Allow Remote sessions to outlive connection forms

internal/tentaclewire/interaction.go

@@ -26,6 +26,9 @@ type Interaction struct {
 	Done      bool              `json:"done,omitempty"`
 	Reader    *ReaderRequest    `json:"reader,omitempty"`
 	Remote    *RemoteRequest    `json:"remote,omitempty"`
+	// RemoteBackground ends this interaction while retaining an already-open
+	// lease owned by this process session. It grants no new access or lifetime.
+	RemoteBackground *RemoteLease `json:"remote_background,omitempty"`
 }
 
 // RemoteRequest asks the reader to show its own local consent form. It never
@@ -80,7 +83,11 @@ func DecodeInteraction(data []byte) (Interaction, error) {
 	if value.Source != "" && value.Source != "focus" && value.Source != "clipboard" {
 		return value, ErrProtocol
 	}
-	if value.Remote != nil {
+	if value.RemoteBackground != nil {
+		if len(value.RemoteBackground.Lease) != 32 || value.RemoteBackground.Epoch == 0 || !value.Done || value.Next != "" || value.Poll != "" || value.Form != nil || value.Source != "" || value.Clipboard != nil || value.Reader != nil || value.Remote != nil || value.Uninterruptible {
+			return value, ErrProtocol
+		}
+	} else if value.Remote != nil {
 		if !ValidRoleGrants(value.Remote.Role, value.Remote.Grants) || value.Next == "" || value.Reader != nil || value.Form != nil || value.Source != "" || value.Poll != "" || value.Clipboard != nil || value.Done {
 			return value, ErrProtocol
 		}

internal/tentaclewire/remote_interaction_test.go

@@ -4,6 +4,7 @@ package tentaclewire
 
 import (
 	"encoding/json"
+	"strings"
 	"testing"
 )
 
@@ -32,3 +33,29 @@ func TestRemoteConsentInteractionValidation(t *testing.T) {
 		}
 	}
 }
+
+func TestRemoteBackgroundInteractionValidation(t *testing.T) {
+	lease := RemoteLease{Lease: strings.Repeat("a", 32), Epoch: 1}
+	valid := Interaction{RemoteBackground: &lease, Done: true, Presentation: Presentation{Speech: "Connection controls closed"}}
+	data, _ := json.Marshal(valid)
+	if _, err := DecodeInteraction(data); err != nil {
+		t.Fatal(err)
+	}
+	for _, raw := range []string{
+		`{"remote_background":null,"done":true}`,
+		`{"remote_background":{"lease":"short","epoch":1},"done":true}`,
+		`{"remote_background":{"lease":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","epoch":0},"done":true}`,
+		`{"remote_background":{"lease":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","epoch":1,"session":"other"},"done":true}`,
+		`{"remote_background":{"lease":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","epoch":1}}`,
+	} {
+		if _, err := DecodeInteraction([]byte(raw)); err == nil {
+			t.Fatal("invalid background interaction accepted", raw)
+		}
+	}
+	for _, field := range []string{`"form":{"title":"Menu","elements":[]}`, `"next":"submit"`, `"poll":"poll"`, `"source":"focus"`, `"clipboard":"text"`, `"reader":{"snapshot":true}`, `"remote":{"role":"controller","grants":["remote-present"]}`, `"uninterruptible":true`} {
+		raw := `{"remote_background":{"lease":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","epoch":1},"done":true,"speech":"Closed",` + field + `}`
+		if _, err := DecodeInteraction([]byte(raw)); err == nil {
+			t.Fatal("background interaction mixed with another effect", field)
+		}
+	}
+}