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This section describes format of userinfo filter files pointed by \sv_filter server cvar.

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Common format and expression syntax:

<key> [op] <value> [ { key [op] <value> { [ ... ] } } ]

Where:

<key> - arbitrary userinfo key to compare, special built-in keys:
    'drop' - action key, can be followed by ban reason string, no further ops or nested keys is allowed
    'date' - represents current date in "YYYY-MM-DD HH:mm" format
    'fname' - filtered 'name' userinfo key (without color sequences)

[op] - optional operator, can be '==', '!=', '>', '>=', '<', '<=', '*' (string pattern match)
		default operator is '==' (equal) and '<' (less) for 'date' key

<value> - integer or string value to compare with the <key>
		default is integer comparison, if you want to force string comparison - use double-quoted values, i.e. "0" instead of 0

Examples:

	ip "127.0.0.1" {
		name * "Unnamed*" {
			drop "You have bad name"
		}
	}

	cl_guid "" { // disallow empty guids
		drop
	}

One-line format (without brackets) is also acceptable:

	ip "127.0.0.1" name * "Unnamed*" drop "You have bad name"
	cl_guid "" drop

Multiple keys/comparisons inside single scope:

	ip "127.0.0.1" {
		name * "*^0*" {
			drop "Black color is not allowed on this server"
		}
		name "SomeBadGuy" {
			drop "Bad Guy."
		}
	}

Date key usage example:

	ip "192.168.11.12" {
		date "2019-06-01" { // hours:minutes can be omitted for this particular case
			drop "Banned till summer."
		}
	}

If there is "date" keys which may expire - engine will perform regular checks and rewrite filter file contents to clear expired ban entries

You can also use '$' prefix in <value> to dereference any server-side cvar, for example:

	snaps < $sv_fps {
		drop "raize your \snaps"
	}

Example of custom password cvar fltering:

	xxpassword != "12345678" {
		drop "sorry, this is a private server"
	}

	I.e. user must do "\setu xxpassword 12345678" to be able to connect


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This section describes available server-side options and commands

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\sv_filter - cvar that point on filter file, if it is "" then filtering will be disabled
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\filter <id> [key1] [key2] ... [keyN] [date +<duration[h|d|w|m]>|<date> ] [reason <text>]
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	this command will kick and ban player with specified <id>
	specified key values will be extracted from his current userinfo and used to construct filter command, acceptable by filter engine
	if no keys specified - "ip" key will be used by default
	default duration unit used with '+' is minutes, additional h(ours), d(ays), w(eeks), m(onths) suffixes can also be specified

Examples:
	\filter 0 name cl_guid

		ban client 0 by his "name" and "cl_guid" userinfo fields

	\filter 0 reason "bad guy."

		ban client by his "ip" address field with a reason "bad guy."

	\filter 0 ip name date +1d

		ban client for 1 day by his ip and name


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\filtercmd <filter format string>
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	pass manually constructed filter string (described in previous section) to the engine

Examples:

	\filtercmd ip "127.0.0.1" name "name" drop "reason"

	\filtercmd name * "*^0*" drop "black color is not allowed"

	scopes are acceptable as well:

	\filtercmd name * "*^0*" { ip != "127.0.0.1" { drop "black color is not allowed" } }


