CODEWITHSUNDEEP
rubybase64zlibcompression
narzero
narzero

Reputation: 2299

Zlib::DataError: incorrect header check

I have a string, but I don't know the type of encoding.

Here's what the raw data looks like:

{
   "securityProxyResponseEnvelope":{
      "resultCode":"OK",
      "apiResponse":"{zlibe}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",
      "session":"n3qp6jzHwZkXWSMW3VBF:jitqBjBmlZbrgcEgY7Od",
      "parameters":{

      }
   }
}

I want to decompress the string in data['securityProxyResponseEnvelope']['apiResponse'].

Here's what I'm doing:

@clear_string_from_data = '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'

@decoded = Base64.decode64(@clear_string_from_data)
@inflated = Zlib::Inflate.inflate(@decoded)

But this returns

#=> Zlib::DataError: incorrect header check

What's causing this and what could I try next to decompress the data?

Upvotes: 5

Views: 7700

Answers (4)

stevec
stevec

Reputation: 52268

This is a very unsatisfying answer (as it doesn't give an explanation of the cause). But I was using rails 6.1 and hadn't updated gems for a long time (at least a couple of years). I did so and the Zlib problem went away. I'm really sorry it's such a non-technical answer, but I put it here because it might be the most practical solution (it was in my case).

Upvotes: 0

shoaib sabir
shoaib sabir

Reputation: 745

Zlib::GzipReader is designed specifically for decompressing data that has been compressed with the Gzip compression format. Gzip is a widely used compression format for files and streams. If your data is Gzip-compressed, this is the appropriate choice.

result = Zlib::GzipReader.new(StringIO.new(response.to_s)).read

Zlib::Inflate inflate is a more general-purpose decompression method. It can handle various compression formats supported by the Zlib library, including Gzip, Deflate, and others. If your data is compressed using a format other than Gzip, this method allows you to handle it.

result = Zlib::Inflate.inflate(response)

Upvotes: 0

Gayle
Gayle

Reputation: 3092

I was getting this when trying to call inflate on a data that hadn't been deflated by Zlib. In my case it was for a unit test and I sent in a plain string and simply forgot to call .deflate on it first.

In your case, if you do this instead you don't get the error:

@decoded = Zlib::Deflate.deflate(@clear_string_from_data) @inflated = Zlib::Inflate.inflate(@decoded)

Upvotes: 2

Mark Adler
Mark Adler

Reputation: 112349

What's causing it is that it is not zlib data. You should ask whoever is producing that raw data.

Upvotes: 1

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