Add error code extension mechanism and use malformed currency code (#396)

Fixes #275

src/rpc/Errors.cpp

@@ -0,0 +1,135 @@
+#include <rpc/Errors.h>
+
+#include <algorithm>
+
+using namespace std;
+
+namespace {
+template <class... Ts>
+struct overloadSet : Ts...
+{
+    using Ts::operator()...;
+};
+
+// explicit deduction guide (not needed as of C++20, but clang be clang)
+template <class... Ts>
+overloadSet(Ts...) -> overloadSet<Ts...>;
+}  // namespace
+
+namespace RPC {
+
+WarningInfo const&
+getWarningInfo(WarningCode code)
+{
+    constexpr static WarningInfo infos[]{
+        {warnUNKNOWN, "Unknown warning"},
+        {warnRPC_CLIO,
+         "This is a clio server. clio only serves validated data. If you "
+         "want to talk to rippled, include 'ledger_index':'current' in your "
+         "request"},
+        {warnRPC_OUTDATED, "This server may be out of date"},
+        {warnRPC_RATE_LIMIT, "You are about to be rate limited"}};
+
+    auto matchByCode = [code](auto const& info) { return info.code == code; };
+    if (auto it = find_if(begin(infos), end(infos), matchByCode);
+        it != end(infos))
+        return *it;
+
+    throw(out_of_range("Invalid WarningCode"));
+}
+
+boost::json::object
+makeWarning(WarningCode code)
+{
+    boost::json::object json;
+    auto const& info = getWarningInfo(code);
+    json["id"] = code;
+    json["message"] = static_cast<string>(info.message);
+    return json;
+}
+
+ClioErrorInfo const&
+getErrorInfo(ClioError code)
+{
+    constexpr static ClioErrorInfo infos[]{
+        {ClioError::rpcMALFORMED_CURRENCY,
+         "malformedCurrency",
+         "Malformed currency."},
+    };
+
+    auto matchByCode = [code](auto const& info) { return info.code == code; };
+    if (auto it = find_if(begin(infos), end(infos), matchByCode);
+        it != end(infos))
+        return *it;
+
+    throw(out_of_range("Invalid error code"));
+}
+
+boost::json::object
+makeError(
+    RippledError err,
+    optional<string_view> customError,
+    optional<string_view> customMessage)
+{
+    boost::json::object json;
+    auto const& info = ripple::RPC::get_error_info(err);
+
+    json["error"] = customError.value_or(info.token.c_str()).data();
+    json["error_code"] = static_cast<uint32_t>(err);
+    json["error_message"] = customMessage.value_or(info.message.c_str()).data();
+    json["status"] = "error";
+    json["type"] = "response";
+    return json;
+}
+
+boost::json::object
+makeError(
+    ClioError err,
+    optional<string_view> customError,
+    optional<string_view> customMessage)
+{
+    boost::json::object json;
+    auto const& info = getErrorInfo(err);
+
+    json["error"] = customError.value_or(info.error).data();
+    json["error_code"] = static_cast<uint32_t>(info.code);
+    json["error_message"] = customMessage.value_or(info.message).data();
+    json["status"] = "error";
+    json["type"] = "response";
+    return json;
+}
+
+boost::json::object
+makeError(Status const& status)
+{
+    auto wrapOptional = [](string_view const& str) {
+        return str.empty() ? nullopt : make_optional(str);
+    };
+
+    return visit(
+        overloadSet{
+            [&status, &wrapOptional](RippledError err) {
+                if (err == ripple::rpcUNKNOWN)
+                {
+                    return boost::json::object{
+                        {"error", status.message},
+                        {"type", "response"},
+                        {"status", "error"}};
+                }
+
+                return makeError(
+                    err,
+                    wrapOptional(status.error),
+                    wrapOptional(status.message));
+            },
+            [&status, &wrapOptional](ClioError err) {
+                return makeError(
+                    err,
+                    wrapOptional(status.error),
+                    wrapOptional(status.message));
+            },
+        },
+        status.code);
+}
+
+}  // namespace RPC