/* http_get_bearssl - HTTPS version of the http_get example, using BearSSL.
*
* Retrieves a JSON response from the howsmyssl.com API via HTTPS over TLS v1.2.
*
* Validates the server's certificate using a hardcoded public key.
*
* Adapted from the client_basic sample in BearSSL.
*
* Original Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>, MIT License.
* Additions Copyright (C) 2016 Stefan Schake, MIT License.
*/
#include "espressif/esp_common.h"
#include "esp/uart.h"
#include "esp/hwrand.h"
#include <unistd.h>
#include <string.h>
#include "FreeRTOS.h"
#include "task.h"
#include "lwip/err.h"
#include "lwip/sockets.h"
#include "lwip/sys.h"
#include "lwip/netdb.h"
#include "lwip/dns.h"
#include "lwip/api.h"
#include "ssid_config.h"
#include "bearssl.h"
#define CLOCK_SECONDS_PER_MINUTE (60UL)
#define CLOCK_MINUTES_PER_HOUR (60UL)
#define CLOCK_HOURS_PER_DAY (24UL)
#define CLOCK_SECONDS_PER_HOUR (CLOCK_MINUTES_PER_HOUR*CLOCK_SECONDS_PER_MINUTE)
#define CLOCK_SECONDS_PER_DAY (CLOCK_HOURS_PER_DAY*CLOCK_SECONDS_PER_HOUR)
#define WEB_SERVER "www.howsmyssl.com"
#define WEB_PORT "443"
#define WEB_URL "https://www.howsmyssl.com/a/check"
#define GET_REQUEST "GET "WEB_URL" HTTP/1.1\nHost: "WEB_SERVER"\n\n"
/*
* Low-level data read callback for the simplified SSL I/O API.
*/
static int
sock_read(void *ctx, unsigned char *buf, size_t len)
{
for (;;) {
ssize_t rlen;
rlen = read(*(int *)ctx, buf, len);
if (rlen <= 0) {
if (rlen < 0 && errno == EINTR) {
continue;
}
return -1;
}
return (int)rlen;
}
}
/*
* Low-level data write callback for the simplified SSL I/O API.
*/
static int
sock_write(void *ctx, const unsigned char *buf, size_t len)
{
for (;;) {
ssize_t wlen;
wlen = write(*(int *)ctx, buf, len);
if (wlen <= 0) {
if (wlen < 0 && errno == EINTR) {
continue;
}
return -1;
}
return (int)wlen;
}
}
/*
* The hardcoded trust anchors. These are the two DN + public key that
* correspond to the self-signed certificates cert-root-rsa.pem and
* cert-root-ec.pem.
*
* C code for hardcoded trust anchors can be generated with the "brssl"
* command-line tool (with the "ta" command).
*
* Below is the imported "Let's Encrypt" root certificate, as howsmyssl
* is depending on it:
*
* https://letsencrypt.org/certs/letsencryptauthorityx3.pem
*
*/
static const unsigned char TA0_DN[] = {
0x30, 0x4A, 0x31, 0x0B, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13,
0x02, 0x55, 0x53, 0x31, 0x16, 0x30, 0x14, 0x06, 0x03, 0x55, 0x04, 0x0A,
0x13, 0x0D, 0x4C, 0x65, 0x74, 0x27, 0x73, 0x20, 0x45, 0x6E, 0x63, 0x72,
0x79, 0x70, 0x74, 0x31, 0x23, 0x30, 0x21, 0x06, 0x03, 0x55, 0x04, 0x03,
0x13, 0x1A, 0x4C, 0x65, 0x74, 0x27, 0x73, 0x20, 0x45, 0x6E, 0x63, 0x72,
0x79, 0x70, 0x74, 0x20, 0x41, 0x75, 0x74, 0x68, 0x6F, 0x72, 0x69, 0x74,
0x79, 0x20, 0x58, 0x33
};
static const unsigned char TA0_RSA_N[] = {
0x9C, 0xD3, 0x0C, 0xF0, 0x5A, 0xE5, 0x2E, 0x47, 0xB7, 0x72, 0x5D, 0x37,
0x83, 0xB3, 0x68, 0x63, 0x30, 0xEA, 0xD7, 0x35, 0x26, 0x19, 0x25, 0xE1,
0xBD, 0xBE, 0x35, 0xF1, 0x70, 0x92, 0x2F, 0xB7, 0xB8, 0x4B, 0x41, 0x05,
