Limit CNode::mapAskFor

Tighten resource constraints on CNode.

Rebased-From: d4168c8
Rebased-By: Wladimir J. van der Laan <laanwj@gmail.com>

src/net.h

@@ -38,6 +38,8 @@ namespace boost {
 
 /** The maximum number of entries in an 'inv' protocol message */
 static const unsigned int MAX_INV_SZ = 50000;
+/** The maximum number of entries in mapAskFor */
+static const size_t MAPASKFOR_MAX_SZ = MAX_INV_SZ;
 
 inline unsigned int ReceiveFloodSize() { return 1000*GetArg("-maxreceivebuffer", 5*1000); }
 inline unsigned int SendBufferSize() { return 1000*GetArg("-maxsendbuffer", 1*1000); }
@@ -422,6 +424,9 @@ class CNode
 
     void AskFor(const CInv& inv)
     {
+        if (mapAskFor.size() > MAPASKFOR_MAX_SZ)
+            return;
+
         // We're using mapAskFor as a priority queue,
         // the key is the earliest time the request can be sent
         int64_t nRequestTime;