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pico-examples/pico_w/access_point/picow_access_point.c
Peter Harper 566ce86a6e Improve ap example (#233) 
* Add dns server

The access point example is a bit complicated to use as you have to open
a browser and enter a url with the IP address of the device

Add a simple dns server that can be used to make the access point behave
like a captive portal. All DNS requests point back to the gateway IP.

* Improve AP example

The web page /ledtest gives you a web page with an option to turn the
led on and off

Start the DNS server and redirect all HTTP requests to this page.

Improve the code so it can handle more than one request at a time.

Fixes: #232
2023-01-23 08:35:33 -06:00

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/**
* Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <string.h>
#include "pico/cyw43_arch.h"
#include "pico/stdlib.h"
#include "lwip/pbuf.h"
#include "lwip/tcp.h"
#include "dhcpserver.h"
#include "dnsserver.h"
#define TCP_PORT 80
#define DEBUG_printf printf
#define POLL_TIME_S 5
#define HTTP_GET "GET"
#define HTTP_RESPONSE_HEADERS "HTTP/1.1 %d OK\nContent-Length: %d\nContent-Type: text/html; charset=utf-8\nConnection: close\n\n"
#define LED_TEST_BODY "<html><body><h1>Hello from Pico W.</h1><p>Led is %s</p><p><a href=\"?led=%d\">Turn led %s</a></body></html>"
#define LED_PARAM "led=%d"
#define LED_TEST "/ledtest"
#define LED_GPIO 0
#define HTTP_RESPONSE_REDIRECT "HTTP/1.1 302 Redirect\nLocation: http://%s" LED_TEST "\n\n"
typedef struct TCP_SERVER_T_ {
struct tcp_pcb *server_pcb;
bool complete;
ip_addr_t gw;
} TCP_SERVER_T;
typedef struct TCP_CONNECT_STATE_T_ {
struct tcp_pcb *pcb;
int sent_len;
char headers[128];
char result[256];
int header_len;
int result_len;
ip_addr_t *gw;
} TCP_CONNECT_STATE_T;
static err_t tcp_close_client_connection(TCP_CONNECT_STATE_T *con_state, struct tcp_pcb *client_pcb, err_t close_err) {
if (client_pcb) {
assert(con_state && con_state->pcb == client_pcb);
tcp_arg(client_pcb, NULL);
tcp_poll(client_pcb, NULL, 0);
tcp_sent(client_pcb, NULL);
tcp_recv(client_pcb, NULL);
tcp_err(client_pcb, NULL);
err_t err = tcp_close(client_pcb);
if (err != ERR_OK) {
DEBUG_printf("close failed %d, calling abort\n", err);
tcp_abort(client_pcb);
close_err = ERR_ABRT;
}
if (con_state) {
free(con_state);
}
}
return close_err;
}
static void tcp_server_close(TCP_SERVER_T *state) {
if (state->server_pcb) {
tcp_arg(state->server_pcb, NULL);
tcp_close(state->server_pcb);
state->server_pcb = NULL;
}
}
static err_t tcp_server_sent(void *arg, struct tcp_pcb *pcb, u16_t len) {
TCP_CONNECT_STATE_T *con_state = (TCP_CONNECT_STATE_T*)arg;
DEBUG_printf("tcp_server_sent %u\n", len);
con_state->sent_len += len;
if (con_state->sent_len >= con_state->header_len + con_state->result_len) {
DEBUG_printf("all done\n");
return tcp_close_client_connection(con_state, pcb, ERR_OK);
}
return ERR_OK;
}
static int test_server_content(const char *request, const char *params, char *result, size_t max_result_len) {
int len = 0;
if (strncmp(request, LED_TEST, sizeof(LED_TEST) - 1) == 0) {
// Get the state of the led
bool value;
cyw43_gpio_get(&cyw43_state, LED_GPIO, &value);
int led_state = value;
// See if the user changed it
if (params) {
