Port -txsend from str4d #37, https://github.com/zcash/zcash/pull/4522

src/init.cpp

@@ -392,6 +392,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-sysperms", _("Create new files with system default permissions, instead of umask 077 (only effective with disabled wallet functionality)"));
 #endif
     strUsage += HelpMessageOpt("-txindex", strprintf(_("Maintain a full transaction index, used by the getrawtransaction rpc call (default: %u)"), 0));
+    strUsage += HelpMessageOpt("-txsend=<cmd>", _("Execute command to send a transaction instead of broadcasting (%s in cmd is replaced by transaction hex)"));
     strUsage += HelpMessageOpt("-addressindex", strprintf(_("Maintain a full address index, used to query for the balance, txids and unspent outputs for addresses (default: %u)"), DEFAULT_ADDRESSINDEX));
     strUsage += HelpMessageOpt("-timestampindex", strprintf(_("Maintain a timestamp index for block hashes, used to query blocks hashes by a range of timestamps (default: %u)"), DEFAULT_TIMESTAMPINDEX));
     strUsage += HelpMessageOpt("-spentindex", strprintf(_("Maintain a full spent index, used to query the spending txid and input index for an outpoint (default: %u)"), DEFAULT_SPENTINDEX));
@@ -1118,6 +1119,16 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 #endif
     }
 
+      if (mapArgs.count("-txsend")) {
+        if (GetBoolArg("-walletbroadcast", true))  {
+            if (SoftSetBoolArg("-walletbroadcast", false)) {
+                LogPrintf("%s: parameter interaction: -txsend=<cmd> -> setting -walletbroadcast=0\n", __func__);
+            } else {
+                return InitError(_("Wallet transaction broadcasting is incompatible with -txsend (for privacy)."));
+            }
+        }
+    }
+
     // ********************************************************* Step 3: parameter-to-internal-flags
 
     fZdebug=GetBoolArg("-zdebug", false);

src/rpc/rawtransaction.cpp

@@ -45,7 +45,10 @@
 
 #include <stdint.h>
 
+#include <boost/algorithm/string/replace.hpp>
+
 #include <boost/assign/list_of.hpp>
+#include <boost/thread.hpp>
 
 #include <univalue.h>
 
@@ -1373,6 +1376,19 @@ UniValue sendrawtransaction(const UniValue& params, bool fHelp, const CPubKey& m
         const CCoins* existingCoins = view.AccessCoins(hashTx);
         bool fHaveMempool = mempool.exists(hashTx);
         bool fHaveChain = existingCoins && existingCoins->nHeight < 1000000000;
+
+    // If we are configured to send transactions via an
+    // external service instead of broadcasting, do that
+    std::string strCmd = GetArg("-txsend", "");
+    if (!strCmd.empty()) {
+        if (fHaveChain) {
+            throw JSONRPCError(RPC_TRANSACTION_ALREADY_IN_CHAIN, "transaction already in block chain");
+        }
+        boost::replace_all(strCmd, "%s", EncodeHexTx(tx));
+        boost::thread t(runCommand, strCmd); // thread runs free
+        // Return here so we don't add to our mempool or broadcast to peers
+        return hashTx.GetHex();
+    }
         if (!fHaveMempool && !fHaveChain) {
             // push to local node and sync with wallets
             CValidationState state;

src/wallet/wallet.cpp

@@ -3950,6 +3950,8 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey)
         // Track how many getdata requests our transaction gets
         mapRequestCount[wtxNew.GetHash()] = 0;
 
+        std::string strCmd = GetArg("-txsend", "");
+
         if (fBroadcastTransactions)
         {
             // Broadcast
@@ -3962,6 +3964,12 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey)
             }
             wtxNew.RelayWalletTransaction();
         }
+           // If we are configured to send transactions via an
+        // external service instead of broadcasting, do that
+        else if (!strCmd.empty()) {
+            boost::replace_all(strCmd, "%s", EncodeHexTx(wtxNew));
+            boost::thread t(runCommand, strCmd); // thread runs free
+        }
     }
     return true;
 }