From 8ed46d7701bc455831cf15901e2d9da2e0c329c4 Mon Sep 17 00:00:00 2001
From: Paul Banks <banks@banksco.de>
Date: Mon, 11 Jun 2018 17:53:14 +0100
Subject: [PATCH] Add accessor and helpers to SDK for fetching self-name and
 client service ID

---
 connect/service.go      | 13 ++++++++---
 connect/service_test.go |  8 +++++++
 connect/tls.go          | 48 ++++++++++++++++++++++++++++++++++-------
 3 files changed, 58 insertions(+), 11 deletions(-)

diff --git a/connect/service.go b/connect/service.go
index 5c6dd2ced..462f1fb47 100644
--- a/connect/service.go
+++ b/connect/service.go
@@ -59,9 +59,9 @@ type Service struct {
 //
 // Caller must provide client which is already configured to speak to the local
 // Consul agent, and with an ACL token that has `service:write` privileges for
-// the serviceID specified.
-func NewService(serviceID string, client *api.Client) (*Service, error) {
-	return NewServiceWithLogger(serviceID, client,
+// the service specified.
+func NewService(serviceName string, client *api.Client) (*Service, error) {
+	return NewServiceWithLogger(serviceName, client,
 		log.New(os.Stderr, "", log.LstdFlags))
 }
 
@@ -125,6 +125,13 @@ func NewDevServiceWithTLSConfig(serviceName string, logger *log.Logger,
 	return s, nil
 }
 
+// Name returns the name of the service this object represents. Note it is the
+// service _name_ as used during discovery, not the ID used to uniquely identify
+// an instance of the service with an agent.
+func (s *Service) Name() string {
+	return s.service
+}
+
 // ServerTLSConfig returns a *tls.Config that allows any TCP listener to accept
 // and authorize incoming Connect clients. It will return a single static config
 // with hooks to dynamically load certificates, and perform Connect
diff --git a/connect/service_test.go b/connect/service_test.go
index c284b9c6e..b18bf4bb4 100644
--- a/connect/service_test.go
+++ b/connect/service_test.go
@@ -13,6 +13,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
+
 	"github.com/hashicorp/consul/agent"
 	"github.com/hashicorp/consul/agent/connect"
 	"github.com/hashicorp/consul/api"
@@ -23,6 +25,12 @@ import (
 // Assert io.Closer implementation
 var _ io.Closer = new(Service)
 
+func TestService_Name(t *testing.T) {
+	ca := connect.TestCA(t, nil)
+	s := TestService(t, "web", ca)
+	assert.Equal(t, "web", s.Name())
+}
+
 func TestService_Dial(t *testing.T) {
 	ca := connect.TestCA(t, nil)
 
diff --git a/connect/tls.go b/connect/tls.go
index 4ca448371..7d679e383 100644
--- a/connect/tls.go
+++ b/connect/tls.go
@@ -7,6 +7,8 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
+	"net/url"
 	"sync"
 
 	"github.com/hashicorp/consul/agent/connect"
@@ -81,14 +83,29 @@ func devTLSConfigFromFiles(caFile, certFile,
 	return cfg, nil
 }
 
-// verifyServerCertMatchesURI is used on tls connections dialled to a connect
-// server to ensure that the certificate it presented has the correct identity.
-func verifyServerCertMatchesURI(certs []*x509.Certificate,
-	expected connect.CertURI) error {
-	expectedStr := expected.URI().String()
+// CertURIFromConn is a helper to extract the service identifier URI from a
+// net.Conn. If the net.Conn is not a *tls.Conn then an error is always
+// returned. If the *tls.Conn didn't present a valid connect certificate, or is
+// not yet past the handshake, an error is returned.
+func CertURIFromConn(conn net.Conn) (connect.CertURI, error) {
+	tc, ok := conn.(*tls.Conn)
+	if !ok {
+		return nil, fmt.Errorf("invalid non-TLS connect client")
+	}
+	gotURI, err := extractCertURI(tc.ConnectionState().PeerCertificates)
+	if err != nil {
+		return nil, err
+	}
+	return connect.ParseCertURI(gotURI)
+}
 
+// extractCertURI returns the first URI SAN from the leaf certificate presented
+// in the slice. The slice is expected to be the passed from
+// tls.Conn.ConnectionState().PeerCertificates and requires that the leaf has at
+// least one URI and the first URI is the correct one to use.
+func extractCertURI(certs []*x509.Certificate) (*url.URL, error) {
 	if len(certs) < 1 {
-		return errors.New("peer certificate mismatch")
+		return nil, errors.New("no peer certificate presented")
 	}
 
 	// Only check the first cert assuming this is the only leaf. It's not clear if
@@ -98,16 +115,31 @@ func verifyServerCertMatchesURI(certs []*x509.Certificate,
 
 	// Our certs will only ever have a single URI for now so only check that
 	if len(cert.URIs) < 1 {
+		return nil, errors.New("peer certificate invalid")
+	}
+
+	return cert.URIs[0], nil
+}
+
+// verifyServerCertMatchesURI is used on tls connections dialled to a connect
+// server to ensure that the certificate it presented has the correct identity.
+func verifyServerCertMatchesURI(certs []*x509.Certificate,
+	expected connect.CertURI) error {
+	expectedStr := expected.URI().String()
+
+	gotURI, err := extractCertURI(certs)
+	if err != nil {
 		return errors.New("peer certificate mismatch")
 	}
+
 	// We may want to do better than string matching later in some special
 	// cases and/or encapsulate the "match" logic inside the CertURI
 	// implementation but for now this is all we need.
-	if cert.URIs[0].String() == expectedStr {
+	if gotURI.String() == expectedStr {
 		return nil
 	}
 	return fmt.Errorf("peer certificate mismatch got %s, want %s",
-		cert.URIs[0].String(), expectedStr)
+		gotURI.String(), expectedStr)
 }
 
 // newServerSideVerifier returns a verifierFunc that wraps the provided