feat: ftp server support (#7634 close #1898)

* feat: ftp server support

* fix(ftp): incorrect mode for dirs in LIST returns

server/ftp/fsup.go

@@ -0,0 +1,91 @@
+package ftp
+
+import (
+	"context"
+	ftpserver "github.com/KirCute/ftpserverlib-pasvportmap"
+	"github.com/alist-org/alist/v3/internal/conf"
+	"github.com/alist-org/alist/v3/internal/errs"
+	"github.com/alist-org/alist/v3/internal/fs"
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/internal/op"
+	"github.com/alist-org/alist/v3/internal/stream"
+	"github.com/alist-org/alist/v3/server/common"
+	"github.com/pkg/errors"
+	"io"
+	"net/http"
+	"os"
+	stdpath "path"
+	"time"
+)
+
+type FileUploadProxy struct {
+	ftpserver.FileTransfer
+	buffer *os.File
+	path   string
+	ctx    context.Context
+}
+
+func OpenUpload(ctx context.Context, path string) (*FileUploadProxy, error) {
+	user := ctx.Value("user").(*model.User)
+	path, err := user.JoinPath(path)
+	if err != nil {
+		return nil, err
+	}
+	meta, err := op.GetNearestMeta(stdpath.Dir(path))
+	if err != nil {
+		if !errors.Is(errors.Cause(err), errs.MetaNotFound) {
+			return nil, err
+		}
+	}
+	if !(common.CanAccess(user, meta, path, ctx.Value("meta_pass").(string)) &&
+		((user.CanFTPManage() && user.CanWrite()) || common.CanWrite(meta, stdpath.Dir(path)))) {
+		return nil, errs.PermissionDenied
+	}
+	tmpFile, err := os.CreateTemp(conf.Conf.TempDir, "file-*")
+	if err != nil {
+		return nil, err
+	}
+	return &FileUploadProxy{buffer: tmpFile, path: path, ctx: ctx}, nil
+}
+
+func (f *FileUploadProxy) Read(p []byte) (n int, err error) {
+	return 0, errs.NotSupport
+}
+
+func (f *FileUploadProxy) Write(p []byte) (n int, err error) {
+	return f.buffer.Write(p)
+}
+
+func (f *FileUploadProxy) Seek(offset int64, whence int) (int64, error) {
+	return 0, errs.NotSupport
+}
+
+func (f *FileUploadProxy) Close() error {
+	dir, name := stdpath.Split(f.path)
+	size, err := f.buffer.Seek(0, io.SeekCurrent)
+	if err != nil {
+		return err
+	}
+	if _, err := f.buffer.Seek(0, io.SeekStart); err != nil {
+		return err
+	}
+	arr := make([]byte, 512)
+	if _, err := f.buffer.Read(arr); err != nil {
+		return err
+	}
+	contentType := http.DetectContentType(arr)
+	if _, err := f.buffer.Seek(0, io.SeekStart); err != nil {
+		return err
+	}
+	s := &stream.FileStream{
+		Obj: &model.Object{
+			Name:     name,
+			Size:     size,
+			Modified: time.Now(),
+		},
+		Mimetype:     contentType,
+		WebPutAsTask: false,
+	}
+	s.SetTmpFile(f.buffer)
+	return fs.PutDirectly(f.ctx, dir, s, true)
+}