Exploring Composable Network Stacks from Isolated Components with WebAssembly and QUIC

Modern web applications demand increasingly sophisticated network protocols. Deploying applications that integrate custom protocols and algorithms is particularly challenging in container, browser, or shared kernel environments, where untrusted code execution must be restricted. While the host-provided network stack is usually highly efficient, it often lacks adaptability. With QUIC emerging as an extensible foundation for networked applications and WebAssembly (WASM) offering a secure, lightweight container runtime, we propose a modular network stack architecture composable of host and isolated guest components. This paper investigates the performance cost of implementing a complete network stack-including HTTP/3, QUIC, and TLS-as isolated WASM components. We evaluate our architecture, built on the WebAssembly System Interface (WASI) 0.2 and the WASM Component Model, through a comprehensive comparison with a native implementation. Our results demonstrate that while building a modular QUIC stack with WASM is technically feasible, its current overhead limits its practical use. The composed WASM implementation achieves a maximum goodput of 0.9 Gbps, compared to 6.1 Gbps with a native implementation. We identified the lack of send-offloading capabilities, missing cryptographic acceleration, and additional memory copies as the major performance bottlenecks. We discuss these limitations and propose potential improvements to bridge the performance gap.