From ffa90a3c74518199426be2401545c6315911ca8a Mon Sep 17 00:00:00 2001
From: Hans Hasselberg <me@hans.io>
Date: Fri, 17 Jan 2020 23:06:01 +0100
Subject: [PATCH] setup grpc server with auto_encrypt certs

---
 agent/agent.go      |  4 ++--
 agent/xds/server.go | 12 +++++-------
 tlsutil/config.go   | 26 ++++++++++++++++++++------
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/agent/agent.go b/agent/agent.go
index ca44d1c9fc68..de819e39a399 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -721,9 +721,9 @@ func (a *Agent) listenAndServeGRPC() error {
 	if a.config.HTTPSPort > 0 {
 		// gRPC uses the same TLS settings as the HTTPS API. If HTTPS is
 		// enabled then gRPC will require HTTPS as well.
-		a.grpcServer, err = a.xdsServer.GRPCServer(a.config.CertFile, a.config.KeyFile)
+		a.grpcServer, err = a.xdsServer.GRPCServer(a.tlsConfigurator)
 	} else {
-		a.grpcServer, err = a.xdsServer.GRPCServer("", "")
+		a.grpcServer, err = a.xdsServer.GRPCServer(nil)
 	}
 	if err != nil {
 		return err
diff --git a/agent/xds/server.go b/agent/xds/server.go
index 7f11994ea067..2c0f1aa63490 100644
--- a/agent/xds/server.go
+++ b/agent/xds/server.go
@@ -10,7 +10,6 @@ import (
 
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 
@@ -25,6 +24,7 @@ import (
 	"github.com/hashicorp/consul/agent/connect"
 	"github.com/hashicorp/consul/agent/proxycfg"
 	"github.com/hashicorp/consul/agent/structs"
+	"github.com/hashicorp/consul/tlsutil"
 )
 
 // ADSStream is a shorter way of referring to this thing...
@@ -536,16 +536,14 @@ func (s *Server) Check(ctx context.Context, r *envoyauthz.CheckRequest) (*envoya
 
 // GRPCServer returns a server instance that can handle XDS and ext_authz
 // requests.
-func (s *Server) GRPCServer(certFile, keyFile string) (*grpc.Server, error) {
+func (s *Server) GRPCServer(tlsConfigurator *tlsutil.Configurator) (*grpc.Server, error) {
 	opts := []grpc.ServerOption{
 		grpc.MaxConcurrentStreams(2048),
 	}
-	if certFile != "" && keyFile != "" {
-		creds, err := credentials.NewServerTLSFromFile(certFile, keyFile)
-		if err != nil {
-			return nil, err
+	if tlsConfigurator != nil {
+		if cert := tlsConfigurator.Cert(); cert != nil {
+			opts = append(opts, grpc.Creds(*tlsConfigurator.TransportCredentials()))
 		}
-		opts = append(opts, grpc.Creds(creds))
 	}
 	srv := grpc.NewServer(opts...)
 	envoydisco.RegisterAggregatedDiscoveryServiceServer(srv, s)
diff --git a/tlsutil/config.go b/tlsutil/config.go
index 58352af1b069..dd01416a2fc4 100644
--- a/tlsutil/config.go
+++ b/tlsutil/config.go
@@ -12,6 +12,8 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"google.golang.org/grpc/credentials"
 )
 
 // DCWrapper is a function that is used to wrap a non-TLS connection
@@ -441,12 +443,7 @@ func (c *Configurator) commonTLSConfig(verifyIncoming bool) *tls.Config {
 	// autoEncrypt cert too so that a client can encrypt incoming
 	// connections without having a manual cert configured.
 	tlsConfig.GetCertificate = func(*tls.ClientHelloInfo) (*tls.Certificate, error) {
-		cert := c.manual.cert
-		if cert == nil {
-			cert = c.autoEncrypt.cert
-		}
-
-		return cert, nil
+		return c.Cert(), nil
 	}
 
 	// GetClientCertificate is used when acting as a client and responding
@@ -477,6 +474,17 @@ func (c *Configurator) commonTLSConfig(verifyIncoming bool) *tls.Config {
 	return tlsConfig
 }
 
+// This function acquires a read lock because it reads from the config.
+func (c *Configurator) Cert() *tls.Certificate {
+	c.RLock()
+	defer c.RUnlock()
+	cert := c.manual.cert
+	if cert == nil {
+		cert = c.autoEncrypt.cert
+	}
+	return cert
+}
+
 // This function acquires a read lock because it reads from the config.
 func (c *Configurator) VerifyIncomingRPC() bool {
 	c.RLock()
@@ -561,6 +569,12 @@ func (c *Configurator) VerifyServerHostname() bool {
 	return c.base.VerifyServerHostname || c.autoEncrypt.verifyServerHostname
 }
 
+// TransportCredentials returns credentials to be used with eg a grpc server.
+func (c *Configurator) TransportCredentials() *credentials.TransportCredentials {
+	creds := credentials.NewTLS(&tls.Config{Certificates: []tls.Certificate{*c.Cert()}})
+	return &creds
+}
+
 // IncomingRPCConfig generates a *tls.Config for incoming RPC connections.
 func (c *Configurator) IncomingRPCConfig() *tls.Config {
 	c.log("IncomingRPCConfig")