From 62a5183fb5de6ab1af682280f8473238cf9064fb Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Fri, 15 Jul 2022 15:29:26 +0930
Subject: [PATCH] common: add ability for gossip_store to track by timestamp.

We'll use this to keep a two-hour-ago "recent gossip offset" as an
optimization.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 common/gossip_store.c | 97 +++++++++++++++++++++++++++++++++++++++++--
 common/gossip_store.h |  6 +++
 2 files changed, 100 insertions(+), 3 deletions(-)

diff --git a/common/gossip_store.c b/common/gossip_store.c
index 2a0ade5ab..c4f167a3d 100644
--- a/common/gossip_store.c
+++ b/common/gossip_store.c
@@ -49,6 +49,64 @@ static size_t reopen_gossip_store(int *gossip_store_fd, const u8 *msg)
 	return equivalent_offset;
 }
 
+static bool public_msg_type(enum peer_wire type)
+{
+	/* This switch statement makes you think about new types as they
+	 * are introduced. */
+	switch (type) {
+	case WIRE_INIT:
+	case WIRE_ERROR:
+	case WIRE_WARNING:
+	case WIRE_PING:
+	case WIRE_PONG:
+	case WIRE_TX_ADD_INPUT:
+	case WIRE_TX_ADD_OUTPUT:
+	case WIRE_TX_REMOVE_INPUT:
+	case WIRE_TX_REMOVE_OUTPUT:
+	case WIRE_TX_COMPLETE:
+	case WIRE_TX_SIGNATURES:
+	case WIRE_OPEN_CHANNEL:
+	case WIRE_ACCEPT_CHANNEL:
+	case WIRE_FUNDING_CREATED:
+	case WIRE_FUNDING_SIGNED:
+	case WIRE_FUNDING_LOCKED:
+	case WIRE_OPEN_CHANNEL2:
+	case WIRE_ACCEPT_CHANNEL2:
+	case WIRE_INIT_RBF:
+	case WIRE_ACK_RBF:
+	case WIRE_SHUTDOWN:
+	case WIRE_CLOSING_SIGNED:
+	case WIRE_UPDATE_ADD_HTLC:
+	case WIRE_UPDATE_FULFILL_HTLC:
+	case WIRE_UPDATE_FAIL_HTLC:
+	case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+	case WIRE_COMMITMENT_SIGNED:
+	case WIRE_REVOKE_AND_ACK:
+	case WIRE_UPDATE_FEE:
+	case WIRE_UPDATE_BLOCKHEIGHT:
+	case WIRE_CHANNEL_REESTABLISH:
+	case WIRE_ANNOUNCEMENT_SIGNATURES:
+	case WIRE_QUERY_SHORT_CHANNEL_IDS:
+	case WIRE_REPLY_SHORT_CHANNEL_IDS_END:
+	case WIRE_QUERY_CHANNEL_RANGE:
+	case WIRE_REPLY_CHANNEL_RANGE:
+	case WIRE_GOSSIP_TIMESTAMP_FILTER:
+	case WIRE_OBS2_ONION_MESSAGE:
+	case WIRE_ONION_MESSAGE:
+#if EXPERIMENTAL_FEATURES
+	case WIRE_STFU:
+#endif
+		return false;
+	case WIRE_CHANNEL_ANNOUNCEMENT:
+	case WIRE_NODE_ANNOUNCEMENT:
+	case WIRE_CHANNEL_UPDATE:
+		return true;
+	}
+
+	/* Actually, we do have other (internal) messages. */
+	return false;
+}
+
 u8 *gossip_store_next(const tal_t *ctx,
 		      int *gossip_store_fd,
 		      u32 timestamp_min, u32 timestamp_max,
@@ -111,9 +169,7 @@ u8 *gossip_store_next(const tal_t *ctx,
 			*off = *end = reopen_gossip_store(gossip_store_fd, msg);
 			msg = tal_free(msg);
 		/* Ignore gossipd internal messages. */
-		} else if (type != WIRE_CHANNEL_ANNOUNCEMENT
-			   && type != WIRE_CHANNEL_UPDATE
-			   && type != WIRE_NODE_ANNOUNCEMENT) {
+		} else if (!public_msg_type(type)) {
 			msg = tal_free(msg);
 		} else if (!push && push_only) {
 			msg = tal_free(msg);
@@ -148,3 +204,38 @@ size_t find_gossip_store_end(int gossip_store_fd, size_t off)
 	}
 	return off;
 }
+
+/* Keep seeking forward until we hit something >= timestamp */
+size_t find_gossip_store_by_timestamp(int gossip_store_fd,
+				      size_t off,
+				      u32 timestamp)
+{
+	/* We cheat and read first two bytes of message too. */
+	struct {
+		struct gossip_hdr hdr;
+		be16 type;
+	} buf;
+	int r;
+
+	while ((r = pread(gossip_store_fd, &buf,
+			  sizeof(buf.hdr) + sizeof(buf.type), off))
+	       == sizeof(buf.hdr) + sizeof(buf.type)) {
+		u32 msglen = be32_to_cpu(buf.hdr.len) & GOSSIP_STORE_LEN_MASK;
+		u16 type = be16_to_cpu(buf.type);
+
+		/* Don't swallow end marker!  Reset, as they will call
+		 * gossip_store_next and reopen file. */
+		if (type == WIRE_GOSSIP_STORE_ENDED)
+			return 1;
+
+		/* Only to-be-broadcast types have valid timestamps! */
+		if (!(be32_to_cpu(buf.hdr.len) & GOSSIP_STORE_LEN_DELETED_BIT)
+		    && public_msg_type(type)
+		    && be32_to_cpu(buf.hdr.timestamp) >= timestamp) {
+			break;
+		}
+
+		off += sizeof(buf.hdr) + msglen;
+	}
+	return off;
+}
diff --git a/common/gossip_store.h b/common/gossip_store.h
index 136186e8e..c4f6f52bd 100644
--- a/common/gossip_store.h
+++ b/common/gossip_store.h
@@ -63,4 +63,10 @@ u8 *gossip_store_next(const tal_t *ctx,
  */
 size_t find_gossip_store_end(int gossip_store_fd, size_t old_end);
 
+/**
+ * Return offset of first entry >= this timestamp.
+ */
+size_t find_gossip_store_by_timestamp(int gossip_store_fd,
+				      size_t off,
+				      u32 timestamp);
 #endif /* LIGHTNING_COMMON_GOSSIP_STORE_H */