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OVMS3-idf/components/esp-tls/esp_tls.c

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// Copyright 2017-2018 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <http_parser.h>
#include "esp_tls.h"
#include <errno.h>
static const char *TAG = "esp-tls";
static mbedtls_x509_crt *global_cacert = NULL;
#ifdef ESP_PLATFORM
#include <esp_log.h>
#else
#define ESP_LOGD(TAG, ...) //printf(__VA_ARGS__);
#define ESP_LOGE(TAG, ...) printf(__VA_ARGS__);
#endif
static struct addrinfo *resolve_host_name(const char *host, size_t hostlen)
{
struct addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
char *use_host = strndup(host, hostlen);
if (!use_host) {
return NULL;
}
ESP_LOGD(TAG, "host:%s: strlen %lu", use_host, (unsigned long)hostlen);
struct addrinfo *res;
if (getaddrinfo(use_host, NULL, &hints, &res)) {
ESP_LOGE(TAG, "couldn't get hostname for :%s:", use_host);
free(use_host);
return NULL;
}
free(use_host);
return res;
}
static ssize_t tcp_read(esp_tls_t *tls, char *data, size_t datalen)
{
return recv(tls->sockfd, data, datalen, 0);
}
static ssize_t tls_read(esp_tls_t *tls, char *data, size_t datalen)
{
ssize_t ret = mbedtls_ssl_read(&tls->ssl, (unsigned char *)data, datalen);
if (ret < 0) {
if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
return 0;
}
if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
ESP_LOGE(TAG, "read error :%d:", ret);
}
}
return ret;
}
static void ms_to_timeval(int timeout_ms, struct timeval *tv)
{
tv->tv_sec = timeout_ms / 1000;
tv->tv_usec = (timeout_ms % 1000) * 1000;
}
static int esp_tcp_connect(const char *host, int hostlen, int port, int *sockfd, const esp_tls_cfg_t *cfg)
{
int ret = -1;
struct addrinfo *res = resolve_host_name(host, hostlen);
if (!res) {
return ret;
}
int fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (fd < 0) {
ESP_LOGE(TAG, "Failed to create socket (family %d socktype %d protocol %d)", res->ai_family, res->ai_socktype, res->ai_protocol);
goto err_freeaddr;
}
*sockfd = fd;
void *addr_ptr;
if (res->ai_family == AF_INET) {
struct sockaddr_in *p = (struct sockaddr_in *)res->ai_addr;
p->sin_port = htons(port);
addr_ptr = p;
} else if (res->ai_family == AF_INET6) {
struct sockaddr_in6 *p = (struct sockaddr_in6 *)res->ai_addr;
p->sin6_port = htons(port);
p->sin6_family = AF_INET6;
addr_ptr = p;
} else {
ESP_LOGE(TAG, "Unsupported protocol family %d", res->ai_family);
goto err_freesocket;
}
if (cfg) {
if (cfg->timeout_ms >= 0) {
struct timeval tv;
ms_to_timeval(cfg->timeout_ms, &tv);
setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
}
if (cfg->non_block) {
int flags = fcntl(fd, F_GETFL, 0);
fcntl(fd, F_SETFL, flags | O_NONBLOCK);
}
}
ret = connect(fd, addr_ptr, res->ai_addrlen);
if (ret < 0 && !(errno == EINPROGRESS && cfg->non_block)) {
ESP_LOGE(TAG, "Failed to connnect to host (errno %d)", errno);
