Add maximum data size limits.

README.md

@@ -14,7 +14,7 @@ to add scripting to any application.
 Features
 --------
 
-* Easy-to-use language similar to JS+Rust with dynamic typing but _no_ garbage collector.
+* Easy-to-use language similar to JS+Rust with dynamic typing.
 * Tight integration with native Rust [functions](#working-with-functions) and [types](#custom-types-and-methods),
   including [getters/setters](#getters-and-setters), [methods](#members-and-methods) and [indexers](#indexers).
 * Freely pass Rust variables/constants into a script via an external [`Scope`].
@@ -25,7 +25,7 @@ Features
   one single source file, all with names starting with `"unsafe_"`).
 * Re-entrant scripting [`Engine`] can be made `Send + Sync` (via the [`sync`] feature).
 * Sand-boxed - the scripting [`Engine`], if declared immutable, cannot mutate the containing environment unless explicitly permitted (e.g. via a `RefCell`).
-* Rugged (protection against [stack-overflow](#maximum-call-stack-depth) and [runaway scripts](#maximum-number-of-operations) etc.).
+* Rugged - protection against malicious attacks (such as [stack-overflow](#maximum-call-stack-depth), [over-sized data](#maximum-length-of-strings), and [runaway scripts](#maximum-number-of-operations) etc.) that may come from untrusted third-party user-land scripts.
 * Track script evaluation [progress](#tracking-progress-and-force-terminate-script-run) and manually terminate a script run.
 * [`no-std`](#optional-features) support.
 * [Function overloading](#function-overloading).
@@ -1191,13 +1191,16 @@ fn main() -> Result<(), Box<EvalAltResult>>
 Engine configuration options
 ---------------------------
 
-| Method                   | Description                                                                                                                                         |
+| Method                   | Not available under          | Description                                                                                                                                         |
-| ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------- |
+| ------------------------ | ---------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `set_optimization_level` | Set the amount of script _optimizations_ performed. See [script optimization].                                                                      |
+| `set_optimization_level` | [`no_optimize`]              | Set the amount of script _optimizations_ performed. See [script optimization].                                                                      |
-| `set_max_expr_depths`    | Set the maximum nesting levels of an expression/statement. See [maximum statement depth](#maximum-statement-depth).                                 |
+| `set_max_expr_depths`    | [`unchecked`]                | Set the maximum nesting levels of an expression/statement. See [maximum statement depth](#maximum-statement-depth).                                 |
-| `set_max_call_levels`    | Set the maximum number of function call levels (default 50) to avoid infinite recursion. See [maximum call stack depth](#maximum-call-stack-depth). |
+| `set_max_call_levels`    | [`unchecked`]                | Set the maximum number of function call levels (default 50) to avoid infinite recursion. See [maximum call stack depth](#maximum-call-stack-depth). |
-| `set_max_operations`     | Set the maximum number of _operations_ that a script is allowed to consume. See [maximum number of operations](#maximum-number-of-operations).      |
+| `set_max_operations`     | [`unchecked`]                | Set the maximum number of _operations_ that a script is allowed to consume. See [maximum number of operations](#maximum-number-of-operations).      |
-| `set_max_modules`        | Set the maximum number of [modules] that a script is allowed to load. See [maximum number of modules](#maximum-number-of-modules).                  |
+| `set_max_modules`        | [`unchecked`]                | Set the maximum number of [modules] that a script is allowed to load. See [maximum number of modules](#maximum-number-of-modules).                  |
+| `set_max_string_size`    | [`unchecked`]                | Set the maximum length (in UTF-8 bytes) for [strings]. See [maximum length of strings](#maximum-length-of-strings).                                 |
+| `set_max_array_size`     | [`unchecked`], [`no_index`]  | Set the maximum size for [arrays]. See [maximum size of arrays](#maximum-size-of-arrays).                                                           |
+| `set_max_map_size`       | [`unchecked`], [`no_object`] | Set the maximum number of properties for [object maps]. See [maximum size of object maps](#maximum-size-of-object-maps).                            |
 
 -------
 
@@ -1498,6 +1501,9 @@ record == "Bob X. Davis: age 42 ❤\n";
 'C' in record == false;
 ```
 
+The maximum allowed length of a string can be controlled via `Engine::set_max_string_size`
+(see [maximum length of strings](#maximum-length-of-strings)).
