pping: Refactor event handling code

Refactor code for how events are handled in the user space
application. Preparation for adding an additional event type which
should not be handled by the normal functions for printing RTT and
flow events.

Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>

Author: simosund

pping/pping.c

@@ -91,7 +91,7 @@ struct pping_config {
 
 static volatile int keep_running = 1;
 static json_writer_t *json_ctx = NULL;
-static void (*print_event_func)(void *, int, void *, __u32) = NULL;
+static void (*print_event_func)(const union pping_event *) = NULL;
 
 static const struct option long_options[] = {
 	{ "help",             no_argument,       NULL, 'h' },
@@ -511,7 +511,7 @@ static bool flow_timeout(void *key_ptr, void *val_ptr, __u64 now)
 			fe.flow_event_type = FLOW_EVENT_CLOSING;
 			fe.reason = EVENT_REASON_FLOW_TIMEOUT;
 			fe.source = EVENT_SOURCE_USERSPACE;
-			print_event_func(NULL, 0, &fe, sizeof(fe));
+			print_event_func((union pping_event *)&fe);
 		}
 		return true;
 	}
@@ -722,11 +722,8 @@ static void print_ns_datetime(FILE *stream, __u64 monotonic_ns)
 	fprintf(stream, "%s.%09llu", timestr, ts % NS_PER_SECOND);
 }
 
-static void print_event_standard(void *ctx, int cpu, void *data,
-				 __u32 data_size)
+static void print_event_standard(const union pping_event *e)
 {
-	const union pping_event *e = data;
-
 	if (e->event_type == EVENT_TYPE_RTT) {
 		print_ns_datetime(stdout, e->rtt_event.timestamp);
 		printf(" %llu.%06llu ms %llu.%06llu ms %s ",
@@ -748,19 +745,19 @@ static void print_event_standard(void *ctx, int cpu, void *data,
 	}
 }
 
-static void print_event_ppviz(void *ctx, int cpu, void *data, __u32 data_size)
+static void print_event_ppviz(const union pping_event *e)
 {
-	const struct rtt_event *e = data;
-	__u64 time = convert_monotonic_to_realtime(e->timestamp);
-
 	// ppviz format does not support flow events
 	if (e->event_type != EVENT_TYPE_RTT)
 		return;
 
+	const struct rtt_event *re = &e->rtt_event;
+	__u64 time = convert_monotonic_to_realtime(re->timestamp);
+
 	printf("%llu.%09llu %llu.%09llu %llu.%09llu ", time / NS_PER_SECOND,
-	       time % NS_PER_SECOND, e->rtt / NS_PER_SECOND,
-	       e->rtt % NS_PER_SECOND, e->min_rtt / NS_PER_SECOND, e->min_rtt);
-	print_flow_ppvizformat(stdout, &e->flow);
+	       time % NS_PER_SECOND, re->rtt / NS_PER_SECOND,
+	       re->rtt % NS_PER_SECOND, re->min_rtt / NS_PER_SECOND, re->min_rtt);
+	print_flow_ppvizformat(stdout, &re->flow);
 	printf("\n");
 }
 
@@ -805,10 +802,8 @@ static void print_flowevent_fields_json(json_writer_t *ctx,
 	jsonw_string_field(ctx, "triggered_by", eventsource_to_str(fe->source));
 }
 
-static void print_event_json(void *ctx, int cpu, void *data, __u32 data_size)
+static void print_event_json(const union pping_event *e)
 {
-	const union pping_event *e = data;
-
 	if (e->event_type != EVENT_TYPE_RTT && e->event_type != EVENT_TYPE_FLOW)
 		return;
 
@@ -826,9 +821,27 @@ static void print_event_json(void *ctx, int cpu, void *data, __u32 data_size)
 	jsonw_end_object(json_ctx);
 }
 
-static void handle_missed_rtt_event(void *ctx, int cpu, __u64 lost_cnt)
+static void handle_event(void *ctx, int cpu, void *data, __u32 data_size)
+{
+	const union pping_event *e = data;
+
+	if (data_size < sizeof(e->event_type))
+		return;
+
+	switch (e->event_type) {
+	case EVENT_TYPE_RTT:
+	case EVENT_TYPE_FLOW:
+		print_event_func(e);
+		break;
+	default:
+		fprintf(stderr, "Warning: Unknown event type %llu\n",
+			e->event_type);
+	};
+}
+
+static void handle_missed_events(void *ctx, int cpu, __u64 lost_cnt)
 {
-	fprintf(stderr, "Lost %llu RTT events on CPU %d\n", lost_cnt, cpu);
+	fprintf(stderr, "Lost %llu events on CPU %d\n", lost_cnt, cpu);
 }
 
 /*
@@ -1081,8 +1094,8 @@ int main(int argc, char *argv[])
 	// Set up perf buffer
 	pb = perf_buffer__new(bpf_object__find_map_fd_by_name(obj,
 							      config.event_map),
-			      PERF_BUFFER_PAGES, print_event_func,
-			      handle_missed_rtt_event, NULL, NULL);
+			      PERF_BUFFER_PAGES, handle_event,
+			      handle_missed_events, NULL, NULL);
 	err = libbpf_get_error(pb);
 	if (err) {
 		fprintf(stderr, "Failed to open perf buffer %s: %s\n",

pping/pping.h

@@ -93,10 +93,15 @@ struct packet_id {
 };
 
 /*
- * An RTT event message that can be passed from the bpf-programs to user-space.
+ * Events that can be passed from the BPF-programs to the user space
+ * application.
  * The initial event_type memeber is used to allow multiplexing between
  * different event types in a single perf buffer. Memebers up to and including
- * flow are identical to other event types.
+ * flow are identical for all event types.
+ */
+
+/*
+ * An RTT event message passed when an RTT has been calculated
  * Uses explicit padding instead of packing based on recommendations in cilium's
  * BPF reference documentation at https://docs.cilium.io/en/stable/bpf/#llvm.
  */
@@ -116,10 +121,7 @@ struct rtt_event {
 };
 
 /*
- * A flow event message that can be passed from the bpf-programs to user-space.
- * The initial event_type memeber is used to allow multiplexing between
- * different event types in a single perf buffer. Memebers up to and including
- * flow are identical to other event types.
+ * A flow event message passed when a flow has changed state (opened/closed)
  */
 struct flow_event {
 	__u64 event_type;