Merge #10387: Eventually connect to NODE_NETWORK_LIMITED peers

eb91835 Add setter for g_initial_block_download_completed (Jonas Schnelli)
3f56df5 [QA] add NODE_NETWORK_LIMITED address relay and sync test (Jonas Schnelli)
158e1a6 [QA] fix mininode CAddress ser/deser (Jonas Schnelli)
fa999af [QA] Allow addrman loopback tests (add debug option -addrmantest) (Jonas Schnelli)
6fe57bd Connect to peers signaling NODE_NETWORK_LIMITED when out-of-IBD (Jonas Schnelli)
31c45a9 Accept addresses with NODE_NETWORK_LIMITED flag (Jonas Schnelli)

Pull request description:

  Eventually connect to peers signalling NODE_NETWORK_LIMITED if we are out of IBD.
  Accept and relay NODE_NETWORK_LIMITED peers in addrman.

Tree-SHA512: 8a238fc97f767f81cae1866d6cc061390f23a72af4a711d2f7158c77f876017986abb371d213d1c84019eef7be4ca951e8e6f83fda36769c4e1a1d763f787037

6 files changed, 38 insertions, 9 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 1cc5c5f9c7..47bcdf2294 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -448,6 +448,7 @@ std::string HelpMessage(HelpMessageMode mode)
         strUsage += HelpMessageOpt("-limitdescendantcount=<n>", strprintf("Do not accept transactions if any ancestor would have <n> or more in-mempool descendants (default: %u)", DEFAULT_DESCENDANT_LIMIT));
         strUsage += HelpMessageOpt("-limitdescendantsize=<n>", strprintf("Do not accept transactions if any ancestor would have more than <n> kilobytes of in-mempool descendants (default: %u).", DEFAULT_DESCENDANT_SIZE_LIMIT));
         strUsage += HelpMessageOpt("-vbparams=deployment:start:end", "Use given start/end times for specified version bits deployment (regtest-only)");
+        strUsage += HelpMessageOpt("-addrmantest", "Allows to test address relay on localhost");
     }
     strUsage += HelpMessageOpt("-debug=<category>", strprintf(_("Output debugging information (default: %u, supplying <category> is optional)"), 0) + ". " +
         _("If <category> is not supplied or if <category> = 1, output all debugging information.") + " " + _("<category> can be:") + " " + ListLogCategories() + ".");
diff --git a/src/net.cpp b/src/net.cpp
index 201914685c..c7c19f83a1 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -181,6 +181,10 @@ void AdvertiseLocal(CNode *pnode)
     if (fListen && pnode->fSuccessfullyConnected)
     {
         CAddress addrLocal = GetLocalAddress(&pnode->addr, pnode->GetLocalServices());
+        if (gArgs.GetBoolArg("-addrmantest", false)) {
+            // use IPv4 loopback during addrmantest
+            addrLocal = CAddress(CService(LookupNumeric("127.0.0.1", GetListenPort())), pnode->GetLocalServices());
+        }
         // If discovery is enabled, sometimes give our peer the address it
         // tells us that it sees us as in case it has a better idea of our
         // address than we do.
@@ -189,7 +193,7 @@ void AdvertiseLocal(CNode *pnode)
         {
             addrLocal.SetIP(pnode->GetAddrLocal());
         }
-        if (addrLocal.IsRoutable())
+        if (addrLocal.IsRoutable() || gArgs.GetBoolArg("-addrmantest", false))
         {
             LogPrint(BCLog::NET, "AdvertiseLocal: advertising address %s\n", addrLocal.ToString());
             FastRandomContext insecure_rand;
@@ -2718,6 +2722,7 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
     fOneShot = false;
     m_manual_connection = false;
     fClient = false; // set by version message
+    m_limited_node = false; // set by version message
     fFeeler = false;
     fSuccessfullyConnected = false;
     fDisconnect = false;
diff --git a/src/net.h b/src/net.h
index 8378a303b8..96f04d83e0 100644
--- a/src/net.h
+++ b/src/net.h
@@ -641,6 +641,7 @@ public:
     bool fOneShot;
     bool m_manual_connection;
     bool fClient;
+    bool m_limited_node; //after BIP159
     const bool fInbound;
     std::atomic_bool fSuccessfullyConnected;
     std::atomic_bool fDisconnect;
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index bf9307727a..ddf0dbbbea 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -892,6 +892,7 @@ void PeerLogicValidation::UpdatedBlockTip(const CBlockIndex *pindexNew, const CB
     const int nNewHeight = pindexNew->nHeight;
     connman->SetBestHeight(nNewHeight);
 