+
 ### Built-in functions
 
 The following standard methods (mostly defined in the [`MoreStringPackage`](#packages) but excluded if using a [raw `Engine`]) operate on strings:
@@ -1673,6 +1679,9 @@ y.len == 0;
 engine.register_fn("push", |list: &mut Array, item: MyType| list.push(Box::new(item)) );
 ```
 
+The maximum allowed size of an array can be controlled via `Engine::set_max_array_size`
+(see [maximum size of arrays](#maximum-size-of-arrays)).
+
 Object maps
 -----------
 
@@ -1776,6 +1785,9 @@ y.clear();              // empty the object map
 y.len() == 0;
 ```
 
+The maximum allowed size of an object map can be controlled via `Engine::set_max_map_size`
+(see [maximum size of object maps](#maximum-size-of-object-maps)).
+
 ### Parsing from JSON
 
 The syntax for an object map is extremely similar to JSON, with the exception of `null` values which can
@@ -2439,7 +2451,7 @@ a script so that it does not consume more resources that it is allowed to.
 
 The most important resources to watch out for are:
 
-* **Memory**: A malicous script may continuously grow an [array] or [object map] until all memory is consumed.
+* **Memory**: A malicous script may continuously grow a [string], an [array] or [object map] until all memory is consumed.
   It may also create a large [array] or [object map] literal that exhausts all memory during parsing.
 * **CPU**: A malicous script may run an infinite tight loop that consumes all CPU cycles.
 * **Time**: A malicous script may run indefinitely, thereby blocking the calling system which is waiting for a result.
@@ -2455,6 +2467,60 @@ The most important resources to watch out for are:
 * **Data**: A malicous script may attempt to read from and/or write to data that it does not own. If this happens,
   it is a severe security breach and may put the entire system at risk.
 
+### Maximum length of strings
+
+Rhai by default does not limit how long a [string] can be.
+This can be changed via the `Engine::set_max_string_size` method, with zero being unlimited (the default).
+
+```rust
+let mut engine = Engine::new();
+
+engine.set_max_string_size(500);            // allow strings only up to 500 bytes long (in UTF-8 format)
+
+engine.set_max_string_size(0);              // allow unlimited string length
+```
+
+A script attempting to create a string literal longer than the maximum will terminate with a parse error.
+Any script operation that produces a string longer than the maximum also terminates the script with an error result.
+This check can be disabled via the [`unchecked`] feature for higher performance
+(but higher risks as well).
+
+### Maximum size of arrays
+
+Rhai by default does not limit how large an [array] can be.
+This can be changed via the `Engine::set_max_array_size` method, with zero being unlimited (the default).
+
+```rust
+let mut engine = Engine::new();
+
+engine.set_max_array_size(500);             // allow arrays only up to 500 items
+
+engine.set_max_array_size(0);               // allow unlimited arrays
+```
+
+A script attempting to create an array literal larger than the maximum will terminate with a parse error.
+Any script operation that produces an array larger than the maximum also terminates the script with an error result.
+This check can be disabled via the [`unchecked`] feature for higher performance
+(but higher risks as well).
+
+### Maximum size of object maps
+
+Rhai by default does not limit how large (i.e. the number of properties) an [object map] can be.
+This can be changed via the `Engine::set_max_map_size` method, with zero being unlimited (the default).
+
+```rust
+let mut engine = Engine::new();
+
+engine.set_max_map_size(500);               // allow object maps with only up to 500 properties
+
+engine.set_max_map_size(0);                 // allow unlimited object maps
+```
+
+A script attempting to create an object map literal with more properties than the maximum will terminate with a parse error.
+Any script operation that produces an object map with more properties than the maximum also terminates the script with an error result.
+This check can be disabled via the [`unchecked`] feature for higher performance
+(but higher risks as well).
+
 ### Maximum number of operations
 
 Rhai by default does not limit how much time or CPU a script consumes.

RELEASES.md

@@ -21,6 +21,7 @@ New features
 
 * Indexers are now split into getters and setters (which now support updates).  The API is split into `Engine::register_indexer_get` and `Engine::register_indexer_set` with `Engine::register_indexer_get_set` being a shorthand.  Similarly, `Module::set_indexer_get_fn` and `Module::set_indexer_set_fn` are added.
 * `Engine:register_fn` and `Engine:register_result_fn` accepts functions that take parameters of type `&str` (immutable string slice), which maps directly to `ImmutableString`. This is to avoid needing wrappers for functions taking string parameters.