goto err_freesocket;
}
freeaddrinfo(res);
return 0;
err_freesocket:
close(fd);
err_freeaddr:
freeaddrinfo(res);
return ret;
}
esp_err_t esp_tls_init_global_ca_store()
{
if (global_cacert == NULL) {
global_cacert = (mbedtls_x509_crt *)calloc(1, sizeof(mbedtls_x509_crt));
if (global_cacert == NULL) {
ESP_LOGE(TAG, "global_cacert not allocated");
return ESP_ERR_NO_MEM;
}
mbedtls_x509_crt_init(global_cacert);
}
return ESP_OK;
}
esp_err_t esp_tls_set_global_ca_store(const unsigned char *cacert_pem_buf, const unsigned int cacert_pem_bytes)
{
int ret;
if (cacert_pem_buf == NULL) {
ESP_LOGE(TAG, "cacert_pem_buf is null");
return ESP_ERR_INVALID_ARG;
}
if (global_cacert == NULL) {
ret = esp_tls_init_global_ca_store();
if (ret != ESP_OK) {
return ret;
}
}
ret = mbedtls_x509_crt_parse(global_cacert, cacert_pem_buf, cacert_pem_bytes);
if (ret < 0) {
ESP_LOGE(TAG, "mbedtls_x509_crt_parse returned -0x%x\n\n", -ret);
mbedtls_x509_crt_free(global_cacert);
global_cacert = NULL;
return ESP_FAIL;
} else if (ret > 0) {
ESP_LOGE(TAG, "mbedtls_x509_crt_parse was partly successful. No. of failed certificates: %d", ret);
}
return ESP_OK;
}
mbedtls_x509_crt *esp_tls_get_global_ca_store()
{
return global_cacert;
}
void esp_tls_free_global_ca_store()
{
if (global_cacert) {
mbedtls_x509_crt_free(global_cacert);
global_cacert = NULL;
}
}
static void verify_certificate(esp_tls_t *tls)
{
int flags;
char buf[100];
if ((flags = mbedtls_ssl_get_verify_result(&tls->ssl)) != 0) {
ESP_LOGI(TAG, "Failed to verify peer certificate!");
bzero(buf, sizeof(buf));
mbedtls_x509_crt_verify_info(buf, sizeof(buf), " ! ", flags);
ESP_LOGI(TAG, "verification info: %s", buf);
} else {
ESP_LOGI(TAG, "Certificate verified.");
}
}
static void mbedtls_cleanup(esp_tls_t *tls)
{
if (!tls) {
return;
}
if (tls->cacert_ptr != global_cacert) {
mbedtls_x509_crt_free(tls->cacert_ptr);
}
tls->cacert_ptr = NULL;
mbedtls_x509_crt_free(&tls->cacert);
mbedtls_x509_crt_free(&tls->clientcert);
mbedtls_pk_free(&tls->clientkey);
mbedtls_entropy_free(&tls->entropy);
mbedtls_ssl_config_free(&tls->conf);
mbedtls_ctr_drbg_free(&tls->ctr_drbg);
mbedtls_ssl_free(&tls->ssl);
mbedtls_net_free(&tls->server_fd);
}
static int create_ssl_handle(esp_tls_t *tls, const char *hostname, size_t hostlen, const esp_tls_cfg_t *cfg)
{
int ret;
mbedtls_net_init(&tls->server_fd);
tls->server_fd.fd = tls->sockfd;
mbedtls_ssl_init(&tls->ssl);
mbedtls_ctr_drbg_init(&tls->ctr_drbg);
mbedtls_ssl_config_init(&tls->conf);
mbedtls_entropy_init(&tls->entropy);
if ((ret = mbedtls_ctr_drbg_seed(&tls->ctr_drbg,
mbedtls_entropy_func, &tls->entropy, NULL, 0)) != 0) {
ESP_LOGE(TAG, "mbedtls_ctr_drbg_seed returned %d", ret);
goto exit;
}
if (!cfg->skip_common_name) {
char *use_host = NULL;
if (cfg->common_name != NULL) {
use_host = strndup(cfg->common_name, strlen(cfg->common_name));
} else {
use_host = strndup(hostname, hostlen);
