json: Add timestampt primitives to print timestamps in results

The timestamps are UNIX-Timestamps with 3 decimal places, even though we have
the timestamp with nanosecond granularity. This is deliberate choice not to
over overload the users :-)

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/json.c

@@ -368,3 +368,10 @@ void json_add_amount_sat(struct json_stream *result,
 		json_add_member(result, msatfieldname, "\"%s\"",
 				type_to_string(tmpctx, struct amount_msat, &msat));
 }
+
+void json_add_timeabs(struct json_stream *result, const char *fieldname,
+		      struct timeabs t)
+{
+	json_add_member(result, fieldname, "%" PRIu64 ".%03" PRIu64,
+			(u64)t.ts.tv_sec, (u64)t.ts.tv_nsec / 1000000);
+}

lightningd/json.h

@@ -7,6 +7,7 @@
 #include "config.h"
 #include <ccan/short_types/short_types.h>
 #include <ccan/tal/tal.h>
+#include <ccan/time/time.h>
 #include <common/amount.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -170,4 +171,8 @@ enum address_parse_result json_tok_address_scriptpubkey(const tal_t *ctx,
 			     const struct chainparams *chainparams,
 			     const char *buffer,
 			     const jsmntok_t *tok, const u8 **scriptpubkey);
+
+void json_add_timeabs(struct json_stream *result, const char *fieldname,
+		      struct timeabs t);
+
 #endif /* LIGHTNING_LIGHTNINGD_JSON_H */