VSCode Rejects Backslash as Valid Host Name

[Somainer]

VSCode Version: 1.67.0
What type of remote connection you were using: SSH
Remote - SSH Version: 0.78.0
Local OS: Darwin x64 21.4.0
Remote OS Version: Windows 10.0.22000.613

Steps to reproduce:

1. In command palette, select Remote-SSH: Connect to Host...
2. Type in user@host where user contains backslash.

Background

I am trying to connect to a windows device using vscode via ssh, and my windows account is an AAD account.

Problem

According to this comment, to connect to a windows Azure AD account via SSH, a workaround is to use connection with format ssh azuread\user@microsoft.com@ipaddress. This format contains backslash \, which will be rejected by VSCode remote SSH extension.

Workaround

I tried to remove the backslash in ~/.vscode/extensions/ms-vscode-remote.remote-ssh-0.78.0/out/extension.js:1:672307,
change const V="'\"!%\r\n".split(""); in function assertValidHost, removing the first \ character, and then it worked perfectly. Which means in some case \ could be part of a valid host name.

Another workaround is to manually edit ssh config, add host username with backslash, then connect to that host. (#6172 )

Since ssh config allows user name with backslash, does assertValidHost reject backslash make sense?

[tanhakabir]

Thank you for investigating this! I'll have this fixed with #6172 so I'll close this as a duplicate