Tag broadcasted events with UUID and hop

When API have mutual dependencies, leading to
loops in dependecies, broadcasting an event
never ends because of the loop (see SPEC-2625).

To avoid that weird flood of events, a unic
identifier (UUID) is attached to broadcasted
event and a tiny memory records previously
broadcasted events to avoid re-sending an
already sent event.

The size of the memory can be set using the
macro variable EVENT_BROADCAST_MEMORY_COUNT
whose default value is 8. It can be reduced
to 0.

An other mecanism is added to limit the count
of hops that a broadcasted event can do. That
count can be set using the macro variable
EVENT_BROADCAST_HOP_MAX whose default value
is 10.

Bug-AGL: SPEC-2625

Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Change-Id: I45877583dbf478a79d405c3650880a5579ac1f9e

10 files changed, 139 insertions, 39 deletions

diff --git a/bindings/samples/hello3.c b/bindings/samples/hello3.c
index 1d7c1954..37da6127 100644
--- a/bindings/samples/hello3.c
+++ b/bindings/samples/hello3.c
@@ -424,7 +424,7 @@ static void broadcast(afb_req_t request)
 			afb_req_success(request, NULL, NULL);
 		pthread_mutex_unlock(&mutex);
 	} else if (name != NULL) {
-		if (0 > afb_daemon_broadcast_event(name, object))
+		if (0 > afb_daemon_broadcast_event(name, json_object_get(object)))
 			afb_req_fail(request, "failed", "broadcast error");
 		else
 			afb_req_success(request, NULL, NULL);
diff --git a/src/afb-api-dbus.c b/src/afb-api-dbus.c
index 966c9656..ec2ca760 100644
--- a/src/afb-api-dbus.c
+++ b/src/afb-api-dbus.c
@@ -634,7 +634,7 @@ error:
 static void afb_api_dbus_server_event_add(void *closure, const char *event, int eventid);
 static void afb_api_dbus_server_event_remove(void *closure, const char *event, int eventid);
 static void afb_api_dbus_server_event_push(void *closure, const char *event, int eventid, struct json_object *object);
-static void afb_api_dbus_server_event_broadcast(void *closure, const char *event, struct json_object *object);
+static void afb_api_dbus_server_event_broadcast(void *closure, const char *event, struct json_object *object, const char *uuid);
 
 /* the interface for events broadcasting */
 static const struct afb_evt_itf evt_broadcast_itf = {
@@ -916,7 +916,7 @@ static void afb_api_dbus_server_event_push(void *closure, const char *event, int
 	json_object_put(object);
 }
 
-static void afb_api_dbus_server_event_broadcast(void *closure, const char *event, struct json_object *object)
+static void afb_api_dbus_server_event_broadcast(void *closure, const char *event, struct json_object *object, const char *uuid)
 {
 	int rc;
 	struct api_dbus *api;
diff --git a/src/afb-evt.c b/src/afb-evt.c
index ddad5759..24ac8bee 100644
--- a/src/afb-evt.c
+++ b/src/afb-evt.c
@@ -31,6 +31,7 @@
 #include "afb-hook.h"
 #include "verbose.h"
 #include "jobs.h"
+#include "uuid.h"
 
 struct afb_evt_watch;
 
@@ -120,6 +121,12 @@ struct job_broadcast
 	/** object atached to the event */
 	struct json_object *object;
 
+	/** the uuid of the event */
+	uuid_binary_t  uuid;
+
+	/** remaining hop */
+	uint8_t hop;
+
 	/** name of the event to broadcast */
 	char event[];
 };
@@ -168,16 +175,39 @@ static struct afb_evtid *evtids = NULL;
 static int event_id_counter = 0;
 static int event_id_wrapped = 0;
 
+/* head of uniqueness of events */
+#if !defined(EVENT_BROADCAST_HOP_MAX)
+#  define EVENT_BROADCAST_HOP_MAX  10
+#endif
+#if !defined(EVENT_BROADCAST_MEMORY_COUNT)
+#  define EVENT_BROADCAST_MEMORY_COUNT  8
+#endif
+
+#if EVENT_BROADCAST_MEMORY_COUNT
+static struct {
+	pthread_mutex_t mutex;
+	uint8_t base;
+	uint8_t count;
+	uuid_binary_t uuids[EVENT_BROADCAST_MEMORY_COUNT];
+} uniqueness = {
+	.mutex = PTHREAD_MUTEX_INITIALIZER,
+	.base = 0,
+	.count = 0
+};
+#endif
+
 /*
  * Create structure for job of broadcasting string 'event' with 'object'
  * Returns the created structure or NULL if out of memory
  */
-static struct job_broadcast *make_job_broadcast(const char *event, struct json_object *object)
+static struct job_broadcast *make_job_broadcast(const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop)
 {
 	size_t sz = 1 + strlen(event);
 	struct job_broadcast *jb = malloc(sz + sizeof *jb);
 	if (jb) {
 		jb->object = object;
+		memcpy(jb->uuid, uuid, sizeof jb->uuid);
+		jb->hop = hop;
 		memcpy(jb->event, event, sz);
 	}
 	return jb;
@@ -219,7 +249,7 @@ static void destroy_job_evtid(struct job_evtid *je)
 /*
  * Broadcasts the 'event' of 'id' with its 'object'
  */
-static void broadcast(const char *event, struct json_object *object)
+static void broadcast(struct job_broadcast *jb)
 {
 	struct afb_evt_listener *listener;
 
