_context *imessaging_init(TALLOC_CTX *mem_ctx,
+					   struct loadparm_context *lp_ctx,
+					   struct server_id server_id,
+					   struct tevent_context *ev)
+{
+	if (ev == NULL) {
+		return NULL;
+	}
+
+	if (tevent_context_is_wrapper(ev)) {
+		/*
+		 * This is really a programmer error!
+		 *
+		 * The main/raw tevent context should
+		 * have been registered first!
+		 */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		errno = EINVAL;
+		return NULL;
+	}
+
+	return imessaging_init_internal(mem_ctx, lp_ctx, server_id, ev);
+}
+
 /*
    A hack, for the short term until we get 'client only' messaging in place
 */
@@ -589,7 +613,7 @@ struct imessaging_context *imessaging_client_init(TALLOC_CTX *mem_ctx,
 	/* This is because we are not in the s3 serverid database */
 	id.unique_id = SERVERID_UNIQUE_ID_NOT_TO_VERIFY;
 
-	return imessaging_init(mem_ctx, lp_ctx, id, ev);
+	return imessaging_init_internal(mem_ctx, lp_ctx, id, ev);
 }
 /*
   a list of registered irpc server functions