cs16-dm-server/windows/join.ps1

# "How will your friends join?" - the last step of setup.cmd, and option 10 in the cs.cmd menu.
# Each choice either sets things up or walks you through it.
param([Parameter(Mandatory = $true)][string]$Root)
. (Join-Path $PSScriptRoot 'common.ps1')

$settingsFile = Join-Path $Root 'settings.txt'
$s = Read-Settings $settingsFile
$port = [int]$s.CS_PORT

function Pause-Enter($text = 'Press Enter when done') { [void](Read-Host "  $text") }

function Ensure-Firewall {
  if (Test-FirewallRule $Root) { Write-Host '  Windows Firewall: the server is allowed in.'; return }
  Write-Host '  Windows Firewall blocks players from other PCs until you allow the server.'
  Write-Host '  Windows will now ask for admin permission (one time).'
  if (Add-FirewallRule $Root) { Write-Host '  Firewall: allowed.' -ForegroundColor Green }
  else {
    Warn '  Firewall not changed. Only players on this PC can join until you allow it:'
    Warn '  run cs.cmd -> 10 (how friends join) and say Yes to the admin prompt.'
  }
}

function Show-Connect($addr) { Write-Host "      connect $addr" -ForegroundColor Green }

function Join-Lan {
  Ensure-Firewall
  $ips = @(Get-LanIPv4)
  Write-Host ''
  Write-Host '  Players in your home open Counter-Strike, press ~ for the console and type:'
  if ($ips.Count -eq 0) { Show-Connect "<this PC's IP>:$port"; Write-Host '  (no network address found: are you connected to your router?)' }
  foreach ($ip in $ips) { Show-Connect "${ip}:$port" }
  Write-Host '  On this same PC:'; Show-Connect "127.0.0.1:$port"
}

function Join-Playit {
  Write-Host ''
  Write-Host '  playit.gg gives your server a public address without touching your router. It is free.'
  Write-Host '  1. Your browser opens playit.gg/download: download and install the Windows app.'
  Write-Host '  2. Start playit. It opens a page to sign up (or log in) and link this PC: follow it.'
  Write-Host '  3. On playit.gg, add a tunnel:'
  Write-Host '       type:          UDP' -ForegroundColor Green
  Write-Host "       local address: 127.0.0.1   local port: $port" -ForegroundColor Green
  Write-Host '  4. playit shows the address of the tunnel, something like  name.ply.gg:12345'
  Write-Host '  Keep the playit app running while you play.'
  Pause-Enter 'Press Enter to open playit.gg'
  Start-Process 'https://playit.gg/download'
  $addr = (Read-Host '  Paste the tunnel address here (or Enter to do it later)').Trim()
  if ($addr) {
    $addr = $addr -replace '^(udp|https?)://', '' -replace '/.*$', ''
    Write-Setting $settingsFile 'CS_PUBLIC_ADDR' $addr
    Write-Host '  Saved. Your friends open Counter-Strike, press ~ and type:'
    Show-Connect $addr
    $hp = $addr -split ':'
    if ($hp.Count -eq 2 -and (Get-A2SInfo $hp[0] ([int]$hp[1]) 4000)) { Write-Host '  Checked: the server answers through the tunnel.' -ForegroundColor Green }
    else { Write-Host "  (could not reach the server through the tunnel yet: check the tunnel is UDP and points to 127.0.0.1:$port)" }
  }
}

function Join-PortForward {
  Ensure-Firewall
  $gw = (Get-NetRoute -DestinationPrefix '0.0.0.0/0' -ErrorAction SilentlyContinue | Sort-Object RouteMetric | Select-Object -First 1).NextHop
  $lan = @(Get-LanIPv4)
  $pub = $null
  try { $pub = (Invoke-WebRequest -UseBasicParsing -Uri 'https://api.ipify.org' -TimeoutSec 10).Content.Trim() } catch { }
  Write-Host ''
  Write-Host '  Your router has to send game traffic to this PC:'
  Write-Host "  1. Open your router's page in a browser: http://$gw  (the login is often on a sticker on the router)"
  Write-Host '  2. Find "Port forwarding" (sometimes under NAT, Virtual server or Gaming) and add:'
  Write-Host "       protocol: UDP    external port: $port    internal port: $port" -ForegroundColor Green
  Write-Host "       device / internal IP: $(if ($lan.Count) { $lan[0] } else { "this PC's IP" })" -ForegroundColor Green
  Write-Host '  3. Save. Some routers need a restart.'
  Write-Host '  Tip: in your router, give this PC a fixed (reserved) IP, or the rule breaks when the IP changes.'
  Write-Host ''
  if ($pub) { Write-Host '  Your friends then type in the Counter-Strike console:'; Show-Connect "${pub}:$port"; Write-Setting $settingsFile 'CS_PUBLIC_ADDR' "${pub}:$port" }
  else { Write-Host "  Your friends then use  connect <your public IP>:$port  (look it up on whatismyip.com)" }
  Write-Host '  You cannot test this from your own PC (most routers do not loop back): ask a friend to connect.'
  Write-Host '  If it never works, your internet may be behind CGNAT (common on mobile and some fiber):'
  Write-Host '  use playit.gg instead (option 2).'
}

function Join-Vpn {
  $v = @(Get-VpnIPv4)   # @(): one address would otherwise come back as a single object
  Write-Host ''
  Write-Host '  With a VPN like Tailscale or ZeroTier, everyone installs the same app and joins your network.'
  Write-Host '  Good for a fixed group of friends; no router setup.'
  if ($v.Count) {
    Ensure-Firewall
    Write-Host '  Found on this PC:'
    foreach ($x in $v) { Write-Host "    $($x.Name):"; Show-Connect "$($x.IP):$port" }
  } else {
    Write-Host '  Not installed yet. Get one (free for small groups):'
    Write-Host '    Tailscale:  https://tailscale.com/download'
    Write-Host '    ZeroTier:   https://www.zerotier.com/download/'
    Write-Host '  Invite your friends to your network, then run this step again (cs.cmd -> 10) to see your address.'
  }
}

Say 'How will your friends join?'
Write-Host '   1) same house / LAN'
Write-Host '   2) over the internet with playit.gg (easiest, no router setup)'
Write-Host '   3) over the internet with port forwarding on your router'
Write-Host '   4) VPN (Tailscale / ZeroTier)'
Write-Host '   0) skip for now (cs.cmd -> 10 brings you back here)'
$c = (Read-Host '  >').Trim()
switch ($c) {
  '1' { Join-Lan }
  '2' { Join-Playit }
  '3' { Join-PortForward }
  '4' { Join-Vpn }
  default { Write-Host '  skipped: double-click cs.cmd and pick 10 any time.' }
}