Module `header`

HTTP header types

The module provides HeaderName, HeaderMap, and a number of types used for interacting with HeaderMap. These types allow representing both HTTP/1 and HTTP/2 headers.

`HeaderName`

The HeaderName type represents both standard header names as well as custom header names. The type handles the case insensitive nature of header names and is used as the key portion of HeaderMap. Header names are normalized to lower case. In other words, when creating a HeaderName with a string, even if upper case characters are included, when getting a string representation of the HeaderName, it will be all lower case. This allows for faster HeaderMap comparison operations.

The internal representation is optimized to efficiently handle the cases most commonly encountered when working with HTTP. Standard header names are special cased and are represented internally as an enum. Short custom headers will be stored directly in the HeaderName struct and will not incur any allocation overhead, however longer strings will require an allocation for storage.

Limitations

HeaderName has a max length of 32,768 for header names. Attempting to parse longer names will result in a panic.

`HeaderMap`

The HeaderMap type is a specialized multimap structure for storing header names and values. It is designed specifically for efficient manipulation of HTTP headers. It supports multiple values per header name and provides specialized APIs for insertion, retrieval, and iteration.

See also the HeaderMap type.

Structs

Drain A drain iterator for HeaderMap.
GetAll A view to all values stored in a single entry.
HeaderMap A specialized multimap for header names and values.
HeaderName Represents an HTTP header field name
HeaderValue Represents an HTTP header field value.
IntoIter An owning iterator over the entries of a HeaderMap.
InvalidHeaderName A possible error when converting a HeaderName from another type.
InvalidHeaderValue A possible error when converting a HeaderValue from a string or byte slice.
Iter HeaderMap entry iterator.
IterMut HeaderMap mutable entry iterator
Keys An iterator over HeaderMap keys.
MaxSizeReached Error returned when max capacity of HeaderMap is exceeded
OccupiedEntry A view into a single occupied location in a HeaderMap.
ToStrError A possible error when converting a HeaderValue to a string representation.
VacantEntry A view into a single empty location in a HeaderMap.
ValueDrain An drain iterator of all values associated with a single header name.
ValueIter An iterator of all values associated with a single header name.
ValueIterMut A mutable iterator of all values associated with a single header name.
Values HeaderMap value iterator.
ValuesMut HeaderMap mutable value iterator

Enums

Entry A view into a single location in a HeaderMap, which may be vacant or occupied.

Traits

AsHeaderName A marker trait used to identify values that can be used as search keys to a HeaderMap.
IntoHeaderName A marker trait used to identify values that can be used as insert keys to a HeaderMap.