+* Set maximum limit on data sizes: `Engine::set_max_string_size`, `Engine::set_max_array_size` and `Engine::set_max_map_size`.
 
 
 Version 0.15.0

src/api.rs

@@ -547,7 +547,7 @@ impl Engine {
         scripts: &[&str],
         optimization_level: OptimizationLevel,
     ) -> Result<AST, ParseError> {
-        let stream = lex(scripts);
+        let stream = lex(scripts, self.max_string_size);
         self.parse(&mut stream.peekable(), scope, optimization_level)
     }
 
@@ -669,7 +669,7 @@ impl Engine {
 
         // Trims the JSON string and add a '#' in front
         let scripts = ["#", json.trim()];
-        let stream = lex(&scripts);
+        let stream = lex(&scripts, self.max_string_size);
         let ast =
             self.parse_global_expr(&mut stream.peekable(), &scope, OptimizationLevel::None)?;
 
@@ -750,7 +750,7 @@ impl Engine {
         script: &str,
     ) -> Result<AST, ParseError> {
         let scripts = [script];
-        let stream = lex(&scripts);
+        let stream = lex(&scripts, self.max_string_size);
 
         {
             let mut peekable = stream.peekable();
@@ -904,7 +904,7 @@ impl Engine {
         script: &str,
     ) -> Result<T, Box<EvalAltResult>> {
         let scripts = [script];
-        let stream = lex(&scripts);
+        let stream = lex(&scripts, self.max_string_size);
 
         let ast = self.parse_global_expr(
             &mut stream.peekable(),
@@ -1034,7 +1034,7 @@ impl Engine {
         script: &str,
     ) -> Result<(), Box<EvalAltResult>> {
         let scripts = [script];
-        let stream = lex(&scripts);
+        let stream = lex(&scripts, self.max_string_size);
 
         let ast = self.parse(&mut stream.peekable(), scope, self.optimization_level)?;
         self.consume_ast_with_scope(scope, &ast)

src/engine.rs

@@ -67,6 +67,13 @@ pub const MAX_EXPR_DEPTH: usize = usize::MAX;
 #[cfg(feature = "unchecked")]
 pub const MAX_FUNCTION_EXPR_DEPTH: usize = usize::MAX;
 
+#[cfg(feature = "unchecked")]
+pub const MAX_STRING_SIZE: usize = usize::MAX;
+#[cfg(feature = "unchecked")]
+pub const MAX_ARRAY_SIZE: usize = usize::MAX;
+#[cfg(feature = "unchecked")]
+pub const MAX_MAP_SIZE: usize = usize::MAX;
+
 pub const KEYWORD_PRINT: &str = "print";
 pub const KEYWORD_DEBUG: &str = "debug";
 pub const KEYWORD_TYPE_OF: &str = "type_of";
@@ -262,6 +269,12 @@ pub struct Engine {
     pub(crate) max_operations: u64,
     /// Maximum number of modules allowed to load.
     pub(crate) max_modules: u64,
+    /// Maximum length of a string.
+    pub(crate) max_string_size: usize,
+    /// Maximum length of an array.
+    pub(crate) max_array_size: usize,
+    /// Maximum number of properties in a map.
+    pub(crate) max_map_size: usize,
 }
 
 impl Default for Engine {
@@ -298,6 +311,9 @@ impl Default for Engine {
             max_function_expr_depth: MAX_FUNCTION_EXPR_DEPTH,
             max_operations: u64::MAX,
             max_modules: u64::MAX,
+            max_string_size: usize::MAX,
+            max_array_size: usize::MAX,
+            max_map_size: usize::MAX,
         };
 
         engine.load_package(StandardPackage::new().get());
@@ -442,6 +458,9 @@ impl Engine {
             max_function_expr_depth: MAX_FUNCTION_EXPR_DEPTH,
             max_operations: u64::MAX,
             max_modules: u64::MAX,
+            max_string_size: usize::MAX,
+            max_array_size: usize::MAX,
+            max_map_size: usize::MAX,
         }
     }
 
@@ -495,13 +514,33 @@ impl Engine {
         self.max_modules = if modules == 0 { u64::MAX } else { modules };
     }
 
-    /// Set the depth limits for expressions/statements.
+    /// Set the depth limits for expressions/statements (0 for unlimited).
     #[cfg(not(feature = "unchecked"))]
     pub fn set_max_expr_depths(&mut self, max_expr_depth: usize, max_function_expr_depth: usize) {
         self.max_expr_depth = max_expr_depth;
         self.max_function_expr_depth = max_function_expr_depth;
     }
 
+    /// Set the maximum length of strings (0 for unlimited).
