ObsidianDragon/src/rpc/rpc_failure.h

// DragonX Wallet - ImGui Edition
// Copyright 2024-2026 The Hush Developers
// Released under the GPLv3

#pragma once

// Classifying a failed RPC call from structured data (curl code, request-sent bit, HTTP status,
// JSON-RPC error code, non-JSON body) instead of substrings of what(). Header-only and pure, so the
// test target can use it without compiling rpc_client.cpp.

#include <curl/curl.h>

#include <stdexcept>
#include <string>

namespace dragonx {
namespace rpc {

enum class RpcFailureKind {
    None,            // the call succeeded
    NotListening,    // connection refused: nothing bound to the RPC port (not started, or already unbound)
    ConnectTimeout,  // TCP connect didn't complete in time (Windows after the daemon unbinds; filtered port)
    ReplyTimeout,    // request sent, no reply in time: the daemon holds it (busy, e.g. blocked on cs_main)
    QueueFull,       // HTTP 500 "Work queue depth exceeded": rejected before any handler ran; holds no slot
    ShuttingDown,    // HTTP 503: the daemon's HTTP server was interrupted for shutdown
    Unhandled,       // HTTP 500 "Unhandled request": queued, then dropped by a shutting-down daemon
    Auth,            // HTTP 401: wrong rpcuser/rpcpassword (or a stale .cookie)
    Warmup,          // JSON-RPC -28 (RPC_IN_WARMUP): the node is still loading
    AppError,        // the daemon ran the method and answered with a JSON-RPC error
    Aborted,         // our own requestAbort() cut the transfer
    Deferred,        // not sent: the node is busy (RpcBusyGate), so we held back rather than queue more
    Other,
};

inline const char* rpcFailureKindName(RpcFailureKind kind)
{
    switch (kind) {
    case RpcFailureKind::None:           return "None";
    case RpcFailureKind::NotListening:   return "NotListening";
    case RpcFailureKind::ConnectTimeout: return "ConnectTimeout";
    case RpcFailureKind::ReplyTimeout:   return "ReplyTimeout";
    case RpcFailureKind::QueueFull:      return "QueueFull";
    case RpcFailureKind::ShuttingDown:   return "ShuttingDown";
    case RpcFailureKind::Unhandled:      return "Unhandled";
    case RpcFailureKind::Auth:           return "Auth";
    case RpcFailureKind::Warmup:         return "Warmup";
    case RpcFailureKind::AppError:       return "AppError";
    case RpcFailureKind::Aborted:        return "Aborted";
    case RpcFailureKind::Deferred:       return "Deferred";
    case RpcFailureKind::Other:          return "Other";
    }
    return "Other";
}

// True for the two curl timeouts: what the old `what().find("Timeout")` checks meant.
inline bool isRpcTimeout(RpcFailureKind kind)
{
    return kind == RpcFailureKind::ConnectTimeout || kind == RpcFailureKind::ReplyTimeout;
}

/**
 * @param curlCode     CURLcode of the transfer (CURLE_OK when a response arrived)
 * @param requestSent  the request reached the daemon (CURLINFO_REQUEST_SIZE > 0). libcurl reports
 *                     connect- and reply-phase timeouts with the same code; this tells them apart.
 * @param httpStatus   HTTP status, 0 when there was no response
 * @param rpcCode      JSON-RPC error.code from a JSON error body, 0 when there was none
 * @param plainBody    the response body when it was NOT JSON (dragonxd's HTTP-layer replies), else ""
 */
inline RpcFailureKind classifyRpcFailure(int curlCode, bool requestSent, long httpStatus, int rpcCode,
                                         const std::string& plainBody)
{
    if (curlCode != CURLE_OK) {
        switch (curlCode) {
        case CURLE_ABORTED_BY_CALLBACK:   return RpcFailureKind::Aborted;
        case CURLE_COULDNT_CONNECT:       return RpcFailureKind::NotListening;
        case CURLE_OPERATION_TIMEDOUT:
            return requestSent ? RpcFailureKind::ReplyTimeout : RpcFailureKind::ConnectTimeout;
        default:                          return RpcFailureKind::Other;
        }
    }
    if (rpcCode == -28) return RpcFailureKind::Warmup;         // takes precedence over the HTTP status
    if (rpcCode != 0) return RpcFailureKind::AppError;         // 500, or 400/404 (invalid request / no method)
    if (httpStatus == 200) return RpcFailureKind::None;
    if (httpStatus == 401) return RpcFailureKind::Auth;
    if (httpStatus == 503) return RpcFailureKind::ShuttingDown;
    if (httpStatus == 500) {
        if (plainBody.find("Work queue depth exceeded") != std::string::npos) return RpcFailureKind::QueueFull;
        if (plainBody.find("Unhandled request") != std::string::npos) return RpcFailureKind::Unhandled;
    }
    return RpcFailureKind::Other;
}

