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esp-idf/examples/network/sta2eth/main/ethernet_iface.c

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15 KiB
C
Czysty Wina Historia

/*
* SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Unlicense OR CC0-1.0
*/
#include <string.h>
#include "cc.h"
#include "esp_log.h"
#include "esp_netif.h"
#include "esp_event.h"
#include "wired_iface.h"
#include "dhcpserver/dhcpserver_options.h"
#include "esp_mac.h"
#include "ethernet_init.h"
#include "esp_eth_netif_glue.h"
/**
* Disable promiscuous mode on Ethernet interface by setting this macro to 0
* if disabled, we'd have to rewrite MAC addressed in frames with the actual Eth interface MAC address
* - this results in better throughput
* - might cause ARP conflicts if the PC is also connected to the same AP with another NIC
*/
#define ETH_BRIDGE_PROMISCUOUS 0
/**
* Set this to 1 to runtime update HW addresses in DHCP messages
* (this is needed if the client uses 61 option and the DHCP server applies strict rules on assigning addresses)
*/
#define MODIFY_DHCP_MSGS 0
static const char *TAG = "example_wired_ethernet";
static esp_eth_handle_t s_eth_handle = NULL;
static bool s_ethernet_is_connected = false;
static uint8_t s_eth_mac[6];
static wired_rx_cb_t s_rx_cb = NULL;
static wired_free_cb_t s_free_cb = NULL;
/**
* @brief Event handler for Ethernet events
*/
void eth_event_handler(void *arg, esp_event_base_t event_base,
int32_t event_id, void *event_data)
{
uint8_t mac_addr[6] = {0};
/* we can get the ethernet driver handle from event data */
esp_eth_handle_t eth_handle = *(esp_eth_handle_t *)event_data;
esp_netif_t *netif = (esp_netif_t*)arg;
switch (event_id) {
case ETHERNET_EVENT_CONNECTED:
ESP_LOGI(TAG, "Ethernet Link Up");
esp_netif_dhcps_start(netif);
esp_eth_ioctl(eth_handle, ETH_CMD_G_MAC_ADDR, mac_addr);
ESP_LOGI(TAG, "Ethernet HW Addr %02x:%02x:%02x:%02x:%02x:%02x",
mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
s_ethernet_is_connected = true;
break;
case ETHERNET_EVENT_DISCONNECTED:
ESP_LOGI(TAG, "Ethernet Link Down");
esp_netif_dhcps_stop(netif);
s_ethernet_is_connected = false;
break;
case ETHERNET_EVENT_START:
ESP_LOGI(TAG, "Ethernet Started");
break;
case ETHERNET_EVENT_STOP:
ESP_LOGI(TAG, "Ethernet Stopped");
break;
default:
ESP_LOGI(TAG, "Default Event");
break;
}
}
/**
* In this scenario of WiFi station to Ethernet bridge mode, we have this configuration
*
* (ISP) router ESP32 PC
* [ AP ] <-> [ sta -- eth ] <-> [ eth-NIC ]
*
* From the PC's NIC perspective the L2 forwarding should be transparent and resemble this configuration:
*
* (ISP) router PC
* [ AP ] <----------> [ virtual wifi-NIC ]
*
* In order for the ESP32 to act as L2 bridge it needs to accept all frames on the interface
* - For Ethernet we just enable `PROMISCUOUS` mode
* - For Wifi we could also enable the promiscuous mode, but in that case we'd receive encoded frames
* from 802.11 and we'd have to decode it and process (using wpa-supplicant).
* The easier option (in this scenario of only one client -- eth-NIC) we could simply "pretend"
* that we have the HW mac address of eth-NIC and receive only ethernet frames for "us" from esp_wifi API
* (we could use the same technique for Ethernet and yield better throughput, see ETH_BRIDGE_PROMISCUOUS flag)
*
* This API updates Ethernet frames to swap mac addresses of ESP32 interfaces with those of eth-NIC and AP.