@@ -227,7 +257,7 @@ static void broadcast(const char *event, struct json_object *object)
 	listener = listeners;
 	while(listener) {
 		if (listener->itf->broadcast != NULL)
-			listener->itf->broadcast(listener->closure, event, json_object_get(object));
+			listener->itf->broadcast(listener->closure, jb->event, json_object_get(jb->object), jb->uuid, jb->hop);
 		listener = listener->next;
 	}
 	pthread_rwlock_unlock(&listeners_rwlock);
@@ -241,19 +271,56 @@ static void broadcast_job(int signum, void *closure)
 	struct job_broadcast *jb = closure;
 
 	if (signum == 0)
-		broadcast(jb->event, jb->object);
+		broadcast(jb);
 	destroy_job_broadcast(jb);
 }
 
 /*
  * Broadcasts the string 'event' with its 'object'
  */
-static int unhooked_broadcast(const char *event, struct json_object *object)
+static int unhooked_broadcast(const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop)
 {
+	uuid_binary_t local_uuid;
 	struct job_broadcast *jb;
 	int rc;
+#if EVENT_BROADCAST_MEMORY_COUNT
+	int iter, count;
+#endif
+
+	/* check if lately sent */
+	if (!uuid) {
+		uuid_new_binary(local_uuid);
+		uuid = local_uuid;
+		hop = EVENT_BROADCAST_HOP_MAX;
+#if EVENT_BROADCAST_MEMORY_COUNT
+		pthread_mutex_lock(&uniqueness.mutex);
+	} else {
+		pthread_mutex_lock(&uniqueness.mutex);
+		iter = (int)uniqueness.base;
+		count = (int)uniqueness.count;
+		while (count) {
+			if (0 == memcmp(uuid, uniqueness.uuids[iter], sizeof(uuid_binary_t))) {
+				pthread_mutex_unlock(&uniqueness.mutex);
+				return 0;
+			}
+			if (++iter == EVENT_BROADCAST_MEMORY_COUNT)
+				iter = 0;
+			count--;
+		}
+	}
+	iter = (int)uniqueness.base;
+	if (uniqueness.count < EVENT_BROADCAST_MEMORY_COUNT)
+		iter += (int)(uniqueness.count++);
+	else if (++uniqueness.base == EVENT_BROADCAST_MEMORY_COUNT)
+		uniqueness.base = 0;
+	memcpy(uniqueness.uuids[iter], uuid, sizeof(uuid_binary_t));
+	pthread_mutex_unlock(&uniqueness.mutex);
+#else
+	}
+#endif
 
-	jb = make_job_broadcast(event, object);
+	/* create the structure for the job */
+	jb = make_job_broadcast(event, object, uuid, hop);
 	if (jb == NULL) {
 		ERROR("Cant't create broadcast string job item for %s(%s)",
 			event, json_object_to_json_string(object));
@@ -261,6 +328,7 @@ static int unhooked_broadcast(const char *event, struct json_object *object)
 		return -1;
 	}
 
+	/* queue the job */
 	rc = jobs_queue(BROADCAST_JOB_GROUP, 0, broadcast_job, jb);
 	if (rc) {
 		ERROR("cant't queue broadcast string job item for %s(%s)",
@@ -277,7 +345,7 @@ static int unhooked_broadcast(const char *event, struct json_object *object)
  */
 int afb_evt_evtid_broadcast(struct afb_evtid *evtid, struct json_object *object)
 {
-	return unhooked_broadcast(evtid->fullname, object);
+	return unhooked_broadcast(evtid->fullname, object, NULL, 0);
 }
 
 /*
@@ -304,12 +372,7 @@ int afb_evt_evtid_hooked_broadcast(struct afb_evtid *evtid, struct json_object *
 	return result;
 }
 