}
if (use_host == NULL) {
goto exit;
}
/* Hostname set here should match CN in server certificate */
if ((ret = mbedtls_ssl_set_hostname(&tls->ssl, use_host)) != 0) {
ESP_LOGE(TAG, "mbedtls_ssl_set_hostname returned -0x%x", -ret);
free(use_host);
goto exit;
}
free(use_host);
}
if ((ret = mbedtls_ssl_config_defaults(&tls->conf,
MBEDTLS_SSL_IS_CLIENT,
MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
ESP_LOGE(TAG, "mbedtls_ssl_config_defaults returned %d", ret);
goto exit;
}
#ifdef CONFIG_MBEDTLS_SSL_ALPN
if (cfg->alpn_protos) {
mbedtls_ssl_conf_alpn_protocols(&tls->conf, cfg->alpn_protos);
}
#endif
if (cfg->use_global_ca_store == true) {
if (global_cacert == NULL) {
ESP_LOGE(TAG, "global_cacert is NULL");
goto exit;
}
tls->cacert_ptr = global_cacert;
mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_REQUIRED);
mbedtls_ssl_conf_ca_chain(&tls->conf, tls->cacert_ptr, NULL);
} else if (cfg->cacert_pem_buf != NULL) {
tls->cacert_ptr = &tls->cacert;
mbedtls_x509_crt_init(tls->cacert_ptr);
ret = mbedtls_x509_crt_parse(tls->cacert_ptr, cfg->cacert_pem_buf, cfg->cacert_pem_bytes);
if (ret < 0) {
ESP_LOGE(TAG, "mbedtls_x509_crt_parse returned -0x%x\n\n", -ret);
goto exit;
}
mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_REQUIRED);
mbedtls_ssl_conf_ca_chain(&tls->conf, tls->cacert_ptr, NULL);
} else {
mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_NONE);
}
if (cfg->clientcert_pem_buf != NULL && cfg->clientkey_pem_buf != NULL) {
mbedtls_x509_crt_init(&tls->clientcert);
mbedtls_pk_init(&tls->clientkey);
ret = mbedtls_x509_crt_parse(&tls->clientcert, cfg->clientcert_pem_buf, cfg->clientcert_pem_bytes);
if (ret < 0) {
ESP_LOGE(TAG, "mbedtls_x509_crt_parse returned -0x%x\n\n", -ret);
goto exit;
}
ret = mbedtls_pk_parse_key(&tls->clientkey, cfg->clientkey_pem_buf, cfg->clientkey_pem_bytes,
cfg->clientkey_password, cfg->clientkey_password_len);
if (ret < 0) {
ESP_LOGE(TAG, "mbedtls_pk_parse_keyfile returned -0x%x\n\n", -ret);
goto exit;
}
ret = mbedtls_ssl_conf_own_cert(&tls->conf, &tls->clientcert, &tls->clientkey);
if (ret < 0) {
ESP_LOGE(TAG, "mbedtls_ssl_conf_own_cert returned -0x%x\n\n", -ret);
goto exit;
}
} else if (cfg->clientcert_pem_buf != NULL || cfg->clientkey_pem_buf != NULL) {
ESP_LOGE(TAG, "You have to provide both clientcert_pem_buf and clientkey_pem_buf for mutual authentication\n\n");
goto exit;
}
mbedtls_ssl_conf_rng(&tls->conf, mbedtls_ctr_drbg_random, &tls->ctr_drbg);
#ifdef CONFIG_MBEDTLS_DEBUG
mbedtls_esp_enable_debug_log(&tls->conf, 4);
#endif
if ((ret = mbedtls_ssl_setup(&tls->ssl, &tls->conf)) != 0) {
ESP_LOGE(TAG, "mbedtls_ssl_setup returned -0x%x\n\n", -ret);
goto exit;
}
mbedtls_ssl_set_bio(&tls->ssl, &tls->server_fd, mbedtls_net_send, mbedtls_net_recv, NULL);
return 0;
exit:
mbedtls_cleanup(tls);
return -1;
}
/**
* @brief Close the TLS connection and free any allocated resources.
