[PATCH nftables 5/8] src: add "typeof" keyword

[Florian Westphal <fw@xxxxxxxxx>]

This allows users to specify named sets by using the expression
directly, rather than having to lookup the data type to use, or
the needed size via 'nft describe".

Example:

table filter {
    set allowed_dports {
        type typeof(tcp dport);
    }
    map nametomark {
        type typeof(osf name) : typeof(meta mark);
    }
    map port2helper {
        type ipv4_addr . inet_service : typeof(ct helper);
    }
}

Currently, listing such a table will lose the typeof() expression:

nft will print the datatype instead, just as if "type inet_service"
would have been used.

For types with non-fixed widths, the new "type, width" format
added in previous patch is used.

Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
 src/parser_bison.y | 5 +++++
 src/scanner.l      | 1 +
 2 files changed, 6 insertions(+)

diff --git a/src/parser_bison.y b/src/parser_bison.y
index ee169fbac194..876050ba6863 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -192,6 +192,7 @@ int nft_lex(void *, void *, void *);
 %token DEFINE			"define"
 %token REDEFINE			"redefine"
 %token UNDEFINE			"undefine"
+%token TYPEOF			"typeof"
 
 %token FIB			"fib"
 
@@ -1844,6 +1845,10 @@ data_type_atom_expr	:	type_identifier
 							 $3, NULL);
 				xfree($1);
 			}
+			|	TYPEOF	'('	primary_expr	')'
+			{
+				$$ = $3;
+			}
 			;
 
 data_type_expr		:	data_type_atom_expr
diff --git a/src/scanner.l b/src/scanner.l
index c1adcbddbd73..cd563aa0ca1f 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -243,6 +243,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 "define"		{ return DEFINE; }
 "redefine"		{ return REDEFINE; }
 "undefine"		{ return UNDEFINE; }
+"typeof"		{ return TYPEOF; }
 
 "describe"		{ return DESCRIBE; }
 
-- 
2.21.0