Merge #12392: Fix ignoring tx data requests when fPauseSend is set on a peer

c4af738 Fix ignoring tx data requests when fPauseSend is set on a peer (Matt Corallo)

Pull request description:

  This resolves a bug introduced in
  66aa1d58a1 where, if when responding
  to a series of transaction requests in a getdata we hit the send
  buffer limit and set fPauseSend, we will skip one transaction per
  call to ProcessGetData.

  Bug found by Cory Fields (@theuni).

  Probably worth slipping into 0.16 :/.

Tree-SHA512: a9313cef8ac6da31eb099c9925c8401a638220cf7bc9b7b7b83151ecae4b02630f2db45ef6668302b9bb0f38571afbd764993427f1ec9e4d74d9a3be6647d299

src/net_processing.cpp

@@ -1226,10 +1226,10 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
         }
     } // release cs_main
 
-    if (it != pfrom->vRecvGetData.end()) {
+    if (it != pfrom->vRecvGetData.end() && !pfrom->fPauseSend) {
         const CInv &inv = *it;
-        it++;
         if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK || inv.type == MSG_CMPCT_BLOCK || inv.type == MSG_WITNESS_BLOCK) {
+            it++;
             ProcessGetBlockData(pfrom, consensusParams, inv, connman, interruptMsgProc);
         }
     }