GoToSocial/internal/processing/media/getfile.go

// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// 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 media

import (
	"context"
	"errors"
	"fmt"
	"net/url"
	"strings"
	"time"

	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
	"github.com/superseriousbusiness/gotosocial/internal/db"
	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
	"github.com/superseriousbusiness/gotosocial/internal/media"
	"github.com/superseriousbusiness/gotosocial/internal/storage"
	"github.com/superseriousbusiness/gotosocial/internal/uris"
)

// GetFile retrieves a file from storage and streams it back
// to the caller via an io.reader embedded in *apimodel.Content.
func (p *Processor) GetFile(
	ctx context.Context,
	requester *gtsmodel.Account,
	form *apimodel.GetContentRequestForm,
) (*apimodel.Content, gtserror.WithCode) {
	// parse the form fields
	mediaSize, err := parseSize(form.MediaSize)
	if err != nil {
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("media size %s not valid", form.MediaSize))
	}

	mediaType, err := parseType(form.MediaType)
	if err != nil {
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("media type %s not valid", form.MediaType))
	}

	spl := strings.Split(form.FileName, ".")
	if len(spl) != 2 || spl[0] == "" || spl[1] == "" {
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("file name %s not parseable", form.FileName))
	}
	wantedMediaID := spl[0]
	owningAccountID := form.AccountID

	// get the account that owns the media and make sure it's not suspended
	owningAccount, err := p.state.DB.GetAccountByID(ctx, owningAccountID)
	if err != nil {
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("account with id %s could not be selected from the db: %s", owningAccountID, err))
	}
	if !owningAccount.SuspendedAt.IsZero() {
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("account with id %s is suspended", owningAccountID))
	}

	// make sure the requesting account and the media account don't block each other
	if requester != nil {
		blocked, err := p.state.DB.IsEitherBlocked(ctx, requester.ID, owningAccountID)
		if err != nil {
			return nil, gtserror.NewErrorNotFound(fmt.Errorf("block status could not be established between accounts %s and %s: %s", owningAccountID, requester.ID, err))
		}
		if blocked {
			return nil, gtserror.NewErrorNotFound(fmt.Errorf("block exists between accounts %s and %s", owningAccountID, requester.ID))
		}
	}

	// the way we store emojis is a little different from the way we store other attachments,
	// so we need to take different steps depending on the media type being requested
	switch mediaType {
	case media.TypeEmoji:
		return p.getEmojiContent(ctx,
			owningAccountID,
			wantedMediaID,
			mediaSize,
		)
	case media.TypeAttachment, media.TypeHeader, media.TypeAvatar:
		return p.getAttachmentContent(ctx,
			requester,
			owningAccountID,
			wantedMediaID,
			mediaSize,
		)
	default:
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("media type %s not recognized", mediaType))
	}
}

func (p *Processor) getAttachmentContent(
	ctx context.Context,
	requester *gtsmodel.Account,
	ownerID string,
	mediaID string,
	sizeStr media.Size,
) (
	*apimodel.Content,
	gtserror.WithCode,
) {
	// Search for media with given ID in the database.
	attach, err := p.state.DB.GetAttachmentByID(ctx, mediaID)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		err := gtserror.Newf("error fetching media from database: %w", err)
		return nil, gtserror.NewErrorInternalError(err)
	}

	if attach == nil {
		const text = "media not found"
		return nil, gtserror.NewErrorNotFound(errors.New(text), text)
	}

	// Ensure the 'owner' owns media.
	if attach.AccountID != ownerID {
		const text = "media was not owned by passed account id"
		return nil, gtserror.NewErrorNotFound(errors.New(text) /* no help text! */)
	}

	var remoteURL *url.URL
	if attach.RemoteURL != "" {

		// Parse media remote URL to valid URL object.
		remoteURL, err = url.Parse(attach.RemoteURL)
		if err != nil {
			err := gtserror.Newf("invalid media remote url %s: %w", attach.RemoteURL, err)
			return nil, gtserror.NewErrorInternalError(err)
		}
	}

	// Uknown file types indicate no *locally*
	// stored data we can serve. Handle separately.
	if attach.Type == gtsmodel.FileTypeUnknown {
		if remoteURL == nil {
			err := gtserror.Newf("missing remote url for unknown type media %s: %w", attach.ID, err)
			return nil, gtserror.NewErrorInternalError(err)
		}

		// If this is an "Unknown" file type, ie., one we
		// tried to process and couldn't, or one we refused
		// to process because it wasn't supported, then we
		// can skip a lot of steps here by simply forwarding
		// the request to the remote URL.
		url := &storage.PresignedURL{
			URL: remoteURL,

			// We might manage to cache the media
			// at some point, so set a low-ish expiry.
			Expiry: time.Now().Add(2 * time.Hour),
		}

		return &apimodel.Content{URL: url}, nil
	}

	var requestUser string

	if requester != nil {
		// Set requesting acc username.
		requestUser = requester.Username
	}

