Struct multer::Constraints

pub struct Constraints { /* private fields */ }

Represents some rules to be applied on the stream and field’s content size to prevent DoS attacks.

It’s recommended to add some rules on field (specially text field) size to avoid potential DoS attacks from attackers running the server out of memory. This type provides some API to apply constraints on very granular level to make multipart/form-data safe. By default, it does not apply any constraint.

Examples

use multer::{Multipart, Constraints, SizeLimit};

// Create some constraints to be applied to the fields to prevent DoS attack.
let constraints = Constraints::new()
     // We only accept `my_text_field` and `my_file_field` fields,
     // For any unknown field, we will throw an error.
     .allowed_fields(vec!["my_text_field", "my_file_field"])
     .size_limit(
         SizeLimit::new()
             // Set 15mb as size limit for the whole stream body.
             .whole_stream(15 * 1024 * 1024)
             // Set 10mb as size limit for all fields.
             .per_field(10 * 1024 * 1024)
             // Set 30kb as size limit for our text field only.
             .for_field("my_text_field", 30 * 1024),
     );

// Create a `Multipart` instance from a stream and the constraints.
let mut multipart = Multipart::with_constraints(some_stream, "X-BOUNDARY", constraints);

while let Some(field) = multipart.next_field().await.unwrap() {
    let content = field.text().await.unwrap();
    assert_eq!(content, "abcd");
}

Implementations

impl Constraints

pub fn new() -> Constraints

Creates a set of rules with default behaviour.

pub fn size_limit(self, size_limit: SizeLimit) -> Constraints

Applies rules on field’s content length.

pub fn allowed_fields<N: Into<String>>(
    self,
    allowed_fields: Vec<N>
) -> Constraints

Specify which fields should be allowed, for any unknown field, the next_field will throw an error.

Trait Implementations

impl Debug for Constraints

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Constraints

fn default() -> Self

Returns the “default value” for a type.