Syslog.psm1

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$script:ModuleRoot = $PSScriptRoot
$script:ModuleVersion = (Import-PowerShellDataFile -Path "$($script:ModuleRoot)\Syslog.psd1").ModuleVersion

# Detect whether at some level dotsourcing was enforced
$script:doDotSource = Get-PSFConfigValue -FullName Syslog.Import.DoDotSource -Fallback $false
if ($Syslog_dotsourcemodule) { $script:doDotSource = $true }

<#
Note on Resolve-Path:
All paths are sent through Resolve-Path/Resolve-PSFPath in order to convert them to the correct path separator.
This allows ignoring path separators throughout the import sequence, which could otherwise cause trouble depending on OS.
Resolve-Path can only be used for paths that already exist, Resolve-PSFPath can accept that the last leaf my not exist.
This is important when testing for paths.
#>


# Detect whether at some level loading individual module files, rather than the compiled module was enforced
$importIndividualFiles = Get-PSFConfigValue -FullName Syslog.Import.IndividualFiles -Fallback $false
if ($Syslog_importIndividualFiles) { $importIndividualFiles = $true }
if (Test-Path (Resolve-PSFPath -Path "$($script:ModuleRoot)\..\.git" -SingleItem -NewChild)) { $importIndividualFiles = $true }
if ("<was compiled>" -eq '<was not compiled>') { $importIndividualFiles = $true }
    
function Import-ModuleFile
{
    <#
        .SYNOPSIS
            Loads files into the module on module import.
         
        .DESCRIPTION
            This helper function is used during module initialization.
            It should always be dotsourced itself, in order to proper function.
             
            This provides a central location to react to files being imported, if later desired
         
        .PARAMETER Path
            The path to the file to load
         
        .EXAMPLE
            PS C:\> . Import-ModuleFile -File $function.FullName
     
            Imports the file stored in $function according to import policy
    #>

    [CmdletBinding()]
    Param (
        [string]
        $Path
    )
    
    $resolvedPath = $ExecutionContext.SessionState.Path.GetResolvedPSPathFromPSPath($Path).ProviderPath
    if ($doDotSource) { . $resolvedPath }
    else { $ExecutionContext.InvokeCommand.InvokeScript($false, ([scriptblock]::Create([io.file]::ReadAllText($resolvedPath))), $null, $null) }
}

#region Load individual files
if ($importIndividualFiles)
{
    # Execute Preimport actions
    foreach ($path in (& "$ModuleRoot\internal\scripts\preimport.ps1")) {
        . Import-ModuleFile -Path $path
    }
    
    # Import all internal functions
    foreach ($function in (Get-ChildItem "$ModuleRoot\internal\functions" -Filter "*.ps1" -Recurse -ErrorAction Ignore))
    {
        . Import-ModuleFile -Path $function.FullName
    }
    
    # Import all public functions
    foreach ($function in (Get-ChildItem "$ModuleRoot\functions" -Filter "*.ps1" -Recurse -ErrorAction Ignore))
    {
        . Import-ModuleFile -Path $function.FullName
    }
    
    # Execute Postimport actions
    foreach ($path in (& "$ModuleRoot\internal\scripts\postimport.ps1")) {
        . Import-ModuleFile -Path $path
    }
    
    # End it here, do not load compiled code below
    return
}
#endregion Load individual files

#region Load compiled code
<#
This file loads the strings documents from the respective language folders.
This allows localizing messages and errors.
Load psd1 language files for each language you wish to support.
Partial translations are acceptable - when missing a current language message,
it will fallback to English or another available language.
#>

Import-PSFLocalizedString -Path "$($script:ModuleRoot)\en-us\*.psd1" -Module 'Syslog' -Language 'en-US'

function Get-SyslogServer
{
<#
    .SYNOPSIS
        Returns currently prepared syslog server.
     
    .DESCRIPTION
        Returns currently prepared syslog server.
        To create a new syslog server, use New-SyslogServer.
     
    .PARAMETER OutServer
        Filter by the target server messages are being forwarded to.
        Defaults to: '*'
     
    .PARAMETER InPort
        Filter by on which port the server listens for incoming messages.
     
    .EXAMPLE
        PS C:\> Get-SyslogServer
     
        List all currently operated syslog servers
#>

    [OutputType([Syslog.Server])]
    [CmdletBinding()]
    param (
        [string]
        $OutServer = '*',
        
        [int]
        $InPort = -1
    )
    
    process
    {
        ($script:servers | Where-Object { $_.OutServer -Like $OutServer -and ($InPort -eq -1 -or $_.InPort -eq $InPort) })
    }
}

function New-SyslogServer
{
<#
    .SYNOPSIS
        Creates a new syslog server.
     
    .DESCRIPTION
        Creates a new syslog server.
        This server will accept incoming messages, transform them and then pass them on using Syslog.
        All connections expected to be TCP
     
    .PARAMETER RegexReplacements
        Regex replacements to execute on incoming messages.
        Provide a set of patterns and their replacements, where the patterns are the keys and the replacements are the values.
        Provide an empty hashtable to pass through messages unaltered.
     
