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44 lines
1.1 KiB
44 lines
1.1 KiB
package codec |
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import ( |
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"encoding/binary" |
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"io" |
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"github.com/go-faster/errors" |
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"github.com/gotd/td/bin" |
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) |
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// Codec is MTProto transport protocol encoding abstraction. |
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type Codec interface { |
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// WriteHeader sends protocol tag if needed. |
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WriteHeader(w io.Writer) error |
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// ReadHeader reads protocol tag if needed. |
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ReadHeader(r io.Reader) error |
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// Write encode to writer message from given buffer. |
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Write(w io.Writer, b *bin.Buffer) error |
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// Read fills buffer with received message. |
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Read(r io.Reader, b *bin.Buffer) error |
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} |
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// TaggedCodec is codec with protocol tag. |
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type TaggedCodec interface { |
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Codec |
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// ObfuscatedTag returns protocol tag for obfuscation. |
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ObfuscatedTag() [4]byte |
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} |
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// readLen reads 32-bit integer and validates it as message length. |
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func readLen(r io.Reader, b *bin.Buffer) (int, error) { |
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b.ResetN(bin.Word) |
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if _, err := io.ReadFull(r, b.Buf[:bin.Word]); err != nil { |
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return 0, errors.Wrap(err, "read length") |
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} |
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n := int(binary.LittleEndian.Uint32(b.Buf[:bin.Word])) |
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if n <= 0 || n > maxMessageSize { |
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return 0, invalidMsgLenErr{n: n} |
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} |
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return n, nil |
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}
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