gossip_store: add a flag for zombie entries

This will allow gossipd to store and persist gossip for channels rather
than deleting them entirely when the channels are pruned from the
network.

common/gossip_store.h

@@ -39,6 +39,11 @@ struct gossip_rcvd_filter;
  */
 #define GOSSIP_STORE_LEN_RATELIMIT_BIT 0x20000000U
 
+/**
+ * Bit used to mark a channel announcement as inactive (needs channel updates.)
+ */
+#define GOSSIP_STORE_LEN_ZOMBIE_BIT 0x10000000U
+
 /**
  * Full flags mask
  */

devtools/dump-gossipstore.c

@@ -12,7 +12,7 @@
 
 /* Current versions we support */
 #define GSTORE_MAJOR 0
-#define GSTORE_MINOR 10
+#define GSTORE_MINOR 12
 
 int main(int argc, char *argv[])
 {
@@ -67,12 +67,13 @@ int main(int argc, char *argv[])
 		struct short_channel_id scid;
 		u32 msglen = be32_to_cpu(hdr.len);
 		u8 *msg, *inner;
-		bool deleted, push, ratelimit;
+		bool deleted, push, ratelimit, zombie;
 		u32 blockheight;
 
 		deleted = (msglen & GOSSIP_STORE_LEN_DELETED_BIT);
 		push = (msglen & GOSSIP_STORE_LEN_PUSH_BIT);
 		ratelimit = (msglen & GOSSIP_STORE_LEN_RATELIMIT_BIT);
+		zombie = (msglen & GOSSIP_STORE_LEN_ZOMBIE_BIT);
 
 		msglen &= GOSSIP_STORE_LEN_MASK;
 		msg = tal_arr(NULL, u8, msglen);
@@ -83,10 +84,11 @@ int main(int argc, char *argv[])
 		    != crc32c(be32_to_cpu(hdr.timestamp), msg, msglen))
 			warnx("Checksum verification failed");
 
-		printf("%zu: %s%s%s", off,
+		printf("%zu: %s%s%s%s", off,
 		       deleted ? "DELETED " : "",
 		       push ? "PUSH " : "",
-		       ratelimit ? "RATE-LIMITED " : "");
+		       ratelimit ? "RATE-LIMITED " : "",
+		       zombie ? "ZOMBIE " : "");
 		if (print_timestamp)
 			printf("T=%u ", be32_to_cpu(hdr.timestamp));
 		if (deleted && !print_deleted) {

gossipd/gossip_store.c

@@ -17,8 +17,8 @@
 #include <wire/peer_wire.h>
 
 #define GOSSIP_STORE_TEMP_FILENAME "gossip_store.tmp"
-/* We write it as major version 0, minor version 11 */
-#define GOSSIP_STORE_VER ((0 << 5) | 11)
+/* We write it as major version 0, minor version 12 */
+#define GOSSIP_STORE_VER ((0 << 5) | 12)
 
 struct gossip_store {
 	/* This is false when we're loading */
@@ -73,7 +73,7 @@ static ssize_t gossip_pwritev(int fd, const struct iovec *iov, int iovcnt,
 #endif /* !HAVE_PWRITEV */
 
 static bool append_msg(int fd, const u8 *msg, u32 timestamp,
-		       bool push, bool spam, u64 *len)
+		       bool push, bool zombie, bool spam, u64 *len)
 {
 	struct gossip_hdr hdr;
 	u32 msglen;
@@ -88,6 +88,8 @@ static bool append_msg(int fd, const u8 *msg, u32 timestamp,
 		hdr.len |= CPU_TO_BE32(GOSSIP_STORE_LEN_PUSH_BIT);
 	if (spam)
 		hdr.len |= CPU_TO_BE32(GOSSIP_STORE_LEN_RATELIMIT_BIT);
+	if (zombie)
+		hdr.len |= CPU_TO_BE32(GOSSIP_STORE_LEN_ZOMBIE_BIT);
 	hdr.crc = cpu_to_be32(crc32c(timestamp, msg, msglen));
 	hdr.timestamp = cpu_to_be32(timestamp);
 
@@ -248,7 +250,7 @@ static u32 gossip_store_compact_offline(struct routing_state *rstate)
 	oldlen = lseek(old_fd, SEEK_END, 0);
 	newlen = lseek(new_fd, SEEK_END, 0);
 	append_msg(old_fd, towire_gossip_store_ended(tmpctx, newlen),
-		   0, true, false, &oldlen);
+		   0, true, false, false, &oldlen);
 	close(old_fd);
 	status_debug("gossip_store_compact_offline: %zu deleted, %zu copied",
 		     deleted, count);
@@ -530,7 +532,7 @@ bool gossip_store_compact(struct gossip_store *gs)
 
