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36 lines
792 B
36 lines
792 B
3 years ago
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package transport
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import (
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"bytes"
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"io"
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"github.com/go-faster/errors"
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"github.com/gotd/td/internal/proto/codec"
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)
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func detectCodec(c io.Reader) (Codec, io.Reader, error) {
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var buf [4]byte
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if _, err := io.ReadFull(c, buf[:1]); err != nil {
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return nil, nil, errors.Wrap(err, "read first byte")
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}
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if buf[0] == codec.AbridgedClientStart[0] {
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return Abridged.Codec(), c, nil
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}
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if _, err := io.ReadFull(c, buf[1:4]); err != nil {
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return nil, nil, errors.Wrap(err, "read header")
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}
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switch buf {
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case codec.IntermediateClientStart:
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return Intermediate.Codec(), c, nil
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case codec.PaddedIntermediateClientStart:
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return PaddedIntermediate.Codec(), c, nil
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default:
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buffered := bytes.NewReader(buf[:])
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r := io.MultiReader(buffered, c)
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return Full.Codec(), r, nil
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}
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}
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