Limited relaying/storing of foreign addresses

Introduce a boolean variable for each "network" (ipv4, ipv6, tor, i2p),
and track whether we are likely to able to connect to it. Addresses in
"addr" messages outside of our network get limited relaying and are not
stored in addrman.

Author: sipa

src/main.cpp

@@ -2418,6 +2418,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         }
 
         // Store the new addresses
+        vector<CAddress> vAddrOk;
         int64 nNow = GetAdjustedTime();
         int64 nSince = nNow - 10 * 60;
         BOOST_FOREACH(CAddress& addr, vAddr)
@@ -2427,6 +2428,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
             if (addr.nTime <= 100000000 || addr.nTime > nNow + 10 * 60)
                 addr.nTime = nNow - 5 * 24 * 60 * 60;
             pfrom->AddAddressKnown(addr);
+            bool fReachable = IsReachable(addr);
             if (addr.nTime > nSince && !pfrom->fGetAddr && vAddr.size() <= 10 && addr.IsRoutable())
             {
                 // Relay to a limited number of other nodes
@@ -2451,13 +2453,16 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
                         hashKey = Hash(BEGIN(hashKey), END(hashKey));
                         mapMix.insert(make_pair(hashKey, pnode));
                     }
-                    int nRelayNodes = 2;
+                    int nRelayNodes = fReachable ? 2 : 1; // limited relaying of addresses outside our network(s)
                     for (multimap<uint256, CNode*>::iterator mi = mapMix.begin(); mi != mapMix.end() && nRelayNodes-- > 0; ++mi)
                         ((*mi).second)->PushAddress(addr);
                 }
             }
+            // Do not store addresses outside our network
+            if (fReachable)
+                vAddrOk.push_back(addr);
         }
-        addrman.Add(vAddr, pfrom->addr, 2 * 60 * 60);
+        addrman.Add(vAddrOk, pfrom->addr, 2 * 60 * 60);
         if (vAddr.size() < 1000)
             pfrom->fGetAddr = false;
         if (pfrom->fOneShot)

src/net.cpp

@@ -45,8 +45,9 @@ bool OpenNetworkConnection(const CAddress& addrConnect, const char *strDest = NU
 bool fClient = false;
 static bool fUseUPnP = false;
 uint64 nLocalServices = (fClient ? 0 : NODE_NETWORK);
-CCriticalSection cs_mapLocalHost;
-map<CNetAddr, int> mapLocalHost;
+static CCriticalSection cs_mapLocalHost;
+static map<CNetAddr, int> mapLocalHost;
+static bool vfReachable[NET_MAX] = {};
 static CNode* pnodeLocalHost = NULL;
 uint64 nLocalHostNonce = 0;
 array<int, THREAD_MAX> vnThreadsRunning;
@@ -214,6 +215,9 @@ bool AddLocal(const CNetAddr& addr, int nScore)
     {
         LOCK(cs_mapLocalHost);
         mapLocalHost[addr] = std::max(nScore, mapLocalHost[addr]) + (mapLocalHost.count(addr) ? 1 : 0);
+        enum Network net = addr.GetNetwork();
+        vfReachable[net] = true;
+        if (net == NET_IPV6) vfReachable[NET_IPV4] = true;
     }
 
     AdvertizeLocal();
@@ -243,6 +247,12 @@ bool IsLocal(const CNetAddr& addr)
     return mapLocalHost.count(addr) > 0;
 }
 
+// check whether a given address is in a network we can probably connect to
+bool IsReachable(const CNetAddr& addr)
+{
+    LOCK(cs_mapLocalHost);
+    return vfReachable[addr.GetNetwork()];
+}
 
 bool GetMyExternalIP2(const CService& addrConnect, const char* pszGet, const char* pszKeyword, CNetAddr& ipRet)
 {

src/net.h

@@ -58,8 +58,10 @@ bool AddLocal(const CNetAddr& addr, int nScore = LOCAL_NONE);
 bool SeenLocal(const CNetAddr& addr);
 bool IsLocal(const CNetAddr& addr);
 bool GetLocal(CNetAddr &addr, const CNetAddr *paddrPeer = NULL);
+bool IsReachable(const CNetAddr &addr);
 CAddress GetLocalAddress(const CNetAddr *paddrPeer = NULL);
 
+
 enum
 {
     MSG_TX = 1,

src/netbase.cpp

@@ -25,6 +25,14 @@ int nConnectTimeout = 5000;
 
 static const unsigned char pchIPv4[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff };
 
+enum Network ParseNetwork(std::string net) {
+    if (net == "ipv4") return NET_IPV4;
+    if (net == "ipv6") return NET_IPV6;
+    if (net == "tor")  return NET_TOR;
+    if (net == "i2p")  return NET_I2P;
+    return NET_UNROUTABLE;
+}
+
 bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsigned int nMaxSolutions, bool fAllowLookup)
 {
     vIP.clear();
@@ -688,6 +696,23 @@ bool CNetAddr::IsRoutable() const
     return IsValid() && !(IsRFC1918() || IsRFC3927() || IsRFC4862() || (IsRFC4193() && !IsOnionCat() && !IsGarliCat()) || IsRFC4843() || IsLocal());
 }
 
+enum Network CNetAddr::GetNetwork() const
+{
+    if (!IsRoutable())
+        return NET_UNROUTABLE;
+
+    if (IsIPv4())
+        return NET_IPV4;
+
+    if (IsOnionCat())
+        return NET_TOR;
+
+    if (IsGarliCat())
+        return NET_I2P;
+
+    return NET_IPV6;
+}
+
 std::string CNetAddr::ToStringIP() const
 {
     if (IsIPv4())

src/netbase.h

@@ -17,6 +17,19 @@ extern int nConnectTimeout;
 #undef SetPort
 #endif
 
+enum Network
+{
+    NET_UNROUTABLE,
+    NET_IPV4,
+    NET_IPV6,
+    NET_TOR,
+    NET_I2P,
+
+    NET_MAX
+};
+
+enum Network ParseNetwork(std::string net);
+
 /** IP address (IPv6, or IPv4 using mapped IPv6 range (::FFFF:0:0/96)) */
 class CNetAddr
 {
@@ -48,6 +61,7 @@ class CNetAddr
         bool IsRoutable() const;
         bool IsValid() const;
         bool IsMulticast() const;
+        enum Network GetNetwork() const;
         std::string ToString() const;
         std::string ToStringIP() const;
         int GetByte(int n) const;