+    #[cfg(not(feature = "unchecked"))]
+    pub fn set_max_string_size(&mut self, max_size: usize) {
+        self.max_string_size = max_size;
+    }
+
+    /// Set the maximum length of arrays (0 for unlimited).
+    #[cfg(not(feature = "unchecked"))]
+    #[cfg(not(feature = "no_index"))]
+    pub fn set_max_array_size(&mut self, max_size: usize) {
+        self.max_array_size = max_size;
+    }
+
+    /// Set the maximum length of object maps (0 for unlimited).
+    #[cfg(not(feature = "unchecked"))]
+    #[cfg(not(feature = "no_object"))]
+    pub fn set_max_map_size(&mut self, max_size: usize) {
+        self.max_map_size = max_size;
+    }
+
     /// Set the module resolution service used by the `Engine`.
     ///
     /// Not available under the `no_module` feature.
@@ -1395,7 +1434,7 @@ impl Engine {
         self.inc_operations(state)
             .map_err(|err| EvalAltResult::new_position(err, expr.position()))?;
 
-        match expr {
+        let result = match expr {
             Expr::Expr(x) => self.eval_expr(scope, state, lib, x.as_ref(), level),
 
             Expr::IntegerConstant(x) => Ok(x.0.into()),
@@ -1731,7 +1770,13 @@ impl Engine {
             Expr::Unit(_) => Ok(().into()),
 
             _ => unreachable!(),
+        };
+
+        if let Ok(val) = &result {
+            self.check_data_size(val)?;
         }
+
+        result
     }
 
     /// Evaluate a statement
@@ -1746,7 +1791,7 @@ impl Engine {
         self.inc_operations(state)
             .map_err(|err| EvalAltResult::new_position(err, stmt.position()))?;
 
-        match stmt {
+        let result = match stmt {
             // No-op
             Stmt::Noop(_) => Ok(Default::default()),
 
@@ -1998,6 +2043,52 @@ impl Engine {
                 }
                 Ok(Default::default())
             }
+        };
+
+        if let Ok(val) = &result {
+            self.check_data_size(val)?;
+        }
+
+        result
+    }
+
+    /// Check a `Dynamic` value to ensure that its size is within allowable limit.
+    fn check_data_size(&self, value: &Dynamic) -> Result<(), Box<EvalAltResult>> {
+        #[cfg(feature = "unchecked")]
+        return Ok(());
+
+        match value {
+            Dynamic(Union::Str(s))
+                if self.max_string_size > 0 && s.len() > self.max_string_size =>
+            {
+                Err(Box::new(EvalAltResult::ErrorDataTooLarge(
+                    "Length of string".to_string(),
+                    self.max_string_size,
+                    s.len(),
+                    Position::none(),
+                )))
+            }
+            #[cfg(not(feature = "no_index"))]
+            Dynamic(Union::Array(arr))
+                if self.max_array_size > 0 && arr.len() > self.max_array_size =>
+            {
+                Err(Box::new(EvalAltResult::ErrorDataTooLarge(
+                    "Length of array".to_string(),
+                    self.max_array_size,
+                    arr.len(),
+                    Position::none(),
+                )))
+            }
+            #[cfg(not(feature = "no_object"))]
+            Dynamic(Union::Map(map)) if self.max_map_size > 0 && map.len() > self.max_map_size => {
+                Err(Box::new(EvalAltResult::ErrorDataTooLarge(
+                    "Number of properties in object map".to_string(),
+                    self.max_map_size,
+                    map.len(),
+                    Position::none(),
+                )))
+            }
+            _ => Ok(()),
         }
     }
 

src/error.rs

@@ -12,6 +12,8 @@ pub enum LexError {
     UnexpectedChar(char),
     /// A string literal is not terminated before a new-line or EOF.
     UnterminatedString,
+    /// An identifier is in an invalid format.
+    StringTooLong(usize),
     /// An string/character/numeric escape sequence is in an invalid format.
     MalformedEscapeSequence(String),
     /// An numeric literal is in an invalid format.
