httpencoding

README

httpencoding

-- import "vimagination.zapto.org/httpencoding"

Package httpencoding provides a function to deal with the Accept-Encoding header.

Highlights

• Simple handling of Accept-Encoding HTTP header.
• Supports identity, wildcards, and q-values.

Usage

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"

	"vimagination.zapto.org/httpencoding"
)

func main() {
	handler := func(w http.ResponseWriter, r *http.Request) {
		if !httpencoding.HandleEncoding(r, httpencoding.HandlerFunc(func(e httpencoding.Encoding) bool {
			if e == "gzip" || httpencoding.IsWildcard(e) && !httpencoding.IsDisallowedInWildcard(e, "gzip") {
				io.WriteString(w, "gzip")
			} else if e == "" || httpencoding.IsWildcard(e) && !httpencoding.IsDisallowedInWildcard(e, "") {
				io.WriteString(w, "identity")
			} else {
				return false
			}

			return true
		})) {
			io.WriteString(w, "none")
		}
	}

	w := httptest.NewRecorder()
	r, _ := http.NewRequest(http.MethodGet, "/", nil)
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "identity")
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "gzip, identity")
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "gzip;q=0.5, identity;q=0.6")
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "identity;q=0")
	handler(w, r)
	fmt.Println(w.Body)

	// Output:
	// gzip
	// identity
	// gzip
	// identity
	// none
}

Documentation

Full API docs can be found at:

https://pkg.go.dev/vimagination.zapto.org/httpencoding

Documentation

Overview

Package httpencoding provides a function to deal with the Accept-Encoding header.

Example

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"

	"vimagination.zapto.org/httpencoding"
)

func main() {
	handler := func(w http.ResponseWriter, r *http.Request) {
		if !httpencoding.HandleEncoding(r, httpencoding.HandlerFunc(func(e httpencoding.Encoding) bool {
			if e == "gzip" || httpencoding.IsWildcard(e) && !httpencoding.IsDisallowedInWildcard(e, "gzip") {
				io.WriteString(w, "gzip")
			} else if e == "" || httpencoding.IsWildcard(e) && !httpencoding.IsDisallowedInWildcard(e, "") {
				io.WriteString(w, "identity")
			} else {
				return false
			}

			return true
		})) {
			io.WriteString(w, "none")
		}
	}

	w := httptest.NewRecorder()
	r, _ := http.NewRequest(http.MethodGet, "/", nil)
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "identity")
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "gzip, identity")
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "gzip;q=0.5, identity;q=0.6")
	handler(w, r)
	fmt.Println(w.Body)

	w = httptest.NewRecorder()
	r.Header.Set("Accept-encoding", "identity;q=0")
	handler(w, r)
	fmt.Println(w.Body)

}

Output:

gzip
identity
gzip
identity
none

Index

• func ClearEncoding(r *http.Request)
• func HandleEncoding(r *http.Request, h Handler) bool
• func InvalidEncoding(w http.ResponseWriter)
• func IsDisallowedInWildcard(accept, encoding Encoding) bool
• func IsWildcard(accept Encoding) bool
• type Encoding
• type Handler
• type HandlerFunc
  • func (h HandlerFunc) Handle(e Encoding) bool

Examples

• Package

Functions

func ClearEncoding

func ClearEncoding(r *http.Request)

ClearEncoding removes the Accept-Encoding header so that any further attempts to establish an encoding will simply used the default, plain text, encoding.

Useful when you don't want a handler down the chain to also handle encoding.

func HandleEncoding

func HandleEncoding(r *http.Request, h Handler) bool

HandleEncoding will process the Accept-Encoding header and calls the given handler for each encoding until the handler returns true.

This function returns true when the Handler returns true, false otherwise.

For the identity (plain text) encoding the encoding string will be the empty string.

The wildcard encoding (*) will, after the '*', contain a semi-colon separated list of all disallowed encodings (q=0).

func InvalidEncoding

func InvalidEncoding(w http.ResponseWriter)

InvalidEncoding writes the 406 header.

func IsDisallowedInWildcard

func IsDisallowedInWildcard(accept, encoding Encoding) bool

IsDisallowedInWildcard will return true if the given encoding is disallowed in the given accept string.

func IsWildcard

func IsWildcard(accept Encoding) bool

IsWildcard returns true when the given accept string is a wildcard match.

Types

type Encoding

type Encoding string

Encoding represents an encoding string as used by the client. Examples are gzip, br and deflate.

type Handler

type Handler interface {
	Handle(encoding Encoding) bool
}

Handler provides an interface to handle an encoding.

The encoding string (e.g. gzip, br, deflate) is passed to the handler, which is expected to return true if no more encodings are required and false otherwise.

The empty string "" is used to signify the identity encoding, or plain text.

type HandlerFunc

type HandlerFunc func(Encoding) bool

HandlerFunc wraps a func to make it satisfy the Handler interface.

func (HandlerFunc) Handle

func (h HandlerFunc) Handle(e Encoding) bool

Handle calls the underlying func.