mirror of
https://github.com/v2fly/v2ray-core.git
synced 2024-09-14 07:58:16 -04:00
32 lines
1.1 KiB
Go
32 lines
1.1 KiB
Go
package wire
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import (
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"bytes"
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"crypto/rand"
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"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/protocol"
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"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/utils"
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)
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// ComposeVersionNegotiation composes a Version Negotiation
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func ComposeVersionNegotiation(destConnID, srcConnID protocol.ConnectionID, versions []protocol.VersionNumber) ([]byte, error) {
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greasedVersions := protocol.GetGreasedVersions(versions)
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expectedLen := 1 /* type byte */ + 4 /* version field */ + 1 /* connection ID length field */ + destConnID.Len() + srcConnID.Len() + len(greasedVersions)*4
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buf := bytes.NewBuffer(make([]byte, 0, expectedLen))
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r := make([]byte, 1)
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_, _ = rand.Read(r) // ignore the error here. It is not critical to have perfect random here.
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buf.WriteByte(r[0] | 0x80)
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utils.BigEndian.WriteUint32(buf, 0) // version 0
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connIDLen, err := encodeConnIDLen(destConnID, srcConnID)
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if err != nil {
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return nil, err
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}
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buf.WriteByte(connIDLen)
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buf.Write(destConnID)
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buf.Write(srcConnID)
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for _, v := range greasedVersions {
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utils.BigEndian.WriteUint32(buf, uint32(v))
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}
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return buf.Bytes(), nil
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}
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