Constants

ACCEPT Advertises which content types the client is able to understand.
ACCEPT_CHARSET Advertises which character set the client is able to understand.
ACCEPT_ENCODING Advertises which content encoding the client is able to understand.
ACCEPT_LANGUAGE Advertises which languages the client is able to understand.
ACCEPT_RANGES Marker used by the server to advertise partial request support.
ACCESS_CONTROL_ALLOW_CREDENTIALS Preflight response indicating if the response to the request can be exposed to the page.
ACCESS_CONTROL_ALLOW_HEADERS Preflight response indicating permitted HTTP headers.
ACCESS_CONTROL_ALLOW_METHODS Preflight header response indicating permitted access methods.
ACCESS_CONTROL_ALLOW_ORIGIN Indicates whether the response can be shared with resources with the given origin.
ACCESS_CONTROL_EXPOSE_HEADERS Indicates which headers can be exposed as part of the response by listing their names.
ACCESS_CONTROL_MAX_AGE Indicates how long the results of a preflight request can be cached.
ACCESS_CONTROL_REQUEST_HEADERS Informs the server which HTTP headers will be used when an actual request is made.
ACCESS_CONTROL_REQUEST_METHOD Informs the server know which HTTP method will be used when the actual request is made.
AGE Indicates the time in seconds the object has been in a proxy cache.
ALLOW Lists the set of methods support by a resource.
ALT_SVC Advertises the availability of alternate services to clients.
AUTHORIZATION Contains the credentials to authenticate a user agent with a server.
CACHE_CONTROL Specifies directives for caching mechanisms in both requests and responses.
CACHE_STATUS Indicates how caches have handled a response and its corresponding request.
CDN_CACHE_CONTROL Specifies directives that allow origin servers to control the behavior of CDN caches interposed between them and clients separately from other caches that might handle the response.
CONNECTION Controls whether or not the network connection stays open after the current transaction finishes.
CONTENT_DISPOSITION Indicates if the content is expected to be displayed inline.
CONTENT_ENCODING Used to compress the media-type.
CONTENT_LANGUAGE Used to describe the languages intended for the audience.
CONTENT_LENGTH Indicates the size of the entity-body.
CONTENT_LOCATION Indicates an alternate location for the returned data.
CONTENT_RANGE Indicates where in a full body message a partial message belongs.
CONTENT_SECURITY_POLICY Allows controlling resources the user agent is allowed to load for a given page.
CONTENT_SECURITY_POLICY_REPORT_ONLY Allows experimenting with policies by monitoring their effects.
CONTENT_TYPE Used to indicate the media type of the resource.
COOKIE Contains stored HTTP cookies previously sent by the server with the Set-Cookie header.
DATE Contains the date and time at which the message was originated.
DNT Indicates the client's tracking preference.
ETAG Identifier for a specific version of a resource.
EXPECT Indicates expectations that need to be fulfilled by the server in order to properly handle the request.
EXPIRES Contains the date/time after which the response is considered stale.
FORWARDED Contains information from the client-facing side of proxy servers that is altered or lost when a proxy is involved in the path of the request.
FROM Contains an Internet email address for a human user who controls the requesting user agent.
HOST Specifies the domain name of the server and (optionally) the TCP port number on which the server is listening.
IF_MATCH Makes a request conditional based on the E-Tag.
IF_MODIFIED_SINCE Makes a request conditional based on the modification date.
IF_NONE_MATCH Makes a request conditional based on the E-Tag.
IF_RANGE Makes a request conditional based on range.
IF_UNMODIFIED_SINCE Makes the request conditional based on the last modification date.
LAST_MODIFIED The Last-Modified header contains the date and time when the origin believes the resource was last modified.
LINK Allows the server to point an interested client to another resource containing metadata about the requested resource.
LOCATION Indicates the URL to redirect a page to.
MAX_FORWARDS Indicates the max number of intermediaries the request should be sent through.
ORIGIN Indicates where a fetch originates from.
PRAGMA HTTP/1.0 header usually used for backwards compatibility.
PROXY_AUTHENTICATE Defines the authentication method that should be used to gain access to a proxy.
PROXY_AUTHORIZATION Contains the credentials to authenticate a user agent to a proxy server.
PUBLIC_KEY_PINS Associates a specific cryptographic public key with a certain server.
PUBLIC_KEY_PINS_REPORT_ONLY Sends reports of pinning violation to the report-uri specified in the header.
RANGE Indicates the part of a document that the server should return.
REFERER Contains the address of the previous web page from which a link to the currently requested page was followed.
REFERRER_POLICY Governs which referrer information should be included with requests made.
REFRESH Informs the web browser that the current page or frame should be refreshed.
RETRY_AFTER The Retry-After response HTTP header indicates how long the user agent should wait before making a follow-up request. There are two main cases this header is used:
SEC_WEBSOCKET_ACCEPT The |Sec-WebSocket-Accept| header field is used in the WebSocket opening handshake. It is sent from the server to the client to confirm that the server is willing to initiate the WebSocket connection.
SEC_WEBSOCKET_EXTENSIONS The |Sec-WebSocket-Extensions| header field is used in the WebSocket opening handshake. It is initially sent from the client to the server, and then subsequently sent from the server to the client, to agree on a set of protocol-level extensions to use for the duration of the connection.
SEC_WEBSOCKET_KEY The |Sec-WebSocket-Key| header field is used in the WebSocket opening handshake. It is sent from the client to the server to provide part of the information used by the server to prove that it received a valid WebSocket opening handshake. This helps ensure that the server does not accept connections from non-WebSocket clients (e.g., HTTP clients) that are being abused to send data to unsuspecting WebSocket servers.
SEC_WEBSOCKET_PROTOCOL The |Sec-WebSocket-Protocol| header field is used in the WebSocket opening handshake. It is sent from the client to the server and back from the server to the client to confirm the subprotocol of the connection. This enables scripts to both select a subprotocol and be sure that the server agreed to serve that subprotocol.
SEC_WEBSOCKET_VERSION The |Sec-WebSocket-Version| header field is used in the WebSocket opening handshake. It is sent from the client to the server to indicate the protocol version of the connection. This enables servers to correctly interpret the opening handshake and subsequent data being sent from the data, and close the connection if the server cannot interpret that data in a safe manner.
SERVER Contains information about the software used by the origin server to handle the request.
SET_COOKIE Used to send cookies from the server to the user agent.
STRICT_TRANSPORT_SECURITY Tells the client to communicate with HTTPS instead of using HTTP.
TE Informs the server of transfer encodings willing to be accepted as part of the response.
TRAILER Allows the sender to include additional fields at the end of chunked messages.
TRANSFER_ENCODING Specifies the form of encoding used to safely transfer the entity to the client.
UPGRADE Used as part of the exchange to upgrade the protocol.
UPGRADE_INSECURE_REQUESTS Sends a signal to the server expressing the client’s preference for an encrypted and authenticated response.
USER_AGENT Contains a string that allows identifying the requesting client's software.
VARY Determines how to match future requests with cached responses.
VIA Added by proxies to track routing.
WARNING General HTTP header contains information about possible problems with the status of the message.
WWW_AUTHENTICATE Defines the authentication method that should be used to gain access to a resource.
X_CONTENT_TYPE_OPTIONS Marker used by the server to indicate that the MIME types advertised in the content-type headers should not be changed and be followed.
X_DNS_PREFETCH_CONTROL Controls DNS prefetching.
X_FRAME_OPTIONS Indicates whether or not a browser should be allowed to render a page in a frame.
X_XSS_PROTECTION Stop pages from loading when an XSS attack is detected.