rpc: Fail to return undocumented or misdocumented JSON

Author: MarcoFalke

src/rpc/util.cpp

@@ -774,7 +774,7 @@ void RPCResult::ToSections(Sections& sections, const OuterType outer_type, const
     // Elements in a JSON structure (dictionary or array) are separated by a comma
     const std::string maybe_separator{outer_type != OuterType::NONE ? "," : ""};
 
-    // The key name if recursed into an dictionary
+    // The key name if recursed into a dictionary
     const std::string maybe_key{
         outer_type == OuterType::OBJ ?
             "\"" + this->m_key_name + "\" : " :
@@ -865,10 +865,11 @@ void RPCResult::ToSections(Sections& sections, const OuterType outer_type, const
 
 bool RPCResult::MatchesType(const UniValue& result) const
 {
-    switch (m_type) {
-    case Type::ELISION: {
-        return false;
+    if (m_skip_type_check) {
+        return true;
     }
+    switch (m_type) {
+    case Type::ELISION:
     case Type::ANY: {
         return true;
     }
@@ -889,11 +890,52 @@ bool RPCResult::MatchesType(const UniValue& result) const
     }
     case Type::ARR_FIXED:
     case Type::ARR: {
-        return UniValue::VARR == result.getType();
+        if (UniValue::VARR != result.getType()) return false;
+        for (size_t i{0}; i < result.get_array().size(); ++i) {
+            // If there are more results than documented, re-use the last doc_inner.
+            const RPCResult& doc_inner{m_inner.at(std::min(m_inner.size() - 1, i))};
+            if (!doc_inner.MatchesType(result.get_array()[i])) return false;
+        }
+        return true; // empty result array is valid
     }
     case Type::OBJ_DYN:
     case Type::OBJ: {
-        return UniValue::VOBJ == result.getType();
+        if (UniValue::VOBJ != result.getType()) return false;
+        if (!m_inner.empty() && m_inner.at(0).m_type == Type::ELISION) return true;
+        if (m_type == Type::OBJ_DYN) {
+            const RPCResult& doc_inner{m_inner.at(0)}; // Assume all types are the same, randomly pick the first
+            for (size_t i{0}; i < result.get_obj().size(); ++i) {
+                if (!doc_inner.MatchesType(result.get_obj()[i])) {
+                    return false;
+                }
+            }
+            return true; // empty result obj is valid
+        }
+        std::set<std::string> doc_keys;
+        for (const auto& doc_entry : m_inner) {
+            doc_keys.insert(doc_entry.m_key_name);
+        }
+        std::map<std::string, UniValue> result_obj;
+        result.getObjMap(result_obj);
+        for (const auto& result_entry : result_obj) {
+            if (doc_keys.find(result_entry.first) == doc_keys.end()) {
+                return false; // missing documentation
+            }
+        }
+
+        for (const auto& doc_entry : m_inner) {
+            const auto result_it{result_obj.find(doc_entry.m_key_name)};
+            if (result_it == result_obj.end()) {
+                if (!doc_entry.m_optional) {
+                    return false; // result is missing a required key
+                }
+                continue;
+            }
+            if (!doc_entry.MatchesType(result_it->second)) {
+                return false; // wrong type
+            }
+        }
+        return true;
     }
     } // no default case, so the compiler can warn about missing cases
     CHECK_NONFATAL(false);

src/wallet/rpc/wallet.cpp

@@ -56,7 +56,7 @@ static RPCHelpMan getwalletinfo()
                         {
                             {RPCResult::Type::NUM, "duration", "elapsed seconds since scan start"},
                             {RPCResult::Type::NUM, "progress", "scanning progress percentage [0.0, 1.0]"},
-                        }},
+                        }, /*skip_type_check=*/true},
                         {RPCResult::Type::BOOL, "descriptors", "whether this wallet uses descriptors for scriptPubKey management"},
                         {RPCResult::Type::BOOL, "external_signer", "whether this wallet is configured to use an external signer such as a hardware wallet"},
                     }},