Add unit test for GCP provider

This commit is contained in:
Mariano Cano 2019-04-18 16:01:30 -07:00
parent b4729cd670
commit 1ea4b0ad64
4 changed files with 468 additions and 76 deletions

View file

@ -16,6 +16,12 @@ import (
"github.com/smallstep/cli/jose" "github.com/smallstep/cli/jose"
) )
// googleOauth2Certs is the url that servers Google OAuth2 public keys.
var googleOauth2Certs = "https://www.googleapis.com/oauth2/v3/certs"
// gcpIdentityURL is the base url for the identity document in GCP.
var gcpIdentityURL = "http://metadata/computeMetadata/v1/instance/service-accounts/default/identity"
// gcpPayload extends jwt.Claims with custom GCP attributes. // gcpPayload extends jwt.Claims with custom GCP attributes.
type gcpPayload struct { type gcpPayload struct {
jose.Claims jose.Claims
@ -69,8 +75,11 @@ func (p *GCP) GetTokenID(token string) (string, error) {
if err = jwt.UnsafeClaimsWithoutVerification(&claims); err != nil { if err = jwt.UnsafeClaimsWithoutVerification(&claims); err != nil {
return "", errors.Wrap(err, "error verifying claims") return "", errors.Wrap(err, "error verifying claims")
} }
// This string should be mostly unique
unique := fmt.Sprintf("%s.%d.%d", claims.Google.ComputeEngine.InstanceID, claims.IssuedAt, claims.Expiry) unique := fmt.Sprintf("%s.%s.%d.%d",
p.GetID(), claims.Google.ComputeEngine.InstanceID,
*claims.IssuedAt, *claims.Expiry,
)
sum := sha256.Sum256([]byte(unique)) sum := sha256.Sum256([]byte(unique))
return strings.ToLower(hex.EncodeToString(sum[:])), nil return strings.ToLower(hex.EncodeToString(sum[:])), nil
} }
@ -90,6 +99,37 @@ func (p *GCP) GetEncryptedKey() (kid string, key string, ok bool) {
return "", "", false return "", "", false
} }
// GetIdentityURL returns the url that generates the GCP token.
func (p *GCP) GetIdentityURL() string {
q := url.Values{}
q.Add("audience", p.GetID())
q.Add("format", "full")
q.Add("licenses", "FALSE")
return fmt.Sprintf("%s?%s", gcpIdentityURL, q.Encode())
}
// GetIdentityToken does an HTTP request to the identity url.
func (p *GCP) GetIdentityToken() (string, error) {
req, err := http.NewRequest("GET", p.GetIdentityURL(), http.NoBody)
if err != nil {
return "", errors.Wrap(err, "error creating identity request")
}
req.Header.Set("Metadata-Flavor", "Google")
resp, err := http.DefaultClient.Do(req)
if err != nil {
return "", errors.Wrap(err, "error doing identity request, are you in a GCP VM?")
}
defer resp.Body.Close()
b, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", errors.Wrap(err, "error reading identity request response")
}
if resp.StatusCode >= 400 {
return "", errors.Errorf("error on identity response: status=%d, response=%s", resp.StatusCode, b)
}
return string(bytes.TrimSpace(b)), nil
}
// Init validates and initializes the GCP provider. // Init validates and initializes the GCP provider.
func (p *GCP) Init(config Config) error { func (p *GCP) Init(config Config) error {
var err error var err error
@ -104,7 +144,7 @@ func (p *GCP) Init(config Config) error {
return err return err
} }
// Initialize key store // Initialize key store
p.keyStore, err = newKeyStore("https://www.googleapis.com/oauth2/v3/certs") p.keyStore, err = newKeyStore(googleOauth2Certs)
if err != nil { if err != nil {
return err return err
} }
@ -149,31 +189,6 @@ func (p *GCP) AuthorizeRevoke(token string) error {
return err return err
} }
// GetIdentityURL returns the url that generates the GCP token.
func (p *GCP) GetIdentityURL() string {
audience := url.QueryEscape(p.GetID())
return fmt.Sprintf("http://metadata/computeMetadata/v1/instance/service-accounts/default/identity?audience=%s&format=full&licenses=FALSE", audience)
