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feat(lwip/dhcps): Add support for reporting clients hostname

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This commit is contained in:
David Cermak
2025-09-22 14:29:49 +02:00
parent b789198c9b
commit 75e0d62739
6 changed files with 173 additions and 7 deletions
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22
components/esp_netif/include/esp_netif_types.h
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@@ -152,11 +152,31 @@ typedef struct {
bool preferred; /*!< The default preference of the address */
} ip_event_add_ip6_t;
/** Event structure for IP_EVENT_ASSIGNED_IP_TO_CLIENT event */
/** Event structure for IP_EVENT_ASSIGNED_IP_TO_CLIENT event
*
* This event is posted when a local DHCP server (e.g., SoftAP) assigns an IPv4
* address to a client. The structure carries the assigned IPv4 address and the
* client's MAC address. If DHCP server support is disabled via Kconfig
* (CONFIG_LWIP_DHCPS=n), the \c ip field is not populated.
*
* If enabled by Kconfig (CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME=y), the
* optional DHCP client hostname (option 12) is also included in the \c hostname
* field. The hostname is a null-terminated UTF-8 string and may be empty if the
* client did not provide one. Its maximum length (including the terminator) is
* bounded by CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN; longer hostnames are truncated.
* The value is sanitized to contain only letters, digits, dot, dash, and
* underscore. Applications should treat this field as untrusted input.
*/
typedef struct {
esp_netif_t *esp_netif; /*!< Pointer to the associated netif handle */
esp_ip4_addr_t ip; /*!< IP address which was assigned to the station */
uint8_t mac[6]; /*!< MAC address of the connected client */
/* Client hostname as provided via DHCP option 12 (if available). */
#ifndef CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN
#define CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN 64
#endif
#define ESP_NETIF_HOSTNAME_MAX_LEN CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN
char hostname[ESP_NETIF_HOSTNAME_MAX_LEN]; /*!< Optional DHCP client hostname (may be empty string) */
} ip_event_assigned_ip_to_client_t;
/** Compatibility event structure for ip_event_ap_staipassigned_t event

12
components/esp_netif/lwip/esp_netif_lwip.c
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@@ -1129,6 +1129,18 @@ static void esp_netif_dhcps_cb(void* arg, uint8_t ip[4], uint8_t mac[6])
ESP_LOGI(TAG, "DHCP server assigned IP to a client, IP is: " IPSTR, IP2STR(&evt.ip));
ESP_LOGD(TAG, "Client's MAC: %x:%x:%x:%x:%x:%x", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
/* Try to fetch hostname for this MAC if available */
if (esp_netif && esp_netif->dhcps) {
/* Ensure zero-terminated even if not found */
if (!dhcps_get_hostname_on_mac(esp_netif->dhcps, mac, evt.hostname, sizeof(evt.hostname))) {
if (sizeof(evt.hostname) > 0) {
evt.hostname[0] = '\0';
}
}
}
#endif
int ret = esp_event_post(IP_EVENT, IP_EVENT_ASSIGNED_IP_TO_CLIENT, &evt, sizeof(evt), 0);
if (ESP_OK != ret) {
ESP_LOGE(TAG, "dhcps cb: failed to post IP_EVENT_ASSIGNED_IP_TO_CLIENT (%x)", ret);

19
components/lwip/Kconfig
View File

@@ -405,6 +405,15 @@ menu "LWIP"
Enabling this option allows the device to run the DHCP server
(to dynamically assign IPv4 addresses to clients).
config LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
bool "DHCPS: Report client hostname in assigned-IP event"
default y
depends on LWIP_DHCPS
help
When enabled, the DHCP server parses client hostname (DHCP option 12)
and makes it available via IP_EVENT_ASSIGNED_IP_TO_CLIENT. This adds
a small amount of RAM usage per lease to store the hostname.
config LWIP_DHCPS_LEASE_UNIT
int "Multiplier for lease time, in seconds"
range 1 3600
@@ -425,6 +434,16 @@ menu "LWIP"
After this number is exceeded, DHCP server removes of the oldest device
from it's address pool, without notification.
config LWIP_DHCPS_MAX_HOSTNAME_LEN
int "Maximum client hostname length stored by DHCPS"
range 1 255
default 64
depends on LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
help
Maximum number of bytes stored per-client for DHCP option 12 (hostname),
including the terminating null when used in esp-netif events. Longer hostnames
will be truncated.
config LWIP_DHCPS_STATIC_ENTRIES
bool "Enable ARP static entries"
default y

