github.com/caddyserver/caddy/v2/modules/caddyhttp/push

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Package

Files: 3. Third party imports: 2. Imports from organisation: 0. Tests: 0. Benchmarks: 0.

Constants

Vars

safeHeaders is a list of header fields that are safe to copy to push requests implicitly. It is assumed that requests for certain kinds of content would fail without these fields present.

Types

Handler

Handler is a middleware for HTTP/2 server push. Note that HTTP/2 server push has been deprecated by some clients and its use is discouraged unless you can accurately predict which resources actually need to be pushed to the client; it can be difficult to know what the client already has cached. Pushing unnecessary resources results in worse performance. Consider using HTTP 103 Early Hints instead.

This handler supports pushing from Link headers; in other words, if the eventual response has Link headers, this handler will push the resources indicated by those headers, even without specifying any resources in its config.

Field name	Field type	Comment
Resources	`[]Resource`	The resources to push.
Headers	`*HeaderConfig`	Headers to modify for the push requests.
logger	`*zap.Logger`	No comment on field.

HeaderConfig

HeaderConfig configures headers for synthetic push requests.

Field name	Field type	Comment
	`headers.HeaderOps`	No comment on field.

Resource

Resource represents a request for a resource to push.

Field name	Field type	Comment
Method	`string`	Method is the request method, which must be GET or HEAD. Default is GET.
Target	`string`	Target is the path to the resource being pushed.

linkPusher

linkPusher is a http.ResponseWriter that intercepts the WriteHeader() call to ensure that any resources described by Link response headers get pushed before the response is allowed to be written.

Field name	Field type	Comment
	`*caddyhttp.ResponseWriterWrapper`	No comment on field.
handler	`Handler`	No comment on field.
pusher	`http.Pusher`	No comment on field.
header	`http.Header`	No comment on field.
request	`*http.Request`	No comment on field.

linkResource

linkResource contains the results of a parsed Link header.

Field name	Field type	Comment
uri	`string`	No comment on field.
params	`map[string]string`	No comment on field.

Functions

func (*Handler) Provision

Provision sets up h.

Uses: fmt.Errorf.

func (Handler) CaddyModule

CaddyModule returns the Caddy module information.

func (Handler) ServeHTTP

Uses: caddyhttp.LoggableHTTPHeader, caddyhttp.ResponseWriterWrapper, caddyhttp.Server, caddyhttp.ServerCtxKey, http.PushOptions, http.Pusher, zap.Object, zap.String, zapcore.DebugLevel.

func (linkPusher) WriteHeader

Uses: caddyhttp.GetVar, caddyhttp.SetVar, zap.Strings, zapcore.DebugLevel.

Private functions

func init

References: httpcaddyfile.RegisterHandlerDirective.

func isRemoteResource

isRemoteResource returns true if resource starts with a scheme or is a protocol-relative URI.

References: strings.HasPrefix.

func parseCaddyfile

parseCaddyfile sets up the push handler. Syntax:

push [<matcher>] [<resource>] {
    [GET|HEAD] <resource>
    headers {
        [+]<field> [<value|regexp> [<replacement>]]
        -<field>
    }
}

A single resource can be specified inline without opening a block for the most common/simple case. Or, a block can be opened and multiple resources can be specified, one per line, optionally preceded by the method. The headers subdirective can be used to customize the headers that are set on each (synthetic) push request, using the same syntax as the 'header' directive for request headers. Placeholders are accepted in resource and header field name and value and replacement tokens.

References: headers.CaddyfileHeaderOp.

func parseLinkHeader

parseLinkHeader is responsible for parsing Link header and returning list of found resources.

Accepted formats are:

Link: <resource>; as=script
Link: <resource>; as=script,<resource>; as=style
Link: <resource>;<resource2>

where <resource> begins with a forward slash (/).

References: strings.Cut, strings.Index, strings.Split, strings.TrimSpace.

func initializePushHeaders

References: http.Header.

func servePreloadLinks

servePreloadLinks parses Link headers from upstream and pushes resources described by them. If a resource has the "nopush" attribute or describes an external entity (meaning, the resource URI includes a scheme), it will not be pushed.

References: http.PushOptions.

Tests

Files: 1. Third party imports: 0. Imports from organisation: 0. Tests: 1. Benchmarks: 0.

Test functions

TestParseLinkHeader

References: reflect.DeepEqual.