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spiffe.go
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spiffe.go
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/*
*
* Copyright 2020 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
// Package credentials defines APIs for parsing SPIFFE ID.
//
// All APIs in this package are experimental.
package credentials
import (
"crypto/tls"
"crypto/x509"
"net/url"
"google.golang.org/grpc/grpclog"
)
var logger = grpclog.Component("credentials")
// SPIFFEIDFromState parses the SPIFFE ID from State. If the SPIFFE ID format
// is invalid, return nil with warning.
func SPIFFEIDFromState(state tls.ConnectionState) *url.URL {
if len(state.PeerCertificates) == 0 || len(state.PeerCertificates[0].URIs) == 0 {
return nil
}
return SPIFFEIDFromCert(state.PeerCertificates[0])
}
// SPIFFEIDFromCert parses the SPIFFE ID from x509.Certificate. If the SPIFFE
// ID format is invalid, return nil with warning.
func SPIFFEIDFromCert(cert *x509.Certificate) *url.URL {
if cert == nil || cert.URIs == nil {
return nil
}
var spiffeID *url.URL
for _, uri := range cert.URIs {
if uri == nil || uri.Scheme != "spiffe" || uri.Opaque != "" || (uri.User != nil && uri.User.Username() != "") {
continue
}
// From this point, we assume the uri is intended for a SPIFFE ID.
if len(uri.String()) > 2048 {
logger.Warning("invalid SPIFFE ID: total ID length larger than 2048 bytes")
return nil
}
if len(uri.Host) == 0 || len(uri.Path) == 0 {
logger.Warning("invalid SPIFFE ID: domain or workload ID is empty")
return nil
}
if len(uri.Host) > 255 {
logger.Warning("invalid SPIFFE ID: domain length larger than 255 characters")
return nil
}
// A valid SPIFFE certificate can only have exactly one URI SAN field.
if len(cert.URIs) > 1 {
logger.Warning("invalid SPIFFE ID: multiple URI SANs")
return nil
}
spiffeID = uri
}
return spiffeID
}