From 1111b80df84aa7bc72fbddcc7bafde43f0835d90 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 28 May 2016 15:32:30 +0200
Subject: Rework addnode behaviour

* Use CNode::addeName to track whether a connection to a name is already open
  * A new connection to a previously-connected by-name addednode is only opened when
    the previous one closes (even if the name starts resolving to something else)
  * At most one connection is opened per addednode (even if the name resolves to multiple)
* Unify the code between ThreadOpenAddedNodeConnections and getaddednodeinfo
  * Information about open connections is always returned, and the dns argument becomes a dummy
  * An IP address and inbound/outbound is only reported for the (at most 1) open connection
---
 src/net.cpp | 107 +++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 59 insertions(+), 48 deletions(-)

(limited to 'src/net.cpp')

diff --git a/src/net.cpp b/src/net.cpp
index a390eca776..4d27db7604 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1616,68 +1616,79 @@ void ThreadOpenConnections()
     }
 }
 
-void ThreadOpenAddedConnections()
+std::vector<AddedNodeInfo> GetAddedNodeInfo()
 {
+    std::vector<AddedNodeInfo> ret;
+
+    std::list<std::string> lAddresses(0);
     {
         LOCK(cs_vAddedNodes);
-        vAddedNodes = mapMultiArgs["-addnode"];
+        ret.reserve(vAddedNodes.size());
+        BOOST_FOREACH(const std::string& strAddNode, vAddedNodes)
+            lAddresses.push_back(strAddNode);
     }
 
-    if (HaveNameProxy()) {
-        while(true) {
-            std::list<std::string> lAddresses(0);
-            {
-                LOCK(cs_vAddedNodes);
-                BOOST_FOREACH(const std::string& strAddNode, vAddedNodes)
-                    lAddresses.push_back(strAddNode);
+
+    // Build a map of all already connected addresses (by IP:port and by name) to inbound/outbound and resolved CService
+    std::map<CService, bool> mapConnected;
+    std::map<std::string, std::pair<bool, CService>> mapConnectedByName;
+    {
+        LOCK(cs_vNodes);
+        for (const CNode* pnode : vNodes) {
+            if (pnode->addr.IsValid()) {
+                mapConnected[pnode->addr] = pnode->fInbound;
             }
-            BOOST_FOREACH(const std::string& strAddNode, lAddresses) {
-                CAddress addr;
-                CSemaphoreGrant grant(*semOutbound);
-                OpenNetworkConnection(addr, false, &grant, strAddNode.c_str());
-                MilliSleep(500);
+            if (!pnode->addrName.empty()) {
+                mapConnectedByName[pnode->addrName] = std::make_pair(pnode->fInbound, static_cast<const CService&>(pnode->addr));
             }
-            MilliSleep(120000); // Retry every 2 minutes
         }
     }
 
+    BOOST_FOREACH(const std::string& strAddNode, lAddresses) {
+        CService service(strAddNode, Params().GetDefaultPort());
+        if (service.IsValid()) {
+            // strAddNode is an IP:port
+            auto it = mapConnected.find(service);
+            if (it != mapConnected.end()) {
+                ret.push_back(AddedNodeInfo{strAddNode, service, true, it->second});
+            } else {
+                ret.push_back(AddedNodeInfo{strAddNode, CService(), false, false});
+            }
+        } else {
+            // strAddNode is a name
+            auto it = mapConnectedByName.find(strAddNode);
+            if (it != mapConnectedByName.end()) {
+                ret.push_back(AddedNodeInfo{strAddNode, it->second.second, true, it->second.first});
+            } else {
+                ret.push_back(AddedNodeInfo{strAddNode, CService(), false, false});
+            }
+        }
+    }
+
+    return ret;
+}
+
+void ThreadOpenAddedConnections()
+{
+    {
+        LOCK(cs_vAddedNodes);
+        vAddedNodes = mapMultiArgs["-addnode"];
+    }
+
     for (unsigned int i = 0; true; i++)
     {
-        std::list<std::string> lAddresses(0);
-        {
-            LOCK(cs_vAddedNodes);
-            BOOST_FOREACH(const std::string& strAddNode, vAddedNodes)
-                lAddresses.push_back(strAddNode);
+        std::vector<AddedNodeInfo> vInfo = GetAddedNodeInfo();
+        for (const AddedNodeInfo& info : vInfo) {
+            if (!info.fConnected) {
+                CSemaphoreGrant grant(*semOutbound);
+                // If strAddedNode is an IP/port, decode it immediately, so
+                // OpenNetworkConnection can detect existing connections to that IP/port.
+                CService service(info.strAddedNode, Params().GetDefaultPort());
+                OpenNetworkConnection(CAddress(service, NODE_NONE), false, &grant, info.strAddedNode.c_str(), false);
+                MilliSleep(500);
+            }
         }
 
-        std::list<std::vector<CService> > lservAddressesToAdd(0);
-        BOOST_FOREACH(const std::string& strAddNode, lAddresses) {
-            std::vector<CService> vservNode(0);
-            if(Lookup(strAddNode.c_str(), vservNode, Params().GetDefaultPort(), fNameLookup, 0))
-                lservAddressesToAdd.push_back(vservNode);
-        }
-        // Attempt to connect to each IP for each addnode entry until at least one is successful per addnode entry
-        // (keeping in mind that addnode entries can have many IPs if fNameLookup)
-        {
-            LOCK(cs_vNodes);
-            BOOST_FOREACH(CNode* pnode, vNodes)
-                for (std::list<std::vector<CService> >::iterator it = lservAddressesToAdd.begin(); it != lservAddressesToAdd.end(); it++)
-                    BOOST_FOREACH(const CService& addrNode, *(it))
-                        if (pnode->addr == addrNode)
-                        {
-                            it = lservAddressesToAdd.erase(it);
-                            it--;
-                            break;
-                        }
-        }
-        BOOST_FOREACH(std::vector<CService>& vserv, lservAddressesToAdd)
-        {
-            CSemaphoreGrant grant(*semOutbound);
-            /* We want -addnode to work even for nodes that don't provide all
-             * wanted services, so pass in nServices=NODE_NONE to CAddress. */
-            OpenNetworkConnection(CAddress(vserv[i % vserv.size()], NODE_NONE), false, &grant);
-            MilliSleep(500);
-        }
         MilliSleep(120000); // Retry every 2 minutes
     }
 }
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