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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 fileserver
import (
"bytes"
"fmt"
"io"
"net/http"
"strconv"
"github.com/gin-gonic/gin"
apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/log"
"github.com/superseriousbusiness/gotosocial/internal/oauth"
)
// ServeFile is for serving attachments, headers, and avatars to the requester from instance storage.
//
// Note: to mitigate scraping attempts, no information should be given out on a bad request except "404 page not found".
// Don't give away account ids or media ids or anything like that; callers shouldn't be able to infer anything.
func (m *Module) ServeFile(c *gin.Context) {
authed, err := oauth.Authed(c, false, false, false, false)
if err != nil {
apiutil.ErrorHandler(c, gtserror.NewErrorNotFound(err), m.processor.InstanceGet)
return
}
// We use request params to check what to pull out of the database/storage so check everything. A request URL should be formatted as follows:
// "https://example.org/fileserver/[ACCOUNT_ID]/[MEDIA_TYPE]/[MEDIA_SIZE]/[FILE_NAME]"
// "FILE_NAME" consists of two parts, the attachment's database id, a period, and the file extension.
accountID := c.Param(AccountIDKey)
if accountID == "" {
err := fmt.Errorf("missing %s from request", AccountIDKey)
apiutil.ErrorHandler(c, gtserror.NewErrorNotFound(err), m.processor.InstanceGet)
return
}
mediaType := c.Param(MediaTypeKey)
if mediaType == "" {
err := fmt.Errorf("missing %s from request", MediaTypeKey)
apiutil.ErrorHandler(c, gtserror.NewErrorNotFound(err), m.processor.InstanceGet)
return
}
mediaSize := c.Param(MediaSizeKey)
if mediaSize == "" {
err := fmt.Errorf("missing %s from request", MediaSizeKey)
apiutil.ErrorHandler(c, gtserror.NewErrorNotFound(err), m.processor.InstanceGet)
return
}
fileName := c.Param(FileNameKey)
if fileName == "" {
err := fmt.Errorf("missing %s from request", FileNameKey)
apiutil.ErrorHandler(c, gtserror.NewErrorNotFound(err), m.processor.InstanceGet)
return
}
content, errWithCode := m.processor.FileGet(c.Request.Context(), authed, &apimodel.GetContentRequestForm{
AccountID: accountID,
MediaType: mediaType,
MediaSize: mediaSize,
FileName: fileName,
})
if errWithCode != nil {
apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
return
}
defer func() {
// close content when we're done
if content.Content != nil {
if err := content.Content.Close(); err != nil {
log.Errorf("ServeFile: error closing readcloser: %s", err)
}
}
}()
if content.URL != nil {
c.Redirect(http.StatusFound, content.URL.String())
return
}
// TODO: if the requester only accepts text/html we should try to serve them *something*.
// This is mostly needed because when sharing a link to a gts-hosted file on something like mastodon, the masto servers will
// attempt to look up the content to provide a preview of the link, and they ask for text/html.
format, err := apiutil.NegotiateAccept(c, apiutil.MIME(content.ContentType))
if err != nil {
apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGet)
return
}
// if this is a head request, just return info + throw the reader away
if c.Request.Method == http.MethodHead {
c.Header("Content-Type", format)
c.Header("Content-Length", strconv.FormatInt(content.ContentLength, 10))
c.Status(http.StatusOK)
return
}
// try to slurp the first few bytes to make sure we have something
b := bytes.NewBuffer(make([]byte, 0, 64))
if _, err := io.CopyN(b, content.Content, 64); err != nil {
err = fmt.Errorf("ServeFile: error reading from content: %w", err)
apiutil.ErrorHandler(c, gtserror.NewErrorNotFound(err, err.Error()), m.processor.InstanceGet)
return
}
// we're good, return the slurped bytes + the rest of the content
c.DataFromReader(http.StatusOK, content.ContentLength, format, io.MultiReader(b, content.Content), nil)
}
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