rpc: verify address is for correct net

Verify that the addresses we're decoding when sending coins onchain are
for the correct network. Without this check we'll convert the users
addresses to their equivalent on other networks, which is a gross
violation of the principle of least astonishment.

docs/release-notes/release-notes-0.17.0.md

@@ -72,6 +72,9 @@ package](https://github.com/lightningnetwork/lnd/pull/7356)
   `grpc.keepalive_time_ms=5100` is recommended on the client side (adding 100ms
   to account for slightly different clock speeds).
 
+* [Fixed a bug where we didn't check for correct networks when submitting
+  onchain transactions](https://github.com/lightningnetwork/lnd/pull/6448).
+
 ## Misc
 
 * [Generate default macaroons

lnrpc/invoicesrpc/addinvoice.go

@@ -292,12 +292,19 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 
 	// If specified, add a fallback address to the payment request.
 	if len(invoice.FallbackAddr) > 0 {
-		addr, err := btcutil.DecodeAddress(invoice.FallbackAddr,
-			cfg.ChainParams)
+		addr, err := btcutil.DecodeAddress(
+			invoice.FallbackAddr, cfg.ChainParams,
+		)
 		if err != nil {
 			return nil, nil, fmt.Errorf("invalid fallback "+
 				"address: %v", err)
 		}
+
+		if !addr.IsForNet(cfg.ChainParams) {
+			return nil, nil, fmt.Errorf("fallback address is not "+
+				"for %s", cfg.ChainParams.Name)
+		}
+
 		options = append(options, zpay32.FallbackAddr(addr))
 	}
 

lnrpc/walletrpc/walletkit_server.go

@@ -1104,6 +1104,12 @@ func (w *WalletKit) FundPsbt(_ context.Context,
 					"%s for network %s: %v", addrStr,
 					w.cfg.ChainParams.Name, err)
 			}
+
+			if !addr.IsForNet(w.cfg.ChainParams) {
+				return nil, fmt.Errorf("address is not for %s",
+					w.cfg.ChainParams.Name)
+			}
+
 			pkScript, err := txscript.PayToAddrScript(addr)
 			if err != nil {
 				return nil, fmt.Errorf("error getting pk "+

rpcserver.go

@@ -970,6 +970,11 @@ func addrPairsToOutputs(addrPairs map[string]int64,
 			return nil, err
 		}
 
+		if !addr.IsForNet(params) {
+			return nil, fmt.Errorf("address is not for %s",
+				params.Name)
+		}
+
 		pkscript, err := txscript.PayToAddrScript(addr)
 		if err != nil {
 			return nil, err
@@ -2579,7 +2584,14 @@ func (r *rpcServer) CloseChannel(in *lnrpc.CloseChannelRequest,
 				in.DeliveryAddress, r.cfg.ActiveNetParams.Params,
 			)
 			if err != nil {
-				return fmt.Errorf("invalid delivery address: %v", err)
+				return fmt.Errorf("invalid delivery address: "+
+					"%v", err)
+			}
+
+			if !addr.IsForNet(r.cfg.ActiveNetParams.Params) {
+				return fmt.Errorf("delivery address is not "+
+					"for %s",
+					r.cfg.ActiveNetParams.Params.Name)
 			}
 
 			// Create a script to pay out to the address provided.