@@ -35,6 +37,11 @@ impl fmt::Display for LexError {
             Self::MalformedChar(s) => write!(f, "Invalid character: '{}'", s),
             Self::MalformedIdentifier(s) => write!(f, "Variable name is not proper: '{}'", s),
             Self::UnterminatedString => write!(f, "Open string is not terminated"),
+            Self::StringTooLong(max) => write!(
+                f,
+                "Length of string literal exceeds the maximum limit ({})",
+                max
+            ),
             Self::ImproperKeyword(s) => write!(f, "{}", s),
         }
     }
@@ -109,12 +116,16 @@ pub enum ParseErrorType {
     WrongExport,
     /// Assignment to a copy of a value.
     AssignmentToCopy,
-    /// Assignment to an a constant variable.
+    /// Assignment to an a constant variable. Wrapped value is the constant variable name.
     AssignmentToConstant(String),
     /// Expression exceeding the maximum levels of complexity.
     ///
     /// Never appears under the `unchecked` feature.
     ExprTooDeep,
+    /// Literal exceeding the maximum size. Wrapped values are the data type name and the maximum size.
+    ///
+    /// Never appears under the `unchecked` feature.
+    LiteralTooLarge(String, usize),
     /// Break statement not inside a loop.
     LoopBreak,
 }
@@ -149,6 +160,7 @@ impl ParseErrorType {
             Self::AssignmentToCopy => "Only a copy of the value is change with this assignment",
             Self::AssignmentToConstant(_) => "Cannot assign to a constant value",
             Self::ExprTooDeep => "Expression exceeds maximum complexity",
+            Self::LiteralTooLarge(_, _) => "Literal exceeds maximum limit",
             Self::LoopBreak => "Break statement should only be used inside a loop"
         }
     }
@@ -197,6 +209,9 @@ impl fmt::Display for ParseErrorType {
 
             Self::AssignmentToConstant(s) if s.is_empty() => write!(f, "{}", self.desc()),
             Self::AssignmentToConstant(s) => write!(f, "Cannot assign to constant '{}'", s),
+            Self::LiteralTooLarge(typ, max) => {
+                write!(f, "{} exceeds the maximum limit ({})", typ, max)
+            }
             _ => write!(f, "{}", self.desc()),
         }
     }

src/parser.rs

@@ -201,13 +201,27 @@ struct ParseState {
     stack: Vec<(String, ScopeEntryType)>,
     /// Maximum levels of expression nesting.
     max_expr_depth: usize,
+    /// Maximum length of a string.
+    pub max_string_size: usize,
+    /// Maximum length of an array.
+    pub max_array_size: usize,
+    /// Maximum number of properties in a map.
+    pub max_map_size: usize,
 }
 
 impl ParseState {
     /// Create a new `ParseState`.
-    pub fn new(max_expr_depth: usize) -> Self {
+    pub fn new(
+        max_expr_depth: usize,
+        max_string_size: usize,
+        max_array_size: usize,
+        max_map_size: usize,
+    ) -> Self {
         Self {
             max_expr_depth,
+            max_string_size,
+            max_array_size,
+            max_map_size,
             ..Default::default()
         }
     }
@@ -1070,6 +1084,14 @@ fn parse_array_literal(
 
     if !match_token(input, Token::RightBracket)? {
         while !input.peek().unwrap().0.is_eof() {
+            if state.max_array_size > 0 && arr.len() >= state.max_array_size {
+                return Err(PERR::LiteralTooLarge(
+                    "Size of array literal".to_string(),
+                    state.max_array_size,
+                )
+                .into_err(input.peek().unwrap().1));
+            }
+
             let expr = parse_expr(input, state, settings.level_up())?;
             arr.push(expr);
 
@@ -1155,8 +1177,15 @@ fn parse_map_literal(
                 }
             };
 
-            let expr = parse_expr(input, state, settings.level_up())?;
+            if state.max_map_size > 0 && map.len() >= state.max_map_size {
+                return Err(PERR::LiteralTooLarge(
+                    "Number of properties in object map literal".to_string(),
+                    state.max_map_size,
+                )
+                .into_err(input.peek().unwrap().1));
+            }
 
+            let expr = parse_expr(input, state, settings.level_up())?;
             map.push(((name, pos), expr));
 
             match input.peek().unwrap() {
@@ -2408,15 +2437,60 @@ fn parse_fn(
     })
 }
 
+impl Engine {
+    pub(crate) fn parse_global_expr(
+        &self,
+        input: &mut TokenStream,
+        scope: &Scope,
+        optimization_level: OptimizationLevel,
+    ) -> Result<AST, ParseError> {
+        let mut state = ParseState::new(
+            self.max_expr_depth,
+            self.max_string_size,
+            self.max_array_size,
+            self.max_map_size,
+        );
+        let settings = ParseSettings {
+            allow_if_expr: false,
+            allow_stmt_expr: false,
+            is_global: true,
+            is_breakable: false,
+            level: 0,
+            pos: Position::none(),
+        };
+        let expr = parse_expr(input, &mut state, settings)?;
+
+        match input.peek().unwrap() {
+            (Token::EOF, _) => (),
+            // Return error if the expression doesn't end
+            (token, pos) => {
+                return Err(
+                    PERR::BadInput(format!("Unexpected '{}'", token.syntax())).into_err(*pos)
+                )
+            }
+        }
+
+        let expr = vec![Stmt::Expr(Box::new(expr))];
+
+        Ok(
+            // Optimize AST
+            optimize_into_ast(self, scope, expr, Default::default(), optimization_level),
+        )
+    }
+
     /// Parse the global level statements.