0xAB, 0xA9, 0x9E, 0x35, 0x08, 0x58, 0xEC, 0xB1, 0x2A, 0xC4, 0x68, 0x87,
0x0B, 0xA3, 0xE3, 0x75, 0xE4, 0xE6, 0xF3, 0xA7, 0x62, 0x71, 0xBA, 0x79,
0x81, 0x60, 0x1F, 0xD7, 0x91, 0x9A, 0x9F, 0xF3, 0xD0, 0x78, 0x67, 0x71,
0xC8, 0x69, 0x0E, 0x95, 0x91, 0xCF, 0xFE, 0xE6, 0x99, 0xE9, 0x60, 0x3C,
0x48, 0xCC, 0x7E, 0xCA, 0x4D, 0x77, 0x12, 0x24, 0x9D, 0x47, 0x1B, 0x5A,
0xEB, 0xB9, 0xEC, 0x1E, 0x37, 0x00, 0x1C, 0x9C, 0xAC, 0x7B, 0xA7, 0x05,
0xEA, 0xCE, 0x4A, 0xEB, 0xBD, 0x41, 0xE5, 0x36, 0x98, 0xB9, 0xCB, 0xFD,
0x6D, 0x3C, 0x96, 0x68, 0xDF, 0x23, 0x2A, 0x42, 0x90, 0x0C, 0x86, 0x74,
0x67, 0xC8, 0x7F, 0xA5, 0x9A, 0xB8, 0x52, 0x61, 0x14, 0x13, 0x3F, 0x65,
0xE9, 0x82, 0x87, 0xCB, 0xDB, 0xFA, 0x0E, 0x56, 0xF6, 0x86, 0x89, 0xF3,
0x85, 0x3F, 0x97, 0x86, 0xAF, 0xB0, 0xDC, 0x1A, 0xEF, 0x6B, 0x0D, 0x95,
0x16, 0x7D, 0xC4, 0x2B, 0xA0, 0x65, 0xB2, 0x99, 0x04, 0x36, 0x75, 0x80,
0x6B, 0xAC, 0x4A, 0xF3, 0x1B, 0x90, 0x49, 0x78, 0x2F, 0xA2, 0x96, 0x4F,
0x2A, 0x20, 0x25, 0x29, 0x04, 0xC6, 0x74, 0xC0, 0xD0, 0x31, 0xCD, 0x8F,
0x31, 0x38, 0x95, 0x16, 0xBA, 0xA8, 0x33, 0xB8, 0x43, 0xF1, 0xB1, 0x1F,
0xC3, 0x30, 0x7F, 0xA2, 0x79, 0x31, 0x13, 0x3D, 0x2D, 0x36, 0xF8, 0xE3,
0xFC, 0xF2, 0x33, 0x6A, 0xB9, 0x39, 0x31, 0xC5, 0xAF, 0xC4, 0x8D, 0x0D,
0x1D, 0x64, 0x16, 0x33, 0xAA, 0xFA, 0x84, 0x29, 0xB6, 0xD4, 0x0B, 0xC0,
0xD8, 0x7D, 0xC3, 0x93
};
static const unsigned char TA0_RSA_E[] = {
0x01, 0x00, 0x01
};
static const br_x509_trust_anchor TAs[1] = {
{
{ (unsigned char *)TA0_DN, sizeof TA0_DN },
BR_X509_TA_CA,
{
BR_KEYTYPE_RSA,
{ .rsa = {
(unsigned char *)TA0_RSA_N, sizeof TA0_RSA_N,
(unsigned char *)TA0_RSA_E, sizeof TA0_RSA_E,
} }
}
}
};
#define TAs_NUM 1
/*
* Buffer to store a record + BearSSL state
* We use MONO mode to save 16k of RAM.
* This could be even smaller by using max_fragment_len, but
* the howsmyssl.com server doesn't seem to support it.
*/
static unsigned char bearssl_buffer[BR_SSL_BUFSIZE_MONO];
static br_ssl_client_context sc;
static br_x509_minimal_context xc;
static br_sslio_context ioc;
void http_get_task(void *pvParameters)
{
int successes = 0, failures = 0;
int provisional_time = 0;
while (1) {
/*
* Wait until we can resolve the DNS for the server, as an indication
* our network is probably working...
*/
const struct addrinfo hints = {
.ai_family = AF_INET,
.ai_socktype = SOCK_STREAM,
};
struct addrinfo *res = NULL;
int dns_err = 0;
do {
if (res)
freeaddrinfo(res);
vTaskDelay(1000 / portTICK_PERIOD_MS);
dns_err = getaddrinfo(WEB_SERVER, WEB_PORT, &hints, &res);
} while(dns_err != 0 || res == NULL);
int fd = socket(res->ai_family, res->ai_socktype, 0);
if (fd < 0) {
freeaddrinfo(res);
printf("socket failed\n");
failures++;
continue;
}
printf("Initializing BearSSL... ");
br_ssl_client_init_full(&sc, &xc, TAs, TAs_NUM);
/*
* Set the I/O buffer to the provided array. We allocated a
* buffer large enough for full-duplex behaviour with all
* allowed sizes of SSL records, hence we set the last argument
* to 1 (which means "split the buffer into separate input and
* output areas").
