From 25b4b55ee108576217259bd850781f5a5f4fc3ce Mon Sep 17 00:00:00 2001
From: KirCute_ECT <951206789@qq.com>
Date: Fri, 10 Jan 2025 20:50:20 +0800
Subject: [PATCH] feat(ftp-server): support resumable downloading (#7792)

---
 go.mod               |  4 ++--
 go.sum               |  8 ++++----
 server/ftp/afero.go  |  8 ++++----
 server/ftp/fsread.go | 47 ++++++++++++++++++++++++++++++++++++++------
 server/ftp/fsup.go   |  2 +-
 5 files changed, 52 insertions(+), 17 deletions(-)

diff --git a/go.mod b/go.mod
index 1deaa1d5..7ca66e15 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,7 @@ go 1.22.4
 
 require (
 	github.com/KirCute/ftpserverlib-pasvportmap v1.25.0
-	github.com/KirCute/sftpd-alist v0.0.11
+	github.com/KirCute/sftpd-alist v0.0.12
 	github.com/SheltonZhu/115driver v1.0.32
 	github.com/Xhofe/go-cache v0.0.0-20240804043513-b1a71927bc21
 	github.com/Xhofe/rateg v0.0.0-20230728072201-251a4e1adad4
@@ -62,7 +62,7 @@ require (
 	github.com/xhofe/tache v0.1.3
 	github.com/xhofe/wopan-sdk-go v0.1.3
 	github.com/zzzhr1990/go-common-entity v0.0.0-20221216044934-fd1c571e3a22
-	golang.org/x/crypto v0.30.0
+	golang.org/x/crypto v0.31.0
 	golang.org/x/exp v0.0.0-20240904232852-e7e105dedf7e
 	golang.org/x/image v0.19.0
 	golang.org/x/net v0.28.0
diff --git a/go.sum b/go.sum
index a4e8e12d..101a0bea 100644
--- a/go.sum
+++ b/go.sum
@@ -6,8 +6,8 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/KirCute/ftpserverlib-pasvportmap v1.25.0 h1:ikwCzeqoqN6wvBHOB9OI6dde/jbV7EoTMpUcxtYl5Po=
 github.com/KirCute/ftpserverlib-pasvportmap v1.25.0/go.mod h1:v0NgMtKDDi/6CM6r4P+daCljCW3eO9yS+Z+pZDTKo1E=
-github.com/KirCute/sftpd-alist v0.0.11 h1:BGInXmmLBI+v6S9WZCwvY0DRK1vDprGNcTv/57p2GSo=
-github.com/KirCute/sftpd-alist v0.0.11/go.mod h1:pPFzr6GrKqXvFXLr46ZpoqmtSpwH8DKTYloSp/ybzKQ=
+github.com/KirCute/sftpd-alist v0.0.12 h1:GNVM5QLbQLAfXP4wGUlXFA2IO6fVek0n0IsGnOuISdg=
+github.com/KirCute/sftpd-alist v0.0.12/go.mod h1:2wNK7yyW2XfjyJq10OY6xB4COLac64hOwfV6clDJn6s=
 github.com/Max-Sum/base32768 v0.0.0-20230304063302-18e6ce5945fd h1:nzE1YQBdx1bq9IlZinHa+HVffy+NmVRoKr+wHN8fpLE=
 github.com/Max-Sum/base32768 v0.0.0-20230304063302-18e6ce5945fd/go.mod h1:C8yoIfvESpM3GD07OCHU7fqI7lhwyZ2Td1rbNbTAhnc=
 github.com/RoaringBitmap/roaring v1.9.3 h1:t4EbC5qQwnisr5PrP9nt0IRhRTb9gMUgQF4t4S2OByM=
@@ -574,8 +574,8 @@ golang.org/x/crypto v0.13.0/go.mod h1:y6Z2r+Rw4iayiXXAIxJIDAJ1zMW4yaTpebo8fPOliY
 golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
 golang.org/x/crypto v0.23.0/go.mod h1:CKFgDieR+mRhux2Lsu27y0fO304Db0wZe70UKqHu0v8=
 golang.org/x/crypto v0.25.0/go.mod h1:T+wALwcMOSE0kXgUAnPAHqTLW+XHgcELELW8VaDgm/M=
-golang.org/x/crypto v0.30.0 h1:RwoQn3GkWiMkzlX562cLB7OxWvjH1L8xutO2WoJcRoY=
-golang.org/x/crypto v0.30.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
+golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
+golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
 golang.org/x/exp v0.0.0-20240904232852-e7e105dedf7e h1:I88y4caeGeuDQxgdoFPUq097j7kNfw6uvuiNxUBfcBk=
 golang.org/x/exp v0.0.0-20240904232852-e7e105dedf7e/go.mod h1:akd2r19cwCdwSwWeIdzYQGa/EZZyqcOdwWiwj5L5eKQ=
 golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
diff --git a/server/ftp/afero.go b/server/ftp/afero.go
index 448744b1..75ae2e43 100644
--- a/server/ftp/afero.go
+++ b/server/ftp/afero.go
@@ -83,9 +83,6 @@ func (a *AferoAdapter) ReadDir(name string) ([]os.FileInfo, error) {
 func (a *AferoAdapter) GetHandle(name string, flags int, offset int64) (ftpserver.FileTransfer, error) {
 	fileSize := a.nextFileSize
 	a.nextFileSize = 0
-	if offset != 0 {
-		return nil, errs.NotSupport
-	}
 	if (flags & os.O_SYNC) != 0 {
 		return nil, errs.NotSupport
 	}
@@ -106,6 +103,9 @@ func (a *AferoAdapter) GetHandle(name string, flags int, offset int64) (ftpserve
 		return nil, errors.New("file already exists")
 	}
 	if (flags & os.O_WRONLY) != 0 {
+		if offset != 0 {
+			return nil, errs.NotSupport
+		}
 		trunc := (flags & os.O_TRUNC) != 0
 		if fileSize > 0 {
 			return OpenUploadWithLength(a.ctx, path, trunc, fileSize)
@@ -113,7 +113,7 @@ func (a *AferoAdapter) GetHandle(name string, flags int, offset int64) (ftpserve
 			return OpenUpload(a.ctx, path, trunc)
 		}
 	}
-	return OpenDownload(a.ctx, path)
+	return OpenDownload(a.ctx, path, offset)
 }
 