*/
void esp_tls_conn_delete(esp_tls_t *tls)
{
if (tls != NULL) {
mbedtls_cleanup(tls);
if (tls->sockfd) {
close(tls->sockfd);
}
free(tls);
}
};
static ssize_t tcp_write(esp_tls_t *tls, const char *data, size_t datalen)
{
return send(tls->sockfd, data, datalen, 0);
}
static ssize_t tls_write(esp_tls_t *tls, const char *data, size_t datalen)
{
ssize_t ret = mbedtls_ssl_write(&tls->ssl, (unsigned char*) data, datalen);
if (ret < 0) {
if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
ESP_LOGE(TAG, "write error :%d:", ret);
}
}
return ret;
}
static int esp_tls_low_level_conn(const char *hostname, int hostlen, int port, const esp_tls_cfg_t *cfg, esp_tls_t *tls)
{
if (!tls) {
ESP_LOGE(TAG, "empty esp_tls parameter");
return -1;
}
/* These states are used to keep a tab on connection progress in case of non-blocking connect,
and in case of blocking connect these cases will get executed one after the other */
switch (tls->conn_state) {
case ESP_TLS_INIT:
;
int sockfd;
int ret = esp_tcp_connect(hostname, hostlen, port, &sockfd, cfg);
if (ret < 0) {
return -1;
}
tls->sockfd = sockfd;
if (!cfg) {
tls->read = tcp_read;
tls->write = tcp_write;
ESP_LOGD(TAG, "non-tls connection established");
return 1;
}
if (cfg->non_block) {
FD_ZERO(&tls->rset);
FD_SET(tls->sockfd, &tls->rset);
tls->wset = tls->rset;
}
tls->conn_state = ESP_TLS_CONNECTING;
/* falls through */
case ESP_TLS_CONNECTING:
if (cfg->non_block) {
ESP_LOGD(TAG, "connecting...");
struct timeval tv;
ms_to_timeval(cfg->timeout_ms, &tv);
/* In case of non-blocking I/O, we use the select() API to check whether
connection has been estbalished or not*/
if (select(tls->sockfd + 1, &tls->rset, &tls->wset, NULL,
cfg->timeout_ms ? &tv : NULL) == 0) {
ESP_LOGD(TAG, "select() timed out");
return 0;
}
if (FD_ISSET(tls->sockfd, &tls->rset) || FD_ISSET(tls->sockfd, &tls->wset)) {
int error;
unsigned int len = sizeof(error);
/* pending error check */
if (getsockopt(tls->sockfd, SOL_SOCKET, SO_ERROR, &error, &len) < 0) {
ESP_LOGD(TAG, "Non blocking connect failed");
tls->conn_state = ESP_TLS_FAIL;
return -1;
}
}
}
/* By now, the connection has been established */
ret = create_ssl_handle(tls, hostname, hostlen, cfg);
if (ret != 0) {
ESP_LOGD(TAG, "create_ssl_handshake failed");
tls->conn_state = ESP_TLS_FAIL;
return -1;
}
tls->read = tls_read;
tls->write = tls_write;
tls->conn_state = ESP_TLS_HANDSHAKE;
/* falls through */
case ESP_TLS_HANDSHAKE:
ESP_LOGD(TAG, "handshake in progress...");
ret = mbedtls_ssl_handshake(&tls->ssl);
if (ret == 0) {
tls->conn_state = ESP_TLS_DONE;
return 1;
} else {
if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
ESP_LOGE(TAG, "mbedtls_ssl_handshake returned -0x%x", -ret);
if (cfg->cacert_pem_buf != NULL || cfg->use_global_ca_store == true) {
/* This is to check whether handshake failed due to invalid certificate*/
verify_certificate(tls);
}
tls->conn_state = ESP_TLS_FAIL;
return -1;
}
/* Irrespective of blocking or non-blocking I/O, we return on getting MBEDTLS_ERR_SSL_WANT_READ
