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Michael_A__Fied's avatar
Michael_A__Fied
Icon for Nimbostratus rankNimbostratus
Jun 23, 2009

Broken b64 decoding

Following this article:

 

http://devcentral.f5.com/wiki/default.aspx/iRules/LTMMaintenancePage.html

 

 

I have a nicely implemented maintenance page.

 

 

I want to add a new png file in b64 encoding, and all went well except that the decoding seems to break about 30% down.

 

 

The image is about 700x700 pixels, in png format. Using the web-based decoder at http://www.motobit.com/util/base64-decoder-encoder.asp I can confirm that the file is b64 encoded and decoded properly.

 

 

File size is about 95k - is that even a factor?

 

 

Any ideas would be great at this point.
config
design

8 Replies

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  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Jun 23, 2009
    I haven't seen any posts about the base64 decode failing. Maybe it's the format of the encoded string in the file? It should be in the format of:

     

     

    "base64encodedtext",

     

     

    with no new lines or carriage returns in between the double quotes.

     

     

    If that doesn't solve the problem, can you elaborate on how the decoding is breaking 30% through the image?

     

     

    Aaron
  • Michael_A__Fied's avatar
    Michael_A__Fied
    Icon for Nimbostratus rankNimbostratus
    Jun 23, 2009
    The image has been properly formatted with quotes and comma. We use other images that work just fine (albeit they are smaller images).

     

     

    The image properties are transmitted correctly - pixels of size (683 x 730).

     

     

    The first 200 or so pixels are rendered correctly, and then the rest is shown as white.

     

     

    I took the same properly formatted string, used the online decoder, and it renders correctly.
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Jun 23, 2009
    Are there any spaces in the base64 encoded text? If so, I think they'd need to be replaced with +. Are you okay with posting the encoded text?

     

     

    Aaron
  • hwidjaja_37598's avatar
    hwidjaja_37598
    Icon for Altostratus rankAltostratus
    Jun 23, 2009
    Could it be due to there are '\r' characters in your base64? What about trying to remove it in step 4:

     

     

    tr -d '\n|\r' < file_with_newlines > file_without_newlines

     

     

    Or, try to verify your base64 in LTM (eg. file_with_newlines):

     

     

    openssl enc -d -base64 -in file_with_newlines -out file.png
  • hwidjaja_37598's avatar
    hwidjaja_37598
    Icon for Altostratus rankAltostratus
    Jun 23, 2009
    Correction, the tr command should be:

     

     

    tr -d '\n\r' < file_with_newlines > file_without_newlines
  • hwidjaja_37598's avatar
    hwidjaja_37598
    Icon for Altostratus rankAltostratus
    Jun 23, 2009
    Or, copy the png file (eg. image.png) to LTM and run this:

     

     

    openssl enc -base64 -in image.png | tr -d '\n' > /var/class/maint.logo.png.class

     

     

    Sorry for spamming :D
  • Michael_A__Fied's avatar
    Michael_A__Fied
    Icon for Nimbostratus rankNimbostratus
    Jul 01, 2009
    Thanks y'all for your assistance - the file was formatted correctly all along from the get-go.

     

     

    Seems like there's a upper limit on the size of an external class file.

     

     

    From F5 Support:

     

    One of my colleagues is working on an AskF5 solution article, but it is not yet ready for publication. He tells me that the maximum size of a list item (not including the surrounding double-quotes and trailing comma) is 65520 bytes.

     

     

     

    So all we did was split the file into smaller segments and it worked just fine.