 	/* Write end marker now new one is ready */
 	append_msg(gs->fd, towire_gossip_store_ended(tmpctx, len),
-		   0, true, false, &gs->len);
+		   0, true, false, false, &gs->len);
 
 	gs->count = count;
 	gs->deleted = 0;
@@ -550,20 +552,20 @@ bool gossip_store_compact(struct gossip_store *gs)
 }
 
 u64 gossip_store_add(struct gossip_store *gs, const u8 *gossip_msg,
-		     u32 timestamp, bool push,
+		     u32 timestamp, bool push, bool zombie,
 		     bool spam, const u8 *addendum)
 {
 	u64 off = gs->len;
 
 	/* Should never get here during loading! */
 	assert(gs->writable);
 
-	if (!append_msg(gs->fd, gossip_msg, timestamp, push, spam, &gs->len)) {
+	if (!append_msg(gs->fd, gossip_msg, timestamp, push, zombie, spam, &gs->len)) {
 		status_broken("Failed writing to gossip store: %s",
 			      strerror(errno));
 		return 0;
 	}
-	if (addendum && !append_msg(gs->fd, addendum, 0, false, false, &gs->len)) {
+	if (addendum && !append_msg(gs->fd, addendum, 0, false, false, false, &gs->len)) {
 		status_broken("Failed writing addendum to gossip store: %s",
 			      strerror(errno));
 		return 0;
@@ -580,7 +582,7 @@ u64 gossip_store_add_private_update(struct gossip_store *gs, const u8 *update)
 	/* A local update for an unannounced channel: not broadcastable, but
 	 * otherwise the same as a normal channel_update */
 	const u8 *pupdate = towire_gossip_store_private_update(tmpctx, update);
-	return gossip_store_add(gs, pupdate, 0, false, false, NULL);
+	return gossip_store_add(gs, pupdate, 0, false, false, false, NULL);
 }
 
 /* Returns index of following entry. */
@@ -640,7 +642,7 @@ void gossip_store_mark_channel_deleted(struct gossip_store *gs,
 				       const struct short_channel_id *scid)
 {
 	gossip_store_add(gs, towire_gossip_store_delete_chan(tmpctx, scid),
-			 0, false, false, NULL);
+			 0, false, false, false, NULL);
 }
 
 const u8 *gossip_store_get(const tal_t *ctx,

gossipd/gossip_store.h

@@ -41,11 +41,13 @@ u64 gossip_store_add_private_update(struct gossip_store *gs, const u8 *update);
  * @timestamp: the timestamp for filtering of this messsage.
  * @push: true if this should be sent to peers despite any timestamp filters.
  * @spam: true if this message is rate-limited and squelched to peers.
+ * @zombie: true if this channel is missing a current channel_update.
  * @addendum: another message to append immediately after this
  *            (for appending amounts to channel_announcements for internal use).
  */
 u64 gossip_store_add(struct gossip_store *gs, const u8 *gossip_msg,
-		     u32 timestamp, bool push, bool spam, const u8 *addendum);
+		     u32 timestamp, bool push, bool zombie, bool spam,
+		     const u8 *addendum);
 
 
 /**

gossipd/routing.c

@@ -1797,7 +1797,7 @@ bool routing_add_node_announcement(struct routing_state *rstate,
 			= gossip_store_add(rstate->gs, msg, timestamp,
 					   node_id_eq(&node_id,
 						      &rstate->local_id),
-					   spam, NULL);
+					   false, spam, NULL);
 		if (node->bcast.timestamp > rstate->last_timestamp
 		    && node->bcast.timestamp < time_now().ts.tv_sec)
 			rstate->last_timestamp = node->bcast.timestamp;
@@ -2025,7 +2025,8 @@ bool routing_add_private_channel(struct routing_state *rstate,
 		u8 *msg = towire_gossip_store_private_channel(tmpctx,
 							      capacity,
 							      chan_ann);
-		index = gossip_store_add(rstate->gs, msg, 0, false, false, NULL);
+		index = gossip_store_add(rstate->gs, msg, 0, false, false,
+					 false, NULL);
 	}
 	chan->bcast.index = index;
 	return true;
@@ -2170,7 +2171,7 @@ void routing_channel_spent(struct routing_state *rstate,
 
 	/* Save to gossip_store in case we restart */
 	msg = towire_gossip_store_chan_dying(tmpctx, &chan->scid, deadline);
-	index = gossip_store_add(rstate->gs, msg, 0, false, false, NULL);
+	index = gossip_store_add(rstate->gs, msg, 0, false, false, false, NULL);
 