*/
br_ssl_engine_set_buffer(&sc.eng, bearssl_buffer, sizeof bearssl_buffer, 0);
/*
* Inject some entropy from the ESP hardware RNG
* This is necessary because we don't support any of the BearSSL methods
*/
for (int i = 0; i < 10; i++) {
int rand = hwrand();
br_ssl_engine_inject_entropy(&sc.eng, &rand, 4);
}
/*
* Reset the client context, for a new handshake. We provide the
* target host name: it will be used for the SNI extension. The
* last parameter is 0: we are not trying to resume a session.
*/
br_ssl_client_reset(&sc, WEB_SERVER, 0);
/*
* Initialise the simplified I/O wrapper context, to use our
* SSL client context, and the two callbacks for socket I/O.
*/
br_sslio_init(&ioc, &sc.eng, sock_read, &fd, sock_write, &fd);
printf("done.\r\n");
/* FIXME: set date & time using epoch time precompiler flag for now */
provisional_time = CONFIG_EPOCH_TIME + (xTaskGetTickCount()/configTICK_RATE_HZ);
xc.days = (provisional_time / CLOCK_SECONDS_PER_DAY) + 719528;
xc.seconds = provisional_time % CLOCK_SECONDS_PER_DAY;
printf("Time: %02i:%02i\r\n",
(int)(xc.seconds / CLOCK_SECONDS_PER_HOUR),
(int)((xc.seconds % CLOCK_SECONDS_PER_HOUR)/CLOCK_SECONDS_PER_MINUTE)
);
if (connect(fd, res->ai_addr, res->ai_addrlen) != 0)
{
close(fd);
freeaddrinfo(res);
printf("connect failed\n");
failures++;
continue;
}
printf("Connected\r\n");
/*
* Note that while the context has, at that point, already
* assembled the ClientHello to send, nothing happened on the
* network yet. Real I/O will occur only with the next call.
*
* We write our simple HTTP request. We test the call
* for an error (-1), but this is not strictly necessary, since
* the error state "sticks": if the context fails for any reason
* (e.g. bad server certificate), then it will remain in failed
* state and all subsequent calls will return -1 as well.
*/
if (br_sslio_write_all(&ioc, GET_REQUEST, strlen(GET_REQUEST)) != BR_ERR_OK) {
close(fd);
freeaddrinfo(res);
printf("br_sslio_write_all failed: %d\r\n", br_ssl_engine_last_error(&sc.eng));
failures++;
continue;
}
/*
* SSL is a buffered protocol: we make sure that all our request
* bytes are sent onto the wire.
*/
br_sslio_flush(&ioc);
/*
* Read and print the server response
*/
for (;;)
{
int rlen;
unsigned char buf[128];
bzero(buf, 128);
// Leave the final byte for zero termination
rlen = br_sslio_read(&ioc, buf, sizeof(buf) - 1);
if (rlen < 0) {
break;
}
if (rlen > 0) {
printf("%s", buf);
}
}
/*
* If reading the response failed for any reason, we detect it here
*/
if (br_ssl_engine_last_error(&sc.eng) != BR_ERR_OK) {
close(fd);
freeaddrinfo(res);
printf("failure, error = %d\r\n", br_ssl_engine_last_error(&sc.eng));
failures++;
continue;
}
printf("\r\n\r\nfree heap pre = %u\r\n", xPortGetFreeHeapSize());
/*
* Close the connection and start over after a delay
*/
close(fd);
freeaddrinfo(res);
printf("free heap post = %u\r\n", xPortGetFreeHeapSize());
successes++;
printf("successes = %d failures = %d\r\n", successes, failures);
for(int countdown = 10; countdown >= 0; countdown--) {
printf("%d...\n", countdown);
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
printf("Starting again!\r\n\r\n");
}
}
void user_init(void)
{
uart_set_baud(0, 115200);
printf("SDK version:%s\n", sdk_system_get_sdk_version());
struct sdk_station_config config = {
.ssid = WIFI_SSID,
.password = WIFI_PASS,
};
/* required to call wifi_set_opmode before station_set_config */
sdk_wifi_set_opmode(STATION_MODE);
sdk_wifi_station_set_config(&config);
xTaskCreate(&http_get_task, "get_task", 2048, NULL, 2, NULL);
}