+    SetServiceFlagsIBDCache(!fInitialDownload);
     if (!fInitialDownload) {
         // Find the hashes of all blocks that weren't previously in the best chain.
         std::vector<uint256> vHashes;
@@ -1642,7 +1643,13 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             pfrom->cleanSubVer = cleanSubVer;
         }
         pfrom->nStartingHeight = nStartingHeight;
-        pfrom->fClient = !(nServices & NODE_NETWORK);
+
+        // set nodes not relaying blocks and tx and not serving (parts) of the historical blockchain as "clients"
+        pfrom->fClient = (!(nServices & NODE_NETWORK) && !(nServices & NODE_NETWORK_LIMITED));
+
+        // set nodes not capable of serving the complete blockchain history as "limited nodes"
+        pfrom->m_limited_node = (!(nServices & NODE_NETWORK) && (nServices & NODE_NETWORK_LIMITED));
+
         {
             LOCK(pfrom->cs_filter);
             pfrom->fRelayTxes = fRelay; // set to true after we get the first filter* message
@@ -1801,7 +1808,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             // 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))
+            if (!MayHaveUsefulAddressDB(addr.nServices) && !HasAllDesirableServiceFlags(addr.nServices))
                 continue;
 
             if (addr.nTime <= 100000000 || addr.nTime > nNow + 10 * 60)
@@ -3611,7 +3618,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto, std::atomic<bool>& interruptM
         // Message: getdata (blocks)
         //
         std::vector<CInv> vGetData;
-        if (!pto->fClient && (fFetch || !IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
+        if (!pto->fClient && ((fFetch && !pto->m_limited_node) || !IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
             std::vector<const CBlockIndex*> vToDownload;
             NodeId staller = -1;
             FindNextBlocksToDownload(pto->GetId(), MAX_BLOCKS_IN_TRANSIT_PER_PEER - state.nBlocksInFlight, vToDownload, staller, consensusParams);
diff --git a/src/protocol.cpp b/src/protocol.cpp
index c412ad9ffe..2ec26fbd3e 100644
--- a/src/protocol.cpp
+++ b/src/protocol.cpp
@@ -12,6 +12,8 @@
 # include <arpa/inet.h>
 #endif
 
+static std::atomic<bool> g_initial_block_download_completed(false);
+
 namespace NetMsgType {
 const char *VERSION="version";
 const char *VERACK="verack";
@@ -127,6 +129,17 @@ bool CMessageHeader::IsValid(const MessageStartChars& pchMessageStartIn) const
 }
 
 
+ServiceFlags GetDesirableServiceFlags(ServiceFlags services) {
+    if ((services & NODE_NETWORK_LIMITED) && g_initial_block_download_completed) {
+        return ServiceFlags(NODE_NETWORK_LIMITED | NODE_WITNESS);
+    }
+    return ServiceFlags(NODE_NETWORK | NODE_WITNESS);
+}
+
+void SetServiceFlagsIBDCache(bool state) {
+    g_initial_block_download_completed = state;
+}
+
 
 CAddress::CAddress() : CService()
 {
diff --git a/src/protocol.h b/src/protocol.h
index 42eb57e4f0..e518d11944 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -15,6 +15,7 @@
 #include <uint256.h>
 #include <version.h>
 
+#include <atomic>
 #include <stdint.h>
 #include <string>
 
@@ -301,9 +302,10 @@ enum ServiceFlags : uint64_t {
  * If the NODE_NONE return value is changed, contrib/seeds/makeseeds.py
  * should be updated appropriately to filter for the same nodes.
  */
-static ServiceFlags GetDesirableServiceFlags(ServiceFlags services) {
-    return ServiceFlags(NODE_NETWORK | NODE_WITNESS);
-}
+ServiceFlags GetDesirableServiceFlags(ServiceFlags services);
+
+/** Set the current IBD status in order to figure out the desirable service flags */
+void SetServiceFlagsIBDCache(bool status);
 
 /**
  * A shortcut for (services & GetDesirableServiceFlags(services))
@@ -316,10 +318,10 @@ static inline bool HasAllDesirableServiceFlags(ServiceFlags services) {
 
 /**
  * Checks if a peer with the given service flags may be capable of having a
- * robust address-storage DB. Currently an alias for checking NODE_NETWORK.
+ * robust address-storage DB.
  */
 static inline bool MayHaveUsefulAddressDB(ServiceFlags services) {
-    return services & NODE_NETWORK;
+    return (services & NODE_NETWORK) || (services & NODE_NETWORK_LIMITED);
 }
 
 /** A CService with information about it as peer */