afb-xreq: Forbids (un)subscribes after reply

Allowing to subscribe to a request that was replied
was possible and lead to problem revealed by issues
SPEC-2542 and SPEC-2599 (these issues are more related
to processing unordered incoming messages).

The choice was
 - fix the bug and authorize (un)subscribe after reply
 - forbids to (un)subscribe after reply

Second solution was chosen for its simplicity and
its networking efficiency.

Bug-AGL: SPEC-2542
Bug-AGL: SPEC-2599

Change-Id: I09f48b760b1fd6f70d42b80df3c8053696c45966
Signed-off-by: Jose Bollo <jose.bollo@iot.bzh>

1 files changed, 22 insertions, 12 deletions

diff --git a/src/afb-xreq.c b/src/afb-xreq.c
index 8cc22c3f..790a384f 100644
--- a/src/afb-xreq.c
+++ b/src/afb-xreq.c
@@ -202,12 +202,17 @@ static int xreq_legacy_subscribe_event_x1_cb(struct afb_req_x2 *closure, struct
 
 int afb_xreq_subscribe(struct afb_xreq *xreq, struct afb_event_x2 *event)
 {
-	if (xreq->listener)
-		return afb_evt_event_x2_add_watch(xreq->listener, event);
-	if (xreq->queryitf->subscribe)
-		return xreq->queryitf->subscribe(xreq, event);
-	ERROR("no event listener, subscription impossible");
-	errno = EINVAL;
+	if (xreq->replied) {
+		ERROR("request replied, subscription impossible");
+		errno = EINVAL;
+	} else {
+		if (xreq->listener)
+			return afb_evt_event_x2_add_watch(xreq->listener, event);
+		if (xreq->queryitf->subscribe)
+			return xreq->queryitf->subscribe(xreq, event);
+		ERROR("no event listener, subscription impossible");
+		errno = ENOTSUP;
+	}
 	return -1;
 }
 
@@ -224,12 +229,17 @@ static int xreq_legacy_unsubscribe_event_x1_cb(struct afb_req_x2 *closure, struc
 
 int afb_xreq_unsubscribe(struct afb_xreq *xreq, struct afb_event_x2 *event)
 {
-	if (xreq->listener)
-		return afb_evt_event_x2_remove_watch(xreq->listener, event);
-	if (xreq->queryitf->unsubscribe)
-		return xreq->queryitf->unsubscribe(xreq, event);
-	ERROR("no event listener, unsubscription impossible");
-	errno = EINVAL;
+	if (xreq->replied) {
+		ERROR("request replied, unsubscription impossible");
+		errno = EINVAL;
+	} else {
+		if (xreq->listener)
+			return afb_evt_event_x2_remove_watch(xreq->listener, event);
+		if (xreq->queryitf->unsubscribe)
+			return xreq->queryitf->unsubscribe(xreq, event);
+		ERROR("no event listener, unsubscription impossible");
+		errno = ENOTSUP;
+	}
 	return -1;
 }