Add new bootstrap method that creates a listener.

ca/bootstrap.go

@@ -2,6 +2,8 @@ package ca
 
 import (
 	"context"
+	"crypto/tls"
+	"net"
 	"net/http"
 	"strings"
 
@@ -145,3 +147,54 @@ func BootstrapClient(ctx context.Context, token string, options ...TLSOption) (*
 		Transport: transport,
 	}, nil
 }
+
+// BootstrapListener is a helper function that using the given token returns a
+// TLS listener which accepts connections from an inner listener and wraps each
+// connection with Server.
+//
+// Without any extra option the server will be configured for mTLS, it will
+// require and verify clients certificates, but options can be used to drop this
+// requirement, the most common will be only verify the certs if given with
+// ca.VerifyClientCertIfGiven(), or add extra CAs with
+// ca.AddClientCA(*x509.Certificate).
+//
+// Usage:
+//   inner, err := net.Listen("tcp", ":443")
+//   if err != nil {
+//     return nil
+//   }
+//   ctx, cancel := context.WithCancel(context.Background())
+//   defer cancel()
+//   lis, err := ca.BootstrapListener(ctx, token, inner)
+//   if err != nil {
+//       return err
+//   }
+//   srv := grpc.NewServer()
+//   ... // register services
+//   srv.Serve(lis)
+func BootstrapListener(ctx context.Context, token string, inner net.Listener, options ...TLSOption) (net.Listener, error) {
+	client, err := Bootstrap(token)
+	if err != nil {
+		return nil, err
+	}
+
+	req, pk, err := CreateSignRequest(token)
+	if err != nil {
+		return nil, err
+	}
+
+	sign, err := client.Sign(req)
+	if err != nil {
+		return nil, err
+	}
+
+	// Make sure the tlsConfig have all supported roots on ClientCAs and RootCAs
+	options = append(options, AddRootsToCAs())
+
+	tlsConfig, err := client.GetServerTLSConfig(ctx, sign, pk, options...)
+	if err != nil {
+		return nil, err
+	}
+
+	return tls.NewListener(inner, tlsConfig), nil
+}

ca/bootstrap_test.go

@@ -8,13 +8,13 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"reflect"
+	"sync"
 	"testing"
 	"time"
 
 	"github.com/pkg/errors"
 	"github.com/smallstep/certificates/api"
 	"github.com/smallstep/certificates/authority"
-
 	"github.com/smallstep/cli/crypto/randutil"
 	stepJOSE "github.com/smallstep/cli/jose"
 	jose "gopkg.in/square/go-jose.v2"
@@ -530,3 +530,71 @@ func doReload(ca *CA) error {
 	newCA.srv.Addr = ca.srv.Addr
 	return ca.srv.Reload(newCA.srv)
 }
+
+func TestBootstrapListener(t *testing.T) {
+	srv := startCABootstrapServer()
+	defer srv.Close()
+	token := func() string {
+		return generateBootstrapToken(srv.URL, "127.0.0.1", "ef742f95dc0d8aa82d3cca4017af6dac3fce84290344159891952d18c53eefe7")
+	}
+	type args struct {
+		token string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr bool
+	}{
+		{"ok", args{token()}, false},
+		{"fail", args{"bad-token"}, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			inner := newLocalListener()
+			defer inner.Close()
+			lis, err := BootstrapListener(context.Background(), tt.args.token, inner)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("BootstrapListener() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if tt.wantErr {
+				if lis != nil {
+					t.Errorf("BootstrapListener() = %v, want nil", lis)
+				}
+				return
+			}
+			wg := new(sync.WaitGroup)
+			go func() {
+				wg.Add(1)
+				http.Serve(lis, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					w.Write([]byte("ok"))
+				}))
+				wg.Done()
+			}()
+			defer wg.Wait()
+			defer lis.Close()
+
+			client, err := BootstrapClient(context.Background(), token())
+			if err != nil {
+				t.Errorf("BootstrapClient() error = %v", err)
+				return
+			}
+			println("https://" + lis.Addr().String())
+			resp, err := client.Get("https://" + lis.Addr().String())
+			if err != nil {
+				t.Errorf("client.Get() error = %v", err)
+				return
+			}
+			defer resp.Body.Close()
+			b, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				t.Errorf("ioutil.ReadAll() error = %v", err)
+				return
+			}
+			if string(b) != "ok" {
+				t.Errorf("client.Get() = %s, want ok", string(b))
+				return
+			}
+		})
+	}
+}