Introduce -maxuploadtarget

* -maxuploadtarget can be set in MiB
* if <limit> - ( time-left-in-24h-cycle / 600 * MAX_BLOCK_SIZE ) has reach, stop serve blocks older than one week and filtered blocks
* no action if limit has reached, no guarantee that the target will not be  surpassed
* add outbound limit informations to rpc getnettotals

src/net.h

@@ -400,6 +400,12 @@ private:
     static uint64_t nTotalBytesRecv;
     static uint64_t nTotalBytesSent;
 
+    // outbound limit & stats
+    static uint64_t nMaxOutboundTotalBytesSentInCycle;
+    static uint64_t nMaxOutboundCycleStartTime;
+    static uint64_t nMaxOutboundLimit;
+    static uint64_t nMaxOutboundTimeframe;
+
     CNode(const CNode&);
     void operator=(const CNode&);
 
@@ -701,6 +707,27 @@ public:
 
     static uint64_t GetTotalBytesRecv();
     static uint64_t GetTotalBytesSent();
+
+    //!set the max outbound target in bytes
+    static void SetMaxOutboundTarget(uint64_t limit);
+    static uint64_t GetMaxOutboundTarget();
+
+    //!set the timeframe for the max outbound target
+    static void SetMaxOutboundTimeframe(uint64_t timeframe);
+    static uint64_t GetMaxOutboundTimeframe();
+
+    //!check if the outbound target is reached
+    // if param historicalBlockServingLimit is set true, the function will
+    // response true if the limit for serving historical blocks has been reached
+    static bool OutboundTargetReached(bool historicalBlockServingLimit);
+
+    //!response the bytes left in the current max outbound cycle
+    // in case of no limit, it will always response 0
+    static uint64_t GetOutboundTargetBytesLeft();
+
+    //!response the time in second left in the current max outbound cycle
+    // in case of no limit, it will always response 0
+    static uint64_t GetMaxOutboundTimeLeftInCycle();
 };