     fn parse_global_level(
+        &self,
         input: &mut TokenStream,
-    max_expr_depth: usize,
-    max_function_expr_depth: usize,
     ) -> Result<(Vec<Stmt>, Vec<ScriptFnDef>), ParseError> {
         let mut statements = Vec::<Stmt>::new();
         let mut functions = HashMap::<u64, ScriptFnDef, _>::with_hasher(StraightHasherBuilder);
-    let mut state = ParseState::new(max_expr_depth);
+        let mut state = ParseState::new(
+            self.max_expr_depth,
+            self.max_string_size,
+            self.max_array_size,
+            self.max_map_size,
+        );
 
         while !input.peek().unwrap().0.is_eof() {
             // Collect all the function definitions
@@ -2431,7 +2505,12 @@ fn parse_global_level(
                 match input.peek().unwrap() {
                     #[cfg(not(feature = "no_function"))]
                     (Token::Fn, pos) => {
-                    let mut state = ParseState::new(max_function_expr_depth);
+                        let mut state = ParseState::new(
+                            self.max_function_expr_depth,
+                            self.max_string_size,
+                            self.max_array_size,
+                            self.max_map_size,
+                        );
                         let settings = ParseSettings {
                             allow_if_expr: true,
                             allow_stmt_expr: true,
@@ -2504,42 +2583,6 @@ fn parse_global_level(
         Ok((statements, functions.into_iter().map(|(_, v)| v).collect()))
     }
 
-impl Engine {
-    pub(crate) fn parse_global_expr(
-        &self,
-        input: &mut TokenStream,
-        scope: &Scope,
-        optimization_level: OptimizationLevel,
-    ) -> Result<AST, ParseError> {
-        let mut state = ParseState::new(self.max_expr_depth);
-        let settings = ParseSettings {
-            allow_if_expr: false,
-            allow_stmt_expr: false,
-            is_global: true,
-            is_breakable: false,
-            level: 0,
-            pos: Position::none(),
-        };
-        let expr = parse_expr(input, &mut state, settings)?;
-
-        match input.peek().unwrap() {
-            (Token::EOF, _) => (),
-            // Return error if the expression doesn't end
-            (token, pos) => {
-                return Err(
-                    PERR::BadInput(format!("Unexpected '{}'", token.syntax())).into_err(*pos)
-                )
-            }
-        }
-
-        let expr = vec![Stmt::Expr(Box::new(expr))];
-
-        Ok(
-            // Optimize AST
-            optimize_into_ast(self, scope, expr, Default::default(), optimization_level),
-        )
-    }
-
     /// Run the parser on an input stream, returning an AST.
     pub(crate) fn parse(
         &self,
@@ -2547,8 +2590,7 @@ impl Engine {
         scope: &Scope,
         optimization_level: OptimizationLevel,
     ) -> Result<AST, ParseError> {
-        let (statements, lib) =
+        let (statements, lib) = self.parse_global_level(input)?;
-            parse_global_level(input, self.max_expr_depth, self.max_function_expr_depth)?;
 
         Ok(
             // Optimize AST

src/result.rs

@@ -81,6 +81,8 @@ pub enum EvalAltResult {
     ErrorTooManyModules(Position),
     /// Call stack over maximum limit.
     ErrorStackOverflow(Position),
+    /// Data value over maximum size limit. Wrapped values are the data type, maximum size and current size.
+    ErrorDataTooLarge(String, usize, usize, Position),
     /// The script is prematurely terminated.
