core\files\curl_security_helper Class Reference

Host and port checking for curl. More...

Inheritance diagram for core\files\curl_security_helper:

Public Member Functions
	get_blocked_url_string ()
	Returns a string message describing a blocked URL.
	is_enabled ()
	Convenience method to check whether we have any entries in the host blocklist or ports allowlist admin settings.
	url_is_blocked ($urlstring, $notused=null)
	Checks whether the given URL is blocked by checking its address and port number against the allow/block lists.
	url_is_blocked ($url)
	Check whether the input url should be blocked or not.

Protected Member Functions
	address_explicitly_blocked ($addr)
	Checks whether the input address is blocked by at any of the IPv4 or IPv6 address rules.
	get_allowed_ports ()
	Helper that returns the allowed ports, as defined in the 'curlsecurityallowedport' setting.
	get_blocked_hosts ()
	Helper that returns the blocked hosts, as defined in the 'curlsecurityblockedhosts' setting.
	get_blocked_hosts_by_category ()
	Helper to get all entries from the admin setting, as an array, sorted by classification.
	get_host_list_by_name ($host)
	Retrieve all hosts for a domain name.
	host_explicitly_blocked ($host)
	Checks whether the input hostname is blocked by any of the domain/wildcard rules.
	host_is_blocked ($host)
	Checks whether the host portion of a url is blocked.
	port_is_blocked ($port)
	Checks whether the given port is blocked, as determined by its absence on the ports allowlist.

Protected Attributes
array	$transportschemes
	of supported transport schemes and their respective default ports.

Detailed Description

Host and port checking for curl.

This class provides a means to check URL/host/port against the system-level cURL security entries. It does not provide a means to add URLs, hosts or ports to the allowed/blocked lists; this is configured manually via the site admin section of Moodle (See: 'Site admin' > 'Security' > 'HTTP Security').

This class is currently used by the 'curl' wrapper class in lib/filelib.php. Depends on: core\ip_utils (several functions) moodlelib (clean_param)

Copyright

2016 Jake Dallimore

License

http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

Author

Jake Dallimore jrhda.nosp@m.llim.nosp@m.ore@g.nosp@m.mail.nosp@m..com

Member Function Documentation

address_explicitly_blocked()

core\files\curl_security_helper::address_explicitly_blocked ( $addr )

protected

Checks whether the input address is blocked by at any of the IPv4 or IPv6 address rules.

Parameters

string

$addr

the ip address to check.

Return values

bool	true if the address is covered by an entry in the blocklist, false otherwise.

get_allowed_ports()

core\files\curl_security_helper::get_allowed_ports ( )

protected

Helper that returns the allowed ports, as defined in the 'curlsecurityallowedport' setting.

Return values

array

the array of allowed ports.

get_blocked_hosts()

core\files\curl_security_helper::get_blocked_hosts ( )

protected

Helper that returns the blocked hosts, as defined in the 'curlsecurityblockedhosts' setting.

Return values

array

the array of blocked host entries.

get_blocked_hosts_by_category()

core\files\curl_security_helper::get_blocked_hosts_by_category ( )

protected

Helper to get all entries from the admin setting, as an array, sorted by classification.

Classifications include 'ipv4', 'ipv6', 'domain', 'domainwildcard'.

Return values

array

of host/domain/ip entries from the 'curlsecurityblockedhosts' config.

get_blocked_url_string()

core\files\curl_security_helper::get_blocked_url_string

(

)

Returns a string message describing a blocked URL.

E.g. 'This URL is blocked'.

Return values

string

the string error.

Reimplemented from core\files\curl_security_helper_base.

get_host_list_by_name()

core\files\curl_security_helper::get_host_list_by_name ( $host )

protected

Retrieve all hosts for a domain name.

Parameters

string

$param

Return values

array

An array of IPs associated with the host name.

host_explicitly_blocked()

core\files\curl_security_helper::host_explicitly_blocked ( $host )

protected

Checks whether the input hostname is blocked by any of the domain/wildcard rules.

Parameters

string

$host

the hostname to check

Return values

bool	true if the host is covered by an entry in the blocklist, false otherwise.

host_is_blocked()

core\files\curl_security_helper::host_is_blocked ( $host )

protected

Checks whether the host portion of a url is blocked.

The host portion may be a FQDN, IPv4 address or a IPv6 address wrapped in square brackets, as per standard URL notation. E.g. images.example.com 127.0.0.1 [0.0.0.0.0.0.0.1] The method logic is as follows:

1. Check the host component against the list of IPv4/IPv6 addresses and ranges.
   • This will perform a DNS forward lookup if required.
2. Check the host component against the list of domain names and wildcard domain names.
   • This will perform a DNS reverse lookup if required.

The behaviour of this function can be classified as strict, as it returns true for hosts which are invalid or could not be parsed, as well as those valid URLs which were found in the blocklist.

Parameters

string

$host

the host component of the URL to check against the blocklist.

Return values

bool	true if the host is both valid and blocked, false otherwise.

is_enabled()

core\files\curl_security_helper::is_enabled

(

)

Convenience method to check whether we have any entries in the host blocklist or ports allowlist admin settings.

If no entries are found at all, the assumption is that the blocklist is disabled entirely.

Return values

bool	true if one or more entries exist, false otherwise.

port_is_blocked()

core\files\curl_security_helper::port_is_blocked ( $port )

protected

Checks whether the given port is blocked, as determined by its absence on the ports allowlist.

Ports are assumed to be blocked unless found in the allowlist.

Parameters

integer | string

$port

the port to check against the ports allowlist.

Return values

bool	true if the port is blocked, false otherwise.

url_is_blocked() [1/2]

core\files\curl_security_helper::url_is_blocked	(		$urlstring,
			$notused = null )

Checks whether the given URL is blocked by checking its address and port number against the allow/block lists.

The behaviour of this function can be classified as strict, as it returns true for URLs which are invalid or could not be parsed, as well as those valid URLs which were found in the blocklist.

Parameters

string	$urlstring	the URL to check.
int	$notused	There used to be an optional parameter $maxredirects for a short while here, not used any more.

Return values

bool	true if the URL is blocked or invalid and false if the URL is not blocked.

url_is_blocked() [2/2]

core\files\curl_security_helper_base::url_is_blocked ( $url )

abstractinherited

Check whether the input url should be blocked or not.

Parameters

string

$url

the url to check.

Return values

bool	true if the url is deemed to be blocked, false otherwise.

Member Data Documentation

$transportschemes

array core\files\curl_security_helper::$transportschemes

protected

Initial value:

= [
        'http' => 80,
        'https' => 443
    ]

of supported transport schemes and their respective default ports.

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The documentation for this class was generated from the following file:

• lib/classes/files/curl_security_helper.php