}
// GetIdentityToken does an HTTP request to the identity url.
func (p *GCP) GetIdentityToken() (string, error) {
req, err := http.NewRequest("GET", p.GetIdentityURL(), http.NoBody)
if err != nil {
return "", errors.Wrap(err, "error creating identity request")
}
req.Header.Set("Metadata-Flavor", "Google")
resp, err := http.DefaultClient.Do(req)
if err != nil {
return "", errors.Wrap(err, "error doing identity request, are you in a GCP VM?")
}
defer resp.Body.Close()
b, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", errors.Wrap(err, "error reading identity request response")
}
return string(bytes.TrimSpace(b)), nil
}
// authorizeToken performs common jwt authorization actions and returns the // authorizeToken performs common jwt authorization actions and returns the
// claims for case specific downstream parsing. // claims for case specific downstream parsing.
// e.g. a Sign request will auth/validate different fields than a Revoke request. // e.g. a Sign request will auth/validate different fields than a Revoke request.
@ -191,42 +206,44 @@ func (p *GCP) authorizeToken(token string) (*gcpPayload, error) {
kid := jwt.Headers[0].KeyID kid := jwt.Headers[0].KeyID
keys := p.keyStore.Get(kid) keys := p.keyStore.Get(kid)
for _, key := range keys { for _, key := range keys {
if err := jwt.Claims(key, &claims); err == nil { if err := jwt.Claims(key.Public(), &claims); err == nil {
found = true found = true
break break
} }
} }
if !found { if !found {
return nil, errors.Errorf("failed to validate payload: cannot find certificate for kid %s", kid) return nil, errors.Errorf("failed to validate payload: cannot find key for kid %s", kid)
} }
// According to "rfc7519 JSON Web Token" acceptable skew should be no // According to "rfc7519 JSON Web Token" acceptable skew should be no
// more than a few minutes. // more than a few minutes.
if err = claims.ValidateWithLeeway(jose.Expected{ if err = claims.ValidateWithLeeway(jose.Expected{
Issuer: "https://accounts.google.com", Issuer: "https://accounts.google.com",
Time: time.Now().UTC(),
Audience: []string{p.GetID()}, Audience: []string{p.GetID()},
Time: time.Now().UTC(),
}, time.Minute); err != nil { }, time.Minute); err != nil {
return nil, errors.Wrapf(err, "invalid token") return nil, errors.Wrapf(err, "invalid token")
} }
// validate authorized party // validate subject (service account)
if len(p.ServiceAccounts) > 0 { if len(p.ServiceAccounts) > 0 {
var found bool var found bool
for _, sa := range p.ServiceAccounts { for _, sa := range p.ServiceAccounts {
if sa == claims.AuthorizedParty { if sa == claims.Subject {
found = true found = true
break break
} }
} }
if !found { if !found {
return nil, errors.New("invalid token: invalid authorized party claim (azp)") return nil, errors.New("invalid token: invalid subject claim")
} }
} }
switch { switch {
case claims.Google.ComputeEngine.InstanceID == "": case claims.Google.ComputeEngine.InstanceID == "":
return nil, errors.New("token google.compute_engine.instance_id cannot be empty") return nil, errors.New("token google.compute_engine.instance_id cannot be empty")
case claims.Google.ComputeEngine.InstanceName == "":
return nil, errors.New("token google.compute_engine.instance_name cannot be empty")
case claims.Google.ComputeEngine.ProjectID == "": case claims.Google.ComputeEngine.ProjectID == "":
return nil, errors.New("token google.compute_engine.project_id cannot be empty") return nil, errors.New("token google.compute_engine.project_id cannot be empty")
case claims.Google.ComputeEngine.Zone == "": case claims.Google.ComputeEngine.Zone == "":

