[PATCH nft] src: add misspell hint for ct timeout policy names

[Florian Westphal <fw@strlen.de>]

before:
Error: invalid state for this protocol
add ct timeout t foo { protocol tcp; policy = { estblshed : 2 }; }
                                                ^^^^^^^^^
after:
Error: invalid state 'estblshed' for this protocol; did you mean 'established'?
add ct timeout t foo { protocol tcp; policy = { estblshed : 2 }; }

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/rule.h |  1 +
 src/evaluate.c | 19 +++++++++++++++++--
 src/rule.c     | 19 +++++++++++++++++++
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/include/rule.h b/include/rule.h
index 7b7b7eb1012d..09fd045c7385 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -882,5 +882,6 @@ struct timeout_protocol {
 
 extern struct timeout_protocol timeout_protocol[UINT8_MAX + 1];
 extern int timeout_str2num(uint16_t l4proto, struct timeout_state *ts);
+extern const char *timeout_lookup_fuzzy(uint16_t l4proto, const char *name);
 
 #endif /* NFTABLES_RULE_H */
diff --git a/src/evaluate.c b/src/evaluate.c
index 01b4afbbb10d..f424b987f8f8 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -5826,6 +5826,21 @@ static int ct_expect_evaluate(struct eval_ctx *ctx, struct obj *obj)
 	return 0;
 }
 
+static int timeout_not_found(struct eval_ctx *ctx, const struct location *loc,
+			     uint16_t l4proto, const char *state_name)
+{
+	const char *suggestion;
+
+	suggestion = timeout_lookup_fuzzy(l4proto, state_name);
+	if (suggestion == NULL)
+		return cmd_error(ctx, loc, "invalid state '%s' for this protocol",
+				 state_name);
+
+	return cmd_error(ctx, loc,
+			 "invalid state '%s' for this protocol; did you mean '%s'?",
+			 state_name, suggestion);
+}
+
 static int ct_timeout_evaluate(struct eval_ctx *ctx, struct obj *obj)
 {
 	struct ct_timeout *ct = &obj->ct_timeout;
@@ -5837,8 +5852,8 @@ static int ct_timeout_evaluate(struct eval_ctx *ctx, struct obj *obj)
 
 	list_for_each_entry_safe(ts, next, &ct->timeout_list, head) {
 		if (timeout_str2num(ct->l4proto, ts) < 0)
-			return __stmt_binary_error(ctx, &ts->location, NULL,
-						   "invalid state for this protocol");
+			return timeout_not_found(ctx, &ts->location,
+						 ct->l4proto, ts->timeout_str);
 
 		ct->timeout[ts->timeout_index] = ts->timeout_value;
 		list_del(&ts->head);
diff --git a/src/rule.c b/src/rule.c
index 552c17df05f8..d232582b6080 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -89,6 +89,25 @@ struct timeout_protocol timeout_protocol[UINT8_MAX + 1] = {
 	},
 };
 
+const char *timeout_lookup_fuzzy(uint16_t l4proto, const char *name)
+{
+	struct string_misspell_state st;
+	unsigned int i;
+
+	if (!name)
+		return NULL;
+
+	string_misspell_init(&st);
+
+	for (i = 0; i < timeout_protocol[l4proto].array_size; i++)
+		string_misspell_update(timeout_protocol[l4proto].state_to_name[i],
+				       name,
+				       (void *)timeout_protocol[l4proto].state_to_name[i],
+				       &st);
+
+	return st.obj;
+}
+
 int timeout_str2num(uint16_t l4proto, struct timeout_state *ts)
 {
 	unsigned int i;
-- 
2.55.0