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middleware.go
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middleware.go
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/*
* Copyright 2023 Wang Min Xiang
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package cachecontrol
import (
"bytes"
"github.com/aacfactory/errors"
"github.com/aacfactory/fns/commons/bytex"
"github.com/aacfactory/fns/transports"
"github.com/aacfactory/logs"
"github.com/cespare/xxhash/v2"
"github.com/valyala/bytebufferpool"
"net/http"
"strconv"
"time"
)
var (
nilBodyETag = []byte(strconv.FormatUint(xxhash.Sum64([]byte("nil")), 16))
contextEnableKey = []byte("@fns:cache-control:enable")
)
func NewWithCache(cache Cache) transports.Middleware {
return &Middleware{
cache: cache,
}
}
func New() transports.Middleware {
return NewWithCache(new(DefaultCache))
}
var (
getMethod = []byte("GET")
)
// Middleware
// use @cache-control max-age=10 public=true must-revalidate=false proxy-revalidate=false
type Middleware struct {
log logs.Logger
cache Cache
enable bool
maxAge int
}
func (middleware *Middleware) Name() string {
return "cachecontrol"
}
func (middleware *Middleware) Construct(options transports.MiddlewareOptions) (err error) {
middleware.log = options.Log
config := Config{}
configErr := options.Config.As(&config)
if configErr != nil {
err = errors.Warning("fns: construct cache control middleware failed").WithCause(configErr)
return
}
middleware.enable = config.Enable
middleware.maxAge = config.MaxAge
if middleware.maxAge < 1 {
middleware.maxAge = 60
}
return
}
func (middleware *Middleware) Handler(next transports.Handler) transports.Handler {
if middleware.enable {
return transports.HandlerFunc(func(writer transports.ResponseWriter, request transports.Request) {
isGet := bytes.Equal(request.Method(), getMethod)
if !isGet {
next.Handle(writer, request)
return
}
rch := request.Header().Get(transports.CacheControlHeaderName)
if bytes.Equal(rch, transports.CacheControlHeaderNoStore) || bytes.Equal(rch, transports.CacheControlHeaderNoCache) {
next.Handle(writer, request)
return
}
// request key
var key []byte
// if-no-match
if inm := request.Header().Get(transports.CacheControlHeaderIfNonMatch); len(inm) > 0 {
key = hashRequest(request)
etag, hasEtag, getErr := middleware.cache.Get(request, key)
if getErr != nil {
if middleware.log.WarnEnabled() {
middleware.log.Warn().
With("middleware", "cachecontrol").
Cause(errors.Warning("fns: get etag from cache store failed").WithCause(getErr)).
Message("get etag from cache store failed")
}
next.Handle(writer, request)
return
}
if hasEtag && bytes.Equal(etag, inm) {
writer.SetStatus(http.StatusNotModified)
return
}
}
// set enable
request.SetLocalValue(contextEnableKey, true)
// next
next.Handle(writer, request)
// check response
cch := writer.Header().Get(transports.CacheControlHeaderName)
if len(cch) == 0 {
return
}
maxAgeValue := 0
hasMaxAge := false
if idx := bytes.Index(cch, maxAge); idx > -1 {
segment := cch[idx+8:]
commaIdx := bytes.IndexByte(segment, ',')
if commaIdx > 0 {
segment = segment[:commaIdx]
}
ma, parseErr := strconv.Atoi(bytex.ToString(segment))
if parseErr == nil {
maxAgeValue = ma
hasMaxAge = true
} else {
// remove invalid max-age
if idx == 0 {
cch = cch[idx+8+commaIdx+1:]
} else {
cch = append(cch[:idx], cch[idx+8+commaIdx+1:]...)
}
}
}
if !hasMaxAge {
maxAgeValue = middleware.maxAge
cch = append(cch, ',', ' ')
cch = append(cch, maxAge...)
cch = append(cch, '=')
cch = append(cch, strconv.Itoa(maxAgeValue)...)
writer.Header().Set(transports.CacheControlHeaderName, cch)
}
if len(key) == 0 {
key = hashRequest(request)
}
// etag
var etag []byte
if bodyLen := writer.BodyLen(); bodyLen == 0 {
etag = nilBodyETag
} else {
body := writer.Body()
etag = bytex.FromString(strconv.FormatUint(xxhash.Sum64(body), 16))
}
setErr := middleware.cache.Set(request, key, etag, time.Duration(maxAgeValue)*time.Second)
if setErr == nil {
writer.Header().Set(transports.ETagHeaderName, etag)
} else {
if middleware.log.WarnEnabled() {
middleware.log.Warn().
With("middleware", "cachecontrol").
Cause(errors.Warning("fns: set etag into cache store failed").WithCause(setErr)).
Message("set etag into cache store failed")
}
// use no-cache
writer.Header().Set(transports.CacheControlHeaderName, transports.CacheControlHeaderNoCache)
writer.Header().Set(pragma, transports.CacheControlHeaderNoCache)
}
})
}
return next
}
func (middleware *Middleware) Close() (err error) {
middleware.cache.Close()
return
}
func hashRequest(r transports.Request) (p []byte) {
b := bytebufferpool.Get()
// path
_, _ = b.Write(r.Path())
// param
param := r.Params()
_, _ = b.Write(param.Encode())
// authorization
if authorization := r.Header().Get(transports.AuthorizationHeaderName); len(authorization) > 0 {
_, _ = b.Write(authorization)
}
pp := b.Bytes()
p = bytex.FromString(strconv.FormatUint(xxhash.Sum64(pp), 16))
bytebufferpool.Put(b)
return
}