Lazy Eye Inspection: Capturing the State of Happy Eyeballs Implementations

TL;DR

This paper evaluates the implementation and effectiveness of Happy Eyeballs across various web browsers, revealing differences in features and potential connectivity issues, and provides a framework and tool for testing.

Contribution

It introduces a framework and web-based tool for analyzing and measuring Happy Eyeballs implementations and parameters in different clients.

Findings

Safari supports all HE features and uses dynamic delays.

Chrome and Firefox can experience delays due to DNS A record issues.

Problems with DNS A records can disrupt network connectivity despite IPv6 readiness.

Abstract

Happy Eyeballs (HE) started out by describing a mechanism that prefers IPv6 connections while ensuring a fast fallback to IPv4 when IPv6 fails. The IETF is currently working on the third version of HE. While the standards include recommendations for HE parameters choices, it is up to the client and OS to implement HE. In this paper we investigate the state of HE in various clients, particularly web browsers and recursive resolvers. We introduce a framework to analyze and measure client's HE implementations and parameter choices. According to our evaluation, only Safari supports all HE features. Safari is also the only client implementation in our study that uses a dynamic IPv4 connection attempt delay, a resolution delay, and interlaces addresses. We further show that problems with the DNS A record lookup can even delay and interrupt the network connectivity despite a fully functional IPv6 setup with Chrome and Firefox. We publish our testbed measurement framework and a web-based tool to test HE properties on arbitrary browsers.