-/*
- * Broadcasts the 'event' with its 'object'
- * 'object' is released (like json_object_put)
- * Returns the count of listener having receive the event.
- */
-int afb_evt_broadcast(const char *event, struct json_object *object)
+int afb_evt_rebroadcast(const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop)
 {
 	int result;
 
@@ -318,7 +381,7 @@ int afb_evt_broadcast(const char *event, struct json_object *object)
 	afb_hook_evt_broadcast_before(event, 0, object);
 #endif
 
-	result = unhooked_broadcast(event, object);
+	result = unhooked_broadcast(event, object, uuid, hop);
 
 #if WITH_AFB_HOOK
 	afb_hook_evt_broadcast_after(event, 0, object, result);
@@ -328,6 +391,16 @@ int afb_evt_broadcast(const char *event, struct json_object *object)
 }
 
 /*
+ * Broadcasts the 'event' with its 'object'
+ * 'object' is released (like json_object_put)
+ * Returns the count of listener having receive the event.
+ */
+int afb_evt_broadcast(const char *event, struct json_object *object)
+{
+	return afb_evt_rebroadcast(event, object, NULL, 0);
+}
+
+/*
  * Pushes the event 'evtid' with 'obj' to its listeners
  * Returns the count of listener that received the event.
  */
diff --git a/src/afb-evt.h b/src/afb-evt.h
index 423bd552..02693e9c 100644
--- a/src/afb-evt.h
+++ b/src/afb-evt.h
@@ -17,6 +17,8 @@
 
 #pragma once
 
+#include "uuid.h"
+
 struct afb_event_x1;
 struct afb_event_x2;
 struct afb_evtid;
@@ -27,7 +29,7 @@ struct afb_evt_listener;
 struct afb_evt_itf
 {
 	void (*push)(void *closure, const char *event, int evtid, struct json_object *object);
-	void (*broadcast)(void *closure, const char *event, struct json_object *object);
+	void (*broadcast)(void *closure, const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop);
 	void (*add)(void *closure, const char *event, int evtid);
 	void (*remove)(void *closure, const char *event, int evtid);
 };
@@ -35,6 +37,7 @@ struct afb_evt_itf
 extern struct afb_evt_listener *afb_evt_listener_create(const struct afb_evt_itf *itf, void *closure);
 
 extern int afb_evt_broadcast(const char *event, struct json_object *object);
+extern int afb_evt_rebroadcast(const char *event, struct json_object *object, const  uuid_binary_t uuid, uint8_t hop);
 
 extern struct afb_evt_listener *afb_evt_listener_addref(struct afb_evt_listener *listener);
 extern void afb_evt_listener_unref(struct afb_evt_listener *listener);
diff --git a/src/afb-export.c b/src/afb-export.c
index de6134d3..c146f7e8 100644
--- a/src/afb-export.c
+++ b/src/afb-export.c
@@ -1183,7 +1183,7 @@ static void listener_of_pushed_events(void *closure, const char *event, int even
 	listener_of_events(closure, event, eventid, object);
 }
 
-static void listener_of_broadcasted_events(void *closure, const char *event, struct json_object *object)
+static void listener_of_broadcasted_events(void *closure, const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop)
 {
 	listener_of_events(closure, event, 0, object);
 }
diff --git a/src/afb-proto-ws.c b/src/afb-proto-ws.c
index f4070860..ea95110a 100644
--- a/src/afb-proto-ws.c
+++ b/src/afb-proto-ws.c
@@ -560,11 +560,12 @@ static void client_on_event_unsubscribe(struct afb_proto_ws *protows, struct rea
 /* receives broadcasted events */
 static void client_on_event_broadcast(struct afb_proto_ws *protows, struct readbuf *rb)
 {
-	const char *event_name;
+	const char *event_name, *uuid;
+	char hop;
 	struct json_object *object;
 
-	if (protows->client_itf->on_event_broadcast && readbuf_string(rb, &event_name, NULL) && readbuf_object(rb, &object))
-		protows->client_itf->on_event_broadcast(protows->closure, event_name, object);
+	if (protows->client_itf->on_event_broadcast && readbuf_string(rb, &event_name, NULL) && readbuf_object(rb, &object) && (uuid = readbuf_get(rb, 16)) && readbuf_char(rb, &hop))
+		protows->client_itf->on_event_broadcast(protows->closure, event_name, object, (unsigned char*)uuid, (uint8_t)hop);
 	else
 		ERROR("Ignoring broadcast of event");
 }
@@ -909,9 +910,9 @@ static int server_event_send(struct afb_proto_ws *protows, char order, const cha
 	int rc;
 