* For that we'd have to parse initial DHCP packets (manually) to record the HW addresses of the AP and eth-NIC
* (note, that it is possible to simply spoof the MAC addresses, but that's not recommended technique)
*/
#define IP_V4 0x40
#define IP_PROTO_UDP 0x11
#define DHCP_PORT_IN 0x43
#define DHCP_PORT_OUT 0x44
#define DHCP_MACIG_COOKIE_OFFSET (8 + 236)
#define DHCP_HW_ADDRESS_OFFSET (36)
#define MIN_DHCP_PACKET_SIZE (285)
#define IP_HEADER_SIZE (20)
#define DHCP_DISCOVER 1
#define DHCP_OFFER 2
#define DHCP_COOKIE_WITH_PKT_TYPE(type) {0x63, 0x82, 0x53, 0x63, 0x35, 1, type};
#if MODIFY_DHCP_MSGS
static void update_udp_checksum(uint16_t *udp_header, uint16_t* ip_header)
{
uint32_t sum = 0;
uint16_t *ptr = udp_header;
ptr[3] = 0; // clear the current checksum
int payload_len = htons(ip_header[1]) - IP_HEADER_SIZE;
// add UDP payload
for (int i = 0; i < payload_len/2; i++) {
sum += htons(*ptr++);
}
// add the padding if the packet length is odd
if (payload_len & 1) {
sum += (*((uint8_t *)ptr) << 8);
}
// add some IP header data
ptr = ip_header + 6;
for (int i = 0; i < 4; i++) { // IP addresses
sum += htons(*ptr++);
}
sum += IP_PROTO_UDP + payload_len; // protocol + size
do {
sum = (sum & 0xFFFF) + (sum >> 16);
} while (sum & 0xFFFF0000); // process the carry
ptr = udp_header;
ptr[3] = htons(~sum); // update the UDP header with the new checksum
}
#endif // MODIFY_DHCP_MSGS
void mac_spoof(mac_spoof_direction_t direction, uint8_t *buffer, uint16_t len, uint8_t own_mac[6])
{
if (!s_ethernet_is_connected) {
return;
}
static uint8_t eth_nic_mac[6] = {};
static bool eth_nic_mac_found = false;
#if !ETH_BRIDGE_PROMISCUOUS
static uint8_t ap_mac[6] = {};
static bool ap_mac_found = false;
#endif
uint8_t *dest_mac = buffer;
uint8_t *src_mac = buffer + 6;
uint8_t *eth_type = buffer + 12;
if (eth_type[0] == 0x08) { // support only IPv4
// try to find NIC HW address (look for DHCP discovery packet)
if ( (!eth_nic_mac_found || (MODIFY_DHCP_MSGS)) && direction == FROM_WIRED && eth_type[1] == 0x00) { // ETH IP4
uint8_t *ip_header = eth_type + 2;
if (len > MIN_DHCP_PACKET_SIZE && (ip_header[0] & 0xF0) == IP_V4 && ip_header[9] == IP_PROTO_UDP) {
uint8_t *udp_header = ip_header + IP_HEADER_SIZE;
const uint8_t dhcp_ports[] = {0, DHCP_PORT_OUT, 0, DHCP_PORT_IN};
if (memcmp(udp_header, dhcp_ports, sizeof(dhcp_ports)) == 0) {
uint8_t *dhcp_magic = udp_header + DHCP_MACIG_COOKIE_OFFSET;
const uint8_t dhcp_type[] = DHCP_COOKIE_WITH_PKT_TYPE(DHCP_DISCOVER);
if (!eth_nic_mac_found && memcmp(dhcp_magic, dhcp_type, sizeof(dhcp_type)) == 0) {
eth_nic_mac_found = true;
memcpy(eth_nic_mac, src_mac, 6);
}
#if MODIFY_DHCP_MSGS
if (eth_nic_mac_found) {
bool update_checksum = false;
// Replace the BOOTP HW address
uint8_t *dhcp_client_hw_addr = udp_header + DHCP_HW_ADDRESS_OFFSET;
if (memcmp(dhcp_client_hw_addr, eth_nic_mac, 6) == 0) {
memcpy(dhcp_client_hw_addr, own_mac, 6);
update_checksum = true;
}
// Replace the HW address in opt-61
uint8_t *dhcp_opts = dhcp_magic + 4;
while (*dhcp_opts != 0xFF) {
if (dhcp_opts[0] == 61 && dhcp_opts[1] == 7 /* size (type=1 + mac=6) */ && dhcp_opts[2] == 1 /* HW address type*/ &&
memcmp(dhcp_opts + 3, eth_nic_mac, 6) == 0) {
update_checksum = true;
