Delphi IndyFTP执行PUT后遇Connection Closed Gracefully致大文件损坏

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2026-7-25

Indy TIdFTP大文件上传损坏问题

问题描述

我在Delphi应用中使用Indy的TIdFTP组件通过FTP向服务器发送压缩文件，应用已部署在数百台客户电脑上。目前有三位客户遇到相同问题：执行Put()命令显示100%完成后，出现“Connection Closed Gracefully”错误，且上传的文件损坏。将服务器上的zip文件下载后用WinRAR打开，会提示“存档意外结束”。

补充信息

测试发现仅文件大小超过300MB时触发错误，2MB至140MB文件上传无问题。
同一局域网内其他电脑测试结果一致，推测问题与调制解调器或网络基础设施相关，已关闭电脑和调制解调器的防火墙。

原代码与初始错误

IdFTP1.Connect;
IdFTP1.TransferType := ftBinary;
IdFTP1.Put(strFileName);
IdFTP1.Disconnect;

错误发生在第3行IdFTP1.Put(strFileName);，导致无法执行后续的Disconnect()。

后续调整与问题延续

按照Remy的建议修改后问题依旧：

启用了NATKeepAlive参数；
添加try/except和finally块，代码如下：

IdFTP1.Connect;
IdFTP1.TransferType := ftBinary;
try//finally
  try//except
    IdFTP1.Put(strFileName);
  except
  end;
finally
  IdFTP1.Disconnect;
end;

修改后程序可正常执行Disconnect()，但上传文件仍损坏，WinRAR仍提示“存档意外结束”。

日志对比分析

为TIdFTP启用TIdLogFile，分别测试14MB小文件和350MB大文件：

小文件上传正常日志

Stat Connected.
Recv 03/04/2023 10:29:31: 220 ProFTPD Server (ProFTPD) [***.***.***.***]<EOL>
Sent 03/04/2023 10:29:31: HOST ***.***.***.***<EOL>
Recv 03/04/2023 10:29:31: 220 HOST command successful<EOL>
Sent 03/04/2023 10:29:31: USER *******<EOL>
Recv 03/04/2023 10:29:31: 331 Password required for ******<EOL>
Sent 03/04/2023 10:29:31: PASS *******<EOL>
Recv 03/04/2023 10:29:31: 230 User ****** logged in<EOL>
Sent 03/04/2023 10:29:31: FEAT<EOL>
Recv 03/04/2023 10:29:31: 211-Features:<EOL>
Recv 03/04/2023 10:29:31:  AUTH TLS<EOL> CCC<EOL> CLNT<EOL>
Recv 03/04/2023 10:29:31:  EPRT<EOL> EPSV<EOL> HOST<EOL> LANG en-US.UTF-8*<EOL> MDTM<EOL> MFF modify;UNIX.group;UNIX.mode;<EOL> MFMT<EOL> MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.groupname*;UNIX.mode*;UNIX.owner*;UNIX.ownername*;<EOL> PBSZ<EOL> PROT<EOL> RANG STREAM<EOL> REST STREAM<EOL> SIZE<EOL> SSCN<EOL> TVFS<EOL> UTF8<EOL>211 End<EOL>
Sent 03/04/2023 10:29:31: CLNT Indy 10.6.2.0<EOL>
Recv 03/04/2023 10:29:31: 200 OK<EOL>
Sent 03/04/2023 10:29:31: OPTS UTF8 ON<EOL>
Recv 03/04/2023 10:29:31: 200 UTF8 set to on<EOL>
Sent 03/04/2023 10:29:31: TYPE I<EOL>
Recv 03/04/2023 10:29:31: 200 Type set to I<EOL>
Sent 03/04/2023 10:29:31: SYST<EOL>
Recv 03/04/2023 10:29:31: 215 UNIX Type: L8<EOL>
Sent 03/04/2023 10:29:31: TYPE I<EOL>
Recv 03/04/2023 10:29:31: 200 Type set to I<EOL>
Sent 03/04/2023 10:29:31: PASV<EOL>
Recv 03/04/2023 10:29:31: 227 Entering Passive Mode (***.***.***.***,213,225).<EOL>
Sent 03/04/2023 10:29:32: MLSD _test<EOL>
Recv 03/04/2023 10:29:32: 150 Opening BINARY mode data connection for MLSD<EOL>
Recv 03/04/2023 10:29:32: 226 Transfer complete<EOL>
Sent 03/04/2023 10:29:32: CWD _test<EOL>
Recv 03/04/2023 10:29:32: 250 CWD command successful<EOL>
Sent 03/04/2023 10:29:32: PASV<EOL>
Recv 03/04/2023 10:29:32: 227 Entering Passive Mode (***.***.***.***,232,86).<EOL>
Sent 03/04/2023 10:29:32: STOR MySmallFile.zip<EOL>
Recv 03/04/2023 10:29:32: 150 Opening BINARY mode data connection for MySmallFile.zip<EOL>
Recv 03/04/2023 10:29:52: 226 Transfer complete<EOL>
Sent 03/04/2023 10:29:52: QUIT<EOL>
Recv 03/04/2023 10:29:52: 221 Goodbye.<EOL>
Stat Disconnected.

