[PATCH nft 3/4] src: Display parser and evaluate errors in one shot

[Pablo Neira Ayuso <pablo@netfilter.org>]

This patch restores 61236968b7a1 ("parser: evaluate commands immediately
after parsing") following a different approach.

In this patch, the evaluation phase is done if the parsing phase fails,
hence the user gets parsing and evaluation errors in one shot, which is
the purpose of 61236968b7a1.

Note that evaluation errors are now shown after parser errors, the example
available in 61236968b7a1 displays with this patch the following error:

 # nft -f /tmp/bad.nft
 /tmp/bad.nft:3:32-32: Error: syntax error, unexpected newline
 add rule filter input tcp dport
                                ^
 /tmp/bad.nft:5:37-41: Error: syntax error, unexpected dport, expecting end of file or newline or semicolon
 add rule filter input tcp dport tcp dport
                                     ^^^^^
 /tmp/bad.nft:4:33-35: Error: datatype mismatch, expected internet network service, expression has type Internet protocol
 add rule filter input tcp dport tcp
                       ~~~~~~~~~ ^^^

So evaluation pointing to line 4 happens after line error reporting
generated by the parser that points to line 3, while 61236968b7a1 was
showing errors per line in order. As a future work, we can sort the
error reporting list to restore exactly the same behaviour.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/libnftables.c | 22 ++++++++++++++++------
 src/parser_json.c |  9 ---------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/libnftables.c b/src/libnftables.c
index 8720fe2bebaf..f459ecd50e45 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -400,11 +400,11 @@ static int nft_evaluate(struct nft_ctx *nft, struct list_head *msgs,
 
 int nft_run_cmd_from_buffer(struct nft_ctx *nft, const char *buf)
 {
+	int rc = -EINVAL, parser_rc;
 	struct cmd *cmd, *next;
 	LIST_HEAD(msgs);
 	LIST_HEAD(cmds);
 	char *nlbuf;
-	int rc = -EINVAL;
 
 	nlbuf = xzalloc(strlen(buf) + 2);
 	sprintf(nlbuf, "%s\n", buf);
@@ -413,13 +413,18 @@ int nft_run_cmd_from_buffer(struct nft_ctx *nft, const char *buf)
 		rc = nft_parse_json_buffer(nft, nlbuf, &msgs, &cmds);
 	if (rc == -EINVAL)
 		rc = nft_parse_bison_buffer(nft, nlbuf, &msgs, &cmds);
-	if (rc)
-		goto err;
+
+	parser_rc = rc;
 
 	rc = nft_evaluate(nft, &msgs, &cmds);
 	if (rc < 0)
 		goto err;
 
+	if (parser_rc) {
+		rc = parser_rc;
+		goto err;
+	}
+
 	if (nft_netlink(nft, &cmds, &msgs, nft->nf_sock) != 0)
 		rc = -1;
 err:
@@ -445,9 +450,9 @@ err:
 int nft_run_cmd_from_filename(struct nft_ctx *nft, const char *filename)
 {
 	struct cmd *cmd, *next;
+	int rc, parser_rc;
 	LIST_HEAD(msgs);
 	LIST_HEAD(cmds);
-	int rc;
 
 	rc = cache_update(nft, CMD_INVALID, &msgs);
 	if (rc < 0)
@@ -461,13 +466,18 @@ int nft_run_cmd_from_filename(struct nft_ctx *nft, const char *filename)
 		rc = nft_parse_json_filename(nft, filename, &msgs, &cmds);
 	if (rc == -EINVAL)
 		rc = nft_parse_bison_filename(nft, filename, &msgs, &cmds);
-	if (rc)
-		goto err;
+
+	parser_rc = rc;
 
 	rc = nft_evaluate(nft, &msgs, &cmds);
 	if (rc < 0)
 		goto err;
 
+	if (parser_rc) {
+		rc = parser_rc;
+		goto err;
+	}
+
 	if (nft_netlink(nft, &cmds, &msgs, nft->nf_sock) != 0)
 		rc = -1;
 err:
diff --git a/src/parser_json.c b/src/parser_json.c
index 5532ead36c6a..081cf5da7f39 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -3390,10 +3390,6 @@ static json_t *seqnum_to_json(const uint32_t seqnum)
 
 static int __json_parse(struct json_ctx *ctx)
 {
-	struct eval_ctx ectx = {
-		.nft = ctx->nft,
-		.msgs = ctx->msgs,
-	};
 	json_t *tmp, *value;
 	size_t index;
 
@@ -3435,11 +3431,6 @@ static int __json_parse(struct json_ctx *ctx)
 
 		list_add_tail(&cmd->list, &list);
 
-		if (cmd_evaluate(&ectx, cmd) < 0) {
-			cmd_free(cmd);
-			json_error(ctx, "Evaluating command at index %zd failed.", index);
-			return -1;
-		}
 		list_splice_tail(&list, ctx->cmds);
 
 		if (nft_output_echo(&ctx->nft->output))
-- 
2.11.0