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module_mac32.go
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module_mac32.go
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package codec
import (
"errors"
"fmt"
"git.golaxy.org/core"
"git.golaxy.org/framework/net/gtp"
"git.golaxy.org/framework/util/binaryutil"
"hash"
)
// NewMAC32Module 创建MAC32模块
func NewMAC32Module(h hash.Hash32, pk []byte) IMACModule {
if h == nil {
panic(fmt.Errorf("%w: h is nil", core.ErrArgs))
}
if len(pk) <= 0 {
panic(fmt.Errorf("%w: len(pk) <= 0", core.ErrArgs))
}
return &MAC32Module{
Hash: h,
PrivateKey: pk,
}
}
// MAC32Module MAC32模块
type MAC32Module struct {
Hash hash.Hash32 // hash(32bit)函数
PrivateKey []byte // 秘钥
}
// PatchMAC 补充MAC
func (m *MAC32Module) PatchMAC(msgId gtp.MsgId, flags gtp.Flags, msgBuf []byte) (dst binaryutil.RecycleBytes, err error) {
if m.Hash == nil {
return binaryutil.MakeNonRecycleBytes(nil), errors.New("setting Hash is nil")
}
m.Hash.Reset()
bs := [2]byte{msgId, byte(flags)}
m.Hash.Write(bs[:])
m.Hash.Write(msgBuf)
m.Hash.Write(m.PrivateKey)
msgMAC := gtp.MsgMAC32{
Data: msgBuf,
MAC: m.Hash.Sum32(),
}
buf := binaryutil.MakeRecycleBytes(binaryutil.BytesPool.Get(msgMAC.Size()))
defer func() {
if err != nil {
buf.Release()
}
}()
_, err = msgMAC.Read(buf.Data())
if err != nil {
return binaryutil.MakeNonRecycleBytes(nil), err
}
return buf, nil
}
// VerifyMAC 验证MAC
func (m *MAC32Module) VerifyMAC(msgId gtp.MsgId, flags gtp.Flags, msgBuf []byte) (dst []byte, err error) {
if m.Hash == nil {
return nil, errors.New("setting Hash is nil")
}
msgMAC := gtp.MsgMAC32{}
_, err = msgMAC.Write(msgBuf)
if err != nil {
return nil, err
}
m.Hash.Reset()
bs := [2]byte{msgId, byte(flags)}
m.Hash.Write(bs[:])
m.Hash.Write(msgMAC.Data)
m.Hash.Write(m.PrivateKey)
if m.Hash.Sum32() != msgMAC.MAC {
return nil, ErrIncorrectMAC
}
return msgMAC.Data, nil
}
// SizeofMAC MAC大小
func (m *MAC32Module) SizeofMAC(msgLen int) int {
return binaryutil.SizeofVarint(int64(msgLen)) + binaryutil.SizeofUint32()
}