大文件上传损坏日志

Stat Connected.
Recv 03/04/2023 10:30:51: 220 ProFTPD Server (ProFTPD) [***.***.***.***]<EOL>
Sent 03/04/2023 10:30:51: HOST ***.***.***.***<EOL>
Recv 03/04/2023 10:30:51: 220 HOST command successful<EOL>
Sent 03/04/2023 10:30:51: USER *********<EOL>
Recv 03/04/2023 10:30:51: 331 Password required for *****<EOL>
Sent 03/04/2023 10:30:51: PASS *********<EOL>
Recv 03/04/2023 10:30:51: 230 User ******** logged in<EOL>
Sent 03/04/2023 10:30:51: FEAT<EOL>
Recv 03/04/2023 10:30:51: 211-Features:<EOL> AUTH TLS<EOL> CCC<EOL> CLNT<EOL> EPRT<EOL> EPSV<EOL> HOST<EOL> LANG en-US.UTF-8*<EOL>
Recv 03/04/2023 10:30:51:  MDTM<EOL> MFF modify;UNIX.group;UNIX.mode;<EOL> MFMT<EOL> MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.groupname*;UNIX.mode*;UNIX.owner*;UNIX.ownername*;<EOL> PBSZ<EOL> PROT<EOL> RANG STREAM<EOL> REST STREAM<EOL> SIZE<EOL> SSCN<EOL> TVFS<EOL> UTF8<EOL>211 End<EOL>
Sent 03/04/2023 10:30:51: CLNT Indy 10.6.2.0<EOL>
Recv 03/04/2023 10:30:51: 200 OK<EOL>
Sent 03/04/2023 10:30:51: OPTS UTF8 ON<EOL>
Recv 03/04/2023 10:30:51: 200 UTF8 set to on<EOL>
Sent 03/04/2023 10:30:51: TYPE I<EOL>
Recv 03/04/2023 10:30:51: 200 Type set to I<EOL>
Sent 03/04/2023 10:30:51: SYST<EOL>
Recv 03/04/2023 10:30:51: 215 UNIX Type: L8<EOL>
Sent 03/04/2023 10:30:51: TYPE I<EOL>
Recv 03/04/2023 10:30:51: 200 Type set to I<EOL>
Sent 03/04/2023 10:30:51: PASV<EOL>
Recv 03/04/2023 10:30:51: 227 Entering Passive Mode (***.***.***.***,213,173).<EOL>
Sent 03/04/2023 10:30:51: MLSD _test<EOL>
Recv 03/04/2023 10:30:51: 150 Opening BINARY mode data connection for MLSD<EOL>
Recv 03/04/2023 10:30:51: 226 Transfer complete<EOL>
Sent 03/04/2023 10:30:51: CWD _test<EOL>
Recv 03/04/2023 10:30:51: 250 CWD command successful<EOL>
Sent 03/04/2023 10:30:51: PASV<EOL>
Recv 03/04/2023 10:30:51: 227 Entering Passive Mode (***.***.***.***,222,56).<EOL>
Sent 03/04/2023 10:30:51: STOR MyBigFile.zip<EOL>
Recv 03/04/2023 10:30:51: 150 Opening BINARY mode data connection for MyBigFile.zip<EOL>
Sent 03/04/2023 10:40:24: QUIT<EOL>
Stat Disconnected.

日志差异

小文件上传流程完整：发送STOR命令后，收到服务器的150响应，传输完成后收到226 Transfer complete，再发送QUIT并收到221 Goodbye。

大文件上传时，发送STOR和150响应后，没有收到226 Transfer complete就直接发送了QUIT，说明数据连接在文件传输完成前被中断，导致服务器上的文件不完整，最终出现损坏。

内容的提问来源于stack exchange，提问作者Holy Thirteen

Delphi IndyFTP执行PUT后遇Connection Closed Gracefully致大文件损坏

问题描述 #

补充信息 #

原代码与初始错误 #

后续调整与问题延续 #

日志对比分析 #

小文件上传正常日志 #

大文件上传损坏日志 #

日志差异 #