1 files changed, 36 insertions, 23 deletions

diff --git a/src/net.cpp b/src/net.cpp
index f294e4c667..abc492e2b9 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -877,6 +877,14 @@ public:
     }
 };
 
+/** Try to find a connection to evict when the node is full.
+ *  Extreme care must be taken to avoid opening the node to attacker
+ *   triggered network partitioning.
+ *  The strategy used here is to protect a small number of peers
+ *   for each of several distinct characteristics which are difficult
+ *   to forge.  In order to partition a node the attacker must be
+ *   simultaneously better at all of them than honest peers.
+ */
 static bool AttemptToEvictConnection(bool fPreferNewConnection) {
     std::vector<CNodeRef> vEvictionCandidates;
     {
@@ -905,7 +913,7 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
 
     if (vEvictionCandidates.empty()) return false;
 
-    // Protect the 8 nodes with the best ping times.
+    // Protect the 8 nodes with the lowest minimum ping time.
     // An attacker cannot manipulate this metric without physically moving nodes closer to the target.
     std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), ReverseCompareNodeMinPingTime);
     vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(8, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());
@@ -913,7 +921,7 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
     if (vEvictionCandidates.empty()) return false;
 
     // Protect the half of the remaining nodes which have been connected the longest.
-    // This replicates the existing implicit behavior.
+    // This replicates the non-eviction implicit behavior, and precludes attacks that start later.
     std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), ReverseCompareNodeTimeConnected);
     vEvictionCandidates.erase(vEvictionCandidates.end() - static_cast<int>(vEvictionCandidates.size() / 2), vEvictionCandidates.end());
 
@@ -941,6 +949,7 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
     vEvictionCandidates = mapAddrCounts[naMostConnections];
 
     // Do not disconnect peers if there is only one unprotected connection from their network group.
+    // This step excessively favors netgroup diversity, and should be removed once more protective criteria are established.
     if (vEvictionCandidates.size() <= 1)
         // unless we prefer the new connection (for whitelisted peers)
         if (!fPreferNewConnection)
@@ -1443,7 +1452,7 @@ void ThreadDNSAddressSeed()
         } else {
             vector<CNetAddr> vIPs;
             vector<CAddress> vAdd;
-            if (LookupHost(seed.host.c_str(), vIPs))
+            if (LookupHost(seed.host.c_str(), vIPs, 0, true))
             {
                 BOOST_FOREACH(const CNetAddr& ip, vIPs)
                 {
@@ -1454,7 +1463,15 @@ void ThreadDNSAddressSeed()
                     found++;
                 }
             }
-            addrman.Add(vAdd, CNetAddr(seed.name, true));
+            // TODO: The seed name resolve may fail, yielding an IP of [::], which results in
+            // addrman assigning the same source to results from different seeds.
+            // This should switch to a hard-coded stable dummy IP for each seed name, so that the
+            // resolve is not required at all.
+            if (!vIPs.empty()) {
+                CService seedSource;
+                Lookup(seed.name.c_str(), seedSource, 0, true);
+                addrman.Add(vAdd, seedSource);
+            }
         }
     }
 
@@ -1712,7 +1729,6 @@ void ThreadMessageHandler()
     boost::mutex condition_mutex;
     boost::unique_lock<boost::mutex> lock(condition_mutex);
 
-    SetThreadPriority(THREAD_PRIORITY_BELOW_NORMAL);
     while (true)
     {
         vector<CNode*> vNodesCopy;
@@ -1884,7 +1900,7 @@ void static Discover(boost::thread_group& threadGroup)
     if (gethostname(pszHostName, sizeof(pszHostName)) != SOCKET_ERROR)
     {
         vector<CNetAddr> vaddr;
-        if (LookupHost(pszHostName, vaddr))
+        if (LookupHost(pszHostName, vaddr, 0, true))
         {
             BOOST_FOREACH (const CNetAddr &addr, vaddr)
             {
@@ -1934,6 +1950,7 @@ void StartNode(boost::thread_group& threadGroup, CScheduler& scheduler)
         if (adb.Read(addrman))
             LogPrintf("Loaded %i addresses from peers.dat  %dms\n", addrman.size(), GetTimeMillis() - nStart);
         else {
+            addrman.Clear(); // Addrman can be in an inconsistent state after failure, reset it
             LogPrintf("Invalid or missing peers.dat; recreating\n");
             DumpAddresses();
         }
@@ -2053,7 +2070,7 @@ public:
 instance_of_cnetcleanup;
 
 
-void RelayTransaction(const CTransaction& tx, CFeeRate feerate)
+void RelayTransaction(const CTransaction& tx)
 {
     CInv inv(MSG_TX, tx.GetHash());
     {
@@ -2071,20 +2088,7 @@ void RelayTransaction(const CTransaction& tx, CFeeRate feerate)
     LOCK(cs_vNodes);
     BOOST_FOREACH(CNode* pnode, vNodes)
     {
-        if(!pnode->fRelayTxes)
-            continue;
-        {
-            LOCK(pnode->cs_feeFilter);
-            if (feerate.GetFeePerK() < pnode->minFeeFilter)
-                continue;
-        }
-        LOCK(pnode->cs_filter);
-        if (pnode->pfilter)
-        {
-            if (pnode->pfilter->IsRelevantAndUpdate(tx))
-                pnode->PushInventory(inv);
-        } else
-            pnode->PushInventory(inv);
+        pnode->PushInventory(inv);
     }
 }
 
@@ -2317,6 +2321,11 @@ bool CAddrDB::Read(CAddrMan& addr)
     if (hashIn != hashTmp)
         return error("%s: Checksum mismatch, data corrupted", __func__);
 
+    return Read(addr, ssPeers);
+}
+
+bool CAddrDB::Read(CAddrMan& addr, CDataStream& ssPeers)
+{
     unsigned char pchMsgTmp[4];
     try {
         // de-serialize file header (network specific magic number) and ..
@@ -2330,6 +2339,8 @@ bool CAddrDB::Read(CAddrMan& addr)
         ssPeers >> addr;
     }
     catch (const std::exception& e) {
+        // de-serialization has failed, ensure addrman is left in a clean state
+        addr.Clear();
         return error("%s: Deserialize or I/O error - %s", __func__, e.what());
     }
 
@@ -2370,6 +2381,7 @@ CNode::CNode(SOCKET hSocketIn, const CAddress& addrIn, const std::string& addrNa
     hashContinue = uint256();
     nStartingHeight = -1;
     filterInventoryKnown.reset();
+    fSendMempool = false;
     fGetAddr = false;
     nNextLocalAddrSend = 0;
     nNextAddrSend = 0;
@@ -2626,9 +2638,10 @@ void DumpBanlist()
 
     CBanDB bandb;
     banmap_t banmap;
+    CNode::SetBannedSetDirty(false);
     CNode::GetBanned(banmap);
-    if (bandb.Write(banmap))
-        CNode::SetBannedSetDirty(false);
+    if (!bandb.Write(banmap))
+        CNode::SetBannedSetDirty(true);
 
     LogPrint("net", "Flushed %d banned node ips/subnets to banlist.dat  %dms\n",
         banmap.size(), GetTimeMillis() - nStart);