Fix wallet RPC race by waiting for callbacks in sendrawtransaction

Author: TheBlueMatt

src/rpc/rawtransaction.cpp

@@ -11,6 +11,7 @@
 #include "init.h"
 #include "keystore.h"
 #include "validation.h"
+#include "validationinterface.h"
 #include "merkleblock.h"
 #include "net.h"
 #include "policy/policy.h"
@@ -30,6 +31,7 @@
 #include "wallet/wallet.h"
 #endif
 
+#include <future>
 #include <stdint.h>
 
 #include <univalue.h>
@@ -917,7 +919,9 @@ UniValue sendrawtransaction(const JSONRPCRequest& request)
         );
 
     ObserveSafeMode();
-    LOCK(cs_main);
+
+    std::promise<void> promise;
+
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VBOOL});
 
     // parse hex string from parameter
@@ -931,6 +935,8 @@ UniValue sendrawtransaction(const JSONRPCRequest& request)
     if (!request.params[1].isNull() && request.params[1].get_bool())
         nMaxRawTxFee = 0;
 
+    { // cs_main scope
+    LOCK(cs_main);
     CCoinsViewCache &view = *pcoinsTip;
     bool fHaveChain = false;
     for (size_t o = 0; !fHaveChain && o < tx->vout.size(); o++) {
@@ -952,10 +958,24 @@ UniValue sendrawtransaction(const JSONRPCRequest& request)
                 }
                 throw JSONRPCError(RPC_TRANSACTION_ERROR, state.GetRejectReason());
             }
+        } else {
+            // If wallet is enabled, ensure that the wallet has been made aware
+            // of the new transaction prior to returning. This prevents a race
+            // where a user might call sendrawtransaction with a transaction
+            // to/from their wallet, immediately call some wallet RPC, and get
+            // a stale result because callbacks have not yet been processed.
+            CallFunctionInValidationInterfaceQueue([&promise] {
+                promise.set_value();
+            });
         }
     } else if (fHaveChain) {
         throw JSONRPCError(RPC_TRANSACTION_ALREADY_IN_CHAIN, "transaction already in block chain");
     }
+
+    } // cs_main
+
+    promise.get_future().wait();
+
     if(!g_connman)
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
 
@@ -964,6 +984,7 @@ UniValue sendrawtransaction(const JSONRPCRequest& request)
     {
         pnode->PushInventory(inv);
     });
+
     return hashTx.GetHex();
 }