     ErrorTerminated(Position),
     /// Run-time error encountered. Wrapped value is the error message.
@@ -139,6 +141,7 @@ impl EvalAltResult {
             Self::ErrorTooManyOperations(_) => "Too many operations",
             Self::ErrorTooManyModules(_) => "Too many modules imported",
             Self::ErrorStackOverflow(_) => "Stack overflow",
+            Self::ErrorDataTooLarge(_, _, _, _) => "Data size exceeds maximum limit",
             Self::ErrorTerminated(_) => "Script terminated.",
             Self::ErrorRuntime(_, _) => "Runtime error",
             Self::ErrorLoopBreak(true, _) => "Break statement not inside a loop",
@@ -228,6 +231,9 @@ impl fmt::Display for EvalAltResult {
                 "String index {} is out of bounds: only {} characters in the string",
                 index, max
             )?,
+            Self::ErrorDataTooLarge(typ, max, size, _) => {
+                write!(f, "{} ({}) exceeds the maximum limit ({})", typ, size, max)?
+            }
         }
 
         // Do not write any position if None
@@ -279,6 +285,7 @@ impl EvalAltResult {
             | Self::ErrorTooManyOperations(pos)
             | Self::ErrorTooManyModules(pos)
             | Self::ErrorStackOverflow(pos)
+            | Self::ErrorDataTooLarge(_, _, _, pos)
             | Self::ErrorTerminated(pos)
             | Self::ErrorRuntime(_, pos)
             | Self::ErrorLoopBreak(_, pos)
@@ -316,6 +323,7 @@ impl EvalAltResult {
             | Self::ErrorTooManyOperations(pos)
             | Self::ErrorTooManyModules(pos)
             | Self::ErrorStackOverflow(pos)
+            | Self::ErrorDataTooLarge(_, _, _, pos)
             | Self::ErrorTerminated(pos)
             | Self::ErrorRuntime(_, pos)
             | Self::ErrorLoopBreak(_, pos)

src/token.rs

@@ -429,6 +429,8 @@ impl From<Token> for String {
 
 /// An iterator on a `Token` stream.
 pub struct TokenIterator<'a> {
+    /// Maximum length of a string (0 = unlimited).
+    max_string_size: usize,
     /// Can the next token be a unary operator?
     can_be_unary: bool,
     /// Current position.
@@ -494,6 +496,7 @@ impl<'a> TokenIterator<'a> {
     pub fn parse_string_literal(
         &mut self,
         enclosing_char: char,
+        max_length: usize,
     ) -> Result<String, (LexError, Position)> {
         let mut result = Vec::new();
         let mut escape = String::with_capacity(12);
@@ -505,6 +508,10 @@ impl<'a> TokenIterator<'a> {
 
             self.advance();
 
+            if max_length > 0 && result.len() > max_length {
+                return Err((LexError::StringTooLong(max_length), self.pos));
+            }
+
             match next_char {
                 // \...
                 '\\' if escape.is_empty() => {
@@ -592,7 +599,13 @@ impl<'a> TokenIterator<'a> {
             }
         }
 
-        Ok(result.iter().collect())
+        let s = result.iter().collect::<String>();
+
+        if max_length > 0 && s.len() > max_length {
+            return Err((LexError::StringTooLong(max_length), self.pos));
+        }
+
+        Ok(s)
     }
 
     /// Get the next token.
@@ -779,7 +792,9 @@ impl<'a> TokenIterator<'a> {
 
                 // " - string literal
                 ('"', _) => {
-                    return self.parse_string_literal('"').map_or_else(
+                    return self
+                        .parse_string_literal('"', self.max_string_size)
+                        .map_or_else(
                             |err| Some((Token::LexError(Box::new(err.0)), err.1)),
                             |out| Some((Token::StringConst(out), pos)),
                         );
@@ -793,19 +808,25 @@ impl<'a> TokenIterator<'a> {
                     ));
                 }
                 ('\'', _) => {
-                    return Some(self.parse_string_literal('\'').map_or_else(
+                    return Some(
+                        self.parse_string_literal('\'', self.max_string_size)
+                            .map_or_else(
                                 |err| (Token::LexError(Box::new(err.0)), err.1),
                                 |result| {
                                     let mut chars = result.chars();
                                     let first = chars.next();
 
                                     if chars.next().is_some() {
-                                (Token::LexError(Box::new(LERR::MalformedChar(result))), pos)
+                                        (
+                                            Token::LexError(Box::new(LERR::MalformedChar(result))),
+                                            pos,
+                                        )
                                     } else {
                                         (Token::CharConstant(first.expect("should be Some")), pos)
                                     }
                                 },
-                    ));
+                            ),
+                    );
                 }
 
                 // Braces
@@ -1047,8 +1068,9 @@ impl<'a> Iterator for TokenIterator<'a> {
 }
 
 /// Tokenize an input text stream.
