Support federated credentials in on-behalf-of flow

sdk/azidentity/CHANGELOG.md

@@ -3,6 +3,8 @@
 ## 1.6.0-beta.5 (Unreleased)
 
 ### Features Added
+* `NewOnBehalfOfCredentialWithClientAssertions` creates an on-behalf-of credential
+  that authenticates with client assertions such as federated credentials
 
 ### Breaking Changes
 

sdk/azidentity/example_test.go

@@ -64,7 +64,9 @@ func ExampleNewOnBehalfOfCredentialWithCertificate() {
 		// TODO: handle error
 	}
 
-	cred, err = azidentity.NewClientCertificateCredential(tenantID, clientID, certs, key, nil)
+	// userAssertion is the user's access token for the application. Typically it comes from a client request.
+	userAssertion := "TODO"
+	cred, err = azidentity.NewOnBehalfOfCredentialWithCertificate(tenantID, clientID, userAssertion, certs, key, nil)
 	if err != nil {
 		// TODO: handle error
 	}

sdk/azidentity/on_behalf_of_credential.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"crypto"
 	"crypto/x509"
+	"errors"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
@@ -60,6 +61,19 @@ func NewOnBehalfOfCredentialWithCertificate(tenantID, clientID, userAssertion st
 	return newOnBehalfOfCredential(tenantID, clientID, userAssertion, cred, options)
 }
 
+// NewOnBehalfOfCredentialWithClientAssertions constructs an OnBehalfOfCredential that authenticates with client assertions.
+// userAssertion is the user's access token for the application. The getAssertion function should return client assertions
+// that authenticate the application to Microsoft Entra ID, such as federated credentials.
+func NewOnBehalfOfCredentialWithClientAssertions(tenantID, clientID, userAssertion string, getAssertion func(context.Context) (string, error), options *OnBehalfOfCredentialOptions) (*OnBehalfOfCredential, error) {
+	if getAssertion == nil {
+		return nil, errors.New("getAssertion can't be nil. It must be a function that returns client assertions")
+	}
+	cred := confidential.NewCredFromAssertionCallback(func(ctx context.Context, _ confidential.AssertionRequestOptions) (string, error) {
+		return getAssertion(ctx)
+	})
+	return newOnBehalfOfCredential(tenantID, clientID, userAssertion, cred, options)
+}
+
 // NewOnBehalfOfCredentialWithSecret constructs an OnBehalfOfCredential that authenticates with a client secret.
 func NewOnBehalfOfCredentialWithSecret(tenantID, clientID, userAssertion, clientSecret string, options *OnBehalfOfCredentialOptions) (*OnBehalfOfCredential, error) {
 	cred, err := confidential.NewCredFromSecret(clientSecret)

sdk/azidentity/on_behalf_of_credential_test.go

@@ -15,37 +15,62 @@ import (
 	"time"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
+	"github.com/stretchr/testify/require"
 )
 
 func TestOnBehalfOfCredential(t *testing.T) {
-	expectedAssertion := "user-assertion"
+	clientAssertion := "client-assertion"
+	userAssertion := "user-assertion"
 	certs, key := allCertTests[0].certs, allCertTests[0].key
 	for _, test := range []struct {
-		ctor    func(policy.Transporter) (*OnBehalfOfCredential, error)
-		name    string
-		sendX5C bool
+		ctor             func(policy.Transporter) (*OnBehalfOfCredential, error)
+		name             string
+		sendX5C          bool
+		verifyCredential func(*testing.T, *http.Request)
 	}{
 		{
 			ctor: func(tp policy.Transporter) (*OnBehalfOfCredential, error) {
 				o := OnBehalfOfCredentialOptions{ClientOptions: policy.ClientOptions{Transport: tp}}
-				return NewOnBehalfOfCredentialWithCertificate(fakeTenantID, fakeClientID, expectedAssertion, certs, key, &o)
+				getAssertions := func(context.Context) (string, error) {
+					return clientAssertion, nil
+				}
+				return NewOnBehalfOfCredentialWithClientAssertions(fakeTenantID, fakeClientID, userAssertion, getAssertions, &o)
+			},
+			name: "client assertions",
+			verifyCredential: func(t *testing.T, r *http.Request) {
+				require.Equal(t, clientAssertion, r.FormValue("client_assertion"))
+			},
+		},
+		{
+			ctor: func(tp policy.Transporter) (*OnBehalfOfCredential, error) {
+				o := OnBehalfOfCredentialOptions{ClientOptions: policy.ClientOptions{Transport: tp}}
+				return NewOnBehalfOfCredentialWithCertificate(fakeTenantID, fakeClientID, userAssertion, certs, key, &o)
 			},
 			name: "certificate",
+			verifyCredential: func(t *testing.T, r *http.Request) {
+				require.NotEmpty(t, r.FormValue("client_assertion"))
+			},
 		},
 		{
 			ctor: func(tp policy.Transporter) (*OnBehalfOfCredential, error) {
 				o := OnBehalfOfCredentialOptions{ClientOptions: policy.ClientOptions{Transport: tp}, SendCertificateChain: true}
-				return NewOnBehalfOfCredentialWithCertificate(fakeTenantID, fakeClientID, expectedAssertion, certs, key, &o)
+				return NewOnBehalfOfCredentialWithCertificate(fakeTenantID, fakeClientID, userAssertion, certs, key, &o)
 			},
 			name:    "SNI",
 			sendX5C: true,
+			verifyCredential: func(t *testing.T, r *http.Request) {
+				require.NotEmpty(t, r.FormValue("client_assertion"))
+			},
 		},
 		{
 			ctor: func(tp policy.Transporter) (*OnBehalfOfCredential, error) {
 				o := OnBehalfOfCredentialOptions{ClientOptions: policy.ClientOptions{Transport: tp}}
-				return NewOnBehalfOfCredentialWithSecret(fakeTenantID, fakeClientID, expectedAssertion, "secret", &o)
+				return NewOnBehalfOfCredentialWithSecret(fakeTenantID, fakeClientID, userAssertion, fakeSecret, &o)
 			},
 			name: "secret",
+			verifyCredential: func(t *testing.T, r *http.Request) {
+				require.Equal(t, fakeSecret, r.FormValue("client_secret"))
+			},
 		},
 	} {
 		t.Run(test.name, func(t *testing.T) {
@@ -63,12 +88,13 @@ func TestOnBehalfOfCredential(t *testing.T) {
 				if scope := r.FormValue("scope"); !strings.Contains(scope, liveTestScope) {
 					t.Errorf(`unexpected scopes "%v"`, scope)
 				}
-				if assertion := r.FormValue("assertion"); assertion != expectedAssertion {
-					t.Errorf(`unexpected assertion "%s"`, assertion)
+				if assertion := r.FormValue("assertion"); assertion != userAssertion {
+					t.Errorf(`unexpected user assertion "%s"`, assertion)
 				}
 				if test.sendX5C {
 					validateX5C(t, certs)(r)
 				}
+				test.verifyCredential(t, r)
 				return nil
 			}}
 			cred, err := test.ctor(&srv)