86
components/lwip/apps/dhcpserver/dhcpserver.c
View File

@@ -50,6 +50,7 @@
#define DHCPRELEASE 7
#define DHCP_OPTION_SUBNET_MASK 1
#define DHCP_OPTION_HOST_NAME 12
#define DHCP_OPTION_ROUTER 3
#define DHCP_OPTION_DNS_SERVER 6
#define DHCP_OPTION_REQ_IPADDR 50
@@ -142,6 +143,11 @@ struct dhcps_t {
struct udp_pcb *dhcps_pcb;
dhcps_handle_state state;
bool has_declined_ip;
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
/* Temporary storage for option 12 parsed from the current packet */
char opt_hostname[CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN];
bool opt_hostname_present;
#endif
};
@@ -923,6 +929,33 @@ static u8_t parse_options(dhcps_t *dhcps, u8_t *optptr, s16_t len)
type = *(optptr + 2);
break;
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
case DHCP_OPTION_HOST_NAME: {
/* option format: code(1) len(1) value(len) */
u8_t olen = *(optptr + 1);
const u8_t *oval = optptr + 2;
if (olen > 0) {
/* clamp to configured max, keep room for NUL */
size_t copy_len = olen;
if (copy_len >= CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN) {
copy_len = CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN - 1;
}
size_t j = 0;
for (; j < copy_len; ++j) {
char c = (char)oval[j];
if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '.' || c == '-' || c == '_') {
dhcps->opt_hostname[j] = c;
} else {
dhcps->opt_hostname[j] = '-';
}
}
dhcps->opt_hostname[j] = '\0';
dhcps->opt_hostname_present = true;
}
break;
}
#endif
case DHCP_OPTION_REQ_IPADDR://50
if (memcmp((char *) &client.addr, (char *) optptr + 2, 4) == 0) {
#if DHCPS_DEBUG
@@ -1111,7 +1144,7 @@ POOL_CHECK:
return 4;
}
s16_t ret = parse_options(dhcps, &m->options[4], len);;
s16_t ret = parse_options(dhcps, &m->options[4], len);
if (ret == DHCPS_STATE_RELEASE || ret == DHCPS_STATE_NAK || ret == DHCPS_STATE_DECLINE) {
if (pnode != NULL) {
@@ -1131,6 +1164,21 @@ POOL_CHECK:
memset(&dhcps->client_address, 0x0, sizeof(dhcps->client_address));
}
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
/* If we parsed a hostname from options and we have a lease entry, store it */
if (pdhcps_pool != NULL) {
if (dhcps->opt_hostname_present) {
size_t n = strnlen(dhcps->opt_hostname, CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN);
if (n > 0) {
memset(pdhcps_pool->hostname, 0, sizeof(pdhcps_pool->hostname));
memcpy(pdhcps_pool->hostname, dhcps->opt_hostname, n);
} else {
pdhcps_pool->hostname[0] = '\0';
}
}
}
#endif
#if DHCPS_DEBUG
DHCPS_LOG("dhcps: xid changed\n");
DHCPS_LOG("dhcps: client_address.addr = %x\n", dhcps->client_address.addr);
@@ -1619,4 +1667,40 @@ err_t dhcps_dns_getserver(dhcps_t *dhcps, ip4_addr_t *dnsserver)
return dhcps_dns_getserver_by_type(dhcps, dnsserver, DNS_TYPE_MAIN);
}
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
bool dhcps_get_hostname_on_mac(dhcps_t *dhcps, const u8_t *mac, char *out, size_t out_len)
{
if ((dhcps == NULL) || (mac == NULL) || (out == NULL) || (out_len == 0)) {
return false;
}
list_node *pnode = dhcps->plist;
while (pnode) {
struct dhcps_pool *pool = pnode->pnode;
if (memcmp(pool->mac, mac, sizeof(pool->mac)) == 0) {
size_t maxcpy = (out_len > 0) ? out_len - 1 : 0;
size_t srclen = 0;
/* hostname may be empty string */
srclen = strnlen(pool->hostname, CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN);
if (maxcpy > 0) {
if (srclen > maxcpy) srclen = maxcpy;
if (srclen) memcpy(out, pool->hostname, srclen);
out[srclen] = '\0';
}
return true;
}
pnode = pnode->pnext;
}
return false;
}
#else
bool dhcps_get_hostname_on_mac(dhcps_t *dhcps, const u8_t *mac, char *out, size_t out_len)
{
LWIP_UNUSED_ARG(dhcps);
LWIP_UNUSED_ARG(mac);
if (out && out_len) {
out[0] = '\0';
}
return false;
}
#endif
#endif // ESP_DHCPS

