Support self signed certificates (#291)

* Support self signed certificates

Fix for https://github.com/espressif/arduino-esp32/issues/265

mbedtls_ssl_conf_authmode was defined before mbedtls_ssl_config_defaults causing several bugs when no CA certificate is defined.

* Implement Arduino's log facility

Replace printf by ESP log handling

* Remove \n from debug messages

log_ doesn't need \n to break line.

libraries/WiFiClientSecure/src/ssl_client.cpp

 /* Provide SSL/TLS functions to ESP32 with Arduino IDE
 *
-* Adapted from the ssl_client1 example in mbedtls.
+* Adapted from the ssl_client1 example of mbedtls.
 *
 * Original Copyright (C) 2006-2015, ARM Limited, All Rights Reserved, Apache 2.0 License.
 * Additions Copyright (C) 2017 Evandro Luis Copercini, Apache 2.0 License.
 */
 
 #include "Arduino.h"
+#include <esp32-hal-log.h>
 #include <lwip/sockets.h>
 #include <lwip/err.h>
 #include <lwip/sockets.h>
 #include <lwip/sys.h>
 #include <lwip/netdb.h>
-
 #include "ssl_client.h"
 
-
 const char *pers = "esp32-tls";
 
-#define DEBUG //Comment to supress debug messages
-
-#ifdef DEBUG
-#define DEBUG_PRINT(...) printf( __VA_ARGS__ )
-#else
-#define DEBUG_PRINT(x)
-#endif
-
-#ifdef CONFIG_MBEDTLS_DEBUG
-
-#define MBEDTLS_DEBUG_LEVEL 4
-
-/* mbedtls debug function that translates mbedTLS debug output
-to ESP_LOGx debug output.
-
-MBEDTLS_DEBUG_LEVEL 4 means all mbedTLS debug output gets sent here,
-and then filtered to the ESP logging mechanism.
-*/
-static void mbedtls_debug(void *ctx, int level,
-                          const char *file, int line,
-                          const char *str)
-{
-    const char *MBTAG = "mbedtls";
-    char *file_sep;
-
-    /* Shorten 'file' from the whole file path to just the filename
-
-    This is a bit wasteful because the macros are compiled in with
-    the full _FILE_ path in each case.
-    */
-    file_sep = rindex(file, '/');
-    if (file_sep) {
-        file = file_sep + 1;
-    }
-
-    switch (level) {
-    case 1:
-        printf( "%s:%d %s \n", file, line, str);
-        break;
-    case 2:
-    case 3:
-        printf( "%s:%d %s \n", file, line, str);
-    case 4:
-        printf( "%s:%d %s \n", file, line, str);
-        break;
-    default:
-        printf( "Unexpected log level %d: %s \n", level, str);
-        break;
-    }
-}
-
-#endif
-
-
 static int handle_error(int err)
 {
 #ifdef MBEDTLS_ERROR_C
     char error_buf[100];
-
     mbedtls_strerror(err, error_buf, 100);
-    printf("\n%s\n", error_buf);
+    log_e("%s", error_buf);
 #endif
-    printf("\nMbedTLS message code: %d\n", err);
+    log_e("MbedTLS message code: %d", err);
     return err;
 }
 
 
-
 void ssl_init(sslclient_context *ssl_client)
 {
-    /*
-    * Initialize the RNG and the session data
-    */
-
     mbedtls_ssl_init(&ssl_client->ssl_ctx);
     mbedtls_ssl_config_init(&ssl_client->ssl_conf);
-
     mbedtls_ctr_drbg_init(&ssl_client->drbg_ctx);
 }
 
 
-
 int start_ssl_client(sslclient_context *ssl_client, uint32_t ipAddress, uint32_t port, const char *rootCABuff, const char *cli_cert, const char *cli_key)
 {
     char buf[512];
     int ret, flags, len, timeout;
     int enable = 1;
-    DEBUG_PRINT("Free heap before TLS %u\n", xPortGetFreeHeapSize());
-
+    log_i("Free heap before TLS %u", xPortGetFreeHeapSize());
 
