NAME

Redirectors - Check for redirected URLs

SYNOPSIS

  loadplugin    Mail::SpamAssassin::Plugin::Redirectors
  url_redirector bing.com
  body HAS_REDIR_URL          eval:redir_url()
  describe HAS_REDIR_URL      Message has one or more redirected URLs
  body REDIR_URL_CHAINED      eval:redir_url_chained()
  describe REDIR_URL_CHAINED  Message has redirected URL chained to other redirectors
  body REDIR_URL_CHAINED_DOM      eval:redir_url_chained_domain()
  describe REDIR_URL_CHAINED_DOM  Message has redirected URL chained to another redirector on the same domain
  body REDIR_URL_MAXCHAIN     eval:redir_url_maxchain()
  describe REDIR_URL_MAXCHAIN Message has redirected URL that causes too many redirections
  body REDIR_URL_LOOP         eval:redir_url_loop()
  describe REDIR_URL_LOOP     Message has redirected URL that loops back to itself
  body REDIR_URL_404          eval:redir_url_code('404') # Can check any non-redirect HTTP code
  describe REDIR_URL_404      Message has redirected URL returning HTTP 404

DESCRIPTION

This plugin looks for URLs redirected by a list of URL redirector services. Upon finding a matching URL, plugin will send a HTTP request to the redirector service and retrieve the Location-header which points to the actual redirected URL. It then adds this URL to the list of URIs extracted by SpamAssassin which can then be accessed by uri rules and plugins such as URIDNSBL.

This plugin will follow chained redirections, where a redirected URL redirects to another redirector. Redirection depth limit can be set with "max_redir_url_redirections".

Maximum of "max_redir_urls" redirected URLs are checked in a message (10 by default). Setting it to 0 disables HTTP requests, allowing only redir_url() test to work and report found redirectors.

All supported rule types for checking redirector URLs and redirection status are documented in SYNOPSIS section.

NOTES

This plugin runs at the check_dnsbl hook (priority -100) so that it may modify the parsed URI list prior to normal uri rules or the URIDNSBL plugin.

USER SETTINGS

url_redirector domain [domain...] (default: none)

Domains that should be considered as an URL redirector. If the domain begins with a '.', 3rd level tld of the main domain will be checked. The 3rd level starting with www with always be checked for every 2tld.

Example:

 url_redirector bing.com
 url_redirector .sendgrid.com

clear_url_redirector [domain] [domain...]

Clear configured url_redirector domains, for example to override default settings from an update channel. If domains are specified, then only those are removed from list.

url_redirector_get domain [domain...] (default: none)

Domains that should be considered as an URL redirector. If the domain begins with a '.', 3rd level tld of the main domain will be checked. The http GET method will be used to check those domains.

Regexp used to parse uri parameters in order to detect redirectors and to get redirected domains. The regexp must match only the redirected domain.

PRIVILEGED SETTINGS

url_redirector_cache_type (default: none)

The cache type that is being utilized. Currently only supported value is "dbi" that implies "url_redirector_cache_dsn" is a DBI connect string. DBI module is required.

Example: url_redirector_cache_type dbi

url_redirector_cache_dsn (default: none)

The DBI dsn of the database to use.

For SQLite, the database will be created automatically if it does not already exist, the supplied path and file must be read/writable by the user running spamassassin or spamd.

For MySQL/MariaDB or PostgreSQL, see sql-directory for database table creation clauses.

You will need to have the proper DBI module for your database. For example DBD::SQLite, DBD::mysql, DBD::MariaDB or DBD::Pg.

Minimum required SQLite version is 3.24.0 (available from DBD::SQLite 1.59_01).

Examples:

 url_redirector_cache_dsn dbi:SQLite:dbname=/var/lib/spamassassin/Redirectors.db

url_redirector_cache_username (default: none)

The username that should be used to connect to the database. Not used for SQLite.

url_redirector_cache_password (default: none)

The password that should be used to connect to the database. Not used for SQLite.

url_redirector_cache_ttl (default: 86400)

The length of time a cache entry will be valid for in seconds. Default is 86400 (1 day).

See "url_redirector_cache_autoclean" for database cleaning.

ADMINISTRATOR SETTINGS

url_redirector_cache_autoclean (default: 1000): Automatically purge old entries from database. Value describes a random run chance of 1/x. The default value of 1000 means that cleaning is run approximately once for every 1000 messages processed. Value of 1 would mean database is cleaned every time a message is processed.
Set 0 to disable automatic cleaning and to do it manually.
url_redirector_loginfo (default: 0 (off)): If this option is enabled (set to 1), then redirected URLs and the decoded URLs will be logged with info priority.
url_redirector_timeout (default: 5): Maximum time a redirection URL HTTP request can take, in seconds.
max_redir_urls (default: 10): Maximum amount of redirector URLs that will be looked up per message. Chained redirections are not counted, only initial redirection URLs found.
Setting it to 0 disables HTTP requests, allowing only redir_url() test to work and report any found redirector URLs.
max_redir_url_redirections (default: 10): Maximum depth of chained redirections that a redirector can generate.
url_redirector_user_agent (default: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.67 Safari/537.36): Set User-Agent header for HTTP requests. Some services require it to look like a common browser.