From 9d4eef2dd6d864511808f1a9c55eed2b837969df Mon Sep 17 00:00:00 2001
From: logicog <git@logicog.de>
Date: Tue, 27 Jan 2026 20:48:02 +0100
Subject: [PATCH] Add support for management vlan

This adds support for the verification of a mangement vlan.
When enabled, then the switch's CPU will not listen to any packets
that are not tagged with the respective VLAN tag.
On the command line this is enabled by setting:
> vlan <vlan> mgmt

Setting the vlan ID of the management VLAN to 0 or 1 disables
the mangement VLAN function.
---
 cmd_parser.c    | 13 +++++++++----
 rtlplayground.c | 18 ++++++++++--------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/cmd_parser.c b/cmd_parser.c
index ed7d159..f02cb09 100644
--- a/cmd_parser.c
+++ b/cmd_parser.c
@@ -42,6 +42,7 @@ extern __xdata struct dhcp_state dhcp_state;
 
 __xdata uint8_t vlan_names[VLAN_NAMES_SIZE];
 __xdata uint16_t vlan_ptr;
+extern __xdata uint16_t management_vlan;
 __xdata uint8_t gpio_last_value[8] = { 0 };
 
 // Temporatly for str to hex convertion value.
@@ -289,16 +290,20 @@ void parse_vlan(void)
 			vlan_delete(vlan);
 			return;
 		}
+		if (cmd_words_b[2] > 0 && cmd_compare(2, "mgmt")) {
+			management_vlan = vlan;
+			if (!vlan) 
+				print_string("Management VLAN disabled\n");
+			else
+				print_string("Management VLAN set to "); print_short(management_vlan); write_char('\n');
+			return;
+		}
 		uint8_t w = 2;
-		write_char('#');
-		print_byte(cmd_words_b[w] );
-		write_char('#'); write_char(cmd_buffer[cmd_words_b[w]]);
 		if (cmd_words_b[w] > 0 && isletter(cmd_buffer[cmd_words_b[w]])) {
 			register uint8_t i = 0;
 			vlan_names[vlan_ptr++] = hex[(vlan >> 8) & 0xf];
 			vlan_names[vlan_ptr++] = hex[(vlan >> 4) & 0xf] ;
 			vlan_names[vlan_ptr++] = hex[vlan & 0xf];
-			print_string("COPYING: >");
 			while(cmd_buffer[cmd_words_b[w] + i] != ' ') {
 				write_char(cmd_buffer[cmd_words_b[w] + i]);
 				vlan_names[vlan_ptr++] = cmd_buffer[cmd_words_b[w] + i++];
diff --git a/rtlplayground.c b/rtlplayground.c
index 041282f..8ada438 100644
--- a/rtlplayground.c
+++ b/rtlplayground.c
@@ -105,6 +105,7 @@ __xdata uint8_t rx_headers[16]; // Packet header(s) on RX
 __xdata uint8_t uip_buf[UIP_CONF_BUFFER_SIZE+2];
 
 __xdata uint16_t rx_packet_vlan;
+__xdata uint16_t management_vlan;
 __xdata uint8_t tx_seq;
 
 __xdata uint8_t stpEnabled;
@@ -115,7 +116,6 @@ __code uint16_t bit_mask[16] = {
 };
 
 
-__xdata uint8_t was_offline;
 __xdata uint8_t linkbits_last[4];
 __xdata uint8_t linkbits_last_p89;
 __xdata uint8_t sfp_pins_last;
@@ -921,12 +921,14 @@ void handle_rx(void)
 			    tcpip_output();
 			}
 		} else if (uip_buf[ETHERTYPE_OFFSET] == 0x08 && uip_buf[ETHERTYPE_OFFSET + 1] == 0x00) { // TCP?
-			uip_arp_ipin();	// Learn MAC addresses in TCP packets
-			uip_input();
-			if (uip_len) {
-				// Add ethernet frame
-				uip_arp_out();
-				tcpip_output();
+			if (!management_vlan || management_vlan == rx_packet_vlan) {
+				uip_arp_ipin();	// Learn MAC addresses in TCP packets
+				uip_input();
+				if (uip_len) {
+					// Add ethernet frame
+					uip_arp_out();
+					tcpip_output();
+				}
 			}
 		} else {
 #ifdef RXTXDBG
@@ -1950,7 +1952,7 @@ void bootloader(void)
 	uip_arp_init();
 	httpd_init();
 
-	was_offline = 1;
+	management_vlan = 0; // Disabled
 
 	setup_i2c();