 func (a *AferoAdapter) SetNextFileSize(size int64) {
diff --git a/server/ftp/fsread.go b/server/ftp/fsread.go
index 74d184b6..257d2ec8 100644
--- a/server/ftp/fsread.go
+++ b/server/ftp/fsread.go
@@ -8,6 +8,7 @@ import (
 	"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/pkg/http_range"
 	"github.com/alist-org/alist/v3/server/common"
 	"github.com/pkg/errors"
 	"io"
@@ -19,10 +20,12 @@ import (
 
 type FileDownloadProxy struct {
 	ftpserver.FileTransfer
-	reader io.ReadCloser
+	ss     *stream.SeekableStream
+	reader io.Reader
+	cur    int64
 }
 
-func OpenDownload(ctx context.Context, reqPath string) (*FileDownloadProxy, error) {
+func OpenDownload(ctx context.Context, reqPath string, offset int64) (*FileDownloadProxy, error) {
 	user := ctx.Value("user").(*model.User)
 	meta, err := op.GetNearestMeta(reqPath)
 	if err != nil {
@@ -52,11 +55,22 @@ func OpenDownload(ctx context.Context, reqPath string) (*FileDownloadProxy, erro
 	if err != nil {
 		return nil, err
 	}
-	return &FileDownloadProxy{reader: ss}, nil
+	var reader io.Reader
+	if offset != 0 {
+		reader, err = ss.RangeRead(http_range.Range{Start: offset, Length: -1})
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		reader = ss
+	}
+	return &FileDownloadProxy{ss: ss, reader: reader}, nil
 }
 
 func (f *FileDownloadProxy) Read(p []byte) (n int, err error) {
-	return f.reader.Read(p)
+	n, err = f.reader.Read(p)
+	f.cur += int64(n)
+	return n, err
 }
 
 func (f *FileDownloadProxy) Write(p []byte) (n int, err error) {
@@ -64,11 +78,32 @@ func (f *FileDownloadProxy) Write(p []byte) (n int, err error) {
 }
 
 func (f *FileDownloadProxy) Seek(offset int64, whence int) (int64, error) {
-	return 0, errs.NotSupport
+	switch whence {
+	case io.SeekStart:
+		break
+	case io.SeekCurrent:
+		offset += f.cur
+		break
+	case io.SeekEnd:
+		offset += f.ss.GetSize()
+		break
+	default:
+		return 0, errs.NotSupport
+	}
+	if offset < 0 {
+		return 0, errors.New("Seek: negative position")
+	}
+	reader, err := f.ss.RangeRead(http_range.Range{Start: offset, Length: -1})
+	if err != nil {
+		return f.cur, err
+	}
+	f.cur = offset
+	f.reader = reader
+	return offset, nil
 }
 
 func (f *FileDownloadProxy) Close() error {
-	return f.reader.Close()
+	return f.ss.Close()
 }
 
 type OsFileInfoAdapter struct {
diff --git a/server/ftp/fsup.go b/server/ftp/fsup.go
index 96c84681..4d626d0e 100644
--- a/server/ftp/fsup.go
+++ b/server/ftp/fsup.go
@@ -63,7 +63,7 @@ func (f *FileUploadProxy) Write(p []byte) (n int, err error) {
 }
 
 func (f *FileUploadProxy) Seek(offset int64, whence int) (int64, error) {
-	return 0, errs.NotSupport
+	return f.buffer.Seek(offset, whence)
 }
 
 func (f *FileUploadProxy) Close() error {