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

* feat: ftp server support

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

server/ftp/fsread.go

@@ -0,0 +1,188 @@
+package ftp
+
+import (
+	"context"
+	ftpserver "github.com/KirCute/ftpserverlib-pasvportmap"
+	"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/net"
+	"github.com/alist-org/alist/v3/internal/op"
+	"github.com/alist-org/alist/v3/pkg/http_range"
+	"github.com/alist-org/alist/v3/pkg/utils"
+	"github.com/alist-org/alist/v3/server/common"
+	"github.com/pkg/errors"
+	"io"
+	fs2 "io/fs"
+	"net/http"
+	"os"
+	"time"
+)
+
+type FileDownloadProxy struct {
+	ftpserver.FileTransfer
+	reader  io.ReadCloser
+	closers *utils.Closers
+}
+
+func OpenDownload(ctx context.Context, path string) (*FileDownloadProxy, error) {
+	user := ctx.Value("user").(*model.User)
+	reqPath, err := user.JoinPath(path)
+	if err != nil {
+		return nil, err
+	}
+	meta, err := op.GetNearestMeta(reqPath)
+	if err != nil {
+		if !errors.Is(errors.Cause(err), errs.MetaNotFound) {
+			return nil, err
+		}
+	}
+	ctx = context.WithValue(ctx, "meta", meta)
+	if !common.CanAccess(user, meta, reqPath, ctx.Value("meta_pass").(string)) {
+		return nil, errs.PermissionDenied
+	}
+
+	// directly use proxy
+	header := *(ctx.Value("proxy_header").(*http.Header))
+	link, obj, err := fs.Link(ctx, reqPath, model.LinkArgs{
+		IP:     ctx.Value("client_ip").(string),
+		Header: header,
+	})
+	if err != nil {
+		return nil, err
+	}
+	storage, err := fs.GetStorage(reqPath, &fs.GetStoragesArgs{})
+	if err != nil {
+		return nil, err
+	}
+	if storage.GetStorage().ProxyRange {
+		common.ProxyRange(link, obj.GetSize())
+	}
+	reader, closers, err := proxy(link)
+	if err != nil {
+		return nil, err
+	}
+	return &FileDownloadProxy{reader: reader, closers: closers}, nil
+}
+
+func proxy(link *model.Link) (io.ReadCloser, *utils.Closers, error) {
+	if link.MFile != nil {
+		return link.MFile, nil, nil
+	} else if link.RangeReadCloser != nil {
+		rc, err := link.RangeReadCloser.RangeRead(context.Background(), http_range.Range{Length: -1})
+		if err != nil {
+			return nil, nil, err
+		}
+		closers := link.RangeReadCloser.GetClosers()
+		return rc, &closers, nil
+	} else {
+		res, err := net.RequestHttp(context.Background(), http.MethodGet, link.Header, link.URL)
+		if err != nil {
+			return nil, nil, err
+		}
+		return res.Body, nil, nil
+	}
+}
+
+func (f *FileDownloadProxy) Read(p []byte) (n int, err error) {
+	return f.reader.Read(p)
+}
+
+func (f *FileDownloadProxy) Write(p []byte) (n int, err error) {
+	return 0, errs.NotSupport
+}
+
+func (f *FileDownloadProxy) Seek(offset int64, whence int) (int64, error) {
+	return 0, errs.NotSupport
+}
+
+func (f *FileDownloadProxy) Close() error {
+	defer func() {
+		if f.closers != nil {
+			_ = f.closers.Close()
+		}
+	}()
+	return f.reader.Close()
+}
+
+type OsFileInfoAdapter struct {
+	obj model.Obj
+}
+
+func (o *OsFileInfoAdapter) Name() string {
+	return o.obj.GetName()
+}
+
+func (o *OsFileInfoAdapter) Size() int64 {
+	return o.obj.GetSize()
+}
+
+func (o *OsFileInfoAdapter) Mode() fs2.FileMode {
+	var mode fs2.FileMode = 0755
+	if o.IsDir() {
+		mode |= fs2.ModeDir
+	}
+	return mode
+}
+
+func (o *OsFileInfoAdapter) ModTime() time.Time {
+	return o.obj.ModTime()
+}
+
+func (o *OsFileInfoAdapter) IsDir() bool {
+	return o.obj.IsDir()
+}
+
+func (o *OsFileInfoAdapter) Sys() any {
+	return o.obj
+}
+
+func Stat(ctx context.Context, path string) (os.FileInfo, error) {
+	user := ctx.Value("user").(*model.User)
+	reqPath, err := user.JoinPath(path)
+	if err != nil {
+		return nil, err
+	}
+	meta, err := op.GetNearestMeta(reqPath)
+	if err != nil {
+		if !errors.Is(errors.Cause(err), errs.MetaNotFound) {
+			return nil, err
+		}
+	}
+	ctx = context.WithValue(ctx, "meta", meta)
+	if !common.CanAccess(user, meta, reqPath, ctx.Value("meta_pass").(string)) {
+		return nil, errs.PermissionDenied
+	}
+	obj, err := fs.Get(ctx, reqPath, &fs.GetArgs{})
+	if err != nil {
+		return nil, err
+	}
+	return &OsFileInfoAdapter{obj: obj}, nil
+}
+
+func List(ctx context.Context, path string) ([]os.FileInfo, error) {
+	user := ctx.Value("user").(*model.User)
+	reqPath, err := user.JoinPath(path)
+	if err != nil {
+		return nil, err
+	}
+	meta, err := op.GetNearestMeta(reqPath)
+	if err != nil {
+		if !errors.Is(errors.Cause(err), errs.MetaNotFound) {
+			return nil, err
+		}
+	}
+	ctx = context.WithValue(ctx, "meta", meta)
+	if !common.CanAccess(user, meta, reqPath, ctx.Value("meta_pass").(string)) {
+		return nil, errs.PermissionDenied
+	}
+	objs, err := fs.List(ctx, reqPath, &fs.ListArgs{})
+	if err != nil {
+		return nil, err
+	}
+	ret := make([]os.FileInfo, len(objs))
+	for i, obj := range objs {
+		ret[i] = &OsFileInfoAdapter{obj: obj}
+	}
+	return ret, nil
+}