 	if (writebuf_char(&wb, order)
-	 && (order == CHAR_FOR_EVT_BROADCAST || writebuf_uint32(&wb, event_id))
+	 && writebuf_uint32(&wb, event_id)
 	 && writebuf_string(&wb, event_name)
-	 && (order == CHAR_FOR_EVT_ADD || order == CHAR_FOR_EVT_DEL || writebuf_object(&wb, data))) {
+	 && (order != CHAR_FOR_EVT_PUSH || writebuf_object(&wb, data))) {
 		pthread_mutex_lock(&protows->mutex);
 		rc = afb_ws_binary_v(protows->ws, wb.iovec, wb.count);
 		pthread_mutex_unlock(&protows->mutex);
@@ -936,9 +937,26 @@ int afb_proto_ws_server_event_push(struct afb_proto_ws *protows, const char *eve
 	return server_event_send(protows, CHAR_FOR_EVT_PUSH, event_name, event_id, data);
 }
 
-int afb_proto_ws_server_event_broadcast(struct afb_proto_ws *protows, const char *event_name, struct json_object *data)
+int afb_proto_ws_server_event_broadcast(struct afb_proto_ws *protows, const char *event_name, struct json_object *data, const unsigned char uuid[16], uint8_t hop)
 {
-	return server_event_send(protows, CHAR_FOR_EVT_BROADCAST, event_name, 0, data);
+	struct writebuf wb = { .count = 0 };
+	int rc;
+
+	if (!hop--)
+		return 0;
+
+	if (writebuf_char(&wb, CHAR_FOR_EVT_BROADCAST)
+	 && writebuf_string(&wb, event_name)
+	 && writebuf_object(&wb, data)
+	 && writebuf_put(&wb, uuid, 16)
+	 && writebuf_char(&wb, (char)hop)) {
+		pthread_mutex_lock(&protows->mutex);
+		rc = afb_ws_binary_v(protows->ws, wb.iovec, wb.count);
+		pthread_mutex_unlock(&protows->mutex);
+		if (rc >= 0)
+			return 0;
+	}
+	return -1;
 }
 
 /*****************************************************/
diff --git a/src/afb-proto-ws.h b/src/afb-proto-ws.h
index d797cb6f..df51e6a7 100644
--- a/src/afb-proto-ws.h
+++ b/src/afb-proto-ws.h
@@ -29,6 +29,8 @@ struct afb_proto_ws;
 struct afb_proto_ws_call;
 struct afb_proto_ws_describe;
 
+typedef unsigned char afb_proto_ws_uuid_t[16];
+
 struct afb_proto_ws_client_itf
 {
 	/* can't be NULL */
@@ -40,7 +42,7 @@ struct afb_proto_ws_client_itf
 	void (*on_event_subscribe)(void *closure, void *request, const char *event_name, int event_id);
 	void (*on_event_unsubscribe)(void *closure, void *request, const char *event_name, int event_id);
 	void (*on_event_push)(void *closure, const char *event_name, int event_id, struct json_object *data);
-	void (*on_event_broadcast)(void *closure, const char *event_name, struct json_object *data);
+	void (*on_event_broadcast)(void *closure, const char *event_name, struct json_object *data, const afb_proto_ws_uuid_t uuid, uint8_t hop);
 };
 
 struct afb_proto_ws_server_itf
@@ -70,7 +72,7 @@ extern int afb_proto_ws_client_describe(struct afb_proto_ws *protows, void (*cal
 extern int afb_proto_ws_server_event_create(struct afb_proto_ws *protows, const char *event_name, int event_id);
 extern int afb_proto_ws_server_event_remove(struct afb_proto_ws *protows, const char *event_name, int event_id);
 extern int afb_proto_ws_server_event_push(struct afb_proto_ws *protows, const char *event_name, int event_id, struct json_object *data);
-extern int afb_proto_ws_server_event_broadcast(struct afb_proto_ws *protows, const char *event_name, struct json_object *data);
+extern int afb_proto_ws_server_event_broadcast(struct afb_proto_ws *protows, const char *event_name, struct json_object *data, const afb_proto_ws_uuid_t uuid, uint8_t hop);
 
 extern void afb_proto_ws_call_addref(struct afb_proto_ws_call *call);
 extern void afb_proto_ws_call_unref(struct afb_proto_ws_call *call);
diff --git a/src/afb-stub-ws.c b/src/afb-stub-ws.c
index 0c440bd5..e900ac76 100644
--- a/src/afb-stub-ws.c
+++ b/src/afb-stub-ws.c
@@ -341,12 +341,12 @@ static void server_event_push_cb(void *closure, const char *event, int eventid,
 	json_object_put(object);
 }
 
