Re: [BUG] credential wildcard does not match hostnames containing an underscore

On 2021-10-12 at 21:32:24, Jeff King wrote:

There's a well-known bug on Tumblr, where it allocated hostnames for users that happened to start or end with a dash, which is not allowed. This worked great on Windows systems, which don't care, but every Unix system was broken.

When we decide to allow this particular case, we end up with the problem that people won't see consistent behavior across systems and tools. It may be that libgit2 rejects this, or Git LFS, or some other tool in the ecosystem, and then we'll have people complaining that "Well, Git accepts it, so why don't you?" which I am not eager to see. I, for example, have absolutely zero control over the URL parsing library that's used in Git LFS, and the Go team has demonstrated that they don't care one bit about supporting Git-related tooling. That doesn't even include a variety of proprietary Unix systems that might have different rules or resolvers.

I am also not eager to see additional bug reports for this case that will need to be fixed under the precedent that we accepted a patch to fix it before. If there's a concern that rejecting these hostnames altogether would break existing users, then we can just do nothing, and tell users that their syntax is not valid and they need to fix their hostnames. This rule has been documented since before ISO standardized C, so it shouldn't be new to anyone deploying systems or DNS.

So I'm fine with doing nothing, or rejecting these hostnames, but not allowing more lenient syntax, because it will probably be broken somewhere and we (or someone else in the ecosystem) will have to deal with it again down the line.