int led_param = sscanf(params, LED_PARAM, &led_state);
if (led_param == 1) {
if (led_state) {
// Turn led on
cyw43_gpio_set(&cyw43_state, 0, true);
} else {
// Turn led off
cyw43_gpio_set(&cyw43_state, 0, false);
}
}
}
// Generate result
if (led_state) {
len = snprintf(result, max_result_len, LED_TEST_BODY, "ON", 0, "OFF");
} else {
len = snprintf(result, max_result_len, LED_TEST_BODY, "OFF", 1, "ON");
}
}
return len;
}
err_t tcp_server_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err) {
TCP_CONNECT_STATE_T *con_state = (TCP_CONNECT_STATE_T*)arg;
if (!p) {
DEBUG_printf("connection closed\n");
return tcp_close_client_connection(con_state, pcb, ERR_OK);
}
assert(con_state && con_state->pcb == pcb);
if (p->tot_len > 0) {
DEBUG_printf("tcp_server_recv %d err %d\n", p->tot_len, err);
#if 0
for (struct pbuf *q = p; q != NULL; q = q->next) {
DEBUG_printf("in: %.*s\n", q->len, q->payload);
}
#endif
// Copy the request into the buffer
pbuf_copy_partial(p, con_state->headers, p->tot_len > sizeof(con_state->headers) - 1 ? sizeof(con_state->headers) - 1 : p->tot_len, 0);
// Handle GET request
if (strncmp(HTTP_GET, con_state->headers, sizeof(HTTP_GET) - 1) == 0) {
char *request = con_state->headers + sizeof(HTTP_GET); // + space
char *params = strchr(request, '?');
if (params) {
if (*params) {
char *space = strchr(request, ' ');
*params++ = 0;
if (space) {
*space = 0;
}
} else {
params = NULL;
}
}
// Generate content
con_state->result_len = test_server_content(request, params, con_state->result, sizeof(con_state->result));
DEBUG_printf("Request: %s?%s\n", request, params);
DEBUG_printf("Result: %d\n", con_state->result_len);
// Check we had enough buffer space
if (con_state->result_len > sizeof(con_state->result) - 1) {
DEBUG_printf("Too much result data %d\n", con_state->result_len);
return tcp_close_client_connection(con_state, pcb, ERR_CLSD);
}
// Generate web page
if (con_state->result_len > 0) {
con_state->header_len = snprintf(con_state->headers, sizeof(con_state->headers), HTTP_RESPONSE_HEADERS,
200, con_state->result_len);
if (con_state->header_len > sizeof(con_state->headers) - 1) {
DEBUG_printf("Too much header data %d\n", con_state->header_len);
return tcp_close_client_connection(con_state, pcb, ERR_CLSD);
}
} else {
// Send redirect
con_state->header_len = snprintf(con_state->headers, sizeof(con_state->headers), HTTP_RESPONSE_REDIRECT,
ipaddr_ntoa(con_state->gw));
DEBUG_printf("Sending redirect %s", con_state->headers);
}
// Send the headers to the client
con_state->sent_len = 0;
err_t err = tcp_write(pcb, con_state->headers, con_state->header_len, 0);
if (err != ERR_OK) {
DEBUG_printf("failed to write header data %d\n", err);
return tcp_close_client_connection(con_state, pcb, err);
}
// Send the body to the client
if (con_state->result_len) {
err = tcp_write(pcb, con_state->result, con_state->result_len, 0);
if (err != ERR_OK) {
DEBUG_printf("failed to write result data %d\n", err);
return tcp_close_client_connection(con_state, pcb, err);
}
}
}
tcp_recved(pcb, p->tot_len);
}
pbuf_free(p);
return ERR_OK;
}
static err_t tcp_server_poll(void *arg, struct tcp_pcb *pcb) {
TCP_CONNECT_STATE_T *con_state = (TCP_CONNECT_STATE_T*)arg;
DEBUG_printf("tcp_server_poll_fn\n");
return tcp_close_client_connection(con_state, pcb, ERR_OK); // Just disconnect clent?
