Log file reader for noobs!

LogJammer.rb

@@ -0,0 +1,46 @@
+require 'net/ftp'
+require "openssl"
+require "base64"
+include Base64
+
+#puts "Please connect your DJI drone, verify the RNDIS is up, and press <enter>"
+#gets
+
+ftp = Net::FTP.new('192.168.42.2')
+ftp.passive = true
+ftp.login("LogJammer","IsDaRealest!" )
+puts "Logged into the FTPD"
+begin
+    filename = "/upgrade/dji/log/upgrade00.log"
+    puts "Snagging firmware update log file..."
+    puts "Downloading file: #{filename} to memory"
+    encodedfile = ftp.getbinaryfile(filename,nil)
+    cipher = OpenSSL::Cipher::AES128.new(:CBC)
+    cipher.decrypt
+    cipher.key = "\x74\x68\x69\x73\x2d\x61\x65\x73\x2d\x6b\x65\x79\x00\x00\x00\x00"
+    cipher.iv  = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+    decrypted_plain_text = cipher.update(encodedfile) + cipher.final
+
+    # https://github.com/MAVProxyUser/DJI_ftpd_aes_unscramble/commit/93537fdec26435537399ea8595e0eee8725f5759
+    # undo the weird xor stuff that DJI does to try and beat us
+
+    puts "reversing odd DJI XOR bytes"
+    bytes = decrypted_plain_text.bytes.to_a
+    0.upto(9) do |i|
+        bytes[i] ^= 0x30 + i
+    end
+    10.upto(15) do |i|
+        bytes[i] ^= 0x57 + i
+    end
+
+    # https://github.com/MAVProxyUser/DJI_ftpd_aes_unscramble/commit/73a21718c32ee2be96fc64b9b5acf033c5626176
+    # Ruby uses PKCS7 Padding by default, so there's no need to adjust this
+
+    puts bytes.pack('c*')
+    File.open("upgrade00_logjam.txt", "w+") { |file| file.write(bytes.pack('c*')) }
+    puts "file written to upgrade00_logjam.txt"
+
+rescue Net::FTPPermError
+    puts "Weird FTP problem... unable to retrieve the upgrade00.log file"
+end
+ftp.close