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/*
GoToSocial
Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package web
import (
"bytes"
"errors"
"fmt"
"net/http"
"strings"
"time"
"github.com/gin-gonic/gin"
apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/log"
)
const appRSSUTF8 = string(apiutil.AppRSSXML + "; charset=utf-8")
func (m *Module) GetRSSETag(urlPath string, lastModified time.Time, getRSSFeed func() (string, gtserror.WithCode)) (string, error) {
if cachedETag, ok := m.eTagCache.Get(urlPath); ok && !lastModified.After(cachedETag.lastModified) {
// only return our cached etag if the file wasn't
// modified since last time, otherwise generate a
// new one; eat fresh!
return cachedETag.eTag, nil
}
rssFeed, errWithCode := getRSSFeed()
if errWithCode != nil {
return "", fmt.Errorf("error getting rss feed: %s", errWithCode)
}
eTag, err := generateEtag(bytes.NewReader([]byte(rssFeed)))
if err != nil {
return "", fmt.Errorf("error generating etag: %s", err)
}
// put new entry in cache before we return
m.eTagCache.Set(urlPath, eTagCacheEntry{
eTag: eTag,
lastModified: lastModified,
})
return eTag, nil
}
func extractIfModifiedSince(header string) time.Time {
if header == "" {
return time.Time{}
}
t, err := http.ParseTime(header)
if err != nil {
log.Errorf("couldn't parse if-modified-since %s: %s", header, err)
return time.Time{}
}
return t
}
func (m *Module) rssFeedGETHandler(c *gin.Context) {
// set this Cache-Control header to instruct clients to validate the response with us
// before each reuse (https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control)
c.Header(cacheControlHeader, cacheControlNoCache)
ctx := c.Request.Context()
if _, err := apiutil.NegotiateAccept(c, apiutil.AppRSSXML); err != nil {
apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGet)
return
}
// usernames on our instance will always be lowercase
username := strings.ToLower(c.Param(usernameKey))
if username == "" {
err := errors.New("no account username specified")
apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
return
}
ifNoneMatch := c.Request.Header.Get(ifNoneMatchHeader)
ifModifiedSince := extractIfModifiedSince(c.Request.Header.Get(ifModifiedSinceHeader))
getRssFeed, accountLastPostedPublic, errWithCode := m.processor.AccountGetRSSFeedForUsername(ctx, username)
if errWithCode != nil {
apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
return
}
var rssFeed string
cacheKey := c.Request.URL.Path
cacheEntry, ok := m.eTagCache.Get(cacheKey)
if !ok || cacheEntry.lastModified.Before(accountLastPostedPublic) {
// we either have no cache entry for this, or we have an expired cache entry; generate a new one
rssFeed, errWithCode = getRssFeed()
if errWithCode != nil {
apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
return
}
eTag, err := generateEtag(bytes.NewBufferString(rssFeed))
if err != nil {
apiutil.ErrorHandler(c, gtserror.NewErrorInternalError(err), m.processor.InstanceGet)
return
}
cacheEntry.lastModified = accountLastPostedPublic
cacheEntry.eTag = eTag
m.eTagCache.Set(cacheKey, cacheEntry)
}
c.Header(eTagHeader, cacheEntry.eTag)
c.Header(lastModifiedHeader, accountLastPostedPublic.Format(http.TimeFormat))
if ifNoneMatch == cacheEntry.eTag {
c.AbortWithStatus(http.StatusNotModified)
return
}
lmUnix := cacheEntry.lastModified.Unix()
imsUnix := ifModifiedSince.Unix()
if lmUnix <= imsUnix {
c.AbortWithStatus(http.StatusNotModified)
return
}
if rssFeed == "" {
// we had a cache entry already so we didn't call to get the rss feed yet
rssFeed, errWithCode = getRssFeed()
if errWithCode != nil {
apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
return
}
}
c.Data(http.StatusOK, appRSSUTF8, []byte(rssFeed))
}
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