feat(lwip): dhcp server add support for dhcp inform

components/lwip/apps/dhcpserver/dhcpserver.c

@@ -5,6 +5,7 @@
  */
 #include <stdlib.h>
 #include <string.h>
+#include <stdbool.h>
 #include <assert.h>
 #include "lwip/dhcp.h"
 #include "lwip/err.h"
@@ -48,6 +49,7 @@
 #define DHCPACK       5
 #define DHCPNAK       6
 #define DHCPRELEASE   7
+#define DHCPINFORM    8
 
 #define DHCP_OPTION_PAD           0
 #define DHCP_OPTION_SUBNET_MASK   1
@@ -100,6 +102,7 @@
 #define DHCPS_STATE_NAK 4
 #define DHCPS_STATE_IDLE 5
 #define DHCPS_STATE_RELEASE 6
+#define DHCPS_STATE_INFORM_ACK 7
 
 typedef enum {
     DHCPS_HANDLE_CREATED = 0,
@@ -416,7 +419,7 @@ static u8_t *add_msg_type(u8_t *optptr, u8_t type)
  * Parameters   : optptr -- the addr of DHCP message option
  * Returns      : the addr of DHCP message option
 *******************************************************************************/
-static u8_t *add_offer_options(dhcps_t *dhcps, u8_t *optptr)
+static u8_t *add_offer_options(dhcps_t *dhcps, u8_t *optptr, bool include_lease_time)
 {
     ip4_addr_t ipadd;
 
@@ -426,12 +429,14 @@ static u8_t *add_offer_options(dhcps_t *dhcps, u8_t *optptr)
     *optptr++ = 4;
     optptr = dhcps_option_ip(optptr, &dhcps->dhcps_mask);
 
-    *optptr++ = DHCP_OPTION_LEASE_TIME;
+    if (include_lease_time) {
-    *optptr++ = 4;
+        *optptr++ = DHCP_OPTION_LEASE_TIME;
-    *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 24) & 0xFF;
+        *optptr++ = 4;
-    *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 16) & 0xFF;
+        *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 24) & 0xFF;
-    *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 8) & 0xFF;
+        *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 16) & 0xFF;
-    *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 0) & 0xFF;
+        *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 8) & 0xFF;
+        *optptr++ = ((dhcps->dhcps_lease_time * DHCPS_LEASE_UNIT) >> 0) & 0xFF;
+    }
 
     *optptr++ = DHCP_OPTION_SERVER_ID;
     *optptr++ = 4;
@@ -512,6 +517,44 @@ static u8_t *add_end(u8_t *optptr)
     return optptr;
 }
 
+/**
+ * Read DHCP message type (option 53) from the variable-length option area
+ * (starts after the magic cookie at options[4]).
+ */
+static u8_t dhcps_get_option_msg_type(u8_t *optptr, u16_t len)
+{
+    u8_t *end;
+
+    if (len <= 0) {
+        return 0;
+    }
+    end = optptr + len;
+
+    while (optptr < end) {
+        u8_t code = *optptr;
+        if (code == DHCP_OPTION_END) {
+            break;
+        }
+        if (code == 0) {
+            /* Pad */
+            optptr++;
+            continue;
+        }
+        if (optptr + 1 >= end) {
+            break;
+        }
+        u8_t optlen = optptr[1];
+        if ((optptr + 2 + optlen) > end) {
+            break;
+        }
+        if (code == DHCP_OPTION_MSG_TYPE && optlen >= 1) {
+            return optptr[2];
+        }
+        optptr += (u16_t)optlen + 2;
+    }
+    return 0;
+}
+
 /******************************************************************************
  * FunctionName : create_msg
  * Description  : create response message
@@ -569,7 +612,11 @@ static void dhcps_response_ip_set(dhcps_t *dhcps, struct dhcps_msg *m, ip4_addr_
             /* If the 'giaddr' field is zero and the 'ciaddr' is nonzero,
              * the server unicasts DHCPOFFER and DHCPACK message to the address in 'ciaddr'*/
             ip4_addr_set(ip4_out, &ip4_ciaddr);
-            etharp_add_static_entry(&ip4_ciaddr, &chaddr);
+            /* when 'yiaddr' is zero, means DHCPACK INFO, no need to add static entry */
+            if (!ip4_addr_isany_val(ip4_yiaddr)) {
+                /* add the IP<->MAC as static entry into the arp table. */
+                etharp_add_static_entry(&ip4_ciaddr, &chaddr);
+            }
         } else if (!BROADCAST_BIT_IS_SET(htons(m->flags))) {
             /* If the 'giaddr' is zero and 'ciaddr' is zero, and the broadcast bit is not set,
              * the server unicasts DHCPOFFER and DHCPACK message to the client's hardware address and
@@ -620,7 +667,7 @@ static void send_offer(dhcps_t *dhcps, struct dhcps_msg *m, u16_t len)
     create_msg(dhcps, m);
 
     end = add_msg_type(&m->options[4], DHCPOFFER);
-    end = add_offer_options(dhcps, end);
+    end = add_offer_options(dhcps, end, true);
     LWIP_HOOK_DHCPS_POST_APPEND_OPTS(dhcps->dhcps_netif, dhcps, DHCPOFFER, &end)
     end = add_end(end);
 
