Doc: Minor documentation fixes

variable number of options, they are grouped using the <cf/{ }/ brackets. Each

option is terminated by a <cf/;/. Configuration is case sensitive. There are two

ways how to name symbols (like protocol names, filter names, constants etc.).

You can either use a simple string starting with a letter followed by any

combination of letters and numbers (e.g. <cf/R123/, <cf/myfilter/, <cf/bgp5/) or

you can enclose the name into apostrophes (<cf/'/) and than you can use any

combination of numbers, letters. hyphens, dots and colons (e.g.

<cf/'1:strange-name'/, <cf/'-NAME-'/, <cf/'cool::name'/).

You can either use a simple string starting with a letter (or underscore)

followed by any combination of letters, numbers and underscores (e.g. <cf/R123/,

<cf/my_filter/, <cf/bgp5/) or you can enclose the name into apostrophes (<cf/'/)

and than you can use any combination of numbers, letters, underscores, hyphens,

dots and colons (e.g.  <cf/'1:strange-name'/, <cf/'-NAME-'/, <cf/'cool::name'/).

<p>Here is an example of a simple config file. It enables synchronization of

routing tables with OS kernel, learns network interfaces and runs RIP on all

	<tag><label id="opt-attribute">attribute <m/type/ <m/name/</tag>

	Declare a custom route attribute. You can set and get it in filters like

	any other route atribute. This feature is intended for marking routes

	any other route attribute. This feature is intended for marking routes

	in import filters for export filtering purposes instead of locally

	assigned BGP communities which have to be deleted in export filters.

<label id="data-types">

<p>Each variable and each value has certain type. Booleans, integers and enums

are incompatible with each other (that is to prevent you from shooting in the

foot).

are incompatible with each other (that is to prevent you from shooting oneself

in the foot).

<descrip>

	<tag><label id="type-bool">bool</tag>

	This type can hold a single IP address. The IPv4 addresses are stored as

	IPv4-Mapped IPv6 addresses so one data type for both of them is used.

	Whether the address is IPv4 or not may be checked by <cf>.is_ip4</cf>

	which returns <cf/bool/. IP addresses are written in the standard

	which returns a <cf/bool/. IP addresses are written in the standard

	notation (<cf/10.20.30.40/ or <cf/fec0:3:4::1/). You can apply special

	operator <cf>.mask(<M>num</M>)</cf> on values of type ip. It masks out

	all but first <cf><M>num</M></cf> bits from the IP address. So

	<cf/!&tilde;/ membership operators) can be used to modify or test

	eclists, with ECs instead of pairs as arguments.

	<tag><label id="type-lclist">lclist/</tag>

	<tag><label id="type-lclist">lclist</tag>

	Lclist is a data type used for BGP large community lists. Like eclists,

	lclists are very similar to clists, but they are sets of LCs instead of

	pairs. The same operations (like <cf/add/, <cf/delete/ or <cf/&tilde;/

<p>There is one operator related to ROA infrastructure - <cf/roa_check()/. It

examines a ROA table and does <rfc id="6483"> route origin validation for a

given network prefix. The basic usage is <cf>roa_check(<m/table/)</cf>, which

checks current route (which should be from BGP to have AS_PATH argument) in the

specified ROA table and returns ROA_UNKNOWN if there is no relevant ROA,

checks the current route (which should be from BGP to have AS_PATH argument) in

the specified ROA table and returns ROA_UNKNOWN if there is no relevant ROA,

ROA_VALID if there is a matching ROA, or ROA_INVALID if there are some relevant

ROAs but none of them match. There is also an extended variant

<cf>roa_check(<m/table/, <m/prefix/, <m/asn/)</cf>, which allows to specify a

filter peer_in_v4 {

	if (roa_check(r4, net, bgp_path.last) = ROA_INVALID) then

	{

		print "Ignore invalid ROA ", net, " for ASN ", bgp_path.last;

		print "Ignore RPKI invalid ", net, " for ASN ", bgp_path.last;

		reject;

	}

	accept;