How to redirect an erroneous URL

Question

This question was migrated from Software Engineering Stack Exchange because it can be answered on Stack Overflow. Migrated 8 years ago .

I just noticed that sometimes (even when given a wrong url) load perfectly fine. How do they accomplish this? What I mean is, suppose you click on a link that seems good like www.foo.com but it contains in the end a space character which would appear on the address bar as www.foo.com%20 some sites manage to redirect this to their correct url while others just break. How can this be achieved? I'm guessing it's something to do with the .htaccess but I have no idea what to do or where to do it.

The URL I'd like to redirect looks like this actually: http://foo.com/%C2%A0

I get the following error message:

The requested URL /%C2%A0 was not found on this server.

How can I make this redirection? So far I came up with:

RewriteEngine on
RewriteBase /
RewriteCond %{THE_REQUEST} ^[A-Z]+\ /[^%?\ ]*\%
RewriteCond %{REQUEST_URI} !^/
RewriteRule ^(.*)$ http://www.foo.com/ [R=301,L]

but it's not working at all

Answer 1

URL Rewrite would be the IIS version that may exist in other forms if you want to look at re-writing the URL assuming you mean this kind of case.

Don't forget that browsers may make certain guesses about what someone enters so that if someone types in "foo.com " that the browser may trim white space by default rather than URL encode the text. If "http://foo.com" fails then it may try "http://www.foo.com" for another idea as these could be seen as simple interpretations to take on what someone types in. If both fail then it may just Google the text believing that the address bar should be treated like a search box.