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/*
*
* Copyright 2021 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 google
import (
"context"
"net"
"net/url"
"strings"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/internal"
)
const cfeClusterNamePrefix = "google_cfe_"
const cfeClusterResourceNamePrefix = "/envoy.config.cluster.v3.Cluster/google_cfe_"
const cfeClusterAuthorityName = "traffic-director-c2p.xds.googleapis.com"
// clusterTransportCreds is a combo of TLS + ALTS.
//
// On the client, ClientHandshake picks TLS or ALTS based on address attributes.
// - if attributes has cluster name
// - if cluster name has prefix "google_cfe_", or
// "xdstp://traffic-director-c2p.xds.googleapis.com/envoy.config.cluster.v3.Cluster/google_cfe_",
// use TLS
// - otherwise, use ALTS
//
// - else, do TLS
//
// On the server, ServerHandshake always does TLS.
type clusterTransportCreds struct {
tls credentials.TransportCredentials
alts credentials.TransportCredentials
}
func newClusterTransportCreds(tls, alts credentials.TransportCredentials) *clusterTransportCreds {
return &clusterTransportCreds{
tls: tls,
alts: alts,
}
}
// clusterName returns the xDS cluster name stored in the attributes in the
// context.
func clusterName(ctx context.Context) string {
chi := credentials.ClientHandshakeInfoFromContext(ctx)
if chi.Attributes == nil {
return ""
}
cluster, _ := internal.GetXDSHandshakeClusterName(chi.Attributes)
return cluster
}
// isDirectPathCluster returns true if the cluster in the context is a
// directpath cluster, meaning ALTS should be used.
func isDirectPathCluster(ctx context.Context) bool {
cluster := clusterName(ctx)
if cluster == "" {
// No cluster; not xDS; use TLS.
return false
}
if strings.HasPrefix(cluster, cfeClusterNamePrefix) {
// xDS cluster prefixed by "google_cfe_"; use TLS.
return false
}
if !strings.HasPrefix(cluster, "xdstp:") {
// Other xDS cluster name; use ALTS.
return true
}
u, err := url.Parse(cluster)
if err != nil {
// Shouldn't happen, but assume ALTS.
return true
}
// If authority AND path match our CFE checks, use TLS; otherwise use ALTS.
return u.Host != cfeClusterAuthorityName || !strings.HasPrefix(u.Path, cfeClusterResourceNamePrefix)
}
func (c *clusterTransportCreds) ClientHandshake(ctx context.Context, authority string, rawConn net.Conn) (net.Conn, credentials.AuthInfo, error) {
if isDirectPathCluster(ctx) {
// If attributes have cluster name, and cluster name is not cfe, it's a
// backend address, use ALTS.
return c.alts.ClientHandshake(ctx, authority, rawConn)
}
return c.tls.ClientHandshake(ctx, authority, rawConn)
}
func (c *clusterTransportCreds) ServerHandshake(conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
return c.tls.ServerHandshake(conn)
}
func (c *clusterTransportCreds) Info() credentials.ProtocolInfo {
// TODO: this always returns tls.Info now, because we don't have a cluster
// name to check when this method is called. This method doesn't affect
// anything important now. We may want to revisit this if it becomes more
// important later.
return c.tls.Info()
}
func (c *clusterTransportCreds) Clone() credentials.TransportCredentials {
return &clusterTransportCreds{
tls: c.tls.Clone(),
alts: c.alts.Clone(),
}
}
func (c *clusterTransportCreds) OverrideServerName(s string) error {
if err := c.tls.OverrideServerName(s); err != nil {
return err
}
return c.alts.OverrideServerName(s)
}
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