Add NODE_NETWORK_LIMITED flags and min block amount constants

Author: jonasschnelli

src/protocol.h

@@ -246,9 +246,8 @@ const std::vector<std::string> &getAllNetMessageTypes();
 enum ServiceFlags : uint64_t {
     // Nothing
     NODE_NONE = 0,
-    // NODE_NETWORK means that the node is capable of serving the block chain. It is currently
-    // set by all Bitcoin Core nodes, and is unset by SPV clients or other peers that just want
-    // network services but don't provide them.
+    // NODE_NETWORK means that the node is capable of serving the complete block chain. It is currently
+    // set by all Bitcoin Core non pruned nodes, and is unset by SPV clients or other light clients.
     NODE_NETWORK = (1 << 0),
     // NODE_GETUTXO means the node is capable of responding to the getutxo protocol request.
     // Bitcoin Core does not support this but a patch set called Bitcoin XT does.
@@ -264,6 +263,10 @@ enum ServiceFlags : uint64_t {
     // NODE_XTHIN means the node supports Xtreme Thinblocks
     // If this is turned off then the node will not service nor make xthin requests
     NODE_XTHIN = (1 << 4),
+    // NODE_NETWORK_LIMITED means the same as NODE_NETWORK with the limitation of only
+    // serving the last 288 (2 day) blocks
+    // See BIP159 for details on how this is implemented.
+    NODE_NETWORK_LIMITED = (1 << 10),
 
     // Bits 24-31 are reserved for temporary experiments. Just pick a bit that
     // isn't getting used, or one not being used much, and notify the

src/validation.h

@@ -203,6 +203,8 @@ extern bool fPruneMode;
 extern uint64_t nPruneTarget;
 /** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of chainActive.Tip() will not be pruned. */
 static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
+/** Minimum blocks required to signal NODE_NETWORK_LIMITED */
+static const unsigned int NODE_NETWORK_LIMITED_MIN_BLOCKS = 288;
 
 static const signed int DEFAULT_CHECKBLOCKS = 6;
 static const unsigned int DEFAULT_CHECKLEVEL = 3;