CliMB

Abstract

Click has significant advantages for middlebox development, including modularity, extensibility, and reprogrammability. Despite these features, Click still has no native TCP support and only uses nonblocking I/O, preventing its applicability to middleboxes that require access to L7 data and blocking I/O. We bridge this gap by introducing Click middleboxes (CliMB). CliMB provides a full-fledged modular TCP layer supporting congestion control, TCP options, both blocking and nonblocking I/O, as well as socket and zero-copy APIs to applications. As a result, any TCP network function may now be realized in Click. As proof of concept, we develop a zero-copy SOCKS proxy server using CliMB that shows up to 4x gains compared to an equivalent implementation using the Linux in-kernel network stack.