Limit response to getblocks to half of output buffer size

Introduce SendBufferSize() and ReceiveBufferSize(), and limit
the blocks sent as response to the "getblocks" message to
half of the active send buffer size.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 54902e82eb..699bee2d35 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2040,20 +2040,24 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         if (pindex)
             pindex = pindex->pnext;
         int nLimit = 500 + locator.GetDistanceBack();
+        unsigned int nBytes = 0;
         printf("getblocks %d to %s limit %d\n", (pindex ? pindex->nHeight : -1), hashStop.ToString().substr(0,20).c_str(), nLimit);
         for (; pindex; pindex = pindex->pnext)
         {
             if (pindex->GetBlockHash() == hashStop)
             {
-                printf("  getblocks stopping at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str());
+                printf("  getblocks stopping at %d %s (%u bytes)\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str(), nBytes);
                 break;
             }
             pfrom->PushInventory(CInv(MSG_BLOCK, pindex->GetBlockHash()));
-            if (--nLimit <= 0)
+            CBlock block;
+            block.ReadFromDisk(pindex, true);
+            nBytes += block.GetSerializeSize(SER_NETWORK);
+            if (--nLimit <= 0 || nBytes >= SendBufferSize()/2)
             {
                 // When this block is requested, we'll send an inv that'll make them
                 // getblocks the next batch of inventory.
-                printf("  getblocks stopping at limit %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str());
+                printf("  getblocks stopping at limit %d %s (%u bytes)\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str(), nBytes);
                 pfrom->hashContinue = pindex->GetBlockHash();
                 break;
             }