	// Ensure that stored media is cached.
	// (this handles local media / recaches).
	attach, err = p.federator.RefreshMedia(
		ctx,
		requestUser,
		attach,
		media.AdditionalMediaInfo{},
		false,
	)
	if err != nil {
		err := gtserror.Newf("error recaching media: %w", err)
		return nil, gtserror.NewErrorNotFound(err)
	}

	// Start preparing API content model.
	apiContent := &apimodel.Content{
		ContentUpdated: attach.UpdatedAt,
	}

	// Retrieve appropriate
	// size file from storage.
	switch sizeStr {

	case media.SizeOriginal:
		apiContent.ContentType = attach.File.ContentType
		apiContent.ContentLength = int64(attach.File.FileSize)
		return p.getContent(ctx,
			attach.File.Path,
			apiContent,
		)

	case media.SizeSmall:
		apiContent.ContentType = attach.Thumbnail.ContentType
		apiContent.ContentLength = int64(attach.Thumbnail.FileSize)
		return p.getContent(ctx,
			attach.Thumbnail.Path,
			apiContent,
		)

	default:
		const text = "invalid media attachment size"
		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
	}
}

func (p *Processor) getEmojiContent(
	ctx context.Context,

	ownerID string,
	emojiID string,
	sizeStr media.Size,
) (
	*apimodel.Content,
	gtserror.WithCode,
) {
	// Reconstruct static emoji image URL to search for it.
	// As refreshed emojis use a newly generated path ID to
	// differentiate them (cache-wise) from the original.
	staticURL := uris.URIForAttachment(
		ownerID,
		string(media.TypeEmoji),
		string(media.SizeStatic),
		emojiID,
		"png",
	)

	// Search for emoji with given static URL in the database.
	emoji, err := p.state.DB.GetEmojiByStaticURL(ctx, staticURL)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		err := gtserror.Newf("error fetching emoji from database: %w", err)
		return nil, gtserror.NewErrorInternalError(err)
	}

	if emoji == nil {
		const text = "emoji not found"
		return nil, gtserror.NewErrorNotFound(errors.New(text), text)
	}

	if *emoji.Disabled {
		const text = "emoji has been disabled"
		return nil, gtserror.NewErrorNotFound(errors.New(text), text)
	}

	// Ensure that stored emoji is cached.
	// (this handles local emoji / recaches).
	emoji, err = p.federator.RefreshEmoji(
		ctx,
		emoji,
		media.AdditionalEmojiInfo{},
		false,
	)
	if err != nil {
		err := gtserror.Newf("error recaching emoji: %w", err)
		return nil, gtserror.NewErrorNotFound(err)
	}

	// Start preparing API content model.
	apiContent := &apimodel.Content{}

	// Retrieve appropriate
	// size file from storage.
	switch sizeStr {

	case media.SizeOriginal:
		apiContent.ContentType = emoji.ImageContentType
		apiContent.ContentLength = int64(emoji.ImageFileSize)
		return p.getContent(ctx,
			emoji.ImagePath,
			apiContent,
		)

	case media.SizeStatic:
		apiContent.ContentType = emoji.ImageStaticContentType
		apiContent.ContentLength = int64(emoji.ImageStaticFileSize)
		return p.getContent(ctx,
			emoji.ImageStaticPath,
			apiContent,
		)

	default:
		const text = "invalid media attachment size"
		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
	}
}

// getContent performs the final file fetching of
// stored content at path in storage. This is
// populated in the apimodel.Content{} and returned.
// (note: this also handles un-proxied S3 storage).
func (p *Processor) getContent(
	ctx context.Context,
	path string,
	content *apimodel.Content,
) (
	*apimodel.Content,
	gtserror.WithCode,
) {
	// If running on S3 storage with proxying disabled then
	// just fetch pre-signed URL instead of the content.
	if url := p.state.Storage.URL(ctx, path); url != nil {
		content.URL = url
		return content, nil
	}

	// Fetch file stream for the stored media at path.
	rc, err := p.state.Storage.GetStream(ctx, path)
	if err != nil && !storage.IsNotFound(err) {
		err := gtserror.Newf("error getting file %s from storage: %w", path, err)
		return nil, gtserror.NewErrorInternalError(err)
	}

	// Ensure found.
	if rc == nil {
		const text = "file not found"
		return nil, gtserror.NewErrorNotFound(errors.New(text), text)
	}

	// Return with stream.
	content.Content = rc
	return content, nil
}

func parseType(s string) (media.Type, error) {
	switch s {
	case string(media.TypeAttachment):
		return media.TypeAttachment, nil
	case string(media.TypeHeader):
		return media.TypeHeader, nil
	case string(media.TypeAvatar):
		return media.TypeAvatar, nil
	case string(media.TypeEmoji):
		return media.TypeEmoji, nil
	}
	return "", fmt.Errorf("%s not a recognized media.Type", s)
}

func parseSize(s string) (media.Size, error) {
	switch s {
	case string(media.SizeSmall):
		return media.SizeSmall, nil
	case string(media.SizeOriginal):
		return media.SizeOriginal, nil
	case string(media.SizeStatic):
		return media.SizeStatic, nil
	}
	return "", fmt.Errorf("%s not a recognized media.Size", s)
}