Fix SolidCache JSON sanitisation

The issue lies on the fact that a binary MySQL string (`x"..."`)
appears before a regular MySQL string (`"..."`). This trips the
sanitiser, which recognises the leading `x` as a literal value type
indicator. After the literal value type indicator state is over,
the sanitiser forgets that it's inside a VALUES statement.

Fix this by keeping track of a "context state" to return to after
certain state transitions, instead of always returning to the
default state.

Co-authored-by: Luismi Ramirez <luismi@appsignal.com>

src/sanitizer.rs

@@ -1,6 +1,6 @@
 use super::{Keyword, Sql, Token};
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone, Copy)]
 enum State {
     Default,
     ComparisonOperator,
@@ -28,6 +28,7 @@ impl SqlSanitizer {
 
     pub fn sanitize(mut self) -> Sql {
         let mut state = State::Default;
+        let mut context_state = State::Default;
 
         let mut pos = 0;
         loop {
@@ -55,7 +56,7 @@ impl SqlSanitizer {
                     state = State::KeywordScopeStarted
                 }
                 Token::Keyword(_) => state = State::Keyword,
-                Token::LiteralValueTypeIndicator(_) => state = State::LiteralValueTypeIndicator,
+                Token::LiteralValueTypeIndicator(_) => {context_state = state; state = State::LiteralValueTypeIndicator},
                 Token::ParentheseOpen if state == State::ComparisonOperator => {
                     state = State::ComparisonScopeStarted
                 }
@@ -65,7 +66,8 @@ impl SqlSanitizer {
                 Token::ParentheseOpen if state == State::InsertValues => (),
                 Token::SquareBracketOpen if state == State::Array => state = State::ArrayStarted,
                 Token::ParentheseClose if state == State::InsertValues => {
-                    state = State::InsertValuesJustClosed
+                    state = State::InsertValuesJustClosed;
+                    context_state = State::Default;
                 }
                 Token::Comma if state == State::InsertValuesJustClosed => (),
                 Token::ParentheseOpen if state == State::InsertValuesJustClosed => {
@@ -130,7 +132,7 @@ impl SqlSanitizer {
                 // Keep state the same if we're in a insert values or keyword scope state
                 _ if state == State::InsertValues || state == State::KeywordScopeStarted => (),
                 // Reset state to default if there were no matches
-                _ => state = State::Default,
+                _ => state = context_state,
             }
 
             pos += 1;
@@ -371,6 +373,14 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_solidcache_json() {
+        assert_eq!(
+            sanitize_string("INSERT INTO `solid_cache_entries` (`key`,`value`,`created_at`) VALUES (x'76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31', '{\"p\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31\",\"h\":{\"iv\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31\",\"at\":\"/76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31==\",\"e\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31==\",\"k\":{\"p\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31=\",\"h\":{\"iv\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31\",\"at\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31==\",\"e\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31==\"}},\"i\":\"76696577732f6974656d732f696e6465783a38323536366332313963306634393838626133333533366630623233623336382f6974656d732f31==\",\"c\":true}}', CURRENT_TIMESTAMP(6)) ON DUPLICATE KEY UPDATE `value`=VALUES(`value`)".to_string()),
+            "INSERT INTO `solid_cache_entries` (`key`,`value`,`created_at`) VALUES (x?, ?, CURRENT_TIMESTAMP(?)) ON DUPLICATE KEY UPDATE `value`=VALUES(`value`)"
+        );
+    }
+
     #[test]
     fn test_case_then_else_subquery() {
         assert_eq!(