Incorrect Syntax or misunderstanding powershell Do until loop - variables

Question

I'm currently writing a script to prompt for user input, but want to continue prompting the user until a workstation\IP address or username is entered. This will be implemented into a larger more robust script but i can't get this portion working. Is my syntax off or am I misunderstanding the logic, probably both.
D????-* is our corporate workstation naming standard (ie DOUAW-7811652)
*-admin refers to administrator accounts that are not supported by the larger script
The code looks like this so far:
Function Admin{
Write-host "Admin Accounts are not supported" -ForegroundColor Red
}
Function Workstation{
Write-Host "Workstation $name"
$workstation = $true
}
Function UserName{
Write-Host "User Name $name"
$UserName = $true
}
DO {
$Name = Read-Host "Please enter the User Name or Workstation(or IP)"
switch -Wildcard ($name){
"*-admin" {Admin}
"D????-*"{Workstation}
"*.*.*.*"{Workstation}
Default {UserName}
}
}
until ($UserName -eq "$true" -or $workstation -eq "$true")
Read-Host "Press any key to exit"

Answer 1

(While I might not have written it like this, I just fixed code so you could get out of your infinite loop)
You might want something like
Function Workstation{
Write-Host "Workstation $name"
return $true
}
Function UserName{
Write-Host "User Name $name"
return $true
}
DO {
$Name = Read-Host "Please enter the User Name or Workstation(or IP)"
switch -Wildcard ($name){
"*-admin" {Admin}
"D????-*"{$workstation = Workstation}
"*.*.*.*"{$workstation = Workstation}
Default {$UserName = UserName}
}
} until ($UserName -eq "$true" -or $workstation -eq "$true")

Answer 2

Probably you mean:
until ($UserName -eq $true -or $workstation -eq $true)
(Note no quotes around $true.)

Answer 3

I just wanted to say that this would be a good use of an advanced function. Define your parameters in a way that they do all the validation and enforce requirements. Something like this would get you very close to what you are looking for.
Function Do-Something
{
[CmdletBinding(DefaultParameterSetName="Username")]
param(
[Parameter(
Mandatory = $true,
HelpMessage = "Please enter a username",
Position = 0,
ParameterSetName = "Username",
ValueFromPipeline = $true,
ValueFromPipelineByPropertyName = $true
)]
[string[]]$Username,
[Parameter(
Mandatory = $true,
HelpMessage = "Please enter a computername",
Position = 0,
ParameterSetName = "Computername",
ValueFromPipeline = $true,
ValueFromPipelineByPropertyName = $true
)]
[ValidatePattern('D\w\w\w\w-|(\d+\.){3}\d+')]
[string[]]$ComputerName
)
process
{
if($Username){Username}
if($ComputerName){Computername}
}
}
Show-Command Do-Something