-static void server_event_broadcast_cb(void *closure, const char *event, struct json_object *object)
+static void server_event_broadcast_cb(void *closure, const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop)
 {
 	struct afb_stub_ws *stubws = closure;
 
 	if (stubws->proto != NULL)
-		afb_proto_ws_server_event_broadcast(stubws->proto, event, object);
+		afb_proto_ws_server_event_broadcast(stubws->proto, event, object, uuid, hop);
 	json_object_put(object);
 }
 
@@ -457,9 +457,9 @@ static void client_on_event_push_cb(void *closure, const char *event_name, int e
 		ERROR("unreadable push event");
 }
 
-static void client_on_event_broadcast_cb(void *closure, const char *event_name, struct json_object *data)
+static void client_on_event_broadcast_cb(void *closure, const char *event_name, struct json_object *data, const uuid_binary_t uuid, uint8_t hop)
 {
-	afb_evt_broadcast(event_name, data);
+	afb_evt_rebroadcast(event_name, data, uuid, hop);
 }
 
 /*****************************************************/
diff --git a/src/afb-ws-json1.c b/src/afb-ws-json1.c
index 4f5cb868..5e71ff1f 100644
--- a/src/afb-ws-json1.c
+++ b/src/afb-ws-json1.c
@@ -46,7 +46,7 @@ struct afb_wsreq;
 static void aws_on_hangup_cb(void *closure, struct afb_wsj1 *wsj1);
 static void aws_on_call_cb(void *closure, const char *api, const char *verb, struct afb_wsj1_msg *msg);
 static void aws_on_push_cb(void *closure, const char *event, int eventid, struct json_object *object);
-static void aws_on_broadcast_cb(void *closure, const char *event, struct json_object *object);
+static void aws_on_broadcast_cb(void *closure, const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop);
 
 /* predeclaration of wsreq callbacks */
 static void wsreq_destroy(struct afb_xreq *xreq);
@@ -207,15 +207,19 @@ static void aws_on_call_cb(void *closure, const char *api, const char *verb, str
 	afb_xreq_process(&wsreq->xreq, ws->apiset);
 }
 
+static void aws_on_event(struct afb_ws_json1 *aws, const char *event, struct json_object *object)
+{
+	afb_wsj1_send_event_j(aws->wsj1, event, afb_msg_json_event(event, object));
+}
+
 static void aws_on_push_cb(void *closure, const char *event, int eventid, struct json_object *object)
 {
-	aws_on_broadcast_cb(closure, event, object);
+	aws_on_event(closure, event, object);
 }
 
-static void aws_on_broadcast_cb(void *closure, const char *event, struct json_object *object)
+static void aws_on_broadcast_cb(void *closure, const char *event, struct json_object *object, const uuid_binary_t uuid, uint8_t hop)
 {
-	struct afb_ws_json1 *aws = closure;
-	afb_wsj1_send_event_j(aws->wsj1, event, afb_msg_json_event(event, object));
+	aws_on_event(closure, event, afb_msg_json_event(event, object));
 }
 
 /***************************************************************
diff --git a/src/main-afb-client-demo.c b/src/main-afb-client-demo.c
index 1d056365..b772c9d7 100644
--- a/src/main-afb-client-demo.c
+++ b/src/main-afb-client-demo.c
@@ -60,7 +60,7 @@ static void on_pws_event_remove(void *closure, const char *event_name, int event
 static void on_pws_event_subscribe(void *closure, void *request, const char *event_name, int event_id);
 static void on_pws_event_unsubscribe(void *closure, void *request, const char *event_name, int event_id);
 static void on_pws_event_push(void *closure, const char *event_name, int event_id, struct json_object *data);
-static void on_pws_event_broadcast(void *closure, const char *event_name, struct json_object *data);
+static void on_pws_event_broadcast(void *closure, const char *event_name, struct json_object *data, const afb_proto_ws_uuid_t uuid, uint8_t hop);
 
 static void idle();
 static int process_stdin();
@@ -522,7 +522,7 @@ static void on_pws_event_push(void *closure, const char *event_name, int event_i
 	fflush(stdout);
 }
 
-static void on_pws_event_broadcast(void *closure, const char *event_name, struct json_object *data)
+static void on_pws_event_broadcast(void *closure, const char *event_name, struct json_object *data, const afb_proto_ws_uuid_t uuid, uint8_t hop)
 {
 	if (raw)
 		printf("ON-EVENT-BROADCAST: [%s]\n%s\n", event_name, json_object_to_json_string_ext(data, JSON_C_TO_STRING_NOSLASHESCAPE));