451-Error during read from data connection

Describe the bug There is a repeatable error during file upload in case of specific file size (around 45k, one specific file size is 45017 bytes) and network speed (fast). If the file is smaller or larger, the error disappears (file content does not matter). If the network speed is slower, error also disappears. Reproduces with minimal code (new Client + access + uploadFrom), but as is location-specific, is probably very little use. Typically 32k gets uploaded before error appears (but sometimes less)

Possible racing condition?

Problem does NOT depend on:

• file content
• file name

Ubuntu 18.04 Node v12.22.1 basic-ftp 4.6.6

Would be happy to provide any additional data if requested.

Exception thrown:

FTPError: 451-Error during read from data connection
451-Transfer aborted
451 0.058 seconds (measured here), 0.54 Mbytes per second
    at FTPContext._onControlSocketData (node_modules/basic-ftp/dist/FtpContext.js:282:39)
    at TLSSocket.<anonymous> (node_modules/basic-ftp/dist/FtpContext.js:123:44)
    at TLSSocket.emit (events.js:314:20)
    at addChunk (_stream_readable.js:297:12)
    at readableAddChunk (_stream_readable.js:268:11)
    at TLSSocket.Readable.push (_stream_readable.js:213:10)
    at TLSWrap.onStreamRead (internal/stream_base_commons.js:188:23) {

Verbose log:

Connected to x.x.x.x:21 (No encryption)
< 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
220-You are user number 9 of 500 allowed.
220-Local time is now 07:20. Server port: 21.
220-This is a private system - No anonymous login
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 30 minutes of inactivity.

> AUTH TLS
< 234 AUTH TLS OK.

Control socket is using: TLSv1.3
Login security: TLSv1.3
> USER x
< 331 User x OK. Password required

> PASS ###
< 230-User global permissions: DOWNLOAD (yes) UPLOAD (yes) [NEW (yes) RESUME (yes) OVERWRITE (yes) VIRUSES(no)] RENAME (yes) DELETE (yes) CHMOD (yes) MKDIR (yes) RMDIR (yes) CHDIR (yes) LIST (yes)

< 230 OK. Current restricted directory is /

> FEAT
< 211-Extensions supported:
 UTF8
 EPRT
 IDLE
 MDTM
 SIZE
 MFMT
 REST STREAM
 MLST type*;size*;sizd*;modify*;UNIX.mode*;UNIX.uid*;UNIX.gid*;unique*;
 MLSD
 PRET
 AUTH TLS
 PBSZ
 PROT
 TVFS
 ESTA
 PASV
 EPSV
 SPSV
 ESTP

< 211 End.

> TYPE I
< 200 TYPE is now 8-bit binary

> STRU F
< 200 F OK

> OPTS UTF8 ON
< 200 Always in UTF8 mode

> OPTS MLST type;size;modify;unique;unix.mode;unix.owner;unix.group;unix.ownername;unix.groupname;
< 200  MLST OPTS type;size;sizd;modify;UNIX.mode;UNIX.uid;UNIX.gid;unique;

> PBSZ 0
< 200 PBSZ=0

> PROT P
< 200 Data protection level set to "private"

> CWD /gfx/300x300
< 250 OK. Current directory is /gfx/300x300

Trying to find optimal transfer mode...
> EPSV
< 500 Unknown command

Transfer mode failed: "500 Unknown command", will try next.
> PASV
< 227 Entering Passive Mode (x,x,x,x,240,105)

Optimal transfer mode found.
> STOR 6u711d1f5yd4m3nu7g515k3i34bvon168731.png.part
< 150 Accepted data connection

Uploading to x.x.x.x:61545 (TLSv1.3)
< 451-Error during read from data connection

< 451-Transfer aborted

< 451 0.070 seconds (measured here), 459.00 Kbytes per second

[patrickjuchli]

Sorry, haven’t been aware of this issue for a long time and too busy to do anything here. I wanted to have a look first but if this does help all of you then let’s just do this. Yes, will accept PR. Thanks all, and sorry again.

[PRR24]

Tracked the issue down to transfer.ts

source.pipe(dataSocket).once("finish", () => {
    dataSocket.destroy() // Explicitly close/destroy the socket to signal the end.
    resolver.onDataDone(task)
})

It seems that the dataSocket gets destroyed before all the data is actually sent out by the dataSocket.

Should’t it be

source.pipe(dataSocket).once("end", () => {

instead?