92 lines
2.3 KiB
Go
92 lines
2.3 KiB
Go
package middleware
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// Based on https://github.com/LYY/echo-middleware (MIT License, https://github.com/LYY/echo-middleware/blob/master/LICENSE)
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// Ported from Goji's middleware, source:
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// https://github.com/zenazn/goji/tree/master/web/middleware (MIT License, https://github.com/zenazn/goji/blob/master/LICENSE)
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import (
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"time"
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"github.com/labstack/echo/v4"
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middleware "github.com/labstack/echo/v4/middleware"
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)
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type (
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// NoCacheConfig defines the config for nocache middleware.
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NoCacheConfig struct {
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// Skipper defines a function to skip middleware.
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Skipper middleware.Skipper
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}
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)
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var (
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// Unix epoch time
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epoch = time.Unix(0, 0).Format(time.RFC1123)
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// Taken from https://github.com/mytrile/nocache
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noCacheHeaders = map[string]string{
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"Expires": epoch,
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"Cache-Control": "no-cache, private, max-age=0",
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"Pragma": "no-cache",
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"X-Accel-Expires": "0",
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}
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etagHeaders = []string{
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"ETag",
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"If-Modified-Since",
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"If-Match",
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"If-None-Match",
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"If-Range",
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"If-Unmodified-Since",
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}
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// DefaultNoCacheConfig is the default nocache middleware config.
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DefaultNoCacheConfig = NoCacheConfig{
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Skipper: middleware.DefaultSkipper,
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}
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)
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// NoCache is a simple piece of middleware that sets a number of HTTP headers to prevent
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// a router (or subrouter) from being cached by an upstream proxy and/or client.
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//
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// As per http://wiki.nginx.org/HttpProxyModule - NoCache sets:
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//
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// Expires: Thu, 01 Jan 1970 00:00:00 UTC
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// Cache-Control: no-cache, private, max-age=0
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// X-Accel-Expires: 0
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// Pragma: no-cache (for HTTP/1.0 proxies/clients)
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func NoCache() echo.MiddlewareFunc {
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return NoCacheWithConfig(DefaultNoCacheConfig)
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}
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// NoCacheWithConfig returns a nocache middleware with config.
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func NoCacheWithConfig(config NoCacheConfig) echo.MiddlewareFunc {
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// Defaults
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if config.Skipper == nil {
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config.Skipper = DefaultNoCacheConfig.Skipper
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}
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return func(next echo.HandlerFunc) echo.HandlerFunc {
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return func(c echo.Context) error {
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if config.Skipper(c) {
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return next(c)
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}
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req := c.Request()
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// Delete any ETag headers that may have been set
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for _, v := range etagHeaders {
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if req.Header.Get(v) != "" {
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req.Header.Del(v)
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}
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}
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// Set our NoCache headers
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res := c.Response()
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for k, v := range noCacheHeaders {
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res.Header().Set(k, v)
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}
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return next(c)
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}
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}
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}
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