 	/* Remember locally so we can kill it in 12 blocks */
 	status_debug("channel %s closing soon due"

gossipd/test/run-check_channel_announcement.c

@@ -61,7 +61,8 @@ bool cupdate_different(struct gossip_store *gs UNNEEDED,
 { fprintf(stderr, "cupdate_different called!\n"); abort(); }
 /* Generated stub for gossip_store_add */
 u64 gossip_store_add(struct gossip_store *gs UNNEEDED, const u8 *gossip_msg UNNEEDED,
-		     u32 timestamp UNNEEDED, bool push UNNEEDED, bool spam UNNEEDED, const u8 *addendum UNNEEDED)
+		     u32 timestamp UNNEEDED, bool push UNNEEDED, bool zombie UNNEEDED, bool spam UNNEEDED,
+		     const u8 *addendum UNNEEDED)
 { fprintf(stderr, "gossip_store_add called!\n"); abort(); }
 /* Generated stub for gossip_store_add_private_update */
 u64 gossip_store_add_private_update(struct gossip_store *gs UNNEEDED, const u8 *update UNNEEDED)

gossipd/test/run-txout_failure.c

@@ -32,7 +32,8 @@ bool cupdate_different(struct gossip_store *gs UNNEEDED,
 { fprintf(stderr, "cupdate_different called!\n"); abort(); }
 /* Generated stub for gossip_store_add */
 u64 gossip_store_add(struct gossip_store *gs UNNEEDED, const u8 *gossip_msg UNNEEDED,
-		     u32 timestamp UNNEEDED, bool push UNNEEDED, bool spam UNNEEDED, const u8 *addendum UNNEEDED)
+		     u32 timestamp UNNEEDED, bool push UNNEEDED, bool zombie UNNEEDED, bool spam UNNEEDED,
+		     const u8 *addendum UNNEEDED)
 { fprintf(stderr, "gossip_store_add called!\n"); abort(); }
 /* Generated stub for gossip_store_add_private_update */
 u64 gossip_store_add_private_update(struct gossip_store *gs UNNEEDED, const u8 *update UNNEEDED)

tests/test_gossip.py

@@ -1159,7 +1159,7 @@ def test_gossip_store_load(node_factory):
     """Make sure we can read canned gossip store"""
     l1 = node_factory.get_node(start=False)
     with open(os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, 'gossip_store'), 'wb') as f:
-        f.write(bytearray.fromhex("0a"        # GOSSIP_STORE_VERSION
+        f.write(bytearray.fromhex("0c"        # GOSSIP_STORE_VERSION
                                   "000001b0"  # len
                                   "fea676e8"  # csum
                                   "5b8d9b44"  # timestamp
@@ -1217,7 +1217,7 @@ def test_gossip_store_load_announce_before_update(node_factory):
     """Make sure we can read canned gossip store with node_announce before update.  This happens when a channel_update gets replaced, leaving node_announce before it"""
     l1 = node_factory.get_node(start=False)
     with open(os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, 'gossip_store'), 'wb') as f:
-        f.write(bytearray.fromhex("0a"        # GOSSIP_STORE_VERSION
+        f.write(bytearray.fromhex("0c"        # GOSSIP_STORE_VERSION
                                   "000001b0"  # len
                                   "fea676e8"  # csum
                                   "5b8d9b44"  # timestamp
@@ -1262,7 +1262,7 @@ def test_gossip_store_load_amount_truncated(node_factory):
     """Make sure we can read canned gossip store with truncated amount"""
     l1 = node_factory.get_node(start=False, allow_broken_log=True)
     with open(os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, 'gossip_store'), 'wb') as f:
-        f.write(bytearray.fromhex("0a"        # GOSSIP_STORE_VERSION
+        f.write(bytearray.fromhex("0c"        # GOSSIP_STORE_VERSION
                                   "000001b0"  # len
                                   "fea676e8"  # csum
                                   "5b8d9b44"  # timestamp
@@ -1727,7 +1727,7 @@ def test_gossip_store_load_no_channel_update(node_factory):
 
     # A channel announcement with no channel_update.
     with open(os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, 'gossip_store'), 'wb') as f:
-        f.write(bytearray.fromhex("0b"        # GOSSIP_STORE_VERSION
+        f.write(bytearray.fromhex("0c"        # GOSSIP_STORE_VERSION
                                   "000001b0"  # len
                                   "fea676e8"  # csum
                                   "5b8d9b44"  # timestamp
@@ -1754,7 +1754,7 @@ def test_gossip_store_load_no_channel_update(node_factory):
     l1.rpc.call('dev-compact-gossip-store')
 
     with open(os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, 'gossip_store'), "rb") as f:
-        assert bytearray(f.read()) == bytearray.fromhex("0b")
+        assert bytearray(f.read()) == bytearray.fromhex("0c")
 
 
 @pytest.mark.developer("gossip without DEVELOPER=1 is slow")