1 files changed, 18 insertions, 0 deletions
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 24d8d49c0c..87a3655307 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -2374,6 +2374,24 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                 }
             }
         }
+        // If we're in IBD, we want outbound peers that will serve us a useful
+        // chain. Disconnect peers that are on chains with insufficient work.
+        if (IsInitialBlockDownload() && nCount != MAX_HEADERS_RESULTS) {
+            // When nCount < MAX_HEADERS_RESULTS, we know we have no more
+            // headers to fetch from this peer.
+            if (nodestate->pindexBestKnownBlock && nodestate->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
+                // This peer has too little work on their headers chain to help
+                // us sync -- disconnect if using an outbound slot (unless
+                // whitelisted or addnode).
+                // Note: We compare their tip to nMinimumChainWork (rather than
+                // chainActive.Tip()) because we won't start block download
+                // until we have a headers chain that has at least
+                // nMinimumChainWork, even if a peer has a chain past our tip,
+                if (!(pfrom->fInbound || pfrom->fWhitelisted || pfrom->m_manual_connection)) {
+                    pfrom->fDisconnect = true;
+                }
+            }
+        }
         }
     }