Add allowedDomains to Microsoft connector.

The existing Microsoft connector does not support allowedDomains like Google connector or other connectors allows.

connector/microsoft/microsoft.go

@@ -63,6 +63,8 @@ type Config struct {
 	DomainHint string `json:"domainHint"`
 
 	Scopes []string `json:"scopes"` // defaults to scopeUser (user.read)
+
+	AllowedDomains []string `json:"allowedDomains"`
 }
 
 // Open returns a strategy for logging in through Microsoft.
@@ -83,6 +85,7 @@ func (c *Config) Open(id string, logger log.Logger) (connector.Connector, error)
 		promptType:           c.PromptType,
 		domainHint:           c.DomainHint,
 		scopes:               c.Scopes,
+		allowedDomains:       c.AllowedDomains,
 	}
 
 	if m.apiURL == "" {
@@ -138,6 +141,7 @@ type microsoftConnector struct {
 	promptType           string
 	domainHint           string
 	scopes               []string
+	allowedDomains       []string
 }
 
 func (c *microsoftConnector) isOrgTenant() bool {
@@ -217,6 +221,11 @@ func (c *microsoftConnector) HandleCallback(s connector.Scopes, r *http.Request)
 		user.Email = strings.ToLower(user.Email)
 	}
 
+	// Check if the email's domain is in the allowed list
+	if !c.isAllowedDomain(user.Email) {
+		return identity, fmt.Errorf("email (%s) domain not allowed", user.Email)
+	}
+
 	identity = connector.Identity{
 		UserID:        user.ID,
 		Username:      user.Name,
@@ -531,3 +540,22 @@ func (e *oauth2Error) Error() string {
 	}
 	return e.error + ": " + e.errorDescription
 }
+
+func (c *microsoftConnector) isAllowedDomain(email string) bool {
+
+	if len(c.allowedDomains) == 0 {
+		return true
+	}
+
+	parts := strings.Split(email, "@")
+	if len(parts) != 2 {
+		return false
+	}
+	domain := parts[1]
+	for _, d := range c.allowedDomains {
+		if d == domain {
+			return true
+		}
+	}
+	return false
+}

connector/microsoft/microsoft_test.go

@@ -3,6 +3,7 @@ package microsoft
 import (
 	"encoding/json"
 	"fmt"
+	"github.com/stretchr/testify/assert"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -119,6 +120,66 @@ func TestUserGroupsFromGraphAPI(t *testing.T) {
 	expectEquals(t, identity.Groups, []string{"a", "b"})
 }
 
+func TestDomainNotAllowed(t *testing.T) {
+	s := newTestServer(map[string]testResponse{
+		"/v1.0/me?$select=id,displayName,userPrincipalName": {
+			data: user{ID: "S56767889", Name: "Jane Doe", Email: "jane.doe@example.com"},
+		},
+		"/" + tenant + "/oauth2/v2.0/token": dummyToken,
+	})
+	defer s.Close()
+
+	req, _ := http.NewRequest("GET", s.URL, nil)
+
+	c := microsoftConnector{apiURL: s.URL, graphURL: s.URL, tenant: tenant, allowedDomains: []string{"dcode.tech"}}
+	identity, err := c.HandleCallback(connector.Scopes{Groups: false}, req)
+
+	assert.Error(t, err, "email (jane.doe@example.com) domain not allowed")
+	assert.Equal(t, connector.Identity{}, identity)
+}
+
+func TestDomainListAllowed(t *testing.T) {
+	testCases := []struct {
+		email   string
+		allowed bool
+		domain  string
+	}{
+		{"jane.doe@dcode.tech", true, "dcode.tech"},              // Allowed domain
+		{"joe.bloggs@example.com", true, "example.com"},          // Allowed domain
+		{"john.smith@otherdomain.com", false, "otherdomain.com"}, // Not allowed domain
+	}
+
+	for _, tc := range testCases {
+		s := newTestServer(map[string]testResponse{
+			"/v1.0/me?$select=id,displayName,userPrincipalName": {
+				data: user{ID: "S56767889", Name: "John Doe", Email: tc.email},
+			},
+			"/" + tenant + "/oauth2/v2.0/token": dummyToken,
+		})
+		defer s.Close()
+
+		req, _ := http.NewRequest("GET", s.URL, nil)
+
+		// Setup the microsoftConnector with allowed domains
+		c := microsoftConnector{
+			apiURL:         s.URL,
+			graphURL:       s.URL,
+			tenant:         tenant,
+			allowedDomains: []string{"dcode.tech", "example.com"},
+		}
+
+		identity, err := c.HandleCallback(connector.Scopes{Groups: false}, req)
+
+		if tc.allowed {
+			assert.NoError(t, err, "Expected no error for allowed domain: "+tc.domain)
+			assert.NotEqual(t, connector.Identity{}, identity, "Expected a non-empty identity struct")
+		} else {
+			assert.Error(t, err, "Expected error for non-allowed domain: "+tc.email)
+			assert.Equal(t, connector.Identity{}, identity, "Expected an empty identity struct")
+		}
+	}
+}
+
 func newTestServer(responses map[string]testResponse) *httptest.Server {
 	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		response, found := responses[r.RequestURI]