FTP: Passive transfer fails because curl tries only a single IP address

[mkauf]

I did this

./curl -v -x http://localhost:3128 -p ftp://mirror.switch.ch/doc/standard/rfc/26xx/2616.txt

Output:

* STATE: INIT => CONNECT handle 0xc74768; line 1410 (connection #-5000)
* Added connection 0. The cache now contains 1 members
*   Trying ::1...
* TCP_NODELAY set
* STATE: CONNECT => WAITCONNECT handle 0xc74768; line 1462 (connection #0)
* connect to ::1 port 3128 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 3128 (#0)
* STATE: WAITCONNECT => WAITPROXYCONNECT handle 0xc74768; line 1579 (connection #0)
* Marked for [keep alive]: HTTP default
* Establish HTTP proxy tunnel to mirror.switch.ch:21
> CONNECT mirror.switch.ch:21 HTTP/1.1
> Host: mirror.switch.ch:21
> User-Agent: curl/7.54.1-DEV
> Proxy-Connection: Keep-Alive
>
* Read response immediately from proxy CONNECT
< HTTP/1.0 200 Connection established
<
* Proxy replied OK to CONNECT request
* STATE: WAITPROXYCONNECT => SENDPROTOCONNECT handle 0xc74768; line 1558 (connection #0)
* FTP 0xc830b8 (line 3105) state change from STOP to WAIT220
* STATE: SENDPROTOCONNECT => PROTOCONNECT handle 0xc74768; line 1593 (connection #0)
< 220-SWITCHmirror welcomes you!
< 220
> USER anonymous
* FTP 0xc830b8 (line 799) state change from WAIT220 to USER
< 331 Please specify the password.
> PASS ftp@example.com
* FTP 0xc830b8 (line 2536) state change from USER to PASS
< 230- Welcome to SWITCHmirror                     ftp://mirror.switch.ch/
< 230- -----------------------                    http://mirror.switch.ch/
< 230-
< 230- SWITCHmirror is located in Zurich, Switzerland and
< 230- operated by SWITCH:                           http://www.switch.ch/
< 230-
< 230- If you have problems downloading and are seeing "Access denied"
< 230- or "Permission denied", please make sure that you started your
< 230- FTP client in a directory to which you have write permission.
< 230-
< 230- Contact address: switchmirror@switch.ch
< 230-
< 230- NOTE: ALL transfers are logged and any misuse will be acted upon.
< 230-
< 230 Login successful.
> PWD
* FTP 0xc830b8 (line 811) state change from PASS to PWD
< 257 "/"
* Entry path is '/'
* FTP 0xc830b8 (line 2857) state change from PWD to STOP
* protocol connect phase DONE
* STATE: PROTOCONNECT => DO handle 0xc74768; line 1614 (connection #0)
* DO phase starts
> CWD doc
* FTP 0xc830b8 (line 904) state change from STOP to CWD
* ftp_perform ends with SECONDARY: 0
* STATE: DO => DOING handle 0xc74768; line 1663 (connection #0)
< 250 Directory successfully changed.
> CWD standard
< 250 Directory successfully changed.
> CWD rfc
< 250 Directory successfully changed.
> CWD 26xx
< 250 Directory successfully changed.
> EPSV
* FTP 0xc830b8 (line 1339) state change from CWD to PASV
* Connect data stream passively
< 229 Entering Extended Passive Mode (|||59386|).
* Hostname localhost was found in DNS cache
*   Trying ::1...
* TCP_NODELAY set
* Connecting to mirror.switch.ch (::1) port 3128
* FTP 0xc830b8 (line 1995) state change from PASV to STOP
* DO phase is complete2
* STATE: DOING => DO_MORE handle 0xc74768; line 1752 (connection #0)
* connect to ::1 port 3128 failed: Connection refused
* Failed to connect to localhost port 3128: Connection refused
* Failed EPSV attempt, exiting

* multi_done
* Marked for [closure]: FTP ended with bad error code
* Closing connection 0
* The cache now contains 0 members
* Expire cleared
curl: (8) Failed to connect to localhost port 3128: Connection refused

Squid 2.7.STABLE9 runs on localhost:3128. This old version does not support IPv6.

I expected the following

The download should succeed. After switching to passive mode (EPSV), curl should try all IP addresses for "localhost". Currently it tries ::1, but it should also try 127.0.0.1.

curl/libcurl version

curl 7.54.1-DEV

operating system

Linux

[jay]

bisected to c431274 when easy vs multi internal separation was removed but I don't think that's so relevant at this point