19
components/lwip/include/apps/dhcpserver/dhcpserver.h
View File

@@ -1,5 +1,5 @@
/*
* SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
* SPDX-FileCopyrightText: 2015-2025 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
@@ -8,6 +8,7 @@
#include "sdkconfig.h"
#include <stdbool.h>
#include <stddef.h>
#include "lwip/ip_addr.h"
#include "lwip/err.h"
@@ -78,6 +79,12 @@ struct dhcps_pool{
ip4_addr_t ip;
u8_t mac[6];
u32_t lease_timer;
/* Optional: client's hostname from DHCP option 12, if provided */
#if CONFIG_LWIP_DHCPS
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
char hostname[CONFIG_LWIP_DHCPS_MAX_HOSTNAME_LEN];
#endif
#endif
};
typedef u32_t dhcps_time_t;
@@ -167,6 +174,16 @@ err_t dhcps_set_option_info(dhcps_t *dhcps, u8_t op_id, void *opt_info, u32_t op
*/
bool dhcp_search_ip_on_mac(dhcps_t *dhcps, u8_t *mac, ip4_addr_t *ip);
/**
* @brief Tries to find client hostname corresponding to the supplied MAC
* @param dhcps Pointer to the DHCP handle
* @param mac Supplied MAC address
* @param out Output buffer to receive the hostname (null-terminated)
* @param out_len Size of the output buffer
* @return True if the hostname has been found and copied (may be empty string if not provided by client)
*/
bool dhcps_get_hostname_on_mac(dhcps_t *dhcps, const u8_t *mac, char *out, size_t out_len);
/**
* @brief Sets the DNS server address for the DHCP server
* @param dhcps Pointer to the DHCP handle

16
examples/wifi/softap_sta/main/softap_sta.c
View File

@@ -1,5 +1,5 @@
/*
* SPDX-FileCopyrightText: 2023-2024 Espressif Systems (Shanghai) CO LTD
* SPDX-FileCopyrightText: 2023-2025 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Unlicense OR CC0-1.0
*/
@@ -103,6 +103,15 @@ static void wifi_event_handler(void *arg, esp_event_base_t event_base,
ESP_LOGI(TAG_STA, "Got IP:" IPSTR, IP2STR(&event->ip_info.ip));
s_retry_num = 0;
xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
} else if (event_base == IP_EVENT && event_id == IP_EVENT_ASSIGNED_IP_TO_CLIENT) {
const ip_event_assigned_ip_to_client_t *e = (const ip_event_assigned_ip_to_client_t *)event_data;
#if CONFIG_LWIP_DHCPS_REPORT_CLIENT_HOSTNAME
ESP_LOGI(TAG_AP, "Assigned IP to client: " IPSTR ", MAC=" MACSTR ", hostname='%s'",
IP2STR(&e->ip), MAC2STR(e->mac), e->hostname);
#else
ESP_LOGI(TAG_AP, "Assigned IP to client: " IPSTR ", MAC=" MACSTR,
IP2STR(&e->ip), MAC2STR(e->mac));
#endif
}
}
@@ -203,6 +212,11 @@ void app_main(void)
&wifi_event_handler,
NULL,
NULL));
ESP_ERROR_CHECK(esp_event_handler_instance_register(IP_EVENT,
IP_EVENT_ASSIGNED_IP_TO_CLIENT,
&wifi_event_handler,
NULL,
NULL));
/*Initialize WiFi */
wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();