}
static void tcp_server_err(void *arg, err_t err) {
TCP_CONNECT_STATE_T *con_state = (TCP_CONNECT_STATE_T*)arg;
if (err != ERR_ABRT) {
DEBUG_printf("tcp_client_err_fn %d\n", err);
tcp_close_client_connection(con_state, con_state->pcb, err);
}
}
static err_t tcp_server_accept(void *arg, struct tcp_pcb *client_pcb, err_t err) {
TCP_SERVER_T *state = (TCP_SERVER_T*)arg;
if (err != ERR_OK || client_pcb == NULL) {
DEBUG_printf("failure in accept\n");
return ERR_VAL;
}
DEBUG_printf("client connected\n");
// Create the state for the connection
TCP_CONNECT_STATE_T *con_state = calloc(1, sizeof(TCP_CONNECT_STATE_T));
if (!con_state) {
DEBUG_printf("failed to allocate connect state\n");
return ERR_MEM;
}
con_state->pcb = client_pcb; // for checking
con_state->gw = &state->gw;
// setup connection to client
tcp_arg(client_pcb, con_state);
tcp_sent(client_pcb, tcp_server_sent);
tcp_recv(client_pcb, tcp_server_recv);
tcp_poll(client_pcb, tcp_server_poll, POLL_TIME_S * 2);
tcp_err(client_pcb, tcp_server_err);
return ERR_OK;
}
static bool tcp_server_open(void *arg) {
TCP_SERVER_T *state = (TCP_SERVER_T*)arg;
DEBUG_printf("starting server on port %u\n", TCP_PORT);
struct tcp_pcb *pcb = tcp_new_ip_type(IPADDR_TYPE_ANY);
if (!pcb) {
DEBUG_printf("failed to create pcb\n");
return false;
}
err_t err = tcp_bind(pcb, IP_ANY_TYPE, TCP_PORT);
if (err) {
DEBUG_printf("failed to bind to port %d\n");
return false;
}
state->server_pcb = tcp_listen_with_backlog(pcb, 1);
if (!state->server_pcb) {
DEBUG_printf("failed to listen\n");
if (pcb) {
tcp_close(pcb);
}
return false;
}
tcp_arg(state->server_pcb, state);
tcp_accept(state->server_pcb, tcp_server_accept);
return true;
}
int main() {
stdio_init_all();
TCP_SERVER_T *state = calloc(1, sizeof(TCP_SERVER_T));
if (!state) {
DEBUG_printf("failed to allocate state\n");
return 1;
}
if (cyw43_arch_init()) {
DEBUG_printf("failed to initialise\n");
return 1;
}
const char *ap_name = "picow_test";
#if 1
const char *password = "password";
#else
const char *password = NULL;
#endif
cyw43_arch_enable_ap_mode(ap_name, password, CYW43_AUTH_WPA2_AES_PSK);
ip4_addr_t mask;
IP4_ADDR(ip_2_ip4(&state->gw), 192, 168, 4, 1);
IP4_ADDR(ip_2_ip4(&mask), 255, 255, 255, 0);
// Start the dhcp server
dhcp_server_t dhcp_server;
dhcp_server_init(&dhcp_server, &state->gw, &mask);
// Start the dns server
dns_server_t dns_server;
dns_server_init(&dns_server, &state->gw);
if (!tcp_server_open(state)) {
DEBUG_printf("failed to open server\n");
return 1;
}
while(!state->complete) {
// the following #ifdef is only here so this same example can be used in multiple modes;
// you do not need it in your code
#if PICO_CYW43_ARCH_POLL
// if you are using pico_cyw43_arch_poll, then you must poll periodically from your
// main loop (not from a timer) to check for WiFi driver or lwIP work that needs to be done.
cyw43_arch_poll();
sleep_ms(1);
#else
// if you are not using pico_cyw43_arch_poll, then WiFI driver and lwIP work
// is done via interrupt in the background. This sleep is just an example of some (blocking)
// work you might be doing.
sleep_ms(1000);
#endif
}
dns_server_deinit(&dns_server);
dhcp_server_deinit(&dhcp_server);
cyw43_arch_deinit();
return 0;
}
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