32 lines
1001 B
Go
32 lines
1001 B
Go
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// Copyright (c) 2021 Tulir Asokan
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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package binary
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import (
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"bytes"
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"compress/zlib"
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"fmt"
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"io"
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)
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// Unpack unpacks the given decrypted data from the WhatsApp web API.
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//
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// It checks the first byte to decide whether to uncompress the data with zlib or just return as-is
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// (without the first byte). There's currently no corresponding Pack function because Marshal
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// already returns the data with a leading zero (i.e. not compressed).
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func Unpack(data []byte) ([]byte, error) {
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dataType, data := data[0], data[1:]
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if 2&dataType > 0 {
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if decompressor, err := zlib.NewReader(bytes.NewReader(data)); err != nil {
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return nil, fmt.Errorf("failed to create zlib reader: %w", err)
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} else if data, err = io.ReadAll(decompressor); err != nil {
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return nil, err
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}
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}
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return data, nil
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}
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