DNS_File-Transfer/client.ps1

# Simple Powershell client, also runs on linux with Powershell Core
Function Get-DnsTxt {
    [CmdletBinding()] param([string] $Domain)
    Try {
        return (Resolve-DnsName -Type TXT $Domain).Strings
    } Catch [System.Management.Automation.CommandNotFoundException] {
        return dig +short $Domain TXT
    }
}

Function Get-DnsFile {
    [CmdletBinding()] param(
        [string] $FileName = $(Read-Host -Prompt 'Enter a FileName'),
        [string] $DnsName = $(Read-Host -Prompt 'Enter a DnsName')
    )
    $count = [int](Get-DnsTxt -Domain "$FileName.count.$DnsName")
    $file_base64 = ""
    For ($i=0; $i -le $count; $i++) {
        $file_base64 += (Get-DnsTxt -Domain "$FileName.$i.$DnsName")
    }
    [Text.Encoding]::Utf8.GetString([Convert]::FromBase64String($file_base64))
}

Function Push-DNSFile {
    [CmdletBinding()] param(
        [string] $FileName = $(Read-Host -Prompt 'Enter a Filename'),
        [string] $DnsName = $(Read-Host -Prompt 'Enter a DnsName')
    )
    $id = [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes((Get-FileHash $FileName).Hash)).Substring(0,6)
    $content = [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes((Get-Content -Path $FileName)))
    $i = 0
    While ($true) {
        $url = ".$i-$id.$DnsName"
        $len = 63 - $url.Length
        $i++
        if($len -lt $content.Length) {
            Get-DnsTxt -Domain ($content.Substring(0, $len) + $url)
            $content = $content.Substring($len)
        } else {
            Get-DnsTxt -Domain ($content + $url)
            break
        }
    }
}

# Minimal working example for download in case you have to type it all manually
Function MWE {
    param([string] $f, [string] $d)
    $c = [int]((Resolve-DnsName -Type TXT "$f.count.$d").Strings)
    $o = ""
    For ($i=0; $i -le $c; $i++) {
        $o += (Resolve-DnsName -Type TXT "$f.$i.$d").Strings
    }
    [Text.Encoding]::Utf8.GetString([Convert]::FromBase64String($o))
}