memcpy(dhcp_opts + 3, own_mac, 6);
break;
}
dhcp_opts += dhcp_opts[1]+ 2;
if (dhcp_opts - buffer >= len) {
break;
}
}
if (update_checksum) {
update_udp_checksum((uint16_t *) udp_header, (uint16_t *) ip_header);
}
}
#endif // MODIFY_DHCP_MSGS
} // DHCP
} // UDP/IP
#if !ETH_BRIDGE_PROMISCUOUS || MODIFY_DHCP_MSGS
// try to find AP HW address (look for DHCP offer packet)
} else if ( (!ap_mac_found || (MODIFY_DHCP_MSGS)) && direction == TO_WIRED && eth_type[1] == 0x00) { // ETH IP4
uint8_t *ip_header = eth_type + 2;
if (len > MIN_DHCP_PACKET_SIZE && (ip_header[0] & 0xF0) == IP_V4 && ip_header[9] == IP_PROTO_UDP) {
uint8_t *udp_header = ip_header + IP_HEADER_SIZE;
const uint8_t dhcp_ports[] = {0, DHCP_PORT_IN, 0, DHCP_PORT_OUT};
if (memcmp(udp_header, dhcp_ports, sizeof(dhcp_ports)) == 0) {
uint8_t *dhcp_magic = udp_header + DHCP_MACIG_COOKIE_OFFSET;
#if MODIFY_DHCP_MSGS
if (eth_nic_mac_found) {
uint8_t *dhcp_client_hw_addr = udp_header + DHCP_HW_ADDRESS_OFFSET;
// Replace BOOTP HW address
if (memcmp(dhcp_client_hw_addr, own_mac, 6) == 0) {
memcpy(dhcp_client_hw_addr, eth_nic_mac, 6);
update_udp_checksum((uint16_t*)udp_header, (uint16_t*)ip_header);
}
}
#endif // MODIFY_DHCP_MSGS
const uint8_t dhcp_type[] = DHCP_COOKIE_WITH_PKT_TYPE(DHCP_OFFER);
if (!ap_mac_found && memcmp(dhcp_magic, dhcp_type, sizeof(dhcp_type)) == 0) {
ap_mac_found = true;
memcpy(ap_mac, src_mac, 6);
}
} // DHCP
} // UDP/IP
#endif // !ETH_BRIDGE_PROMISCUOUS || MODIFY_DHCP_MSGS
}
// swap addresses in ARP probes
if (eth_type[1] == 0x06) { // ARP
uint8_t *arp = eth_type + 2 + 8; // points to sender's HW address
if (eth_nic_mac_found && direction == FROM_WIRED && memcmp(arp, eth_nic_mac, 6) == 0) {
/* updates senders HW address to our wireless */
memcpy(arp, own_mac, 6);
#if !ETH_BRIDGE_PROMISCUOUS
} else if (ap_mac_found && direction == TO_WIRED && memcmp(arp, ap_mac, 6) == 0) {
/* updates senders HW address to our wired */
memcpy(arp, s_eth_mac, 6);
#endif // !ETH_BRIDGE_PROMISCUOUS
}
}
// swap HW addresses in ETH frames
#if !ETH_BRIDGE_PROMISCUOUS
if (ap_mac_found && direction == FROM_WIRED && memcmp(dest_mac, s_eth_mac, 6) == 0) {
memcpy(dest_mac, ap_mac, 6);
}
if (ap_mac_found && direction == TO_WIRED && memcmp(src_mac, ap_mac, 6) == 0) {
memcpy(src_mac, s_eth_mac, 6);
}
#endif // !ETH_BRIDGE_PROMISCUOUS
if (eth_nic_mac_found && direction == FROM_WIRED && memcmp(src_mac, eth_nic_mac, 6) == 0) {
memcpy(src_mac, own_mac, 6);
}
if (eth_nic_mac_found && direction == TO_WIRED && memcmp(dest_mac, own_mac, 6) == 0) {
memcpy(dest_mac, eth_nic_mac, 6);
}
} // IP4 section of eth-type (0x08) both ETH-IP4 and ETHARP
}
static esp_err_t wired_recv(esp_eth_handle_t eth_handle, uint8_t *buffer, uint32_t len, void *priv)
{
esp_err_t ret = s_rx_cb(buffer, len, buffer);
free(buffer);
return ret;
}
esp_err_t wired_bridge_init(wired_rx_cb_t rx_cb, wired_free_cb_t free_cb)
{
uint8_t eth_port_cnt = 0;
esp_eth_handle_t *eth_handles;
ESP_ERROR_CHECK(example_eth_init(&eth_handles, &eth_port_cnt));
// Check for multiple Ethernet interfaces
if (1 < eth_port_cnt) {
ESP_LOGW(TAG, "Multiple Ethernet Interface detected: Only the first initialized interface is going to be used.");
}
