feat: Experimental attempt at RPC validation framework

src/xrpld/rpc/detail/Handler.cpp

@@ -3,6 +3,7 @@
 #include <xrpld/rpc/Context.h>
 #include <xrpld/rpc/Role.h>
 #include <xrpld/rpc/handlers/Handlers.h>
+#include <xrpld/rpc/handlers/account/AccountInfo.h>
 #include <xrpld/rpc/handlers/ledger/Ledger.h>
 #include <xrpld/rpc/handlers/server_info/Version.h>
 
@@ -48,6 +49,16 @@ handle(JsonContext& context, Object& object)
         context.apiVersion >= HandlerImpl::minApiVer &&
             context.apiVersion <= HandlerImpl::maxApiVer,
         "xrpl::RPC::handle : valid API version");
+
+    if constexpr (requires { HandlerImpl::requestFields; })
+    {
+        if (auto status = validateFieldSpecs(context.params, HandlerImpl::requestFields))
+        {
+            status.inject(object);
+            return status;
+        }
+    }
+
     HandlerImpl handler(context);
 
     auto status = handler.check();
@@ -78,10 +89,6 @@ handlerFrom()
 Handler const kHANDLER_ARRAY[]{
     // Some handlers not specified here are added to the table via addHandler()
     // Request-response methods
-    {.name = "account_info",
-     .valueMethod = byRef(&doAccountInfo),
-     .role = Role::USER,
-     .condition = Condition::NoCondition},
     {.name = "account_currencies",
      .valueMethod = byRef(&doAccountCurrencies),
      .role = Role::USER,
@@ -410,6 +417,7 @@ private:
         }
 
         // This is where the new-style handlers are added.
+        addHandler<AccountInfoHandler>();
         addHandler<LedgerHandler>();
         addHandler<VersionHandler>();
     }

src/xrpld/rpc/detail/Handler.h

@@ -6,8 +6,11 @@
 #include <xrpld/rpc/detail/Tuning.h>
 
 #include <xrpl/protocol/ApiVersion.h>
+#include <xrpl/protocol/ErrorCodes.h>
 #include <xrpl/server/NetworkOPs.h>
 
+#include <span>
+
 namespace json {
 class Object;
 }  // namespace json
@@ -36,9 +39,37 @@ struct Handler
     unsigned maxApiVer = kAPI_MAXIMUM_VALID_VERSION;
 };
 
+enum class FieldRequirement { Optional, Required };
+
+struct FieldSpec
+{
+    json::StaticString name;
+    FieldRequirement requirement;
+    json::ValueType type;
+};
+
 Handler const*
 getHandler(unsigned int version, bool betaEnabled, std::string const&);
 
+inline Status
+validateFieldSpecs(json::Value const& params, std::span<FieldSpec const> fields)
+{
+    for (auto const& field : fields)
+    {
+        if (!params.isMember(field.name))
+        {
+            if (field.requirement == FieldRequirement::Required)
+                return {RpcInvalidParams, missingFieldMessage(std::string(field.name))};
+            continue;
+        }
+
+        if (params[field.name].type() != field.type)
+            return {RpcInvalidParams, invalidFieldMessage(field.name)};
+    }
+
+    return Status::kOK;
+}
+
 /** Return a json::ValueType::Object with a single entry. */
 template <class Value>
 json::Value

src/xrpld/rpc/handlers/account/AccountInfo.cpp

@@ -1,3 +1,5 @@
+#include <xrpld/rpc/handlers/account/AccountInfo.h>
+
 #include <xrpld/app/main/Application.h>
 #include <xrpld/app/misc/TxQ.h>
 #include <xrpld/rpc/Context.h>
@@ -91,14 +93,10 @@ doAccountInfo(RPC::JsonContext& context)
     std::string strIdent;
     if (params.isMember(jss::account))
     {
-        if (!params[jss::account].isString())
-            return RPC::invalidFieldError(jss::account);
         strIdent = params[jss::account].asString();
     }
     else if (params.isMember(jss::ident))
     {
-        if (!params[jss::ident].isString())
-            return RPC::invalidFieldError(jss::ident);
         strIdent = params[jss::ident].asString();
     }
     else
@@ -340,4 +338,24 @@ doAccountInfo(RPC::JsonContext& context)
     return result;
 }
 
+namespace RPC {
+
+AccountInfoHandler::AccountInfoHandler(JsonContext& context) : context_(context)
+{
+}
+
+Status
+AccountInfoHandler::check()
+{
+    return Status::kOK;
+}
+
+void
+AccountInfoHandler::writeResult(json::Value& value)
+{
+    value = doAccountInfo(context_);
+}
+
+}  // namespace RPC
+
 }  // namespace xrpl

src/xrpld/rpc/handlers/account/AccountInfo.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include <xrpld/rpc/Context.h>
+#include <xrpld/rpc/Role.h>
+#include <xrpld/rpc/Status.h>
+#include <xrpld/rpc/detail/Handler.h>
+
+#include <xrpl/protocol/ApiVersion.h>
+#include <xrpl/protocol/jss.h>
+
+#include <array>
+
+namespace xrpl::RPC {
+
+class AccountInfoHandler
+{
+public:
+    explicit AccountInfoHandler(JsonContext&);
+
+    Status
+    check();
+
+    void
+    writeResult(json::Value&);
+
+    // NOLINTBEGIN(readability-identifier-naming)
+    static constexpr char name[] = "account_info";
+
+    static constexpr unsigned minApiVer = RPC::kAPI_MINIMUM_SUPPORTED_VERSION;
+
+    static constexpr unsigned maxApiVer = RPC::kAPI_MAXIMUM_VALID_VERSION;
+
+    static constexpr Role role = Role::USER;
+
+    static constexpr Condition condition = Condition::NoCondition;
+
+    static constexpr std::array requestFields = {
+        FieldSpec{jss::account, FieldRequirement::Optional, json::ValueType::String},
+        FieldSpec{jss::ident, FieldRequirement::Optional, json::ValueType::String},
+        FieldSpec{jss::queue, FieldRequirement::Optional, json::ValueType::Boolean},
+    };
+    // NOLINTEND(readability-identifier-naming)
+
+private:
+    JsonContext& context_;
+};
+
+}  // namespace xrpl::RPC