Add whitelistforcerelay to control forced relaying.

Also renames whitelistalwaysrelay.

Nodes relay all transactions from whitelisted peers, this
 gets in the way of some useful reasons for whitelisting
 peers-- for example, bypassing bandwidth limitations.

The purpose of this forced relaying is for specialized gateway
 applications where a node is being used as a P2P connection
 filter and multiplexer, but where you don't want it getting
 in the way of (re-)broadcast.

This change makes it configurable with whitelistforcerelay.

src/init.cpp

@@ -388,7 +388,8 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-whitebind=<addr>", _("Bind to given address and whitelist peers connecting to it. Use [host]:port notation for IPv6"));
     strUsage += HelpMessageOpt("-whitelist=<netmask>", _("Whitelist peers connecting from the given netmask or IP address. Can be specified multiple times.") +
         " " + _("Whitelisted peers cannot be DoS banned and their transactions are always relayed, even if they are already in the mempool, useful e.g. for a gateway"));
-    strUsage += HelpMessageOpt("-whitelistalwaysrelay", strprintf(_("Always relay transactions received from whitelisted peers (default: %d)"), DEFAULT_WHITELISTALWAYSRELAY));
+    strUsage += HelpMessageOpt("-whitelistrelay", strprintf(_("Accept relayed transactions received from whitelisted peers even when not relaying transactions (default: %d)"), DEFAULT_WHITELISTRELAY));
+    strUsage += HelpMessageOpt("-whitelistforcerelay", strprintf(_("Force relay of transactions from whitelisted peers even they violate local relay policy (default: %d)"), DEFAULT_WHITELISTFORCERELAY));
     strUsage += HelpMessageOpt("-maxuploadtarget=<n>", strprintf(_("Tries to keep outbound traffic under the given target (in MiB per 24h), 0 = no limit (default: %d)"), DEFAULT_MAX_UPLOAD_TARGET));
 
 #ifdef ENABLE_WALLET
@@ -752,13 +753,19 @@ void InitParameterInteraction()
 
     // disable walletbroadcast and whitelistalwaysrelay in blocksonly mode
     if (GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY)) {
-        if (SoftSetBoolArg("-whitelistalwaysrelay", false))
-            LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting -whitelistalwaysrelay=0\n", __func__);
+        if (SoftSetBoolArg("-whitelistrelay", false))
+            LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting -whitelistrelay=0\n", __func__);
 #ifdef ENABLE_WALLET
         if (SoftSetBoolArg("-walletbroadcast", false))
             LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting -walletbroadcast=0\n", __func__);
 #endif
     }
+
+    // Forcing relay from whitelisted hosts implies we will accept relays from them in the first place.
+    if (GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY)) {
+        if (SoftSetBoolArg("-whitelistrelay", true))
+            LogPrintf("%s: parameter interaction: -whitelistforcerelay=1 -> setting -whitelistrelay=1\n", __func__);
+    }
 }
 
 static std::string ResolveErrMsg(const char * const optname, const std::string& strBind)

src/main.cpp

@@ -4495,8 +4495,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
 
         bool fBlocksOnly = GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY);
 
-        // Allow whitelisted peers to send data other than blocks in blocks only mode if whitelistalwaysrelay is true
-        if (pfrom->fWhitelisted && GetBoolArg("-whitelistalwaysrelay", DEFAULT_WHITELISTALWAYSRELAY))
+        // Allow whitelisted peers to send data other than blocks in blocks only mode if whitelistrelay is true
+        if (pfrom->fWhitelisted && GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY))
             fBlocksOnly = false;
 
         LOCK(cs_main);
@@ -4675,8 +4675,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
     else if (strCommand == NetMsgType::TX)
     {
         // Stop processing the transaction early if
-        // We are in blocks only mode and peer is either not whitelisted or whitelistalwaysrelay is off
-        if (GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY) && (!pfrom->fWhitelisted || !GetBoolArg("-whitelistalwaysrelay", DEFAULT_WHITELISTALWAYSRELAY)))
+        // We are in blocks only mode and peer is either not whitelisted or whitelistrelay is off
+        if (GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY) && (!pfrom->fWhitelisted || !GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY)))
         {
             LogPrint("net", "transaction sent in violation of protocol peer=%d\n", pfrom->id);
             return true;
@@ -4776,7 +4776,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             assert(recentRejects);
             recentRejects->insert(tx.GetHash());
 
-            if (pfrom->fWhitelisted && GetBoolArg("-whitelistalwaysrelay", DEFAULT_WHITELISTALWAYSRELAY)) {
+            if (pfrom->fWhitelisted && GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY)) {
                 // Always relay transactions received from whitelisted peers, even
                 // if they were already in the mempool or rejected from it due
                 // to policy, allowing the node to function as a gateway for

src/main.h

@@ -42,8 +42,10 @@ struct CNodeStateStats;
 
 /** Default for accepting alerts from the P2P network. */
 static const bool DEFAULT_ALERTS = true;
-/** Default for DEFAULT_WHITELISTALWAYSRELAY. */
-static const bool DEFAULT_WHITELISTALWAYSRELAY = true;
+/** Default for DEFAULT_WHITELISTRELAY. */
+static const bool DEFAULT_WHITELISTRELAY = true;
+/** Default for DEFAULT_WHITELISTFORCERELAY. */
+static const bool DEFAULT_WHITELISTFORCERELAY = true;
 /** Default for -minrelaytxfee, minimum relay fee for transactions */
 static const unsigned int DEFAULT_MIN_RELAY_TX_FEE = 1000;
 /** Default for -maxorphantx, maximum number of orphan transactions kept in memory */