more addr message error checking

-- version 0.2.11

main.cpp

@@ -1926,7 +1926,9 @@ bool ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
     {
         vector<CAddress> vAddr;
         vRecv >> vAddr;
-        if (vAddr.size() > 50000) // lower this to 1000 later
+        if (pfrom->nVersion < 200) // don't want addresses from 0.1.5
+            return true;
+        if (vAddr.size() > 1000)
             return error("message addr size() = %d", vAddr.size());
 
         // Store the new addresses
@@ -2311,6 +2313,7 @@ bool SendMessages(CNode* pto, bool fSendTrickle)
                 if (pto->setAddrKnown.insert(addr).second)
                 {
                     vAddr.push_back(addr);
+                    // receiver rejects addr messages larger than 1000
                     if (vAddr.size() >= 1000)
                     {
                         pto->PushMessage("addr", vAddr);

net.cpp

@@ -968,9 +968,9 @@ bool OpenNetworkConnection(const CAddress& addrConnect)
     if (addrLocalHost.IsRoutable() && !fUseProxy)
     {
         // Advertise our address
-        vector<CAddress> vAddrToSend;
-        vAddrToSend.push_back(addrLocalHost);
-        pnode->PushMessage("addr", vAddrToSend);
+        vector<CAddress> vAddr;
+        vAddr.push_back(addrLocalHost);
+        pnode->PushMessage("addr", vAddr);
     }
 
     // Get as many addresses as we can

net.h

@@ -289,16 +289,24 @@ public:
 
     bool IsRoutable() const
     {
-        return !(GetByte(3) == 10 ||
+        return IsValid() &&
+            !(GetByte(3) == 10 ||
               (GetByte(3) == 192 && GetByte(2) == 168) ||
               GetByte(3) == 127 ||
-                 GetByte(3) == 0 ||
-                 ip == 0 ||
-                 ip == INADDR_NONE);
+              GetByte(3) == 0);
     }
 
     bool IsValid() const
     {
+        // Clean up 3-byte shifted addresses caused by garbage in size field
+        // of addr messages from versions before 0.2.9 checksum.
+        // Two consecutive addr messages look like this:
+        // header20 vectorlen3 addr26 addr26 addr26 header20 vectorlen3 addr26 addr26 addr26...
+        // so if the first length field is garbled, it reads the second batch
+        // of addr misaligned by 3 bytes.
+        if (memcmp(pchReserved, pchIPv4+3, sizeof(pchIPv4)-3) == 0)
+            return false;
+
         return (ip != 0 && ip != INADDR_NONE && port != htons(USHRT_MAX));
     }
 
@@ -619,7 +627,7 @@ public:
         // Known checking here is only to save space from duplicates.
         // SendMessages will filter it again for knowns that were added
         // after addresses were pushed.
-        if (!setAddrKnown.count(addr))
+        if (addr.IsValid() && !setAddrKnown.count(addr))
             vAddrToSend.push_back(addr);
     }
 

serialize.h

@@ -19,7 +19,7 @@ class CScript;
 class CDataStream;
 class CAutoFile;
 
-static const int VERSION = 210;
+static const int VERSION = 211;
 static const char* pszSubVer = ".0";