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Match Patterns

Host permissions matching is based on a set of URLs defined by match patterns. A match pattern is essentially a URL that begins with a permitted scheme (http, https, file, or ftp, and that can contain '*' characters. The special pattern <all_urls> matches any URL that starts with a permitted scheme. Each match pattern has 3 parts:

• scheme — for example, http or file or *

  Note: Access to file URLs isn't automatic. The user must visit the extensions management page and opt in to file access for each extension that requests it.

• host — for example, www.google.com or *.google.com or *; if the scheme is file, there is no host part
• path — for example, /*, /foo*, or /foo/bar. The path must be present in a host permission, but is always treated as /*.

Here's the basic syntax:

<url-pattern> := <scheme>://<host><path>
<scheme> := '*' | 'http' | 'https' | 'file' | 'ftp'
<host> := '*' | '*.' <any char except '/' and '*'>+
<path> := '/' <any chars>

The meaning of '*' depends on whether it's in the scheme, host, or path part. If the scheme is *, then it matches either http or https, and not file, or ftp. If the host is just *, then it matches any host. If the host is *.hostname, then it matches the specified host or any of its subdomains. In the path section, each '*' matches 0 or more characters. The following table shows some valid patterns.

Pattern	What it does	Examples of matching URLs
http://*/*	Matches any URL that uses the http scheme	http://www.google.com/ http://example.org/foo/bar.html
http://*/foo*	Matches any URL that uses the http scheme, on any host, as long as the path starts with /foo	http://example.com/foo/bar.html http://www.google.com/foo
https://*.google.com/foo*bar	Matches any URL that uses the https scheme, is on a google.com host (such as www.google.com, docs.google.com, or google.com), as long as the path starts with /foo and ends with bar	https://www.google.com/foo/baz/bar https://docs.google.com/foobar
http://example.org/foo/bar.html	Matches the specified URL	http://example.org/foo/bar.html
file:///foo*	Matches any local file whose path starts with /foo	file:///foo/bar.html file:///foo
http://127.0.0.1/*	Matches any URL that uses the http scheme and is on the host 127.0.0.1	http://127.0.0.1/ http://127.0.0.1/foo/bar.html
*://mail.google.com/*	Matches any URL that starts with http://mail.google.com or https://mail.google.com.	http://mail.google.com/foo/baz/bar https://mail.google.com/foobar
<all_urls>	Matches any URL that uses a permitted scheme. (See the beginning of this section for the list of permitted schemes.)	http://example.org/foo/bar.html file:///bar/baz.html

Here are some examples of invalid pattern matches:

Bad pattern	Why it's bad
http://www.google.com	No path
http://*foo/bar	'*' in the host can be followed only by a '.' or '/'
http://foo.*.bar/baz	If '*' is in the host, it must be the first character
http:/bar	Missing scheme separator ("/" should be "//")
foo://*	Invalid scheme

Some schemes are not supported in all contexts.