General issues with UserAtHost proxy

**FTP OS:** irrelevant

**FTP Server:** irrelevant

**FTP Proxy:** CCProxy 8.0 (and likely others)

**Computer OS:** Windows 10 20H2

**FluentFTP Version:** 34.0

There appear to be two general issues with the UserAtHost proxy.

CCProxy and probably other proxies provide a status 220 banner on connect. With the current UserAtHost proxy implementation it is impossible to connect in such a case, because the `Execute("USER " + userName);` during `Authenticate` will run into the `StaleDataCheck`, which closes the stream, causing another failing `Connect()` attempt and the whole thing continues failing recursively.

Inserting a `GetReply()` during the proxy handshake solves the issue (as in the custom Blue Coat solution for #246), but I think calling `base.Handshake()` should be the preferred way for FTP proxies to override that method anyway, no? I am not sure though whether all FTP proxies provide a banner, or if a direct or indirect call to `GetReply() `during the handshake might actually lead to a potential hang if they do not.

The second issue is that the current method of replacing `Credentials.UserName` with User@Host information is not guarded, which leads to User@Host@Host@Host... if `Handshake` is called repeatedly as in the scenario above.

I'm happy to provide a PR for these issues, if there is some consensus on how to approach the first issue. If proxies exist with or without banner, perhaps a check of whether the stream has data before calling `GetReply()` is an option, or a version of that function that times out instead of blocking when no data is available?

**Logs :**

```
# Connect()
# Connect()
Status:   Connecting to 192.168.40.9:2121
Status:   Connecting to 192.168.40.9:2121
Status:   There is stale data on the socket, maybe our connection timed out or you did not call GetReply(). Re-connecting...
Status:   There is stale data on the socket, maybe our connection timed out or you did not call GetReply(). Re-connecting...
Status:   The stale data was: 220-CCProxy FTP Service(Unregistered)
220-you need to input userid@site as login name.
220 Example: user anonymous@ftp.netscape.com
Status:   The stale data was: 220-CCProxy FTP Service(Unregistered)
220-you need to input userid@site as login name.
220 Example: user anonymous@ftp.netscape.com
Status:   Disposing FtpSocketStream...
Status:   Disposing FtpSocketStream...

# Connect()
# Connect()
Status:   Connecting to 192.168.40.9:2121
Status:   Connecting to 192.168.40.9:2121
Status:   There is stale data on the socket, maybe our connection timed out or you did not call GetReply(). Re-connecting...
Status:   There is stale data on the socket, maybe our connection timed out or you did not call GetReply(). Re-connecting...
Status:   The stale data was: 220-CCProxy FTP Service(Unregistered)
220-you need to input userid@site as login name.
220 Example: user anonymous@ftp.netscape.com
Status:   The stale data was: 220-CCProxy FTP Service(Unregistered)
220-you need to input userid@site as login name.
220 Example: user anonymous@ftp.netscape.com
Status:   Disposing FtpSocketStream...
Status:   Disposing FtpSocketStream...

[continues ad infinitum]
```

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

General issues with UserAtHost proxy #724

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Uh oh!

General issues with UserAtHost proxy #724

Description

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions