46 lines
1.2 KiB
Go
46 lines
1.2 KiB
Go
package transport
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import (
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"encoding/binary"
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"errors"
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"io"
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)
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// MaxFrameSize caps the size of an individual on-wire message. 16 MiB
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// is comfortably above any plausible cluster.yaml or status payload
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// and rejects malicious giants up front.
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const MaxFrameSize = 16 * 1024 * 1024
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// writeFrame emits a single length-prefixed message: 4-byte big-endian
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// length followed by the body.
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func writeFrame(w io.Writer, body []byte) error {
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if len(body) > MaxFrameSize {
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return errors.New("frame too large")
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}
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var hdr [4]byte
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binary.BigEndian.PutUint32(hdr[:], uint32(len(body)))
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if _, err := w.Write(hdr[:]); err != nil {
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return err
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}
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_, err := w.Write(body)
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return err
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}
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// readFrame reads the next length-prefixed message. Returns io.EOF
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// cleanly when the connection closes on a frame boundary.
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func readFrame(r io.Reader) ([]byte, error) {
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var hdr [4]byte
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if _, err := io.ReadFull(r, hdr[:]); err != nil {
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return nil, err
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}
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n := binary.BigEndian.Uint32(hdr[:])
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if n > MaxFrameSize {
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return nil, errors.New("incoming frame exceeds MaxFrameSize")
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}
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buf := make([]byte, n)
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if _, err := io.ReadFull(r, buf); err != nil {
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return nil, err
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}
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return buf, nil
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}
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