s_eth_handle = eth_handles[0];
free(eth_handles);
ESP_ERROR_CHECK(esp_eth_update_input_path(s_eth_handle, wired_recv, NULL));
#if ETH_BRIDGE_PROMISCUOUS
bool eth_promiscuous = true;
ESP_ERROR_CHECK(esp_eth_ioctl(s_eth_handle, ETH_CMD_S_PROMISCUOUS, &eth_promiscuous));
#endif
ESP_ERROR_CHECK(esp_eth_ioctl(s_eth_handle, ETH_CMD_G_MAC_ADDR, &s_eth_mac));
ESP_ERROR_CHECK(esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID, eth_event_handler, NULL));
ESP_ERROR_CHECK(esp_eth_start(s_eth_handle));
s_rx_cb = rx_cb;
s_free_cb = free_cb;
return ESP_OK;
}
esp_err_t wired_send(void *buffer, uint16_t len, void *buff_free_arg)
{
if (s_ethernet_is_connected) {
if (esp_eth_transmit(s_eth_handle, buffer, len) != ESP_OK) {
ESP_LOGE(TAG, "Ethernet send packet failed");
return ESP_FAIL;
}
if (s_free_cb) {
s_free_cb(buff_free_arg, NULL);
}
return ESP_OK;
}
return ESP_ERR_INVALID_STATE;
}
/**
* In this scenario of configuring WiFi, we setup Ethernet to create a network and run DHCP server,
* so it could assign an IP address to the PC
*
* ESP32 PC
* | <DHCP server> eth | <-> [ eth-NIC ]
* | <HTTP server> |
* | (wifi-provisioning) |
*
* From the PC's NIC perspective the board acts as a separate network with it's own IP and MAC address
* (this network's MAC address is the native ESP32's Ethernet interface MAC)
*/
esp_err_t wired_netif_init(void)
{
uint8_t eth_port_cnt = 0;
esp_eth_handle_t *eth_handles;
ESP_ERROR_CHECK(example_eth_init(&eth_handles, &eth_port_cnt));
// Check or multiple ethernet interface
if (1 < eth_port_cnt) {
ESP_LOGW(TAG, "Multiple Ethernet Interface detected: Only the first initialized interface is going to be used.");
}
s_eth_handle = eth_handles[0];
free(eth_handles);
// 1) Derive the base config (very similar to IDF's default WiFi AP with DHCP server)
esp_netif_inherent_config_t base_cfg = {
.flags = ESP_NETIF_DHCP_SERVER, // Run DHCP server
.ip_info = &_g_esp_netif_soft_ap_ip, // Use the same IP ranges as IDF's soft AP
.if_key = "wired", // Set mame, key, priority
.if_desc = "ethernet config device",
.route_prio = 10
};
// Config the esp-netif with:
// 1) inherent config (behavioural settings of an interface)
// 2) driver's config -- no need, will use the default ethernet-netif glue and attach it to this netif
// 3) stack config -- will use the default ethernet TCP/IP settings
esp_netif_config_t cfg = {
.base = &base_cfg,
.stack = ESP_NETIF_NETSTACK_DEFAULT_ETH
};
esp_netif_t *netif = esp_netif_new(&cfg);
if (netif == NULL) {
return ESP_FAIL;
}
// Now we attach the constructed network interface to IDF's default ethernet glue
esp_eth_netif_glue_handle_t eth_glue = esp_eth_new_netif_glue(s_eth_handle);
ESP_ERROR_CHECK(esp_netif_attach(netif, eth_glue));
uint8_t mac[6];
ESP_ERROR_CHECK(esp_eth_ioctl(s_eth_handle, ETH_CMD_G_MAC_ADDR, &mac));
esp_netif_set_mac(netif, mac);
// set the minimum lease time
uint32_t lease_opt = 1;
esp_netif_dhcps_option(netif, ESP_NETIF_OP_SET, IP_ADDRESS_LEASE_TIME, &lease_opt, sizeof(lease_opt));
ESP_ERROR_CHECK(esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID, eth_event_handler, netif));
ESP_ERROR_CHECK(esp_eth_start(s_eth_handle));
return ESP_OK;
}
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