Struct HeaderName

pub struct HeaderName { /* private fields */ }

Expand description

Represents an HTTP header field name

Header field names identify the header. Header sets may include multiple headers with the same name. The HTTP specification defines a number of standard headers, but HTTP messages may include non-standard header names as well as long as they adhere to the specification.

HeaderName is used as the HeaderMap key. Constants are available for all standard header names in the header module.

§Representation

HeaderName represents standard header names using an enum, as such they will not require an allocation for storage. All custom header names are lower cased upon conversion to a HeaderName value. This avoids the overhead of dynamically doing lower case conversion during the hash code computation and the comparison operation.

Implementations§

§

impl HeaderName

pub fn from_bytes(src: &[u8]) -> Result<HeaderName, InvalidHeaderName>

Converts a slice of bytes to an HTTP header name.

This function normalizes the input.

pub fn from_lowercase(src: &[u8]) -> Result<HeaderName, InvalidHeaderName>

Converts a slice of bytes to an HTTP header name.

This function expects the input to only contain lowercase characters. This is useful when decoding HTTP/2.0 or HTTP/3.0 headers. Both require that all headers be represented in lower case.

§Examples


// Parsing a lower case header
let hdr = HeaderName::from_lowercase(b"content-length").unwrap();
assert_eq!(CONTENT_LENGTH, hdr);

// Parsing a header that contains uppercase characters
assert!(HeaderName::from_lowercase(b"Content-Length").is_err());

pub const fn from_static(src: &'static str) -> HeaderName

Converts a static string to a HTTP header name.

This function requires the static string to only contain lowercase characters, numerals and symbols, as per the HTTP/2.0 specification and header names internal representation within this library.

§Panics

This function panics when the static string is a invalid header.

Until Allow panicking in constants makes its way into stable, the panic message at compile-time is going to look cryptic, but should at least point at your header value:

error: any use of this value will cause an error
    --> http/src/header/name.rs:1241:13
     |
1241 |             ([] as [u8; 0])[0]; // Invalid header name
     |             ^^^^^^^^^^^^^^^^^^
     |             |
     |             index out of bounds: the length is 0 but the index is 0
     |             inside `http::HeaderName::from_static` at http/src/header/name.rs:1241:13
     |             inside `INVALID_NAME` at src/main.rs:3:34
     |
    ::: src/main.rs:3:1
     |
3    | const INVALID_NAME: HeaderName = HeaderName::from_static("Capitalized");
     | ------------------------------------------------------------------------

§Examples

// Parsing a standard header
let hdr = HeaderName::from_static("content-length");
assert_eq!(CONTENT_LENGTH, hdr);

// Parsing a custom header
let CUSTOM_HEADER: &'static str = "custom-header";

let a = HeaderName::from_lowercase(b"custom-header").unwrap();
let b = HeaderName::from_static(CUSTOM_HEADER);
assert_eq!(a, b);

// Parsing a header that contains invalid symbols(s):
HeaderName::from_static("content{}{}length"); // This line panics!

// Parsing a header that contains invalid uppercase characters.
let a = HeaderName::from_static("foobar");
let b = HeaderName::from_static("FOOBAR"); // This line panics!