queries: make sure scids are in order.

I thought LND had a bug, but turns out it doesn't like out-of-order short_channel_ids: in fact, the spec says they have to be in order! This means we use uintmap instead of a htable for unknown_scids and stale_scids so they're nicely ordered. But our nodes-missing-announcements probe is harder since they can also contain duplicates: we switch that to iterate through channels rather than nodes. Signed-off-by: Rusty Russell <[email protected]>
owldock · Oct 11, 2019 · 9485919 · 9485919
1 parent 1f9de04
commit 9485919
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diff --git a/gossipd/queries.c b/gossipd/queries.c
@@ -183,8 +183,17 @@ bool query_short_channel_ids(struct daemon *daemon,
 		return false;
 
 	encoded = encoding_start(tmpctx);
-	for (size_t i = 0; i < tal_count(scids); i++)
+	for (size_t i = 0; i < tal_count(scids); i++) {
+		/* BOLT #7:
+		 *
+		 * Encoding types:
+		 * * `0`: uncompressed array of `short_channel_id` types, in
+		 *   ascending order.
+		 * * `1`: array of `short_channel_id` types, in ascending order
+		 */
+		assert(i == 0 || scids[i].u64 > scids[i-1].u64);
 		encoding_add_short_channel_id(&encoded, &scids[i]);
+	}
 
 	if (!encoding_end_prepend_type(&encoded, max_encoded_bytes)) {
 		status_broken("query_short_channel_ids: %zu is too many",