exthdr: Implement existence check

This allows to check for existence of an IPv6 extension or TCP
option header by using the following syntax:

| exthdr frag exists
| tcpopt window exists

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/scanner.l b/src/scanner.l
index b0d57198..c2c008d6 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -507,6 +507,8 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 "exists"		{ return EXISTS; }
 "missing"		{ return MISSING; }
 
+"exthdr"		{ return EXTHDR; }
+
 {addrstring}		{
 				yylval->string = xstrdup(yytext);
 				return STRING;