Merge pull request #1081 from jgarzik/pong

BIP 0031: pong message

1 files changed, 31 insertions, 8 deletions

diff --git a/src/main.cpp b/src/main.cpp
index f2932804e3..11bcdc83fe 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2183,7 +2183,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         CAddress addrFrom;
         uint64 nNonce = 1;
         vRecv >> pfrom->nVersion >> pfrom->nServices >> nTime >> addrMe;
-        if (pfrom->nVersion < 209)
+        if (pfrom->nVersion < MIN_PROTO_VERSION)
         {
             // Since February 20, 2012, the protocol is initiated at version 209,
             // and earlier versions are no longer supported
@@ -2233,7 +2233,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
             }
 
             // Get recent addresses
-            if (pfrom->nVersion >= 31402 || addrman.size() < 1000)
+            if (pfrom->nVersion >= CADDR_TIME_VERSION || addrman.size() < 1000)
             {
                 pfrom->PushMessage("getaddr");
                 pfrom->fGetAddr = true;
@@ -2250,7 +2250,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         // Ask the first connected node for block updates
         static int nAskedForBlocks = 0;
         if (!pfrom->fClient &&
-            (pfrom->nVersion < 32000 || pfrom->nVersion >= 32400) &&
+            (pfrom->nVersion < NOBLKS_VERSION_START ||
+	     pfrom->nVersion >= NOBLKS_VERSION_END) &&
              (nAskedForBlocks < 1 || vNodes.size() <= 1))
         {
             nAskedForBlocks++;
@@ -2292,7 +2293,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         vRecv >> vAddr;
 
         // Don't want addr from older versions unless seeding
-        if (pfrom->nVersion < 31402 && addrman.size() > 1000)
+        if (pfrom->nVersion < CADDR_TIME_VERSION && addrman.size() > 1000)
             return true;
         if (vAddr.size() > 1000)
         {
@@ -2329,7 +2330,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
                     multimap<uint256, CNode*> mapMix;
                     BOOST_FOREACH(CNode* pnode, vNodes)
                     {
-                        if (pnode->nVersion < 31402)
+                        if (pnode->nVersion < CADDR_TIME_VERSION)
                             continue;
                         unsigned int nPointer;
                         memcpy(&nPointer, &pnode, sizeof(nPointer));
@@ -2651,6 +2652,23 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
 
     else if (strCommand == "ping")
     {
+        if (pfrom->nVersion > BIP0031_VERSION)
+        {
+            uint64 nonce = 0;
+            vRecv >> nonce;
+            // Echo the message back with the nonce. This allows for two useful features:
+            //
+            // 1) A remote node can quickly check if the connection is operational
+            // 2) Remote nodes can measure the latency of the network thread. If this node
+            //    is overloaded it won't respond to pings quickly and the remote node can
+            //    avoid sending us more work, like chain download requests.
+            //
+            // The nonce stops the remote getting confused between different pings: without
+            // it, if the remote node sends a ping once per second and this node takes 5
+            // seconds to respond to each, the 5th ping the remote sends would appear to
+            // return very quickly.
+            pfrom->PushMessage("pong", nonce);
+        }
     }
 
 
@@ -2813,9 +2831,14 @@ bool SendMessages(CNode* pto, bool fSendTrickle)
         if (pto->nVersion == 0)
             return true;
 
-        // Keep-alive ping
-        if (pto->nLastSend && GetTime() - pto->nLastSend > 30 * 60 && pto->vSend.empty())
-            pto->PushMessage("ping");
+        // Keep-alive ping. We send a nonce of zero because we don't use it anywhere 
+        // right now.
+        if (pto->nLastSend && GetTime() - pto->nLastSend > 30 * 60 && pto->vSend.empty()) {
+            if (pto->nVersion > BIP0031_VERSION)
+                pto->PushMessage("ping", 0);
+            else
+                pto->PushMessage("ping");
+        }
 
         // Resend wallet transactions that haven't gotten in a block yet
         ResendWalletTransactions();