-pub fn lex<'a>(input: &'a [&'a str]) -> TokenIterator<'a> {
+pub fn lex<'a>(input: &'a [&'a str], max_string_size: usize) -> TokenIterator<'a> {
     TokenIterator {
+        max_string_size,
         can_be_unary: true,
         pos: Position::new(1, 0),
         streams: input.iter().map(|s| s.chars().peekable()).collect(),

tests/data_size.rs

@@ -0,0 +1,135 @@
+#![cfg(not(feature = "unchecked"))]
+use rhai::{Engine, EvalAltResult, ParseError, ParseErrorType};
+
+#[cfg(not(feature = "no_index"))]
+use rhai::Array;
+
+#[cfg(not(feature = "no_object"))]
+use rhai::Map;
+
+#[test]
+fn test_max_string_size() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+    engine.set_max_string_size(10);
+
+    assert!(matches!(
+        engine.compile(r#"let x = "hello, world!";"#).expect_err("should error"),
+        ParseError(x, _) if *x == ParseErrorType::BadInput("Length of string literal exceeds the maximum limit (10)".to_string())
+    ));
+
+    assert!(matches!(
+        *engine
+            .eval::<String>(
+                r#"
+                    let x = "hello, ";
+                    let y = "world!";
+                    x + y
+                "#
+            )
+            .expect_err("should error"),
+        EvalAltResult::ErrorDataTooLarge(_, 10, 13, _)
+    ));
+
+    engine.set_max_string_size(0);
+
+    assert_eq!(
+        engine.eval::<String>(
+            r#"
+                let x = "hello, ";
+                let y = "world!";
+                x + y
+    "#
+        )?,
+        "hello, world!"
+    );
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_index"))]
+fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+    engine.set_max_array_size(10);
+
+    assert!(matches!(
+        engine
+            .compile("let x = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];")
+            .expect_err("should error"),
+        ParseError(x, _) if *x == ParseErrorType::LiteralTooLarge("Size of array literal".to_string(), 10)
+    ));
+
+    assert!(matches!(
+        *engine
+            .eval::<Array>(
+                r"
+                    let x = [1,2,3,4,5,6];
+                    let y = [7,8,9,10,11,12];
+                    x + y
+                "
+            )
+            .expect_err("should error"),
+        EvalAltResult::ErrorDataTooLarge(_, 10, 12, _)
+    ));
+
+    engine.set_max_array_size(0);
+
+    assert_eq!(
+        engine
+            .eval::<Array>(
+                r"
+                    let x = [1,2,3,4,5,6];
+                    let y = [7,8,9,10,11,12];
+                    x + y
+        "
+            )?
+            .len(),
+        12
+    );
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_max_map_size() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+    engine.set_max_map_size(10);
+
+    assert!(matches!(
+        engine
+            .compile("let x = #{a:1,b:2,c:3,d:4,e:5,f:6,g:7,h:8,i:9,j:10,k:11,l:12,m:13,n:14,o:15};")
+            .expect_err("should error"),
+        ParseError(x, _) if *x == ParseErrorType::LiteralTooLarge("Number of properties in object map literal".to_string(), 10)
+    ));
+
+    assert!(matches!(
+        *engine
+            .eval::<Map>(
+                r"
+                    let x = #{a:1,b:2,c:3,d:4,e:5,f:6};
+                    let y = #{g:7,h:8,i:9,j:10,k:11,l:12};
+                    x + y
+                "
+            )
+            .expect_err("should error"),
+        EvalAltResult::ErrorDataTooLarge(_, 10, 12, _)
+    ));
+
+    engine.set_max_map_size(0);
+
+    assert_eq!(
+        engine
+            .eval::<Map>(
+                r"
+                    let x = #{a:1,b:2,c:3,d:4,e:5,f:6};
+                    let y = #{g:7,h:8,i:9,j:10,k:11,l:12};
+                    x + y
+    "
+            )?
+            .len(),
+        12
+    );
+
+    Ok(())
+}