+    log_i("Starting socket");
     ssl_client->socket = -1;
-								
+
     ssl_client->socket = lwip_socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
     if (ssl_client->socket < 0) {
-        printf("\r\nERROR opening socket\r\n");
+        log_e("ERROR opening socket");
         return ssl_client->socket;
     }
 
@@ -129,33 +66,35 @@ int start_ssl_client(sslclient_context *ssl_client, uint32_t ipAddress, uint32_t
         lwip_setsockopt(ssl_client->socket, IPPROTO_TCP, TCP_NODELAY, &enable, sizeof(enable));
         lwip_setsockopt(ssl_client->socket, SOL_SOCKET, SO_KEEPALIVE, &enable, sizeof(enable));
     } else {
-        printf("\r\nConnect to Server failed!\r\n");
+        log_e("Connect to Server failed!");
         return -1;
-				  
     }
 
     fcntl( ssl_client->socket, F_SETFL, fcntl( ssl_client->socket, F_GETFL, 0 ) | O_NONBLOCK );
 
-
-    DEBUG_PRINT( "Seeding the random number generator\n");
+    log_i("Seeding the random number generator");
     mbedtls_entropy_init(&ssl_client->entropy_ctx);
 
     ret = mbedtls_ctr_drbg_seed(&ssl_client->drbg_ctx, mbedtls_entropy_func,
                                 &ssl_client->entropy_ctx, (const unsigned char *) pers, strlen(pers));
-																 
-				  
-		 
-
     if (ret < 0) {
         return handle_error(ret);
     }
 
+    log_i("Setting up the SSL/TLS structure...");
+
+    if ((ret = mbedtls_ssl_config_defaults(&ssl_client->ssl_conf,
+                                           MBEDTLS_SSL_IS_CLIENT,
+                                           MBEDTLS_SSL_TRANSPORT_STREAM,
+                                           MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
+        return handle_error(ret);
+    }
 
     /* MBEDTLS_SSL_VERIFY_REQUIRED if a CA certificate is defined on Arduino IDE and
         MBEDTLS_SSL_VERIFY_NONE if not.
         */
     if (rootCABuff != NULL) {
-        DEBUG_PRINT( "Loading CA cert\n");
+        log_i("Loading CA cert");
         mbedtls_x509_crt_init(&ssl_client->ca_cert);
         mbedtls_ssl_conf_authmode(&ssl_client->ssl_conf, MBEDTLS_SSL_VERIFY_REQUIRED);
         ret = mbedtls_x509_crt_parse(&ssl_client->ca_cert, (const unsigned char *)rootCABuff, strlen(rootCABuff) + 1);
@@ -163,35 +102,25 @@ int start_ssl_client(sslclient_context *ssl_client, uint32_t ipAddress, uint32_t
         //mbedtls_ssl_conf_verify(&ssl_client->ssl_ctx, my_verify, NULL );
         if (ret < 0) {
             return handle_error(ret);
-					  
-			 
-				
-																					  
         }
     } else {
-												  
         mbedtls_ssl_conf_authmode(&ssl_client->ssl_conf, MBEDTLS_SSL_VERIFY_NONE);
+        log_i("WARNING: Use certificates for a more secure communication!");
     }
 
     if (cli_cert != NULL && cli_key != NULL) {
         mbedtls_x509_crt_init(&ssl_client->client_cert);
         mbedtls_pk_init(&ssl_client->client_key);
 
-        DEBUG_PRINT( "Loading CRT cert\n");
+        log_i("Loading CRT cert");
 
         ret = mbedtls_x509_crt_parse(&ssl_client->client_cert, (const unsigned char *)cli_cert, strlen(cli_cert) + 1);
-																					 
-					  
-			 
-
         if (ret < 0) {
             return handle_error(ret);
         }
 
-        DEBUG_PRINT( "Loading private key\n");
+        log_i("Loading private key");
         ret = mbedtls_pk_parse_key(&ssl_client->client_key, (const unsigned char *)cli_key, strlen(cli_key) + 1, NULL, 0);
-					  
-			 
 
         if (ret != 0) {
             return handle_error(ret);
@@ -203,48 +132,29 @@ int start_ssl_client(sslclient_context *ssl_client, uint32_t ipAddress, uint32_t
     /*
         // TODO: implement match CN verification
 