or MBEDTLS_ERR_SSL_WANT_WRITE during handshake */
return 0;
}
break;
case ESP_TLS_FAIL:
ESP_LOGE(TAG, "failed to open a new connection");;
break;
default:
ESP_LOGE(TAG, "invalid esp-tls state");
break;
}
return -1;
}
/**
* @brief Create a new TLS/SSL connection
*/
esp_tls_t *esp_tls_conn_new(const char *hostname, int hostlen, int port, const esp_tls_cfg_t *cfg)
{
esp_tls_t *tls = (esp_tls_t *)calloc(1, sizeof(esp_tls_t));
if (!tls) {
return NULL;
}
/* esp_tls_conn_new() API establishes connection in a blocking manner thus this loop ensures that esp_tls_conn_new()
API returns only after connection is established unless there is an error*/
size_t start = xTaskGetTickCount();
while (1) {
int ret = esp_tls_low_level_conn(hostname, hostlen, port, cfg, tls);
if (ret == 1) {
return tls;
} else if (ret == -1) {
esp_tls_conn_delete(tls);
ESP_LOGE(TAG, "Failed to open new connection");
return NULL;
} else if (ret == 0 && cfg->timeout_ms >= 0) {
size_t timeout_ticks = pdMS_TO_TICKS(cfg->timeout_ms);
uint32_t expired = xTaskGetTickCount() - start;
if (expired >= timeout_ticks) {
esp_tls_conn_delete(tls);
ESP_LOGE(TAG, "Failed to open new connection in specified timeout");
return NULL;
}
}
}
return NULL;
}
/*
* @brief Create a new TLS/SSL non-blocking connection
*/
int esp_tls_conn_new_async(const char *hostname, int hostlen, int port, const esp_tls_cfg_t *cfg , esp_tls_t *tls)
{
return esp_tls_low_level_conn(hostname, hostlen, port, cfg, tls);
}
static int get_port(const char *url, struct http_parser_url *u)
{
if (u->field_data[UF_PORT].len) {
return strtol(&url[u->field_data[UF_PORT].off], NULL, 10);
} else {
if (strncasecmp(&url[u->field_data[UF_SCHEMA].off], "http", u->field_data[UF_SCHEMA].len) == 0) {
return 80;
} else if (strncasecmp(&url[u->field_data[UF_SCHEMA].off], "https", u->field_data[UF_SCHEMA].len) == 0) {
return 443;
}
}
return 0;
}
/**
* @brief Create a new TLS/SSL connection with a given "HTTP" url
*/
esp_tls_t *esp_tls_conn_http_new(const char *url, const esp_tls_cfg_t *cfg)
{
/* Parse URI */
struct http_parser_url u;
http_parser_url_init(&u);
http_parser_parse_url(url, strlen(url), 0, &u);
/* Connect to host */
return esp_tls_conn_new(&url[u.field_data[UF_HOST].off], u.field_data[UF_HOST].len,
get_port(url, &u), cfg);
}
size_t esp_tls_get_bytes_avail(esp_tls_t *tls)
{
if (!tls) {
ESP_LOGE(TAG, "empty arg passed to esp_tls_get_bytes_avail()");
return ESP_FAIL;
}
return mbedtls_ssl_get_bytes_avail(&tls->ssl);
}
/**
* @brief Create a new non-blocking TLS/SSL connection with a given "HTTP" url
*/
int esp_tls_conn_http_new_async(const char *url, const esp_tls_cfg_t *cfg, esp_tls_t *tls)
{
/* Parse URI */
struct http_parser_url u;
http_parser_url_init(&u);
http_parser_parse_url(url, strlen(url), 0, &u);
/* Connect to host */
return esp_tls_conn_new_async(&url[u.field_data[UF_HOST].off], u.field_data[UF_HOST].len,
get_port(url, &u), cfg, tls);
}
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