auth: create invoice request with closure, add challenger

auth/interface.go

@@ -1,15 +1,26 @@
 package auth
 
-import "net/http"
+import (
+	"net/http"
+
+	"github.com/lightningnetwork/lnd/lntypes"
+)
 
 // Authenticator is the generic interface for validating client headers and
 // returning new challenge headers.
 type Authenticator interface {
-	// Accept returns whether or not the header successfully authenticates the user
-	// to a given backend service.
+	// Accept returns whether or not the header successfully authenticates
+	// the user to a given backend service.
 	Accept(*http.Header) bool
 
-	// FreshChallengeHeader returns a header containing a challenge for the user to
-	// complete.
+	// FreshChallengeHeader returns a header containing a challenge for the
+	// user to complete.
 	FreshChallengeHeader(r *http.Request) (http.Header, error)
 }
+
+// Challenger is an interface for generating new payment challenges.
+type Challenger interface {
+	// NewChallenge creates a new LSAT payment challenge, returning a
+	// payment request (invoice) and the corresponding payment hash.
+	NewChallenge() (string, lntypes.Hash, error)
+}