Fix invalid json

CMakeLists.txt

@@ -29,6 +29,7 @@ endif()
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
 # Default to Release build
 if(NOT CMAKE_BUILD_TYPE OR CMAKE_BUILD_TYPE STREQUAL "")

src/network/rpc_server.cpp

@@ -679,7 +679,7 @@ std::string RPCServer::HandleGetBlockHash(const std::vector<std::string>& params
     return util::JsonError("Block height out of range");
   }
 
-  return index->GetBlockHash().GetHex() + "\n";
+  return "\"" + index->GetBlockHash().GetHex() + "\"\n";
 }
 
 std::string RPCServer::HandleGetBlockHeader(const std::vector<std::string>& params) {
@@ -755,7 +755,7 @@ std::string RPCServer::HandleGetBestBlockHash(const std::vector<std::string>& pa
     return "null\n";
   }
 
-  return tip->GetBlockHash().GetHex() + "\n";
+  return "\"" + tip->GetBlockHash().GetHex() + "\"\n";
 }
 
 std::string RPCServer::HandleGetConnectionCount(const std::vector<std::string>& params) {

test/integration-network/rpc_integration_tests.cpp

@@ -8,6 +8,7 @@
 #include "network/rpc_client.hpp"
 #include "network/rpc_server.hpp"
 #include "util/logging.hpp"
+#include <nlohmann/json.hpp>
 
 #include <thread>
 #include <chrono>
@@ -604,6 +605,28 @@ TEST_CASE("RPC Commands: getbestblockhash", "[rpc][integration][blockchain]") {
         std::string response = client.ExecuteCommand("getbestblockhash", {});
         // Empty chain should return null/zero hash or error
         REQUIRE(!response.empty());
+
+        auto j = nlohmann::json::parse(response);
+        REQUIRE(j.is_null());
+    }
+}
+
+TEST_CASE("RPC Commands: getblockhash", "[rpc][integration][blockchain]") {
+    RPCTestFixture fixture;
+    REQUIRE(fixture.StartServer());
+    std::this_thread::sleep_for(100ms);
+
+    rpc::RPCClient client(fixture.GetSocketPath());
+    REQUIRE_FALSE(client.Connect().has_value());
+
+    SECTION("Returns error for empty chain") {
+        std::string response = client.ExecuteCommand("getblockhash", {"0"});
+        REQUIRE(!response.empty());
+
+        auto j = nlohmann::json::parse(response);
+        REQUIRE(j.is_object());
+        REQUIRE(j.contains("error"));
+        REQUIRE(j["error"].get<std::string>().find("out of range") != std::string::npos);
     }
 }