    .PARAMETER RegexOptions
        Which regex options to apply to the replace operations.
        Defaults to: "IgnoreCase"
     
    .PARAMETER InPort
        On which port to receive messages.
        Defaults to 514
     
    .PARAMETER ListenOn
        On which IP Address to listen for incoming messages.
        Defaults to "Any"
     
    .PARAMETER OutServer
        To which server to forward messages to.
     
    .PARAMETER OutPort
        On which port on the destination server to connect to.
        Defaults to 514
     
    .PARAMETER WorkerCount
        How many parallel workers to launch for processing and forwarding messages.
        Defaults to 1
     
    .PARAMETER Start
        Start the server after creating it.
     
    .EXAMPLE
        PS C:\> New-SyslogServer -RegexReplacements @{ 'Fabrikam\.org' = 'contoso.com' } -OutServer 'syslog.contoso.com'
     
        Creates a new syslog server that - once started - will pass through messages to syslog.contoso.com, replacing all instances of "Fabrikam.org" with "contoso.com"
#>

    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    [OutputType([Syslog.Server])]
    [CmdletBinding(DefaultParameterSetName = 'RegexWorker')]
    param (
        [Parameter(Mandatory = $true, ParameterSetName = 'RegexWorker')]
        [hashtable]
        $RegexReplacements,
        
        [Parameter(ParameterSetName = 'RegexWorker')]
        [System.Text.RegularExpressions.RegexOptions]
        $RegexOptions = [System.Text.RegularExpressions.RegexOptions]::IgnoreCase,
        
        [int]
        $InPort = 514,
        
        [System.Net.IPAddress]
        $ListenOn = [ipaddress]::Any,
        
        [Parameter(Mandatory = $true)]
        [string]
        $OutServer,
        
        [int]
        $OutPort = 514,
        
        [int]
        $WorkerCount = 1,
        
        [switch]
        $Start
    )
    
    begin
    {
        $parameters = [System.Collections.Generic.Dictionary[string, object]]::new()
        
        if ($RegexReplacements) {
            $kind = 'Regex'
            foreach ($key in $RegexReplacements.Keys) {
                $parameters[$key] = $RegexReplacements[$key]
            }
            $parameters['RegexOptions'] = $RegexOptions
        }
    }
    process
    {
        $serverObject = [Syslog.Server]::new($WorkerCount, $InPort, $ListenOn, $OutPort, $OutServer, $kind, $parameters)
        $script:servers += $serverObject
        if ($Start) { $serverObject.Start() }
        $serverObject
    }
}

function Remove-SyslogServer
{
<#
    .SYNOPSIS
        Stop and remove a syslog server.
     
    .DESCRIPTION
        Stop and remove a syslog server.
     
    .PARAMETER Server
        The server object to remove.
        Provide a 'Syslog.Server' object returned by Get-SyslogServer.
     
    .PARAMETER EnableException
        This parameters disables user-friendly warnings and enables the throwing of exceptions.
        This is less user friendly, but allows catching exceptions in calling scripts.
     
    .PARAMETER Confirm
        If this switch is enabled, you will be prompted for confirmation before executing any operations that change state.
     
    .PARAMETER WhatIf
        If this switch is enabled, no actions are performed but informational messages will be displayed that explain what would happen if the command were to run.
     
    .EXAMPLE
        PS C:\> Get-SyslogServer | Remove-SyslogServer
     
        Stops and removes all currently existing syslog servers.
#>

    [CmdletBinding(SupportsShouldProcess = $true)]
    Param (
        [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [Syslog.Server[]]
        $Server,
        
        [switch]
        $EnableException
    )
    
    process
    {
        foreach ($serverObject in $Server) {
            if ($serverObject.State -eq 'Running') {
                Invoke-PSFProtectedCommand -Action "Stopping Server from $($serverObject.ListenOn):$($serverObject.InPort) to $($serverObject.OutServer):$($serverObject.OutPort)" -ScriptBlock {
                    $serverObject.Stop()
                } -Target $serverObject -EnableException $EnableException -PSCmdlet $PSCmdlet -Continue
            }
            Invoke-PSFProtectedCommand -Action "Removing Server from $($serverObject.ListenOn):$($serverObject.InPort) to $($serverObject.OutServer):$($serverObject.OutPort)" -ScriptBlock {
                $script:servers.Remove($serverObject)
            } -Target $serverObject -EnableException $EnableException -PSCmdlet $PSCmdlet -Continue
        }
    }
}

function Start-SyslogServer
{
<#
    .SYNOPSIS
        Start a syslog server that is not yet currently running.
     
    .DESCRIPTION
        Start a syslog server that is not yet currently running.
        This operation will fail if the port it listens on is already in use.
     
    .PARAMETER Server
        The server object to start.
        Provide a 'Syslog.Server' object returned by Get-SyslogServer.
     
