fix: enforce device authorization grant type

example/server/storage/client.go

@@ -193,6 +193,24 @@ func WebClient(id, secret string, redirectURIs ...string) *Client {
 	}
 }
 
+// DeviceClient creates a device client with Basic authentication.
+func DeviceClient(id, secret string) *Client {
+	return &Client{
+		id:                             id,
+		secret:                         secret,
+		redirectURIs:                   nil,
+		applicationType:                op.ApplicationTypeWeb,
+		authMethod:                     oidc.AuthMethodBasic,
+		loginURL:                       defaultLoginURL,
+		responseTypes:                  []oidc.ResponseType{oidc.ResponseTypeCode},
+		grantTypes:                     []oidc.GrantType{oidc.GrantTypeDeviceCode},
+		accessTokenType:                op.AccessTokenTypeBearer,
+		devMode:                        false,
+		idTokenUserinfoClaimsAssertion: false,
+		clockSkew:                      0,
+	}
+}
+
 type hasRedirectGlobs struct {
 	*Client
 }

pkg/op/device.go

@@ -122,6 +122,13 @@ func ParseDeviceCodeRequest(r *http.Request, o OpenIDProvider) (*oidc.DeviceAuth
 	if err != nil {
 		return nil, err
 	}
+	client, err := o.Storage().GetClientByClientID(r.Context(), clientID)
+	if err != nil {
+		return nil, err
+	}
+	if !ValidateGrantType(client, oidc.GrantTypeDeviceCode) {
+		return nil, oidc.ErrUnauthorizedClient().WithDescription("client missing grant type " + string(oidc.GrantTypeCode))
+	}
 
 	req := new(oidc.DeviceAuthorizationRequest)
 	if err := o.Decoder().Decode(req, r.Form); err != nil {

pkg/op/device_test.go

@@ -51,7 +51,7 @@ func Test_deviceAuthorizationHandler(t *testing.T) {
 
 			req := &oidc.DeviceAuthorizationRequest{
 				Scopes:   []string{"foo", "bar"},
-				ClientID: "web",
+				ClientID: "device",
 			}
 			values := make(url.Values)
 			testProvider.Encoder().Encode(req, values)
@@ -88,11 +88,27 @@ func TestParseDeviceCodeRequest(t *testing.T) {
 			wantErr: true,
 		},
 		{
-			name: "success",
+			name: "missing grant type",
 			req: &oidc.DeviceAuthorizationRequest{
 				Scopes:   oidc.SpaceDelimitedArray{"foo", "bar"},
 				ClientID: "web",
 			},
+			wantErr: true,
+		},
+		{
+			name: "client not found",
+			req: &oidc.DeviceAuthorizationRequest{
+				Scopes:   oidc.SpaceDelimitedArray{"foo", "bar"},
+				ClientID: "foobar",
+			},
+			wantErr: true,
+		},
+		{
+			name: "success",
+			req: &oidc.DeviceAuthorizationRequest{
+				Scopes:   oidc.SpaceDelimitedArray{"foo", "bar"},
+				ClientID: "device",
+			},
 		},
 	}
 	for _, tt := range tests {
@@ -110,8 +126,7 @@ func TestParseDeviceCodeRequest(t *testing.T) {
 			got, err := op.ParseDeviceCodeRequest(r, testProvider)
 			if tt.wantErr {
 				require.Error(t, err)
-			} else {
-				require.NoError(t, err)
+				return
 			}
 			assert.Equal(t, tt.req, got)
 		})

pkg/op/op_test.go

@@ -49,6 +49,7 @@ func init() {
 	storage.RegisterClients(
 		storage.NativeClient("native"),
 		storage.WebClient("web", "secret", "https://example.com"),
+		storage.DeviceClient("device", "secret"),
 		storage.WebClient("api", "secret"),
 	)
 
@@ -336,7 +337,7 @@ func TestRoutes(t *testing.T) {
 			name:      "device authorization",
 			method:    http.MethodGet,
 			path:      testProvider.DeviceAuthorizationEndpoint().Relative(),
-			basicAuth: &basicAuth{"web", "secret"},
+			basicAuth: &basicAuth{"device", "secret"},
 			values: map[string]string{
 				"scope": oidc.SpaceDelimitedArray{oidc.ScopeOpenID, oidc.ScopeOfflineAccess}.Encode(),
 			},