@@ -803,7 +850,7 @@ static void send_ack(dhcps_t *dhcps, struct dhcps_msg *m, u16_t len)
     create_msg(dhcps, m);
 
     end = add_msg_type(&m->options[4], DHCPACK);
-    end = add_offer_options(dhcps, end);
+    end = add_offer_options(dhcps, end, true);
     LWIP_HOOK_DHCPS_POST_APPEND_OPTS(dhcps->dhcps_netif, dhcps, DHCPACK, &end)
     end = add_end(end);
 
@@ -870,6 +917,50 @@ static void send_ack(dhcps_t *dhcps, struct dhcps_msg *m, u16_t len)
     }
 }
 
+/******************************************************************************
+ * FunctionName : send_ack_inform
+ * Description  : DHCPACK response to DHCPINFORM (RFC 2131: yiaddr = 0, no lease time)
+ * Parameters   : m -- DHCP message info
+ * Returns      : none
+*******************************************************************************/
+static void send_ack_inform(dhcps_t *dhcps, struct dhcps_msg *m, u16_t len)
+{
+    u8_t *end;
+    struct pbuf *p, *q;
+    u8_t *data;
+    u16_t cnt = 0;
+    u16_t i;
+    create_msg(dhcps, m);
+    memset(m->yiaddr, 0, sizeof(m->yiaddr));
+
+    end = add_msg_type(&m->options[4], DHCPACK);
+    end = add_offer_options(dhcps, end, false);
+    LWIP_HOOK_DHCPS_POST_APPEND_OPTS(dhcps->dhcps_netif, dhcps, DHCPACK, &end)
+    end = add_end(end);
+
+    p = dhcps_pbuf_alloc(len);
+    if (p == NULL) {
+        return;
+    }
+
+    q = p;
+    while (q != NULL) {
+        data = (u8_t *)q->payload;
+        for (i = 0; i < q->len; i++) {
+            data[i] = ((u8_t *) m)[cnt++];
+        }
+        q = q->next;
+    }
+
+    ip_addr_t ip_temp = IPADDR4_INIT(0x0);
+    dhcps_response_ip_set(dhcps, m, ip_2_ip4(&ip_temp));
+    udp_sendto(dhcps->dhcps_pcb, p, &ip_temp, DHCPS_CLIENT_PORT);
+
+    if (p->ref != 0) {
+        pbuf_free(p);
+    }
+}
+
 /******************************************************************************
  * FunctionName : parse_options
  * Description  : parse DHCP message options
@@ -1002,6 +1093,23 @@ static s16_t parse_msg(dhcps_t *dhcps, struct dhcps_msg *m, u16_t len)
 #if DHCPS_DEBUG
         DHCPS_LOG("dhcps: len = %d\n", len);
 #endif
+        {
+            u8_t msg_type = dhcps_get_option_msg_type(&m->options[4], (s16_t)len);
+            if (msg_type == DHCPINFORM) {
+                ip4_addr_t ciaddr;
+                memcpy(&ciaddr.addr, m->ciaddr, sizeof(ciaddr.addr));
+                if (ip4_addr_isany(&ciaddr)) {
+                    /* RFC 2131: client MUST set ciaddr to its configured address */
+                    return 0;
+                }
+                if (!ip4_addr_netcmp(&ciaddr, &dhcps->server_address, &dhcps->dhcps_mask)) {
+                    /* No configuration for this client */
+                    return 0;
+                }
+                return DHCPS_STATE_INFORM_ACK;
+            }
+        }
+
         ip4_addr_t addr_tmp;
 
         struct dhcps_pool *pdhcps_pool = NULL;
@@ -1226,6 +1334,13 @@ static void handle_dhcp(void *arg,
             send_nak(dhcps, pmsg_dhcps, malloc_len);
             break;
 
+        case DHCPS_STATE_INFORM_ACK://7
+#if DHCPS_DEBUG
+            DHCPS_LOG("dhcps: handle_dhcp-> DHCPD_STATE_INFORM_ACK\n");
+#endif
+            send_ack_inform(dhcps, pmsg_dhcps, malloc_len);
+            break;
+
         default :
             break;
     }

components/lwip/include/apps/dhcpserver/dhcpserver.h

@@ -61,6 +61,7 @@ typedef enum
  * - MAX_STATION_NUM: Maximum number of clients, set to Kconfig value CONFIG_LWIP_DHCPS_MAX_STATION_NUM
  * - LWIP_HOOK_DHCPS_POST_STATE: Used to inject user code after parsing DHCP message, not defined
  *      - could be enabled in lwipopts.h or via CC_FLAGS
+ *      - parse states include DHCPS_STATE_OFFER (1), ACK (3), NAK (4), INFORM_ACK (7), etc.
  *      - basic usage of the hook to print hex representation of the entire option field is below:
  *          #define LWIP_HOOK_DHCPS_POST_STATE(msg, len, state) \
  *          ({ s16_t ret = state; if (state == DHCPS_STATE_ACK) { ESP_LOG_BUFFER_HEXDUMP("DHCPS",msg->options, 312, ESP_LOG_INFO);} ret; })