From 74cc14d9dec56e2147ff809a8dc073c6ff144e22 Mon Sep 17 00:00:00 2001
From: Nazar Mokrynskyi <nazar@mokrynskyi.com>
Date: Sun, 12 Nov 2023 03:56:27 +0200
Subject: [PATCH] Improve DSN sync security

---
 .../segment_header_downloader.rs              | 21 ++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/crates/subspace-service/src/sync_from_dsn/segment_header_downloader.rs b/crates/subspace-service/src/sync_from_dsn/segment_header_downloader.rs
index 69471860cd..78e442c93b 100644
--- a/crates/subspace-service/src/sync_from_dsn/segment_header_downloader.rs
+++ b/crates/subspace-service/src/sync_from_dsn/segment_header_downloader.rs
@@ -181,24 +181,35 @@ impl<'a> SegmentHeaderDownloader<'a> {
             let peer_count = peer_segment_headers.len();
 
             if peer_count < required_peers {
-                if last_peers_count == 0 || last_peers_count != peer_count {
+                // If we've got nothing, we have to retry
+                if last_peers_count == 0 {
                     debug!(
                         %peer_count,
                         %required_peers,
                         %retry_attempt,
-                        "Segment headers consensus requires more peers, will retry"
+                        "Segment headers consensus requires some peers, will retry"
                     );
 
                     continue;
-                } else {
+                }
+                // If number of peers found increased, but there are still attempts left, do more attempts
+                if last_peers_count != peer_count && required_peers > 1 {
                     debug!(
                         %peer_count,
                         %required_peers,
                         %retry_attempt,
-                        "Segment headers consensus requires more peers, but result is the same as \
-                        last time, so continue with what we've got"
+                        "Segment headers consensus requires more peers, will retry"
                     );
+
+                    continue;
                 }
+
+                debug!(
+                    %peer_count,
+                    %required_peers,
+                    %retry_attempt,
+                    "Segment headers consensus requires more peers, but no attempts left, so continue as is"
+                );
             }
 
             // Calculate votes