Create a userscript for rewriting URLs

[ameshkov]

Source request:
http://forum.adguard.com/showthread.php?8695-HowTo-rewrite-a-URL

[TPS]

Recently, I ran into ftp://ftp.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WindowsBestFit/readme.txt while reading about the recent PHP vuln, but it turns out the major browsers dropped FTP capability around the time they integrated HTTPS-by-default everywhere. If this userscript is ever published, the best fallback would be to convert

• [s]ftp[s]:// → https://
• ftp:// → http:// (which the browsers would then try https://, but would allow fallback to http:// with (justified) warning

[ameshkov]

In theory the new $urltransform modifier: AdguardTeam/CoreLibs#1364

[TPS]

I've read the $urltransform sections of the docs several times, but regex always confuses me. This seems simple, but I hesitate b/c of that. What would be the correct rule to attempt?