Restarted test node from wedged state @ +/- few seconds Wed Feb 26 21:42:58 CDT 2020 

Few blocks behind this time from head ... Currently have 619153, head is at 619158

Have 8 connections.

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Code changes:

Here are the code changes that I've compiled in this time -- this time, we go back
to everything as it was, except now we're going to check the SendBufferSize _BEFORE_
we push a message.  

mod6@localhost ~/trb-keccak $ vdiff a b
diff -uNr a/bitcoin/src/main.cpp b/bitcoin/src/main.cpp
--- a/bitcoin/src/main.cpp 1f0735d2cee2f9ca2a177aead4ecc7a1371d59c4375aedb172ee99c28b02fa28e664decec9580a510bfca4738d85e377fb74396fe4979b75adbe1a3ec92b01c9
+++ b/bitcoin/src/main.cpp 31ed2548f3101eb843c379da067cdd869542f6d9681bbe2fe4a89cd4a663fd2fd61178939fea88ed7f0711ba4bdef078d1588864db592652c7aa19ae42eaab6f
@@ -1877,6 +1877,7 @@
             return error("message getdata size() = %d", vInv.size());
         }

+        unsigned int nBytes = 0;
         BOOST_FOREACH(const CInv& inv, vInv)
         {
             if (fShutdown)
@@ -1891,6 +1892,13 @@
                 {
                     CBlock block;
                     block.ReadFromDisk((*mi).second);
+                    nBytes += block.GetSerializeSize(SER_NETWORK);
+                    if (nBytes >= SendBufferSize())
+                    {
+                        printf("getdata stopping at %u bytes\n", nBytes);
+                        pfrom->Misbehaving(100);
+                        break;
+                    }
                     pfrom->PushMessage("block", block);

                     // Trigger them to send a getblocks request for the next batch of inventory
@@ -1913,7 +1921,16 @@
                 {
                     map<CInv, CDataStream>::iterator mi = mapRelay.find(inv);
                     if (mi != mapRelay.end())
+                    {
+                        //nBytes += ((*mi).second).GetSerializeSize(SER_NETWORK);
+                        //if (nBytes >= SendBufferSize())
+                        //{
+                        //    printf("getdata stopping at %u bytes\n", nBytes);
+                        //    pfrom->Misbehaving(100);
+                        //    break;
+                        //}
                         pfrom->PushMessage(inv.GetCommand(), (*mi).second);
+                    }
                 }
             }
             else



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Test 5:  Send 49999 'getdata for block' commands to the node, see how it reacts and if
it recovers.  Host, Port, File = 127.0.0.1, 8333, snap_49999.txt

mod6@localhost ~ $ ./wedger.py 127.0.0.1 8333 snap_49999.txt 
<INCOMING MESSAGE: 'version', 115 bytes>
Alive: V=99999 (/therealbitcoin.org:0.9.99.99/) Jumpers=0x1 (TRB-Compat.) Return Addr=1.2.3.4:8333 Blocks=619153
<INCOMING MESSAGE: 'verack', 0 bytes>
Sending 1799991-byte message packet...
Now listening for replies (Ctl-C to quit...)
<INCOMING MESSAGE: 'getblocks', 1029 bytes>
<INCOMING MESSAGE: 'block', 978262 bytes>
<INCOMING MESSAGE: 'block', 974661 bytes>
Violated BTC Protocol: Invalid payload length!


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In the debug.log after all of the request spam:

mod6@localhost ~ $ grep "getdata stopping" ~/.bitcoin/debug.log
getdata stopping at 10724811 bytes

Bang.  Now we have it.  We just hang up if you request more than 10Mb.  And bonus they also get banhammered.

Next part will be to figure out the tx part.