    .PARAMETER EnableException
        This parameters disables user-friendly warnings and enables the throwing of exceptions.
        This is less user friendly, but allows catching exceptions in calling scripts.
     
    .PARAMETER Confirm
        If this switch is enabled, you will be prompted for confirmation before executing any operations that change state.
     
    .PARAMETER WhatIf
        If this switch is enabled, no actions are performed but informational messages will be displayed that explain what would happen if the command were to run.
     
    .EXAMPLE
        PS C:\> Start-SyslogServer -Server $Server
     
        Start the server stored in $Server.
#>

    [CmdletBinding(SupportsShouldProcess = $true)]
    param (
        [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [Syslog.Server[]]
        $Server,
        
        [switch]
        $EnableException
    )
    
    process
    {
        foreach ($serverObject in $Server) {
            Invoke-PSFProtectedCommand -Action "Starting Server from $($serverObject.ListenOn):$($serverObject.InPort) to $($serverObject.OutServer):$($serverObject.OutPort)" -ScriptBlock {
                $serverObject.Start()
            } -Target $serverObject -EnableException $EnableException -PSCmdlet $PSCmdlet -Continue
        }
    }
}

function Stop-SyslogServer
{
<#
    .SYNOPSIS
        Stop a currently running syslog server.
     
    .DESCRIPTION
        Stop a currently running syslog server.
     
    .PARAMETER Server
        The server object to stop.
        Provide a 'Syslog.Server' object returned by Get-SyslogServer.
     
    .PARAMETER EnableException
        This parameters disables user-friendly warnings and enables the throwing of exceptions.
        This is less user friendly, but allows catching exceptions in calling scripts.
     
    .PARAMETER Confirm
        If this switch is enabled, you will be prompted for confirmation before executing any operations that change state.
     
    .PARAMETER WhatIf
        If this switch is enabled, no actions are performed but informational messages will be displayed that explain what would happen if the command were to run.
     
    .EXAMPLE
        PS C:\> Get-SyslogServer -OutServer syslog.contoso.com | Stop-SyslogServer
     
        Stop the syslog server forwarding to syslog.contoso.com
#>

    [CmdletBinding(SupportsShouldProcess = $true)]
    param (
        [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [Syslog.Server[]]
        $Server,
        
        [switch]
        $EnableException
    )
    
    process {
        foreach ($serverObject in $Server) {
            Invoke-PSFProtectedCommand -Action "Stopping Server from $($serverObject.ListenOn):$($serverObject.InPort) to $($serverObject.OutServer):$($serverObject.OutPort)" -ScriptBlock {
                $serverObject.Stop()
            } -Target $serverObject -EnableException $EnableException -PSCmdlet $PSCmdlet -Continue
        }
    }
}

<#
This is an example configuration file
 
By default, it is enough to have a single one of them,
however if you have enough configuration settings to justify having multiple copies of it,
feel totally free to split them into multiple files.
#>


<#
# Example Configuration
Set-PSFConfig -Module 'Syslog' -Name 'Example.Setting' -Value 10 -Initialize -Validation 'integer' -Handler { } -Description "Example configuration setting. Your module can then use the setting using 'Get-PSFConfigValue'"
#>


Set-PSFConfig -Module 'Syslog' -Name 'Import.DoDotSource' -Value $false -Initialize -Validation 'bool' -Description "Whether the module files should be dotsourced on import. By default, the files of this module are read as string value and invoked, which is faster but worse on debugging."
Set-PSFConfig -Module 'Syslog' -Name 'Import.IndividualFiles' -Value $false -Initialize -Validation 'bool' -Description "Whether the module files should be imported individually. During the module build, all module code is compiled into few files, which are imported instead by default. Loading the compiled versions is faster, using the individual files is easier for debugging and testing out adjustments."

<#
Stored scriptblocks are available in [PsfValidateScript()] attributes.
This makes it easier to centrally provide the same scriptblock multiple times,
without having to maintain it in separate locations.
 
It also prevents lengthy validation scriptblocks from making your parameter block
hard to read.
 
Set-PSFScriptblock -Name 'Syslog.ScriptBlockName' -Scriptblock {
     
}
#>


<#
# Example:
Register-PSFTeppScriptblock -Name "Syslog.alcohol" -ScriptBlock { 'Beer','Mead','Whiskey','Wine','Vodka','Rum (3y)', 'Rum (5y)', 'Rum (7y)' }
#>


<#
# Example:
Register-PSFTeppArgumentCompleter -Command Get-Alcohol -Parameter Type -Name Syslog.alcohol
#>


# List of currently setup servers
$script:servers = @()

New-PSFLicense -Product 'Syslog' -Manufacturer 'Friedrich Weinmann' -ProductVersion $script:ModuleVersion -ProductType Module -Name MIT -Version "1.0.0.0" -Date (Get-Date "2021-01-29") -Text @"
Copyright (c) 2021 Friedrich Weinmann
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"@

#endregion Load compiled code