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

On Tue, Oct 12, 2021 at 04:42:01PM -0400, Jeff King wrote:

That may be so for hostnames in general, but URLs seem to allow it. RFC
3986 says:

      host        = IP-literal / IPv4address / reg-name
      reg-name    = *( unreserved / pct-encoded / sub-delims )
      unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"

So underscore is definitely allowed in the host portion. Our code
complains during url_normalize(), in this code:

          if (allow_globs)
                  spanned = strspn(url, URL_HOST_CHARS "*");
          else
                  spanned = strspn(url, URL_HOST_CHARS);
  
          if (spanned < colon_ptr - url) {
                  /* Host name has invalid characters */
                  if (out_info) {
                          out_info->url = NULL;
                          out_info->err = _("invalid characters in host name");
                  }
                  strbuf_release(&norm);
                  return NULL;
          }

because earlier we define URL_HOST_CHARS without underscore:

  #define URL_HOST_CHARS URL_ALPHADIGIT ".-[:]" /* IPv6 literals need [:] */

I'm not sure why, given that this otherwise seems to match according to
the rfc. This code comes from 3402a8dc48 (config: add helper to
normalize and match URLs, 2013-07-31), but there's no mention of
underscore there. Possibly it came from earlier rules (rfc1738, for
example, has a stricter grammar that allows only alphabit and dashes).

Sorry, I meant to cc the author of 3402a8dc48, which I've now done. It's
been a while, but maybe he remembers something (I couldn't find anything
digging in the archive, either).

-Peff