Merge pull request #6359 from guggero/fix-rest-proxy-fallback

lnd: disable REST proxy HTTP method fallback

docs/release-notes/release-notes-0.14.3.md

@@ -0,0 +1,13 @@
+# Release Notes
+
+## Bug fixes
+
+* The REST proxy (`grpc-gateway` library) had a fallback that redirected `POST`
+  requests to another endpoint _with the same URI_ if no endpoint for `POST` was
+  registered. [This default behavior was turned
+  off](https://github.com/lightningnetwork/lnd/pull/6359), enabling strict
+  HTTP method matching.
+
+# Contributors (Alphabetical Order)
+
+* Oliver Gugger

lnd.go

@@ -973,7 +973,16 @@ func startRestProxy(cfg *Config, rpcServer *rpcServer, restDialOpts []grpc.DialO
 			},
 		},
 	)
-	mux := proxy.NewServeMux(customMarshalerOption)
+	mux := proxy.NewServeMux(
+		customMarshalerOption,
+
+		// Don't allow falling back to other HTTP methods, we want exact
+		// matches only. The actual method to be used can be overwritten
+		// by setting X-HTTP-Method-Override so there should be no
+		// reason for not specifying the correct method in the first
+		// place.
+		proxy.WithDisablePathLengthFallback(),
+	)
 
 	// Register our services with the REST proxy.
 	err := lnrpc.RegisterStateHandlerFromEndpoint(