1 files changed, 36 insertions, 6 deletions

diff --git a/src/net.cpp b/src/net.cpp
index 11638fcc02..b275bdd809 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -616,6 +616,7 @@ void CNode::copyStats(CNodeStats &stats)
     X(nVersion);
     X(cleanSubVer);
     X(fInbound);
+    X(fAddnode);
     X(nStartingHeight);
     X(nSendBytes);
     X(mapSendBytesPerMsgCmd);
@@ -1633,7 +1634,12 @@ void CConnman::ThreadOpenConnections()
         {
             LOCK(cs_vNodes);
             BOOST_FOREACH(CNode* pnode, vNodes) {
-                if (!pnode->fInbound) {
+                if (!pnode->fInbound && !pnode->fAddnode) {
+                    // Netgroups for inbound and addnode peers are not excluded because our goal here
+                    // is to not use multiple of our limited outbound slots on a single netgroup
+                    // but inbound and addnode peers do not use our outbound slots.  Inbound peers
+                    // also have the added issue that they're attacker controlled and could be used
+                    // to prevent us from connecting to particular hosts if we used them here.
                     setConnected.insert(pnode->addr.GetGroup());
                     nOutbound++;
                 }
@@ -1778,27 +1784,35 @@ void CConnman::ThreadOpenAddedConnections()
             vAddedNodes = mapMultiArgs.at("-addnode");
     }
 
-    for (unsigned int i = 0; true; i++)
+    while (true)
     {
+        CSemaphoreGrant grant(*semAddnode);
         std::vector<AddedNodeInfo> vInfo = GetAddedNodeInfo();
+        bool tried = false;
         for (const AddedNodeInfo& info : vInfo) {
             if (!info.fConnected) {
-                CSemaphoreGrant grant(*semOutbound);
+                if (!grant.TryAcquire()) {
+                    // If we've used up our semaphore and need a new one, lets not wait here since while we are waiting
+                    // the addednodeinfo state might change.
+                    break;
+                }
                 // If strAddedNode is an IP/port, decode it immediately, so
                 // OpenNetworkConnection can detect existing connections to that IP/port.
+                tried = true;
                 CService service(LookupNumeric(info.strAddedNode.c_str(), Params().GetDefaultPort()));
-                OpenNetworkConnection(CAddress(service, NODE_NONE), false, &grant, info.strAddedNode.c_str(), false);
+                OpenNetworkConnection(CAddress(service, NODE_NONE), false, &grant, info.strAddedNode.c_str(), false, false, true);
                 if (!interruptNet.sleep_for(std::chrono::milliseconds(500)))
                     return;
             }
         }
-        if (!interruptNet.sleep_for(std::chrono::minutes(2)))
+        // Retry every 60 seconds if a connection was attempted, otherwise two seconds
+        if (!interruptNet.sleep_for(std::chrono::seconds(tried ? 60 : 2)))
             return;
     }
 }
 
 // if successful, this moves the passed grant to the constructed node
-bool CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFailure, CSemaphoreGrant *grantOutbound, const char *pszDest, bool fOneShot, bool fFeeler)
+bool CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFailure, CSemaphoreGrant *grantOutbound, const char *pszDest, bool fOneShot, bool fFeeler, bool fAddnode)
 {
     //
     // Initiate outbound network connection
@@ -1827,6 +1841,8 @@ bool CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFai
         pnode->fOneShot = true;
     if (fFeeler)
         pnode->fFeeler = true;
+    if (fAddnode)
+        pnode->fAddnode = true;
 
     return true;
 }
@@ -2065,8 +2081,10 @@ CConnman::CConnman(uint64_t nSeed0In, uint64_t nSeed1In) : nSeed0(nSeed0In), nSe
     nSendBufferMaxSize = 0;
     nReceiveFloodSize = 0;
     semOutbound = NULL;
+    semAddnode = NULL;
     nMaxConnections = 0;
     nMaxOutbound = 0;
+    nMaxAddnode = 0;
     nBestHeight = 0;
     clientInterface = NULL;
     flagInterruptMsgProc = false;
@@ -2088,6 +2106,7 @@ bool CConnman::Start(CScheduler& scheduler, std::string& strNodeError, Options c
     nLocalServices = connOptions.nLocalServices;
     nMaxConnections = connOptions.nMaxConnections;
     nMaxOutbound = std::min((connOptions.nMaxOutbound), nMaxConnections);
+    nMaxAddnode = connOptions.nMaxAddnode;
     nMaxFeeler = connOptions.nMaxFeeler;
 
     nSendBufferMaxSize = connOptions.nSendBufferMaxSize;
@@ -2140,6 +2159,10 @@ bool CConnman::Start(CScheduler& scheduler, std::string& strNodeError, Options c
         // initialize semaphore
         semOutbound = new CSemaphore(std::min((nMaxOutbound + nMaxFeeler), nMaxConnections));
     }
+    if (semAddnode == NULL) {
+        // initialize semaphore
+        semAddnode = new CSemaphore(nMaxAddnode);
+    }
 
     //
     // Start threads
@@ -2221,6 +2244,10 @@ void CConnman::Stop()
     if (threadSocketHandler.joinable())
         threadSocketHandler.join();
 
+    if (semAddnode)
+        for (int i=0; i<nMaxAddnode; i++)
+            semOutbound->post();
+
     if (fAddressesInitialized)
     {
         DumpData();
@@ -2248,6 +2275,8 @@ void CConnman::Stop()
     vhListenSocket.clear();
     delete semOutbound;
     semOutbound = NULL;
+    delete semAddnode;
+    semAddnode = NULL;
 }
 
 void CConnman::DeleteNode(CNode* pnode)
@@ -2548,6 +2577,7 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
     strSubVer = "";
     fWhitelisted = false;
     fOneShot = false;
+    fAddnode = false;
     fClient = false; // set by version message
     fFeeler = false;
     fSuccessfullyConnected = false;