TL;DR. golang.org/x/net/idna.Lookup.ToASCII runs UTS-46 NFKC mapping 0-9. A pre-IDNA net.ParseIP check rejects the NO_PROXY lists, TLS-SNI routers, and cookie-domain validators that TrimRight + ParseAddr golang.org/x/net/http/httpproxy, the canonical safe pattern, and two I ran into this one while writing a Go HTTP client for a private project. I idna.Lookup.ToASCII canonicalising the host The sha
There's a moment every developer knows. You need to generate a PDF. It looks simple. You've done harder things. Three hours later, you're reading a Stack Overflow thread from 2016 that ends with "works on my machine." This post is about that moment — the actual options, what breaks in each, and where I landed after years of hitting this in production. It uses a stripped-down WebKit engine and conv