Replace relevant services logic with a function suite.

Adds HasAllRelevantServices and GetRelevantServices, which check
for NETWORK|WITNESS.

This changes the following:
 * Removes nRelevantServices from CConnman, disconnecting it a bit
   more from protocol-level logic.
 * Replaces our sometimes-connect-to-!WITNESS-nodes logic with
   simply always requiring WITNESS|NETWORK for outbound non-feeler
   connections (feelers still only require NETWORK).
 * This has the added benefit of removing nServicesExpected from
   CNode - instead letting net_processing's VERSION message
   handling simply check HasAllRelevantServices.
 * This implies we believe WITNESS nodes to continue to be a
   significant majority of nodes on the network, but also because
   we cannot sync properly from !WITNESS nodes, it is strange to
   continue using our valuable outbound slots on them.
 * In order to prevent this change from preventing connection to
   -connect= nodes which have !WITNESS, -connect nodes are now
   given the "addnode" flag. This also allows outbound connections
   to !NODE_NETWORK nodes for -connect nodes (which was already true
   of addnodes).
 * Has the (somewhat unintended) consequence of changing one of the
   eviction metrics from the same
   sometimes-connect-to-!WITNESS-nodes metric to requiring
   HasRelevantServices.

This should make NODE_NETWORK_LIMITED much simpler to implement.

1 files changed, 7 insertions, 4 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 7fced41d4f..39cf989eea 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1232,11 +1232,11 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
         {
             connman->SetServices(pfrom->addr, nServices);
         }
-        if (pfrom->nServicesExpected & ~nServices)
+        if (!pfrom->fInbound && !pfrom->fFeeler && !pfrom->fAddnode && !HasAllDesirableServiceFlags(nServices))
         {
-            LogPrint(BCLog::NET, "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom->GetId(), nServices, pfrom->nServicesExpected);
+            LogPrint(BCLog::NET, "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom->GetId(), nServices, GetDesirableServiceFlags(nServices));
             connman->PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_NONSTANDARD,
-                               strprintf("Expected to offer services %08x", pfrom->nServicesExpected)));
+                               strprintf("Expected to offer services %08x", GetDesirableServiceFlags(nServices))));
             pfrom->fDisconnect = true;
             return false;
         }
@@ -1455,7 +1455,10 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             if (interruptMsgProc)
                 return true;
 
-            if ((addr.nServices & REQUIRED_SERVICES) != REQUIRED_SERVICES)
+            // We only bother storing full nodes, though this may include
+            // things which we would not make an outbound connection to, in
+            // part because we may make feeler connections to them.
+            if (!MayHaveUsefulAddressDB(addr.nServices))
                 continue;
 
             if (addr.nTime <= 100000000 || addr.nTime > nNow + 10 * 60)