libnftables: Store top_scope in struct nft_ctx

Allow for interactive sessions to make use of defines. Since parser is
initialized for each line, top scope defines didn't persist although
they are actually useful for stuff like:

| # nft -i
| define goodports = { 22, 23, 80, 443 }
| add rule inet t c tcp dport $goodports accept
| add rule inet t c tcp sport $goodports accept

While being at it, introduce scope_alloc() and scope_free().

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

3 files changed, 22 insertions, 5 deletions

diff --git a/src/libnftables.c b/src/libnftables.c
index e2037243..cd2fcf2f 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -155,6 +155,7 @@ struct nft_ctx *nft_ctx_new(uint32_t flags)
 	nft_ctx_add_include_path(ctx, DEFAULT_INCLUDE_PATH);
 	ctx->parser_max_errors	= 10;
 	init_list_head(&ctx->cache.list);
+	ctx->top_scope = scope_alloc();
 	ctx->flags = flags;
 	ctx->output.output_fp = stdout;
 	ctx->output.error_fp = stderr;
@@ -292,6 +293,7 @@ void nft_ctx_free(struct nft_ctx *ctx)
 	iface_cache_release();
 	cache_release(&ctx->cache);
 	nft_ctx_clear_include_paths(ctx);
+	scope_free(ctx->top_scope);
 	xfree(ctx->state);
 	nft_exit(ctx);
 	xfree(ctx);
@@ -368,7 +370,7 @@ static int nft_parse_bison_buffer(struct nft_ctx *nft, const char *buf,
 {
 	int ret;
 
-	parser_init(nft, nft->state, msgs, cmds);
+	parser_init(nft, nft->state, msgs, cmds, nft->top_scope);
 	nft->scanner = scanner_init(nft->state);
 	scanner_push_buffer(nft->scanner, &indesc_cmdline, buf);
 
@@ -384,7 +386,7 @@ static int nft_parse_bison_filename(struct nft_ctx *nft, const char *filename,
 {
 	int ret;
 
-	parser_init(nft, nft->state, msgs, cmds);
+	parser_init(nft, nft->state, msgs, cmds, nft->top_scope);
 	nft->scanner = scanner_init(nft->state);
 	if (scanner_read_file(nft, filename, &internal_location) < 0)
 		return -1;
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 6f525d5b..3f283256 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -42,13 +42,13 @@
 #include "parser_bison.h"
 
 void parser_init(struct nft_ctx *nft, struct parser_state *state,
-		 struct list_head *msgs, struct list_head *cmds)
+		 struct list_head *msgs, struct list_head *cmds,
+		 struct scope *top_scope)
 {
 	memset(state, 0, sizeof(*state));
-	init_list_head(&state->top_scope.symbols);
 	state->msgs = msgs;
 	state->cmds = cmds;
-	state->scopes[0] = scope_init(&state->top_scope, NULL);
+	state->scopes[0] = scope_init(top_scope, NULL);
 	init_list_head(&state->indesc_list);
 }
 
diff --git a/src/rule.c b/src/rule.c
index 552b3c6b..4abc13c9 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -645,6 +645,15 @@ struct rule *rule_lookup_by_index(const struct chain *chain, uint64_t index)
 	return NULL;
 }
 
+struct scope *scope_alloc(void)
+{
+	struct scope *scope = xzalloc(sizeof(struct scope));
+
+	init_list_head(&scope->symbols);
+
+	return scope;
+}
+
 struct scope *scope_init(struct scope *scope, const struct scope *parent)
 {
 	scope->parent = parent;
@@ -664,6 +673,12 @@ void scope_release(const struct scope *scope)
 	}
 }
 
+void scope_free(struct scope *scope)
+{
+	scope_release(scope);
+	xfree(scope);
+}
+
 void symbol_bind(struct scope *scope, const char *identifier, struct expr *expr)
 {
 	struct symbol *sym;