Support for DHCP

Author: dgarske

src/port/stm32h563/README.md

@@ -27,7 +27,7 @@ sudo apt install gcc-arm-none-eabi openocd
 
 ```bash
 cd src/port/stm32h563
-make TZEN=0
+make
 ```
 
 This produces `app.elf` and `app.bin` for use with TZEN=0 (TrustZone disabled).
@@ -94,7 +94,7 @@ picocom -b 115200 /dev/ttyACM0
 
 ## Example Output
 
-When the firmware boots successfully, you should see output similar to:
+When the firmware boots successfully with DHCP (default), you should see output similar to:
 
 ```
 === wolfIP STM32H563 Echo Server ===
@@ -113,11 +113,35 @@ Entering main loop. Ready for connections!
 Loop starting...
 ```
 
+When static IP is enabled, the output will show "Setting IP configuration:" instead of "DHCP configuration received:".
+
 The "PHY link: UP" message indicates the Ethernet PHY has established a link with the network.
 
 ## Network Configuration
 
-The example configures the following static IP:
+The example can be configured to use either DHCP or static IP. By default, DHCP is enabled.
+
+### DHCP Configuration (Default)
+
+By default, the device uses DHCP to automatically obtain IP address, subnet mask, gateway, and DNS server from a DHCP server on the network. The obtained configuration will be displayed on the serial console.
+
+**Note:** When DHCP is enabled, the device will wait up to 30 seconds for a DHCP server response during initialization. If no DHCP server is available, the device will timeout and continue without network configuration.
+
+### Static IP Configuration
+
+To use static IP instead of DHCP, set `WOLFIP_ENABLE_DHCP` to `0` in `config.h`:
+
+```c
+#define WOLFIP_ENABLE_DHCP 0
+```
+
+Or compile with:
+
+```bash
+make CFLAGS+="-DWOLFIP_ENABLE_DHCP=0"
+```
+
+When static IP is enabled, the example configures the following:
 
 | Setting | Value |
 |---------|-------|

src/port/stm32h563/config.h

@@ -48,9 +48,17 @@
 #define WOLFIP_ENABLE_LOOPBACK 0
 #endif
 
+#ifndef WOLFIP_ENABLE_DHCP
+#define WOLFIP_ENABLE_DHCP 1
+#endif
+
+#if WOLFIP_ENABLE_DHCP
+#define DHCP
+#else
 #define WOLFIP_IP "192.168.12.11"
 #define WOLFIP_NETMASK "255.255.255.0"
 #define WOLFIP_GW "192.168.12.1"
 #define WOLFIP_STATIC_DNS_IP "9.9.9.9"
+#endif
 
 #endif

src/port/stm32h563/main.c

@@ -230,6 +230,34 @@ static void uart_puthex(uint32_t val)
     }
 }
 
+static void uart_putdec(uint32_t val)
+{
+    char buf[12];
+    int i = 0;
+    if (val == 0) {
+        uart_putc('0');
+        return;
+    }
+    while (val > 0 && i < 11) {
+        buf[i++] = '0' + (val % 10);
+        val /= 10;
+    }
+    while (i > 0) {
+        uart_putc(buf[--i]);
+    }
+}
+
+static void uart_putip4(ip4 ip)
+{
+    uart_putdec((ip >> 24) & 0xFF);
+    uart_putc('.');
+    uart_putdec((ip >> 16) & 0xFF);
+    uart_putc('.');
+    uart_putdec((ip >> 8) & 0xFF);
+    uart_putc('.');
+    uart_putdec(ip & 0xFF);
+}
+
 /* Configure GPIO pin for Ethernet alternate function (AF11) */
 static void gpio_eth_pin(uint32_t base, uint32_t pin)
 {
@@ -420,14 +448,66 @@ int main(void)
         uart_puts("\n");
     }
 