/**
 * "RPC error: HTTP <code>", plus the body when the daemon sent a plain-text one (e.g. ": Work queue
 * depth exceeded"), trimmed and limited to 120 printable ASCII characters so an HTML page or binary
 * junk can't flood a log line. Exactly "RPC error: HTTP <code>" when nothing printable remains.
 */
inline std::string formatHttpError(long httpStatus, const std::string& plainBody)
{
    std::string text;
    bool pendingSpace = false;
    for (unsigned char c : plainBody) {
        if (text.size() >= 120) break;
        if (c == ' ' || c == '\t' || c == '\r' || c == '\n') {
            pendingSpace = !text.empty();
        } else if (c >= 0x21 && c <= 0x7e) {
            if (pendingSpace && text.size() < 119) text.push_back(' ');
            pendingSpace = false;
            text.push_back(static_cast<char>(c));
        }
    }
    std::string out = "RPC error: HTTP " + std::to_string(httpStatus);
    if (!text.empty()) out += ": " + text;
    return out;
}

/**
 * The daemon ran the method and answered with a JSON-RPC error. what() is the daemon's message;
 * `code` is its JSON-RPC error code, notably -28 (RPC_IN_WARMUP). Callers catch this type to mean
 * "the daemon said no" (e.g. no mnemonic -> fall back), as opposed to a transport failure.
 */
class RpcError : public std::runtime_error {
public:
    RpcError(int errorCode, const std::string& message, long status = 0)
        : std::runtime_error(message), code(errorCode), httpStatus(status) {}
    RpcFailureKind kind() const { return code == -28 ? RpcFailureKind::Warmup : RpcFailureKind::AppError; }
    int code = 0;
    long httpStatus = 0;
};

/**
 * The call produced no JSON-RPC answer: curl failed (refused, timed out, aborted), or the daemon's
 * HTTP layer turned the request away (401, 503, queue full, unhandled). what() keeps the historic
 * text ("RPC request failed: <curl error>" / "RPC error: HTTP <code>[: body]").
 */
class RpcTransportError : public std::runtime_error {
public:
    RpcTransportError(RpcFailureKind failureKind, const std::string& message, int curl = CURLE_OK,
                      long status = 0, bool sent = false)
        : std::runtime_error(message), kind(failureKind), curlCode(curl), httpStatus(status), requestSent(sent) {}
    RpcFailureKind kind = RpcFailureKind::Other;
    int curlCode = CURLE_OK;
    long httpStatus = 0;
    bool requestSent = false;
};

// The kind of any exception an RPC call threw (Other for anything that isn't an RPC error).
inline RpcFailureKind rpcFailureKindOf(const std::exception& e)
{
    if (const auto* t = dynamic_cast<const RpcTransportError*>(&e)) return t->kind;
    if (const auto* r = dynamic_cast<const RpcError*>(&e)) return r->kind();
    return RpcFailureKind::Other;
}

} // namespace rpc
} // namespace dragonx