netrw and invalid certificates

Don’t trust invalid certificates. Only do this sort of workaround if you really know what you’re dealing with is okay.

Sometimes I just need to reference the source of an HTML or CSS file online without writing to it. If I need to do this while I’m editing something else in vim, my best course of action is to open a split in vim and do it there. Even if I’m not working on said thing in vim, that is the way that I’m most comfortable moving around in documents, so there’s still a good chance I want to open my source file there.

netrw, the default1 file explorer for vim, handles HTTP and HTTPS. By default, it does this using whichever of the following it finds first: elinks, links, curl, wget, or fetch. At work, we’re going through an HTTPS transition, and at least for the time being, the certificates are… not quite right. Not sure what the discrepancy is (it’s not my problem), but strict clients are wary. This includes curl and wget. When I went to view files via HTTPS in vim, I was presented with errors. This obviously wasn’t vim’s fault, but it took a bit of doing to figure out exactly how these elements interacted and how to modify the behavior of what is (at least originally) perceived as netrw.

When netrw opens up a remote connection, it essentially just opens up a temporary file, and runs a command that uses that temporary file as input or output depending on whether the command is a read or write operation. As previously mentioned, netrw looks for elinks, links, curl, wget, and fetch. My cygwin install has curl and wget, but none of the others. It also has lynx, which I’ll briefly discuss at the end. I don’t know if elinks or links can be set to ignore certificate issues, but I don’t believe so. curl and wget can, however.

We set this up in vim by modifying netrw_HTTP_cmd, keeping in mind that netrw is going to spit out a temporary file name to read in. So we can’t output to STDOUT, we need to end with a file destination. For curl, we can very simply use :let g:netrw_HTTP_cmd="curl -k". For wget, we need to specify output, tell it not to verify certs, and otherwise run quietly: :let g:netrw_HTTP_cmd="wget --no-check-certificate -q -O".

I don’t have an environment handy with links or elinks, but glancing over the manpages leads me to believe this isn’t an option with either. It isn’t with lynx either, but in playing with it, I still think this is useful: for a system with lynx but not any of the default HTTP(s) handlers, netrw can use lynx via :let g:netrw_HTTP_cmd="lynx -source >". Also interesting is that lynx (and presumably links and elinks via different flags) can be used to pull parsed content into vim: :let g:netrw_HTTP_cmd="lynx -dump >".


This is an old post from an old blog; assets may be missing, links may be broken, and my opinions may differ considerably by this point…
I spend a good deal of time inside a terminal. Text-based apps are powerful, when you know what you're doing, and fast (also when you know what you're doing, I suppose). If an equivalent Cocoa or X11 GUI tool offers me little advantage, I'm probably going to stick to either a CLI- or TUI-based piece of software. One of the more important, taken-for-granted pieces of the command line environment is that of the pager.