View file

@ -0,0 +1,352 @@
package provisioner
import (
"crypto/sha256"
"crypto/x509"
"encoding/hex"
"fmt"
"net/http"
"net/http/httptest"
"net/url"
"strings"
"testing"
"time"
"github.com/smallstep/assert"
)
func resetGoogleVars() {
googleOauth2Certs = "https://www.googleapis.com/oauth2/v3/certs"
gcpIdentityURL = "http://metadata/computeMetadata/v1/instance/service-accounts/default/identity"
}
func TestGCP_Getters(t *testing.T) {
p, err := generateGCP()
assert.FatalError(t, err)
aud := "gcp:" + p.Name
if got := p.GetID(); got != aud {
t.Errorf("GCP.GetID() = %v, want %v", got, aud)
}
if got := p.GetName(); got != p.Name {
t.Errorf("GCP.GetName() = %v, want %v", got, p.Name)
}
if got := p.GetType(); got != TypeGCP {
t.Errorf("GCP.GetType() = %v, want %v", got, TypeGCP)
}
kid, key, ok := p.GetEncryptedKey()
if kid != "" || key != "" || ok == true {
t.Errorf("GCP.GetEncryptedKey() = (%v, %v, %v), want (%v, %v, %v)",
kid, key, ok, "", "", false)
}
expected := fmt.Sprintf("http://metadata/computeMetadata/v1/instance/service-accounts/default/identity?audience=%s&format=full&licenses=FALSE", url.QueryEscape(p.GetID()))
if got := p.GetIdentityURL(); got != expected {
t.Errorf("GCP.GetIdentityURL() = %v, want %v", got, expected)
}
}
func TestGCP_GetTokenID(t *testing.T) {
p1, err := generateGCP()
assert.FatalError(t, err)
p1.Name = "name"
now := time.Now()
t1, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", "gcp:name",
"instance-id", "instance-name", "project-id", "zone",
now, &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
unique := fmt.Sprintf("gcp:name.instance-id.%d.%d", now.Unix(), now.Add(5*time.Minute).Unix())
sum := sha256.Sum256([]byte(unique))
want := strings.ToLower(hex.EncodeToString(sum[:]))
type args struct {
token string
}
tests := []struct {
name string
gcp *GCP
args args
want string
wantErr bool
}{
{"ok", p1, args{t1}, want, false},
{"fail token", p1, args{"token"}, "", true},
{"fail claims", p1, args{"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.ey.fooo"}, "", true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got, err := tt.gcp.GetTokenID(tt.args.token)
if (err != nil) != tt.wantErr {
t.Errorf("GCP.GetTokenID() error = %v, wantErr %v", err, tt.wantErr)
return
}
if got != tt.want {
t.Errorf("GCP.GetTokenID() = %v, want %v", got, tt.want)
}
})
}
}
func TestGCP_GetIdentityToken(t *testing.T) {
p1, err := generateGCP()
assert.FatalError(t, err)
defer resetGoogleVars()
t1, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println(r.RequestURI)
switch r.URL.Path {
case "/bad-request":
http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
default:
w.Write([]byte(t1))
}
}))
defer srv.Close()
tests := []struct {
name string
gcp *GCP
identityURL string
want string
wantErr bool
}{
{"ok", p1, srv.URL, t1, false},
{"bad request", p1, srv.URL + "/bad-request", "", true},
{"bad url", p1, "badurl", "", true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
gcpIdentityURL = tt.identityURL
got, err := tt.gcp.GetIdentityToken()
if (err != nil) != tt.wantErr {
t.Errorf("GCP.GetIdentityToken() error = %v, wantErr %v", err, tt.wantErr)
return
}
if got != tt.want {
t.Errorf("GCP.GetIdentityToken() = %v, want %v", got, tt.want)
}
})
}
}
func TestGCP_Init(t *testing.T) {
srv := generateJWKServer(2)
defer srv.Close()
defer resetGoogleVars()
config := Config{
Claims: globalProvisionerClaims,
}
badClaims := &Claims{
DefaultTLSDur: &Duration{0},
}
type fields struct {
Type string
Name string
ServiceAccounts []string
Claims *Claims
}
type args struct {
config Config
certsURL string
}
tests := []struct {
name string
fields fields
args args
wantErr bool
}{
{"ok", fields{"GCP", "name", nil, nil}, args{config, srv.URL}, false},
{"ok", fields{"GCP", "name", []string{"service-account"}, nil}, args{config, srv.URL}, false},
{"bad type", fields{"", "name", nil, nil}, args{config, srv.URL}, true},
{"bad name", fields{"GCP", "", nil, nil}, args{config, srv.URL}, true},
{"bad claims", fields{"GCP", "name", nil, badClaims}, args{config, srv.URL}, true},
