C++ Proxy Like Clash Challenges

C++ Proxy Like Clash Challenges | Generated by AI

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Question: How about using C/C++ to implement a proxy application like Clash?

Answer:

Implementing a full-featured Clash-like proxy client (with 100+ protocol variants, TUN transparent proxy, fake-IP, advanced rule engine, Clash Meta API compatibility, etc.) in pure C or C++ is more feasible than in Java, but still very challenging and rare in practice as of February 2026. No major, actively maintained project has fully rewritten mihomo (Clash Meta) or sing-box in C/C++ — the ecosystem remains dominated by Go (mihomo / Clash Premium) and Rust (sing-box).

That said, C/C++ offers excellent performance, low-level control (especially for TUN/TAP devices and packet manipulation), and is a strong choice if you want maximum speed, small binary size, or deep system integration (e.g. on embedded routers, Android NDK, or performance-critical environments).

Why C/C++ Is More Practical Than Java (but Still Hard)

Advantages over Java:
- Native TUN/TAP device handling (open(“/dev/net/tun”, …) on Linux, Wintun on Windows)
- Direct access to raw sockets, packet capture, and low-level networking
- Lightweight binaries (no JVM overhead)
- Excellent for user-space TCP/IP stacks (lwIP, gVisor ports, or custom)
- Better concurrency models (threads, coroutines with libraries like Boost.Asio, libuv, or C++20 coroutines)
Major Challenges:
- Implementing 20–30+ complex protocols (VMess AEAD, VLESS Reality, Hysteria2 QUIC-based, TUIC v5, ShadowTLS v3, Juicity, etc.) from scratch is enormous work
- YAML/JSON config parsing + dynamic rule engine (domain trie, GeoIP, process name matching) requires careful design
- Cross-platform compatibility (Windows, macOS, Linux, Android) needs abstraction layers
- Security-critical crypto (ChaCha20-Poly1305, AES-GCM, XTLS, uTLS fingerprinting) must be flawless
- No battle-tested reference implementation exists in C/C++ for the full Clash Meta feature set

Recommended Modern C++ Stack (2026 style)

Language: C++20 / C++23 (coroutines, concepts, ranges, std::jthread)
Core async I/O & networking:
- Boost.Asio (still king for high-performance async networking in C++)
- libuv (if you want something lighter / Node.js-like)
- Emerging: C++26 executors + sender/receiver model (experimental in some libs)
TLS / Crypto:
- OpenSSL 3.x or BoringSSL (for uTLS-like fingerprinting)
- libsodium (for easy AEAD ciphers like chacha20-ietf-poly1305)
TUN / Transparent proxy:
- Use tun2socks-style approach → read/write raw IP packets from TUN device
- Excellent pure C++ example: wtdcode/tun2socks (Boost.Asio + blazing fast)
- Alternatives: port parts of gVisor TCP/IP stack to C++ or use lwIP
Protocol implementations:
- Start with Shadowsocks (many C/C++ libs exist, e.g. shadowsocks-libev in C)
- SOCKS5 / HTTP inbound → implement manually or use libs like microsocks (C) or modern C++ forks
- VMess / Trojan → look at partial C implementations in older projects or port from Go/Rust
- QUIC-based (Hysteria2, TUIC) → very hard; consider embedding quiche or lsquic libraries
Config & Rules:
- yaml-cpp or nlohmann/json + custom parser
- Trie for domains (e.g. marisa-trie or hand-rolled)
- MaxMind GeoIP2 C API for GeoIP matching
GUI / API (optional):
- Embed REST API with cpp-httplib or Crow
- GUI: Qt6 (cross-platform) or Dear ImGui for minimal overlay

Realistic Architecture Options in C++

Minimal viable project (recommended starting point)
- SOCKS5 + HTTP inbound
- Shadowsocks outbound (AEAD ciphers)
- Simple rule routing (domain/IP)
- TUN mode via tun2socks-like IP → SOCKS redirection
- Use Boost.Asio + tun2socks base
Medium ambition
- Add VMess, Trojan, Hysteria2
- Fake-IP + enhanced DNS
- YAML Clash-like config
- Still doable in ~1–2 person-years if focused
Full Clash Meta clone
- 100+ protocol combinations
- Clash Meta REST API + WebSocket events
- Rule-providers (remote updating)
- Process-name routing, TUN + auto-route
- Not realistic as solo / small-team project — better fork/extend mihomo (Go) or sing-box (Rust)

Existing C/C++ Projects You Can Study or Extend (2026)

wtdcode/tun2socks — Pure C++ + Boost.Asio, very fast TUN → SOCKS5
shadowsocks-libev — High-performance Shadowsocks in pure C (great reference)
microsocks forks — Modern C++ SOCKS5 servers/clients
Older partial proxies (e.g. SOCKS/HTTP in Boost.Asio examples)

Final Recommendation (2026 Reality)

If you want full feature parity with mihomo/sing-box → stick to Go or Rust — the cores are mature, actively updated, and have huge community/protocol support.
If you want high-performance subset (e.g. Shadowsocks + Hysteria2 + TUN on embedded/router/Android NDK) → C++ is excellent — start from tun2socks + Boost.Asio + libsodium/OpenSSL.
Pure C is possible (like shadowsocks-libev) but much harder for modern async/multi-protocol work — prefer modern C++.

In short: C/C++ can deliver a faster, leaner proxy than Go/Rust in many cases, especially for TUN-heavy or low-resource scenarios — but achieving full Clash compatibility remains extremely time-intensive and is why almost nobody has done it.

References:

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