Fix duplicate initial headers sync

Author: UdjinM6

qa/rpc-tests/bip68-112-113-p2p.py

@@ -98,8 +98,9 @@ def __init__(self):
 
     def setup_network(self):
         # Must set the blockversion for this test
+        # Must also set '-maxtipage=600100' to allow syncing from very old blocks
         self.nodes = start_nodes(self.num_nodes, self.options.tmpdir,
-                                 extra_args=[['-debug', '-whitelist=127.0.0.1', '-blockversion=4']],
+                                 extra_args=[['-debug', '-whitelist=127.0.0.1', '-blockversion=4', '-maxtipage=600100']],
                                  binary=[self.options.testbinary])
 
     def run_test(self):

qa/rpc-tests/maxuploadtarget.py

@@ -91,7 +91,7 @@ def __init__(self):
     def setup_network(self):
         # Start a node with maxuploadtarget of 200 MB (/24h)
         self.nodes = []
-        self.nodes.append(start_node(0, self.options.tmpdir, ["-debug", "-maxuploadtarget=200", "-blockmaxsize=999000"]))
+        self.nodes.append(start_node(0, self.options.tmpdir, ["-debug", "-maxuploadtarget=200", "-blockmaxsize=999000", "-maxtipage="+str(2*60*60*24*7)]))
 
     def run_test(self):
         # Advance all nodes 2 weeks in the future
@@ -205,7 +205,7 @@ def run_test(self):
         #stop and start node 0 with 1MB maxuploadtarget, whitelist 127.0.0.1
         print("Restarting nodes with -whitelist=127.0.0.1")
         stop_node(self.nodes[0], 0)
-        self.nodes[0] = start_node(0, self.options.tmpdir, ["-debug", "-whitelist=127.0.0.1", "-maxuploadtarget=1", "-blockmaxsize=999000"])
+        self.nodes[0] = start_node(0, self.options.tmpdir, ["-debug", "-whitelist=127.0.0.1", "-maxuploadtarget=1", "-blockmaxsize=999000", "-maxtipage="+str(2*60*60*24*7)])
 
         #recreate/reconnect 3 test nodes
         test_nodes = []

src/net_processing.cpp

@@ -1682,7 +1682,24 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
 
             if (inv.type == MSG_BLOCK) {
                 UpdateBlockAvailability(pfrom->GetId(), inv.hash);
-                if (!fAlreadyHave && !fImporting && !fReindex && !mapBlocksInFlight.count(inv.hash)) {
+
+                if (fAlreadyHave || fImporting || fReindex || mapBlocksInFlight.count(inv.hash)) {
+                    continue;
+                }
+
+                CNodeState *state = State(pfrom->id);
+                if (!state) {
+                    continue;
+                }
+
+                // Download if this is a nice peer, or we have no nice peers and this one might do.
+                bool fFetch = state->fPreferredDownload || (nPreferredDownload == 0 && !pfrom->fOneShot);
+                // Only actively request headers from a single peer, unless we're close to end of initial download.
+                if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - nMaxTipAge) {
+                    // Make sure to mark this peer as the one we are currently syncing with etc.
+                    state->fSyncStarted = true;
+                    state->nHeadersSyncTimeout = GetTimeMicros() + HEADERS_DOWNLOAD_TIMEOUT_BASE + HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER * (GetAdjustedTime() - pindexBestHeader->GetBlockTime())/(chainparams.GetConsensus().nPowTargetSpacing);
+                    nSyncStarted++;
                     // We used to request the full block here, but since headers-announcements are now the
                     // primary method of announcement on the network, and since, in the case that a node
                     // fell back to inv we probably have a reorg which we should get the headers for first,
@@ -3099,7 +3116,7 @@ bool SendMessages(CNode* pto, CConnman& connman, const std::atomic<bool>& interr
         bool fFetch = state.fPreferredDownload || (nPreferredDownload == 0 && !pto->fClient && !pto->fOneShot); // Download if this is a nice peer, or we have no nice peers and this one might do.
         if (!state.fSyncStarted && !pto->fClient && !fImporting && !fReindex) {
             // Only actively request headers from a single peer, unless we're close to end of initial download.
-            if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - 6 * 60 * 60) { // NOTE: was "close to today" and 24h in Bitcoin
+            if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - nMaxTipAge) {
                 state.fSyncStarted = true;
                 state.nHeadersSyncTimeout = GetTimeMicros() + HEADERS_DOWNLOAD_TIMEOUT_BASE + HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER * (GetAdjustedTime() - pindexBestHeader->GetBlockTime())/(consensusParams.nPowTargetSpacing);
                 nSyncStarted++;
@@ -3418,7 +3435,7 @@ bool SendMessages(CNode* pto, CConnman& connman, const std::atomic<bool>& interr
         // 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() <= GetAdjustedTime() - 6*60*60) { // was 24*60*60 in bitcoin
+            if (pindexBestHeader->GetBlockTime() <= GetAdjustedTime() - nMaxTipAge) {
                 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.