Replace several network protocol version numbers with named constants

stored in version.h.

Also, a minor CAddress code reformat while we're in there, fixing
some incorrect indentation.

src/main.cpp

@@ -2185,7 +2185,7 @@ 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
@@ -2235,7 +2235,7 @@ 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;
@@ -2252,7 +2252,8 @@ 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++;
@@ -2294,7 +2295,7 @@ 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)
         {
@@ -2331,7 +2332,7 @@ 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));

src/net.h

@@ -163,8 +163,8 @@ public:
         hSocket = hSocketIn;
         vSend.SetType(SER_NETWORK);
         vRecv.SetType(SER_NETWORK);
-        vSend.SetVersion(209);
+        vSend.SetVersion(MIN_PROTO_VERSION);
-        vRecv.SetVersion(209);
+        vRecv.SetVersion(MIN_PROTO_VERSION);
         nLastSend = 0;
         nLastRecv = 0;
         nLastSendEmpty = GetTime();

src/protocol.h

@@ -79,9 +79,10 @@ class CAddress : public CService
              if (fRead)
                  pthis->Init();
              if (nType & SER_DISK)
-             READWRITE(nVersion);
+                 READWRITE(nVersion);
-             if ((nType & SER_DISK) || (nVersion >= 31402 && !(nType & SER_GETHASH)))
+             if ((nType & SER_DISK) ||
-             READWRITE(nTime);
+                 (nVersion >= CADDR_TIME_VERSION && !(nType & SER_GETHASH)))
+                 READWRITE(nTime);
              READWRITE(nServices);
              READWRITE(*pip);
             )

src/version.h

@@ -31,6 +31,17 @@ extern const std::string CLIENT_DATE;
 
 static const int PROTOCOL_VERSION = 60000;
 
+// earlier versions not supported as of Feb 2012, and are disconnected
+static const int MIN_PROTO_VERSION = 209;
+
+// nTime field added to CAddress, starting with this version;
+// if possible, avoid requesting addresses nodes older than this
+static const int CADDR_TIME_VERSION = 31402;
+
+// only request blocks from nodes outside this range of versions
+static const int NOBLKS_VERSION_START = 32000;
+static const int NOBLKS_VERSION_END = 32400;
+
 // BIP 0031, pong message, is enabled for all versions AFTER this one
 static const int BIP0031_VERSION = 60000;