# enet_lib.ps1 — e:net 协议验证公共函数库
$script:pass = 0; $script:fail = 0
function Check($name, $cond, $detail) {
    if ($cond) { $script:pass++; Write-Host ("  [PASS] {0} {1}" -f $name, $detail) }
    else       { $script:fail++; Write-Host ("  [FAIL] {0} {1}" -f $name, $detail) }
}
function Read-Pcap([string]$path) {
    $b = [IO.File]::ReadAllBytes($path)
    function U32([byte[]]$x, [int]$o, [bool]$sw) {
        if ($sw) { return ([uint32]$x[$o] -shl 24) -bor ([uint32]$x[$o+1] -shl 16) -bor ([uint32]$x[$o+2] -shl 8) -bor [uint32]$x[$o+3] }
        return [BitConverter]::ToUInt32($x, $o)
    }
    $magic = U32 $b 0 $false
    $swap = ($magic -eq 0xa1b2c3d4)
    $pkts = New-Object System.Collections.Generic.List[object]
    $o = 24
    while ($o + 16 -le $b.Length) {
        $incl = U32 $b ($o+8) $swap
        if ($o + 16 + $incl -gt $b.Length) { break }
        $data = New-Object byte[] $incl
        [Array]::Copy($b, $o+16, $data, 0, $incl)
        $pkts.Add([pscustomobject]@{ Len = $incl; Data = $data })
        $o += 16 + $incl
    }
    return $pkts
}
function UdpPayload($pkt) {
    $d = $pkt.Data
    if ($d.Length -lt 42) { return $null }
    $ethType = ([uint32]$d[12] -shl 8) -bor $d[13]
    $off = 14
    if ($ethType -eq 0x8100) { $ethType = ([uint32]$d[16] -shl 8) -bor $d[17]; $off = 18 }
    if ($ethType -ne 0x0800) { return $null }
    $ihl = ($d[$off] -band 0x0F) * 4
    if ($d[$off + 9] -ne 17) { return $null }
    $ipStart = $off; $udp = $off + $ihl
    $src = "{0}.{1}.{2}.{3}" -f $d[$ipStart+12], $d[$ipStart+13], $d[$ipStart+14], $d[$ipStart+15]
    $dst = "{0}.{1}.{2}.{3}" -f $d[$ipStart+16], $d[$ipStart+17], $d[$ipStart+18], $d[$ipStart+19]
    $sport = ([uint32]$d[$udp] -shl 8) -bor $d[$udp+1]
    $dport = ([uint32]$d[$udp+2] -shl 8) -bor $d[$udp+3]
    $pl = New-Object byte[] ($d.Length - $udp - 8)
    [Array]::Copy($d, $udp + 8, $pl, 0, $pl.Length)
    return [pscustomobject]@{ Src=$src; Dst=$dst; Sport=$sport; Dport=$dport; Payload=$pl }
}
function LE32([byte[]]$x, [int]$o) { return [uint32]$x[$o] -bor ([uint32]$x[$o+1] -shl 8) -bor ([uint32]$x[$o+2] -shl 16) -bor ([uint32]$x[$o+3] -shl 24) }
function LE16([byte[]]$x, [int]$o) { return [uint32]([uint32]$x[$o] -bor ([uint32]$x[$o+1] -shl 8)) }
function Hex([byte[]]$x, [int]$o, [int]$n) { ($x[$o..($o+$n-1)] | ForEach-Object { $_.ToString('x2') }) -join '' }