Struct Limits 

#[non_exhaustive]
pub struct Limits {

    pub max_body_bytes: u64,
    pub max_fields: u32,
    pub max_name_bytes: u32,
    pub max_value_bytes: u32,
    pub max_text_bytes: u64,
    pub max_parts: u32,
    pub max_files: u32,
    pub max_file_bytes: u64,
    pub max_part_header_bytes: u32,
    pub max_part_headers: u16,
    pub max_filename_bytes: u32,
    pub max_preamble_bytes: u32,
    pub max_epilogue_bytes: u32,
    pub max_padding_bytes: u8,
    pub sniff_bytes: u32,
    pub max_token_bytes: u16,
}

Every budget form-net enforces.

Each budget is checked before the bytes it governs are buffered, stored, or passed on. A limit of 0 means none allowed. A limit larger than the one containing it is capped by it (the effective value is the smaller), so a route sets only the limits it cares about.

Field	Default
max_body_bytes	10 MiB
max_fields	1,000
max_name_bytes	256
max_value_bytes	1 MiB
max_text_bytes	2 MiB
max_parts	100
max_files	20
max_file_bytes	10 MiB
max_part_header_bytes	8 KiB
max_part_headers	8
max_filename_bytes	1,024
max_preamble_bytes	1 KiB
max_epilogue_bytes	1 KiB
max_padding_bytes	32
sniff_bytes	0
max_token_bytes	128

Examples

use form_net::Limits;

// A login route: a small body, a few fields, no files.
const LOGIN: Limits = Limits::DEFAULT
    .with_max_body_bytes(4 * 1024)
    .with_max_fields(8)
    .with_max_files(0);
assert!(LOGIN.validate().is_ok());

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

max_body_bytes: u64

Every byte fed, both formats, preamble and epilogue included.

max_fields: u32

urlencoded pairs; multipart text fields.

max_name_bytes: u32

Raw (encoded) name length. Capped by max_body_bytes.

max_value_bytes: u32

One urlencoded value or one multipart text field. Capped by max_text_bytes.

max_text_bytes: u64

All text values of one body together. Capped by max_body_bytes.

max_parts: u32

Multipart parts of either kind.

max_files: u32

Multipart file parts.

max_file_bytes: u64

One file part. Capped by max_body_bytes.

max_part_header_bytes: u32

One part’s header block, CRLF CRLF included (at least 64).

max_part_headers: u16

Header lines per part.

max_filename_bytes: u32

A raw filename, or a decoded filename*. Capped by max_part_header_bytes.

max_preamble_bytes: u32

Bytes before the first delimiter. Capped by max_body_bytes.

max_epilogue_bytes: u32

Bytes after the close delimiter. Capped by max_body_bytes.

max_padding_bytes: u8

Transport padding after a delimiter.

sniff_bytes: u32

The sniff window per file part (0: off). Capped by max_file_bytes.

max_token_bytes: u16

The captured anti-forgery token. Capped by max_value_bytes.

Implementations

impl Limits

pub const DEFAULT: Limits

The defaults in the table above.

pub const fn with_max_body_bytes(self, value: u64) -> Self

Sets max_body_bytes.

pub const fn with_max_fields(self, value: u32) -> Self

Sets max_fields.

pub const fn with_max_name_bytes(self, value: u32) -> Self

Sets max_name_bytes.

pub const fn with_max_value_bytes(self, value: u32) -> Self

Sets max_value_bytes.

pub const fn with_max_text_bytes(self, value: u64) -> Self

Sets max_text_bytes.

pub const fn with_max_parts(self, value: u32) -> Self

Sets max_parts.

pub const fn with_max_files(self, value: u32) -> Self

Sets max_files.

pub const fn with_max_file_bytes(self, value: u64) -> Self

Sets max_file_bytes.

pub const fn with_max_part_header_bytes(self, value: u32) -> Self

Sets max_part_header_bytes.

pub const fn with_max_part_headers(self, value: u16) -> Self

Sets max_part_headers.

pub const fn with_max_filename_bytes(self, value: u32) -> Self

Sets max_filename_bytes.

pub const fn with_max_preamble_bytes(self, value: u32) -> Self

Sets max_preamble_bytes.

pub const fn with_max_epilogue_bytes(self, value: u32) -> Self

Sets max_epilogue_bytes.

pub const fn with_max_padding_bytes(self, value: u8) -> Self

Sets max_padding_bytes.

pub const fn with_sniff_bytes(self, value: u32) -> Self

Sets sniff_bytes.

pub const fn with_max_token_bytes(self, value: u16) -> Self

Sets max_token_bytes.

pub fn validate(&self) -> Result<(), FormError>

Refuses the values no body could satisfy, so a misconfiguration is found at startup: a max_part_header_bytes below 64 (the shortest useful Content-Disposition line must fit), or buffer sizes that do not fit in usize. Every parser constructor and every *_with function calls it.

Errors

FormError::InvalidLimits naming the refused field.

Examples

use form_net::Limits;

assert!(Limits::DEFAULT.validate().is_ok());
let broken = Limits::DEFAULT.with_max_part_header_bytes(16);
assert_eq!(broken.validate().unwrap_err().code(), "invalid_limits");

pub const fn multipart_buffer_len(&self, policy: &Policy) -> usize

The buffer length the multipart parser needs with these limits and this policy: the header block, the decoded field name, the decoded filename* (only under ExtendedFilenamePolicy::AcceptAlone), the token (only with a token field), and 32 bytes for _charset_.

A const fn, so a stack buffer can be sized at compile time.

Examples

use form_net::{Limits, Policy};

const LIMITS: Limits = Limits::DEFAULT.with_max_part_header_bytes(1024);
const LEN: usize = LIMITS.multipart_buffer_len(&Policy::DEFAULT);
assert_eq!(LEN, 1024 + 256 + 32);
let buffer = [0u8; LEN];

pub const fn urlencoded_buffer_len(&self) -> usize

The scratch length the streaming urlencoded parser needs: max_name_bytes + max_value_bytes + 1 (effective values).

Examples

use form_net::Limits;

const LIMITS: Limits = Limits::DEFAULT.with_max_text_bytes(1000);
assert_eq!(LIMITS.urlencoded_buffer_len(), 256 + 1000 + 1);

Trait Implementations

impl Clone for Limits

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Limits

impl Debug for Limits

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

Formats the value using the given formatter.

impl Default for Limits

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Limits

impl PartialEq for Limits

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Limits