Dag Finstad
Software Developer at Varnish Software
Oslo, Norway
Summary
🤩
Rockstar🎓
Top SchoolDag Finstad is a pragmatic software developer with 14 years of experience building and hardening high-performance network software at Varnish Software from Oslo. He focuses on backend systems and security, contributing to core open-source projects like Varnish Cache and the Hitch TLS proxy where he fixed protocol edge cases, improved HTTP/2 handling, and tightened TLS and PROXY parsing. His work shows a strong attention to correctness in critical reverse-proxy internals—connection recycling, conditional request handling, and unrecognized SNI protection. With a Master's in Informatics from UiO, he combines academic rigor with production-hardened engineering, preferring subtle but impactful fixes over flashy rewrites. Colleagues rely on him for reliability improvements that keep high-throughput infrastructure robust in real-world scenarios.
14 years of coding experience
Master's degree, Informatics, Master's degree, Informatics at Universitetet i Oslo (UiO)
Stackoverflow
29reputation
23kreached
1answer
0questions
Github Skills (15)
c1710
mtls10
http10
caching10
tls1210
reverse-proxy10
c-programming10
c1110
high-performance10
openssl10
proxy-protocol10
tls1310
libtls10
security10
sql6
Programming languages (7)
Github contributions (5)
varnish/hitch
Apr 2015 - Sep 2022
A scalable TLS proxy by Varnish Software.
Role in this project:
Back-end Developer & Security Engineer
Back-end Developer & Security EngineerContributions:5 releases, 448 commits, 50 PRs in 7 years 6 months
Contributions summary:Dag primarily focused on improving the security and functionality of the `hitch` project, a scalable TLS proxy. Their contributions include fixing a copy-paste typo in the source code, ensuring TLS1.0 and newer with SSL3 support, and enhancing the PROXY protocol parsing. The user was also responsible for implementing functionality to prevent connections with unrecognized SNI names.
tls-proxyvarnish
varnishcache/varnish-cache
Mar 2016 - Apr 2020
Varnish Cache source code repository
Role in this project:Back-end Developer
Back-end DeveloperContributions:4 reviews, 59 commits, 66 PRs in 4 years 1 month
Contributions summary:Dag primarily contributes to the Varnish Cache source code, focusing on bug fixes and improvements. They addressed issues related to HTTP/2 protocol implementation, ensuring correct error handling within the data reception process. Additionally, they fixed an issue related to backend connection recycling and addressed the incorrect handling of Content-Encoding headers in conditional requests. These commits demonstrate a focus on the core functionalities of the reverse proxy.
varnishcachingreverse-proxyhigh-performance
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