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hash.go
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hash.go
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// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Cilium
package loader
import (
"crypto/sha256"
"encoding"
"encoding/hex"
"hash"
"io"
"github.com/cilium/cilium/pkg/datapath"
)
var (
// DatapathSHA256 is set during build to the SHA across all datapath BPF
// code. See the definition of CILIUM_DATAPATH_SHA256 in Makefile.defs for
// details.
DatapathSHA256 string
)
// datapathHash represents a unique enumeration of the datapath implementation.
type datapathHash struct {
hash.Hash
}
// newDatapathHash creates a new datapath hash based on the contents of the datapath
// template files under bpf/.
func newDatapathHash() *datapathHash {
d := sha256.New()
io.WriteString(d, DatapathSHA256)
return &datapathHash{
Hash: d,
}
}
// hashDatapath returns a new datapath hash based on the specified datapath.
//
// The endpoint's static data is NOT included in this hash, for that perform:
//
// hash := hashDatapath(dp, nodeCfg, netdevCfg, ep)
// hashStr := hash.sumEndpoint(ep)
func hashDatapath(c datapath.ConfigWriter, nodeCfg *datapath.LocalNodeConfiguration, netdevCfg datapath.DeviceConfiguration, epCfg datapath.EndpointConfiguration) *datapathHash {
d := newDatapathHash()
// Writes won't fail; it's an in-memory hash.
if nodeCfg != nil {
_ = c.WriteNodeConfig(d, nodeCfg)
}
if netdevCfg != nil {
_ = c.WriteNetdevConfig(d, netdevCfg)
}
if epCfg != nil {
_ = c.WriteTemplateConfig(d, epCfg)
}
return d
}
// sumEndpoint returns the hash of the complete datapath for an endpoint.
// It does not change the underlying hash state.
func (d *datapathHash) sumEndpoint(c datapath.ConfigWriter, epCfg datapath.EndpointConfiguration, staticData bool) (string, error) {
result, err := d.Copy()
if err != nil {
return "", err
}
if staticData {
c.WriteEndpointConfig(result, epCfg)
} else {
c.WriteTemplateConfig(result, epCfg)
}
return result.String(), nil
}
func (d *datapathHash) Copy() (*datapathHash, error) {
state, err := d.Hash.(encoding.BinaryMarshaler).MarshalBinary()
if err != nil {
return nil, err
}
newDatapathHash := sha256.New()
if err := newDatapathHash.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
return nil, err
}
return &datapathHash{
Hash: newDatapathHash,
}, nil
}
func (d *datapathHash) String() string {
return hex.EncodeToString(d.Sum(nil))
}