Commit dd8481cc authored by Ondrej Zajicek (work)'s avatar Ondrej Zajicek (work)
Browse files

Flowspec: Do not use comma for bitmask operators 

For numeric operators, comma is used for disjunction in expressions like
"10, 20, 30..40". But for bitmask operators, comma is used for
conjunction in a way that does not really make much sense. Use always
explicit logical operators (&& and ||) to connect bitmask operators.

Thanks to Matt Corallo for the bugreport.
parent e5468d16

doc/bird.sgml

+8 −7
Original line number Diff line number Diff line
@@ -5080,20 +5080,21 @@ options (<cf/bfd/ and <cf/weight 1/), the second nexthop has just <cf/weight 2/. 


<p>The flow specification are rules for routers and firewalls for filtering

purpose. It is described by <rfc id="5575">. There are 3 types of arguments:

<m/inet4/ or <m/inet6/ prefixes, bitmasks matching expressions and numbers

<m/inet4/ or <m/inet6/ prefixes, numeric matching expressions and bitmask

matching expressions.



Bitmasks matching is written using <m/value/<cf>/</cf><m/mask/ or

<cf/!/<m/value/<cf>/</cf><m/mask/ pairs. It means that <cf/(/<m/data/ <cf/&/

<m/mask/<cf/)/ is or is not equal to <m/value/.



Numbers matching is a matching sequence of numbers and ranges separeted by a

Numeric matching is a matching sequence of numbers and ranges separeted by a

commas (<cf/,/) (e.g. <cf/10,20,30/). Ranges can be written using double dots

<cf/../ notation (e.g. <cf/80..90,120..124/). An alternative notation are

sequence of one or more pairs of relational operators and values separated by

logical operators <cf/&&/ or <cf/||/. Allowed relational operators are <cf/=/,

<cf/!=/, <cf/</, <cf/<=/, <cf/>/, <cf/>=/, <cf/true/ and <cf/false/.



Bitmask matching is written using <m/value/<cf>/</cf><m/mask/ or

<cf/!/<m/value/<cf>/</cf><m/mask/ pairs. It means that <cf/(/<m/data/ <cf/&/

<m/mask/<cf/)/ is or is not equal to <m/value/. It is also possible to use

multiple value/mask pairs connected by logical operators <cf/&&/ or <cf/||/.



<sect2>IPv4 Flowspec



<p><descrip>
@@ -5199,7 +5200,7 @@ protocol static { 
		next header = 23;

		sport > 24 && < 30 || = 40 || 50,60,70..80;

		dport = 50;

		tcp flags 0x03/0x0f, !0/0xff || 0x33/0x33;

		tcp flags 0x03/0x0f && !0/0xff || 0x33/0x33;

		fragment !is_fragment || !first_fragment;

		label 0xaaaa/0xaaaa && 0x33/0x33;

	};

filter/test.conf

+1 −1
Original line number Diff line number Diff line
@@ -579,7 +579,7 @@ prefix p; 
	bt_assert(format(flow6 { sport 0..0x400; }) = "flow6 { sport 0..1024; }");

	bt_assert(format(flow6 { icmp type 80; }) = "flow6 { icmp type 80; }");

	bt_assert(format(flow6 { icmp code 90; }) = "flow6 { icmp code 90; }");

	bt_assert(format(flow6 { tcp flags 0x03/0x0f; }) = "flow6 { tcp flags 0x3/0x3,0x0/0xc; }");

	bt_assert(format(flow6 { tcp flags 0x03/0x0f; }) = "flow6 { tcp flags 0x3/0x3 && 0x0/0xc; }");

	bt_assert(format(flow6 { length 0..65535; }) = "flow6 { length 0..65535; }");

	bt_assert(format(flow6 { dscp = 63; }) = "flow6 { dscp 63; }");

	bt_assert(format(flow6 { fragment is_fragment || !first_fragment; }) = "flow6 { fragment is_fragment || !first_fragment; }");

lib/flowspec.c

+2 −11
Original line number Diff line number Diff line
@@ -1278,17 +1278,8 @@ net_format_flow_bitmask(buffer *b, const byte *part) 
  while (1)

  {

    if (!first)

    {

      if (isset_and(op))

      {

	b->pos--; /* Remove last char (it is a space) */

	buffer_puts(b, ",");

      }

      else

      {

	buffer_puts(b, "|| ");

      }

    }

      buffer_puts(b, isset_and(op) ? "&& " : "|| ");



    first = 0;



    len = get_value_length(op);

lib/flowspec_test.c

+1 −1
Original line number Diff line number Diff line
@@ -630,7 +630,7 @@ t_formatting4(void) 
  net_addr_flow4 *input;

  NET_ADDR_FLOW4_(input, ip4_build(5, 6, 7, 0), 24, nlri);



  const char *expect = "flow4 { dst 10.0.0.0/8; proto 23; dport > 24 && < 30 || 40..50,60..70,80 && >= 90; sport > 24 && < 30 || 40,50,60..70,80; icmp type 80; icmp code 90; tcp flags 0x3/0x3,0x0/0xc; length 0..65535; dscp 63; fragment dont_fragment || !is_fragment; }";

  const char *expect = "flow4 { dst 10.0.0.0/8; proto 23; dport > 24 && < 30 || 40..50,60..70,80 && >= 90; sport > 24 && < 30 || 40,50,60..70,80; icmp type 80; icmp code 90; tcp flags 0x3/0x3 && 0x0/0xc; length 0..65535; dscp 63; fragment dont_fragment || !is_fragment; }";



  bt_assert(flow4_net_format(b, sizeof(b), input) == strlen(expect));

  bt_debug(" expect: '%s',\n output: '%s'\n", expect, b);

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