common: implement decoding of query-flags for query_short_channel_ids.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/decode_short_channel_ids.c

@@ -1,5 +1,7 @@
+#include <ccan/cast/cast.h>
 #include <common/decode_short_channel_ids.h>
 #include <common/utils.h>
+#include <wire/gen_peer_wire.h>
 #include <wire/wire.h>
 #include <zlib.h>
 
@@ -60,3 +62,46 @@ struct short_channel_id *decode_short_ids(const tal_t *ctx, const u8 *encoded)
 	}
 	return NULL;
 }
+
+#if EXPERIMENTAL_FEATURES
+bigsize_t *decode_scid_query_flags(const tal_t *ctx,
+				   const struct tlv_query_short_channel_ids_tlvs_query_flags *qf)
+{
+	u8 *encoded = qf->encoded_query_flags;
+	size_t max = tal_count(encoded);
+	bigsize_t *flags;
+
+	/* BOLT-61a1365a45cc8b463ddbbe3429d350f8eac787dd #7:
+	 *
+	 * The receiver:
+	 *...
+	 *  - if the incoming message includes `query_short_channel_ids_tlvs`:
+	 *    - if `encoding_type` is not a known encoding type:
+	 *      - MAY fail the connection
+	 *    - if `encoded_query_flags` does not decode to exactly one flag per
+	 *      `short_channel_id`:
+	 *      - MAY fail the connection.
+	 */
+	switch (qf->encoding_type) {
+	case SHORTIDS_ZLIB:
+		encoded = unzlib(tmpctx, encoded, max);
+		if (!encoded)
+			return NULL;
+		max = tal_count(encoded);
+		/* fall thru */
+	case SHORTIDS_UNCOMPRESSED:
+		flags = tal_arr(ctx, bigsize_t, 0);
+		while (max)
+			tal_arr_expand(&flags,
+				       fromwire_bigsize(cast_const2(const u8 **,
+								    &encoded),
+							&max));
+
+		/* encoded is set to NULL if we ran over */
+		if (!encoded)
+			return tal_free(flags);
+		return flags;
+	}
+	return NULL;
+}
+#endif /* EXPERIMENTAL_FEATURES */

common/decode_short_channel_ids.h

@@ -3,6 +3,9 @@
 #include "config.h"
 #include <ccan/short_types/short_types.h>
 #include <ccan/tal/tal.h>
+#include <common/bigsize.h>
+
+struct tlv_query_short_channel_ids_tlvs_query_flags;
 
 /* BOLT #7:
  *
@@ -16,4 +19,31 @@ enum scid_encode_types {
 };
 
 struct short_channel_id *decode_short_ids(const tal_t *ctx, const u8 *encoded);
+
+/* BOLT-61a1365a45cc8b463ddbbe3429d350f8eac787dd #7:
+ *
+ * `encoded_query_flags` is an array of bitfields, one varint per bitfield,
+ * one bitfield for each `short_channel_id`. Bits have the following meaning:
+ *
+ * | Bit Position  | Meaning                                  |
+ * | ------------- | ---------------------------------------- |
+ * | 0             | Sender wants `channel_announcement`      |
+ * | 1             | Sender wants `channel_update` for node 1 |
+ * | 2             | Sender wants `channel_update` for node 2 |
+ * | 3             | Sender wants `node_announcement` for node 1 |
+ * | 4             | Sender wants `node_announcement` for node 2 |
+ */
+enum scid_query_flag {
+	SCID_QF_ANNOUNCE = 0x1,
+	SCID_QF_UPDATE1 = 0x2,
+	SCID_QF_UPDATE2 = 0x4,
+	SCID_QF_NODE1 = 0x8,
+	SCID_QF_NODE2 = 0x10,
+};
+
+#if EXPERIMENTAL_FEATURES
+bigsize_t *decode_scid_query_flags(const tal_t *ctx,
+				   const struct tlv_query_short_channel_ids_tlvs_query_flags *qf);
+#endif /* EXPERIMENTAL_FEATURES */
+
 #endif /* LIGHTNING_COMMON_DECODE_SHORT_CHANNEL_IDS_H */