39 lines
1.1 KiB
Go
39 lines
1.1 KiB
Go
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package quic
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import (
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"fmt"
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"github.com/google/uuid"
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)
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const (
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sessionIDLen = len(uuid.UUID{})
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MaxDatagramFrameSize = 1220
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)
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// Each QUIC datagram should be suffixed with session ID.
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// ExtractSessionID extracts the session ID and a slice with only the payload
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func ExtractSessionID(b []byte) (uuid.UUID, []byte, error) {
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msgLen := len(b)
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if msgLen < sessionIDLen {
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return uuid.Nil, nil, fmt.Errorf("session ID has %d bytes, but data only has %d", sessionIDLen, len(b))
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}
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// Parse last 16 bytess as UUID and remove it from slice
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sessionID, err := uuid.FromBytes(b[len(b)-sessionIDLen:])
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if err != nil {
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return uuid.Nil, nil, err
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}
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b = b[:len(b)-sessionIDLen]
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return sessionID, b, nil
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}
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// SuffixSessionID appends the session ID at the end of the payload. Suffix is more performant than prefix because
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// the payload slice might already have enough capacity to append the session ID at the end
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func SuffixSessionID(sessionID uuid.UUID, b []byte) ([]byte, error) {
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if len(b)+len(sessionID) > MaxDatagramFrameSize {
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return nil, fmt.Errorf("datagram size exceed %d", MaxDatagramFrameSize)
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}
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b = append(b, sessionID[:]...)
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return b, nil
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}
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