RPC: Strictly enforce the type of parameters passed by name

src/rpc/request.h

@@ -9,6 +9,7 @@
 #include <any>
 #include <optional>
 #include <string>
+#include <vector>
 
 #include <univalue.h>
 #include <util/fs.h>
@@ -38,6 +39,9 @@ class JSONRPCRequest
     std::optional<UniValue> id = UniValue::VNULL;
     std::string strMethod;
     UniValue params;
+    //! List of original parameter names after transformNamedArguments is
+    //! called and params is changed from an object to an array.
+    std::vector<std::optional<std::string>> param_names;
     enum Mode { EXECUTE, GET_HELP, GET_ARGS } mode = EXECUTE;
     std::string URI;
     std::string authUser;

src/rpc/server.cpp

@@ -397,9 +397,11 @@ static inline JSONRPCRequest transformNamedArguments(const JSONRPCRequest& in, c
     for (const auto& [argNamePattern, named_only]: argNames) {
         std::vector<std::string> vargNames = SplitString(argNamePattern, '|');
         auto fr = argsIn.end();
+        std::string fr_name;
         for (const std::string & argName : vargNames) {
             fr = argsIn.find(argName);
             if (fr != argsIn.end()) {
+                fr_name = argName;
                 break;
             }
         }
@@ -424,6 +426,7 @@ static inline JSONRPCRequest transformNamedArguments(const JSONRPCRequest& in, c
                 // but not at the end (for backwards compatibility with calls
                 // that act based on number of specified parameters).
                 out.params.push_back(UniValue());
+                out.param_names.emplace_back(std::nullopt);
             }
             hole = 0;
             if (!initial_param) initial_param = &argNamePattern;
@@ -440,6 +443,7 @@ static inline JSONRPCRequest transformNamedArguments(const JSONRPCRequest& in, c
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Parameter " + fr->first + " conflicts with parameter " + options.getKeys().front());
             }
             out.params.push_back(*fr->second);
+            out.param_names.emplace_back(fr_name);
             argsIn.erase(fr);
         }
         if (!options.empty()) {

src/rpc/util.cpp

@@ -669,7 +669,7 @@ UniValue RPCHelpMan::HandleRequest(const JSONRPCRequest& request) const
     UniValue arg_mismatch{UniValue::VOBJ};
     for (size_t i{0}; i < m_args.size(); ++i) {
         const auto& arg{m_args.at(i)};
-        UniValue match{arg.MatchesType(request.params[i])};
+        UniValue match{arg.MatchesType(request.params[i], i < request.param_names.size() ? request.param_names[i] : std::nullopt)};
         if (!match.isTrue()) {
             arg_mismatch.pushKV(strprintf("Position %s (%s)", i + 1, arg.m_names), std::move(match));
         }
@@ -923,18 +923,24 @@ static std::optional<UniValue::VType> ExpectedType(RPCArg::Type type)
     NONFATAL_UNREACHABLE();
 }
 
-UniValue RPCArg::MatchesType(const UniValue& request) const
+UniValue RPCArg::MatchesType(const UniValue& request, const std::optional<std::string>& param_name) const
 {
     if (m_opts.skip_type_check) return true;
     if (IsOptional() && request.isNull()) return true;
-    for (auto type : m_type_per_name.empty() ? std::vector<RPCArg::Type>{m_type} : m_type_per_name) {
-        const auto exp_type{ExpectedType(type)};
+    const auto names = SplitString(m_names, '|');
+    size_t i = 0;
+    do {
+        // If parameter was passed by name, only allow the specified type for
+        // that name. Otherwise allow any of the specified types.
+        if (param_name && i < names.size() && *param_name != names[i]) {
+            continue;
+        }
+        const auto exp_type{ExpectedType(i < m_type_per_name.size() ? m_type_per_name[i] : m_type)};
         if (!exp_type) return true; // nothing to check
-
         if (*exp_type == request.getType()) {
             return true;
         }
-    }
+    } while (++i < names.size());
     return strprintf("JSON value of type %s is not of expected type %s", uvTypeName(request.getType()), uvTypeName(*ExpectedType(m_type)));
 }
 

src/rpc/util.h

@@ -284,7 +284,7 @@ struct RPCArg {
      * Check whether the request JSON type matches.
      * Returns true if type matches, or object describing error(s) if not.
      */
-    UniValue MatchesType(const UniValue& request) const;
+    UniValue MatchesType(const UniValue& request, const std::optional<std::string>& param_name) const;
 
     /** Return the first of all aliases */
     std::string GetFirstName() const;