From 08f86a4db8dc3c76782a8a852204a789ace6c4cb Mon Sep 17 00:00:00 2001
From: Daira Hopwood <daira@jacaranda.org>
Date: Fri, 2 Dec 2022 23:02:10 +0000
Subject: [PATCH] Revert "Headers-first fix"

---
 src/main.cpp | 38 +-------------------------------------
 src/main.h   |  4 ----
 2 files changed, 1 insertion(+), 41 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 79dd69ec8..a4b8ffe81 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -332,8 +332,6 @@ struct CNodeState {
     CBlockIndex *pindexLastCommonBlock;
     //! Whether we've started headers synchronization with this peer.
     bool fSyncStarted;
-    //! When to potentially disconnect peer for stalling headers download
-    int64_t nHeadersSyncTimeout;
     //! Since when we're stalling block download progress (in microseconds), or 0.
     int64_t nStallingSince;
     list<QueuedBlock> vBlocksInFlight;
@@ -350,7 +348,6 @@ struct CNodeState {
         hashLastUnknownBlock.SetNull();
         pindexLastCommonBlock = NULL;
         fSyncStarted = false;
-        nHeadersSyncTimeout = 0;
         nStallingSince = 0;
         nBlocksInFlight = 0;
         nBlocksInFlightValidHeaders = 0;
@@ -517,7 +514,7 @@ void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<CBl
     // Make sure pindexBestKnownBlock is up to date, we'll need it.
     ProcessBlockAvailability(nodeid);
 
-    if (state->pindexBestKnownBlock == NULL || state->pindexBestKnownBlock->nChainWork < chainActive.Tip()->nChainWork || state->pindexBestKnownBlock->nChainWork < UintToArith256(Params().GetConsensus().nMinimumChainWork)) {
+    if (state->pindexBestKnownBlock == NULL || state->pindexBestKnownBlock->nChainWork < chainActive.Tip()->nChainWork) {
         // This peer has nothing interesting.
         return;
     }
@@ -7651,7 +7648,6 @@ bool SendMessages(const Consensus::Params& params, CNode* pto)
             // Only actively request headers from a single peer, unless we're close to today.
             if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetTime() - 24 * 60 * 60) {
                 state.fSyncStarted = true;
-                state.nHeadersSyncTimeout = GetTimeMicros() + HEADERS_DOWNLOAD_TIMEOUT_BASE + HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER * (EstimateNetHeight(params, pindexBestHeader->nHeight, pindexBestHeader->GetBlockTime()) - pindexBestHeader->nHeight);
                 nSyncStarted++;
                 const CBlockIndex *pindexStart = pindexBestHeader;
                 /* If possible, start at the block preceding the currently
@@ -7837,38 +7833,6 @@ bool SendMessages(const Consensus::Params& params, CNode* pto)
                 pto->fDisconnect = true;
             }
         }
-        // Check for headers sync timeouts
-        if (state.fSyncStarted && state.nHeadersSyncTimeout < std::numeric_limits<int64_t>::max()) {
-            // Detect whether this is a stalling initial-headers-sync peer
-            if (pindexBestHeader->GetBlockTime() <= GetTime() - 24*60*60) {
-                if (nNow > state.nHeadersSyncTimeout && nSyncStarted == 1 && (nPreferredDownload - state.fPreferredDownload >= 1)) {
-                    // Disconnect a (non-whitelisted) peer if it is our only sync peer,
-                    // and we have others we could be using instead.
-                    // Note: If all our peers are inbound, then we won't
-                    // disconnect our sync peer for stalling; we have bigger
-                    // problems if we can't get any outbound peers.
-                    if (!pto->fWhitelisted) {
-                        LogPrintf("Timeout downloading headers from peer=%d, disconnecting\n", pto->GetId());
-                        pto->fDisconnect = true;
-                        return true;
-                    } else {
-                        LogPrintf("Timeout downloading headers from whitelisted peer=%d, not disconnecting\n", pto->GetId());
-                        // Reset the headers sync state so that we have a
-                        // chance to try downloading from a different peer.
-                        // Note: this will also result in at least one more
-                        // getheaders message to be sent to
-                        // this peer (eventually).
-                        state.fSyncStarted = false;
-                        nSyncStarted--;
-                        state.nHeadersSyncTimeout = 0;
-                    }
-                }
-            } else {
-                // After we've caught up once, reset the timeout so we can't trigger
-                // disconnect later.
-                state.nHeadersSyncTimeout = std::numeric_limits<int64_t>::max();
-            }
-        }
 
         //
         // Message: getdata (blocks)
diff --git a/src/main.h b/src/main.h
index 5b57baad5..0034a4969 100644
--- a/src/main.h
+++ b/src/main.h
@@ -98,10 +98,6 @@ static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
 static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
 /** Timeout in seconds during which a peer must stall block download progress before being disconnected. */
 static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
-/** Headers download timeout expressed in microseconds
- *  Timeout = base + per_header * (expected number of headers) */
-static constexpr int64_t HEADERS_DOWNLOAD_TIMEOUT_BASE = 30 * 60 * 1000000; // 30 minutes
-static constexpr int64_t HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER = 10000; // 10 ms/header
 /** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
  *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
 static const unsigned int MAX_HEADERS_RESULTS = 160;