Use the already existing SCANSTATE_TYPE for keyword scoping.
This is a bit of back-n-forth from string to token and back to string
but it eliminates the helper function and also takes care of error
handling.

Note that JSON parser does not validate the type string at all but
relies upon the kernel to reject wrong ones.
---
Changes since RFC:
- Fix for leaking chain_type token.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 include/rule.h     |  1 -
 src/parser_bison.y | 28 ++++++++++++++--------------
 src/rule.c         | 19 -------------------
 src/scanner.l      |  6 ++++++
 4 files changed, 20 insertions(+), 34 deletions(-)

diff --git a/include/rule.h b/include/rule.h
index e67a01522d318..7c704be846485 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -260,7 +260,6 @@ struct chain {
 
 #define STD_PRIO_BUFSIZE 100
 extern int std_prio_lookup(const char *std_prio_name, int family, int hook);
-extern const char *chain_type_name_lookup(const char *name);
 extern const char *chain_hookname_lookup(const char *name);
 extern struct chain *chain_alloc(void);
 extern struct chain *chain_get(struct chain *chain);
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 96d0e151b1586..405fe8f2690ca 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -715,6 +715,10 @@ int nft_lex(void *, void *, void *);
 
 %token XT		"xt"
 
+%token FILTER		"filter"
+%token NAT		"nat"
+%token ROUTE		"route"
+
 %type <limit_rate>		limit_rate_pkts
 %type <limit_rate>		limit_rate_bytes
 
@@ -1034,6 +1038,9 @@ int nft_lex(void *, void *, void *);
 %type <expr>			set_elem_key_expr
 %destructor { expr_free($$); }	set_elem_key_expr
 
+%type <string>			chain_type
+%destructor { free_const($$); }	chain_type
+
 %%
 
 input			:	/* empty */
@@ -2736,22 +2743,10 @@ type_identifier		:	STRING	{ $$ = $1; }
 			|	CLASSID { $$ = xstrdup("classid"); }
 			;
 
-hook_spec		:	TYPE		close_scope_type	STRING		HOOK		STRING		dev_spec	prio_spec
+hook_spec		:	TYPE		chain_type	close_scope_type	HOOK		STRING		dev_spec	prio_spec
 			{
-				const char *chain_type = chain_type_name_lookup($3);
-
-				if (chain_type == NULL) {
-					erec_queue(error(&@3, "unknown chain type"),
-						   state->msgs);
-					free_const($3);
-					free_const($5);
-					expr_free($6);
-					expr_free($7.expr);
-					YYERROR;
-				}
 				$<chain>0->type.loc = @3;
-				$<chain>0->type.str = xstrdup(chain_type);
-				free_const($3);
+				$<chain>0->type.str = $2;
 
 				$<chain>0->loc = @$;
 				$<chain>0->hook.loc = @5;
@@ -2772,6 +2767,11 @@ hook_spec		:	TYPE		close_scope_type	STRING		HOOK		STRING		dev_spec	prio_spec
 			}
 			;
 
+chain_type		:	FILTER	{ $$ = xstrdup("filter"); }
+			|	NAT	{ $$ = xstrdup("nat"); }
+			|	ROUTE	{ $$ = xstrdup("route"); }
+			;
+
 prio_spec		:	PRIORITY extended_prio_spec
 			{
 				$$ = $2;
diff --git a/src/rule.c b/src/rule.c
index dabc16204f108..c32e08319d149 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -676,25 +676,6 @@ struct symbol *symbol_lookup_fuzzy(const struct scope *scope,
 	return st.obj;
 }
 
-static const char * const chain_type_str_array[] = {
-	"filter",
-	"nat",
-	"route",
-	NULL,
-};
-
-const char *chain_type_name_lookup(const char *name)
-{
-	int i;
-
-	for (i = 0; chain_type_str_array[i]; i++) {
-		if (!strcmp(name, chain_type_str_array[i]))
-			return chain_type_str_array[i];
-	}
-
-	return NULL;
-}
-
 static const char * const chain_hookname_str_array[] = {
 	"prerouting",
 	"input",
diff --git a/src/scanner.l b/src/scanner.l
index 99ace05773816..b397a147ef9bd 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -858,6 +858,12 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 	"out"			{ return OUT; }
 }
 
+<SCANSTATE_TYPE>{
+	"filter"		{ return FILTER; }
+	"nat"			{ return NAT; }
+	"route"			{ return ROUTE; }
+}
+
 "secmark"		{ scanner_push_start_cond(yyscanner, SCANSTATE_SECMARK); return SECMARK; }
 
 "xt"			{ scanner_push_start_cond(yyscanner, SCANSTATE_XT); return XT; }
-- 
2.51.0