{"bad certs", fields{"GCP", "name", nil, badClaims}, args{config, srv.URL + "/error"}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
googleOauth2Certs = tt.args.certsURL
p := &GCP{
Type: tt.fields.Type,
Name: tt.fields.Name,
ServiceAccounts: tt.fields.ServiceAccounts,
Claims: tt.fields.Claims,
}
if err := p.Init(tt.args.config); (err != nil) != tt.wantErr {
t.Errorf("GCP.Init() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}
func TestGCP_AuthorizeSign(t *testing.T) {
p1, err := generateGCP()
assert.FatalError(t, err)
aKey, err := generateJSONWebKey()
assert.FatalError(t, err)
t1, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failKey, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now(), aKey)
assert.FatalError(t, err)
failIss, err := generateGCPToken(p1.ServiceAccounts[0],
"https://foo.bar.zar", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
failAud, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", "gcp:foo",
"instance-id", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failExp, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now().Add(-360*time.Second), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failNbf, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now().Add(360*time.Second), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failServiceAccount, err := generateGCPToken("foo",
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failInstanceID, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failInstanceName, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failProjectID, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
failZone, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
type args struct {
token string
}
tests := []struct {
name string
gcp *GCP
args args
wantErr bool
}{
{"ok", p1, args{t1}, false},
{"fail token", p1, args{"token"}, true},
{"fail key", p1, args{failKey}, true},
{"fail iss", p1, args{failIss}, true},
{"fail aud", p1, args{failAud}, true},
{"fail exp", p1, args{failExp}, true},
{"fail nbf", p1, args{failNbf}, true},
{"fail service account", p1, args{failServiceAccount}, true},
{"fail instance id", p1, args{failInstanceID}, true},
{"fail instance name", p1, args{failInstanceName}, true},
{"fail project id", p1, args{failProjectID}, true},
{"fail zone", p1, args{failZone}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got, err := tt.gcp.AuthorizeSign(tt.args.token)
if (err != nil) != tt.wantErr {
t.Errorf("GCP.AuthorizeSign() error = %v, wantErr %v", err, tt.wantErr)
return
}
if err != nil {
assert.Nil(t, got)
} else {
assert.Len(t, 5, got)
}
})
}
}
func TestGCP_AuthorizeRenewal(t *testing.T) {
p1, err := generateGCP()
assert.FatalError(t, err)
p2, err := generateGCP()
assert.FatalError(t, err)
// disable renewal
disable := true
p2.Claims = &Claims{DisableRenewal: &disable}
p2.claimer, err = NewClaimer(p2.Claims, globalProvisionerClaims)
assert.FatalError(t, err)
type args struct {
cert *x509.Certificate
}
tests := []struct {
name string
prov *GCP
args args
wantErr bool
}{
{"ok", p1, args{nil}, false},
{"fail", p2, args{nil}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if err := tt.prov.AuthorizeRenewal(tt.args.cert); (err != nil) != tt.wantErr {
t.Errorf("GCP.AuthorizeRenewal() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}
func TestGCP_AuthorizeRevoke(t *testing.T) {
p1, err := generateGCP()
assert.FatalError(t, err)
t1, err := generateGCPToken(p1.ServiceAccounts[0],
"https://accounts.google.com", p1.GetID(),
"instance-id", "instance-name", "project-id", "zone",
time.Now(), &p1.keyStore.keySet.Keys[0])
assert.FatalError(t, err)
type args struct {
token string
}
tests := []struct {
name string
gcp *GCP
args args
wantErr bool
}{
{"ok", p1, args{t1}, false},
{"fail", p1, args{"token"}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if err := tt.gcp.AuthorizeRevoke(tt.args.token); (err != nil) != tt.wantErr {
t.Errorf("GCP.AuthorizeRevoke() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}

