CoCalc provides the best real-time collaborative environment for Jupyter Notebooks, LaTeX documents, and SageMath, scalable from individual users to large groups and classes!

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require 'spec_helper'
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require 'rex/version'
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require 'rex/text'
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# rubocop:disable Lint/DeprecatedGemVersion
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RSpec.describe Rex::Exploit::ViewState do
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  let(:data) { Random.new.bytes(rand(10..100)) }
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  let(:key) { Random.new.bytes(20) }
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  context 'when the algorithm is SHA-1' do
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    let(:algo) { 'sha1' }
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    describe '.decode_viewstate' do
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      let(:encoded) { described_class.generate_viewstate(data, algo: algo, key: key) }
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      it 'returns the data and HMAC' do
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        decoded = described_class.decode_viewstate(encoded, algo: algo)
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        expect(decoded).to be_a Hash
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        expect(decoded[:data]).to eq data
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        expect(decoded[:hmac]).to eq described_class.generate_viewstate_hmac(data, algo: algo, key: key)
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      end
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    end
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    describe '.generate_viewstate' do
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      it 'generates the HMAC signature' do
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        expect(described_class).to receive(:generate_viewstate_hmac).with(data, algo: algo, key: key).and_call_original
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        described_class.generate_viewstate(data, algo: algo, key: key)
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      end
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      it 'generates a Base64 encoded blob' do
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        viewstate = described_class.generate_viewstate(data, algo: algo, key: key)
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        debase64ed = Rex::Text.decode_base64(viewstate)
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        expect(debase64ed).to eq data + described_class.generate_viewstate_hmac(data, algo: algo, key: key)
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      end
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    end
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    describe '.generate_viewstate_hmac' do
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      it 'delegates to OpenSSL::HMAC' do
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        expect(OpenSSL::HMAC).to receive(:digest).with(algo, key,data)
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        described_class.generate_viewstate_hmac(data, algo: algo, key: key)
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      end
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      it 'generates a 20 byte HMAC' do
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        hmac = described_class.generate_viewstate_hmac(data, algo: algo, key: key)
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        expect(hmac.bytesize).to eq 20
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      end
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    end
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    describe '.is_viewstate_valid?' do
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      let(:encoded) { described_class.generate_viewstate(data, algo: algo, key: key) }
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      it 'raises an Error when it can not be decoded' do
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        # use key.length / 2 to guarantee there is not enough data for the key to be found
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        expect { described_class.is_viewstate_valid?(Rex::Text.encode_base64('A' * (key.length / 2))) }.to raise_error(described_class::Error)
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      end
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      it 'returns true for the correct key' do
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        expect(described_class.is_viewstate_valid?(encoded, algo: algo, key: key)).to be_truthy
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      end
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      it 'returns false for the incorrect key' do
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        expect(described_class.is_viewstate_valid?(encoded, algo: algo, key: key + '#')).to be_falsey
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      end
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    end
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  end
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end
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