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Add maximum data size limits.

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Stephen Chung
2020-06-14 00:09:16 +08:00
parent b690ebac69
commit 22d30c95c9
9 changed files with 518 additions and 138 deletions
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README.md
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@@ -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 |
| ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| `set_optimization_level` | 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_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_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_modules` | Set the maximum number of [modules] that a script is allowed to load. See [maximum number of modules](#maximum-number-of-modules). |
| Method | Not available under | Description |
| ------------------------ | ---------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| `set_optimization_level` | [`no_optimize`] | Set the amount of script _optimizations_ performed. See [script optimization]. |
| `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` | [`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` | [`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` | [`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.