-    uart_puts("Setting IP configuration:\n");
-    uart_puts("  IP: " WOLFIP_IP "\n");
-    uart_puts("  Mask: " WOLFIP_NETMASK "\n");
-    uart_puts("  GW: " WOLFIP_GW "\n");
-    wolfIP_ipconfig_set(IPStack,
-                        atoip4(WOLFIP_IP),
-                        atoip4(WOLFIP_NETMASK),
-                        atoip4(WOLFIP_GW));
+#ifdef DHCP
+    {
+        uint32_t dhcp_start_tick;
+        uint32_t dhcp_timeout;
+
+        dhcp_timeout = 30000;  /* 30 seconds timeout */
+
+        (void)wolfIP_poll(IPStack, tick);
+        if (dhcp_client_init(IPStack) >= 0) {
+            /* Poll immediately to send the DHCP discover packet */
+            (void)wolfIP_poll(IPStack, tick);
+            tick++;
+            delay(1000);
+            (void)wolfIP_poll(IPStack, tick);
+            tick++;
+            delay(1000);
+
+            /* Wait for DHCP to complete - poll frequently */
+            dhcp_start_tick = tick;
+            while (!dhcp_bound(IPStack)) {
+                /* Poll the stack - this processes received packets and sends pending data */
+                (void)wolfIP_poll(IPStack, tick);
+                /* Increment tick counter (approximate 1ms per iteration) */
+                tick++;
+                /* Small delay to allow Ethernet DMA to work */
+                delay(1000);
+                /* Check for timeout */
+                if ((tick - dhcp_start_tick) > dhcp_timeout)
+                    break;
+            }
+            if (dhcp_bound(IPStack)) {
+                ip4 ip = 0, nm = 0, gw = 0;
+                wolfIP_ipconfig_get(IPStack, &ip, &nm, &gw);
+                uart_puts("DHCP configuration received:\n");
+                uart_puts("  IP: ");
+                uart_putip4(ip);
+                uart_puts("\n  Mask: ");
+                uart_putip4(nm);
+                uart_puts("\n  GW: ");
+                uart_putip4(gw);
+                uart_puts("\n");
+            }
+        }
+    }
+#else
+    {
+        ip4 ip = atoip4(WOLFIP_IP);
+        ip4 nm = atoip4(WOLFIP_NETMASK);
+        ip4 gw = atoip4(WOLFIP_GW);
+        uart_puts("Setting IP configuration:\n");
+        uart_puts("  IP: ");
+        uart_putip4(ip);
+        uart_puts("\n  Mask: ");
+        uart_putip4(nm);
+        uart_puts("\n  GW: ");
+        uart_putip4(gw);
+        uart_puts("\n");
+        wolfIP_ipconfig_set(IPStack, ip, nm, gw);
+    }
+#endif
 
     uart_puts("Creating TCP socket on port 7...\n");
     listen_fd = wolfIP_sock_socket(IPStack, AF_INET, IPSTACK_SOCK_STREAM, 0);

src/wolfip.c

@@ -1235,15 +1235,18 @@ static void udp_try_recv(struct wolfIP *s, unsigned int if_idx, struct wolfIP_ud
         return;
     for (i = 0; i < MAX_UDPSOCKETS; i++) {
         struct tsocket *t = &s->udpsockets[i];
-        if (t->src_port == ee16(udp->dst_port) && t->dst_port == ee16(udp->src_port) &&
+        uint32_t expected_len;
+        if (t->src_port == ee16(udp->dst_port) && (t->dst_port == 0 || t->dst_port == ee16(udp->src_port)) &&
                 (((t->local_ip == 0) && DHCP_IS_RUNNING(s)) ||
-                 (t->local_ip == dst_ip && t->remote_ip != local_ip)) ) {
+                 (t->local_ip == dst_ip && (t->remote_ip == 0 || t->remote_ip != local_ip))) ) {
 
             if (t->local_ip == 0)
                 t->if_idx = (uint8_t)if_idx;
 
             /* UDP datagram sanity checks */
-            if ((int)frame_len != ee16(udp->len) + IP_HEADER_LEN + ETH_HEADER_LEN)
+            /* Allow some tolerance for padding/alignment (up to 4 bytes) */
+            expected_len = ee16(udp->len) + IP_HEADER_LEN + ETH_HEADER_LEN;
+            if ((int)frame_len < (int)expected_len)
                 return;
             /* Insert into socket buffer */
             fifo_push(&t->sock.udp.rxbuf, udp, frame_len);