View file

@ -278,7 +278,6 @@ func TestOIDC_AuthorizeSign(t *testing.T) {
t.Run(tt.name, func(t *testing.T) { t.Run(tt.name, func(t *testing.T) {
got, err := tt.prov.AuthorizeSign(tt.args.token) got, err := tt.prov.AuthorizeSign(tt.args.token)
if (err != nil) != tt.wantErr { if (err != nil) != tt.wantErr {
fmt.Println(tt)
t.Errorf("OIDC.Authorize() error = %v, wantErr %v", err, tt.wantErr) t.Errorf("OIDC.Authorize() error = %v, wantErr %v", err, tt.wantErr)
return return
} }
@ -386,47 +385,6 @@ func TestOIDC_AuthorizeRenewal(t *testing.T) {
} }
} }
/*
func TestOIDC_AuthorizeRevoke(t *testing.T) {
srv := generateJWKServer(2)
defer srv.Close()
var keys jose.JSONWebKeySet
assert.FatalError(t, getAndDecode(srv.URL+"/private", &keys))
// Create test provisioners
p1, err := generateOIDC()
assert.FatalError(t, err)
// Update configuration endpoints and initialize
config := Config{Claims: globalProvisionerClaims}
p1.ConfigurationEndpoint = srv.URL + "/.well-known/openid-configuration"
assert.FatalError(t, p1.Init(config))
t1, err := generateSimpleToken("the-issuer", p1.ClientID, &keys.Keys[0])
assert.FatalError(t, err)
type args struct {
token string
}
tests := []struct {
name string
prov *OIDC
args args
wantErr bool
}{
{"disabled", p1, args{t1}, true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if err := tt.prov.AuthorizeRevoke(tt.args.token); (err != nil) != tt.wantErr {
t.Errorf("OIDC.AuthorizeRevoke() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}
*/
func Test_sanitizeEmail(t *testing.T) { func Test_sanitizeEmail(t *testing.T) {
tests := []struct { tests := []struct {
name string name string

View file

@ -163,6 +163,36 @@ func generateOIDC() (*OIDC, error) {
}, nil }, nil
} }
func generateGCP() (*GCP, error) {
name, err := randutil.Alphanumeric(10)
if err != nil {
return nil, err
}
serviceAccount, err := randutil.Alphanumeric(10)
if err != nil {
return nil, err
}
jwk, err := generateJSONWebKey()
if err != nil {
return nil, err
}
claimer, err := NewClaimer(nil, globalProvisionerClaims)
if err != nil {
return nil, err
}
return &GCP{
Type: "GCP",
Name: name,
ServiceAccounts: []string{serviceAccount},
Claims: &globalProvisionerClaims,
claimer: claimer,
keyStore: &keyStore{
keySet: jose.JSONWebKeySet{Keys: []jose.JSONWebKey{*jwk}},
expiry: time.Now().Add(24 * time.Hour),
},
}, nil
}
func generateCollection(nJWK, nOIDC int) (*Collection, error) { func generateCollection(nJWK, nOIDC int) (*Collection, error) {
col := NewCollection(testAudiences) col := NewCollection(testAudiences)
for i := 0; i < nJWK; i++ { for i := 0; i < nJWK; i++ {
@ -220,6 +250,41 @@ func generateToken(sub, iss, aud string, email string, sans []string, iat time.T
return jose.Signed(sig).Claims(claims).CompactSerialize() return jose.Signed(sig).Claims(claims).CompactSerialize()
} }
func generateGCPToken(sub, iss, aud, instanceID, instanceName, projectID, zone string, iat time.Time, jwk *jose.JSONWebKey) (string, error) {
sig, err := jose.NewSigner(
jose.SigningKey{Algorithm: jose.ES256, Key: jwk.Key},
new(jose.SignerOptions).WithType("JWT").WithHeader("kid", jwk.KeyID),
)
if err != nil {
return "", err
}
claims := gcpPayload{
Claims: jose.Claims{
Subject: sub,
Issuer: iss,
IssuedAt: jose.NewNumericDate(iat),
NotBefore: jose.NewNumericDate(iat),
Expiry: jose.NewNumericDate(iat.Add(5 * time.Minute)),
Audience: []string{aud},
},
AuthorizedParty: sub,
Email: "foo@developer.gserviceaccount.com",
EmailVerified: true,
Google: gcpGooglePayload{
ComputeEngine: gcpComputeEnginePayload{
InstanceID: instanceID,
InstanceName: instanceName,
InstanceCreationTimestamp: jose.NewNumericDate(iat.Add(-24 * time.Hour)),
ProjectID: projectID,
ProjectNumber: 1234567890,
Zone: zone,
},
},
}
return jose.Signed(sig).Claims(claims).CompactSerialize()
}
func parseToken(token string) (*jose.JSONWebToken, *jose.Claims, error) { func parseToken(token string) (*jose.JSONWebToken, *jose.Claims, error) {
tok, err := jose.ParseSigned(token) tok, err := jose.ParseSigned(token)
if err != nil { if err != nil {