-        DEBUG_PRINT( "Setting hostname for TLS session...\n");
+        log_i("Setting hostname for TLS session...");
 
                 // Hostname set here should match CN in server certificate
         if((ret = mbedtls_ssl_set_hostname(&ssl_client->ssl_ctx, host)) != 0)
         {
             return handle_error(ret);
-				  
-        }
-        */
 
-    DEBUG_PRINT( "Setting up the SSL/TLS structure...\n");
-
-    if ((ret = mbedtls_ssl_config_defaults(&ssl_client->ssl_conf,
-                                           MBEDTLS_SSL_IS_CLIENT,
-                                           MBEDTLS_SSL_TRANSPORT_STREAM,
-                                           MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
-        return handle_error(ret);
-				  
-    }
+        }
+    */
 
     mbedtls_ssl_conf_rng(&ssl_client->ssl_conf, mbedtls_ctr_drbg_random, &ssl_client->drbg_ctx);
-#ifdef CONFIG_MBEDTLS_DEBUG
-    mbedtls_debug_set_threshold(MBEDTLS_DEBUG_LEVEL);
-    mbedtls_ssl_conf_dbg(&ssl_client->ssl_conf, mbedtls_debug, NULL);
-#endif
 
     if ((ret = mbedtls_ssl_setup(&ssl_client->ssl_ctx, &ssl_client->ssl_conf)) != 0) {
         return handle_error(ret);
-				  
     }
 
     mbedtls_ssl_set_bio(&ssl_client->ssl_ctx, &ssl_client->socket, mbedtls_net_send, mbedtls_net_recv, NULL );
 
-    DEBUG_PRINT( "Performing the SSL/TLS handshake...\n");
+    log_i("Performing the SSL/TLS handshake...");
 
     while ((ret = mbedtls_ssl_handshake(&ssl_client->ssl_ctx)) != 0) {
-        if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret != -76) {
+        if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret != -76) {  //workaround for bug: https://github.com/espressif/esp-idf/issues/434
             return handle_error(ret);
-					  
-			 
-					  
-						 
         }
         delay(10);
         vPortYield();
@@ -252,32 +162,28 @@ int start_ssl_client(sslclient_context *ssl_client, uint32_t ipAddress, uint32_t
 
 
     if (cli_cert != NULL && cli_key != NULL) {
-        DEBUG_PRINT("Protocol is %s \nCiphersuite is %s\n", mbedtls_ssl_get_version(&ssl_client->ssl_ctx), mbedtls_ssl_get_ciphersuite(&ssl_client->ssl_ctx));
+        log_i("Protocol is %s Ciphersuite is %s", mbedtls_ssl_get_version(&ssl_client->ssl_ctx), mbedtls_ssl_get_ciphersuite(&ssl_client->ssl_ctx));
         if ((ret = mbedtls_ssl_get_record_expansion(&ssl_client->ssl_ctx)) >= 0) {
-            DEBUG_PRINT("Record expansion is %d\n", ret);
+            log_i("Record expansion is %d", ret);
         } else {
-            DEBUG_PRINT("Record expansion is unknown (compression)\n");
-			 
+            log_i("Record expansion is unknown (compression)");
         }
     }
 
-
-    DEBUG_PRINT( "Verifying peer X.509 certificate...\n");
+    log_i("Verifying peer X.509 certificate...");
 
     if ((flags = mbedtls_ssl_get_verify_result(&ssl_client->ssl_ctx)) != 0) {
-        printf( "Failed to verify peer certificate!\n");
+        log_e("Failed to verify peer certificate!");
         bzero(buf, sizeof(buf));
         mbedtls_x509_crt_verify_info(buf, sizeof(buf), "  ! ", flags);
-        printf( "verification info: %s\n", buf);
+        log_e("verification info: %s", buf);
         stop_ssl_socket(ssl_client, rootCABuff, cli_cert, cli_key);  //It's not safe continue.
         return handle_error(ret);
     } else {
-        DEBUG_PRINT( "Certificate verified.\n");
+        log_i("Certificate verified.");
     }
 
-				
-
-    DEBUG_PRINT("Free heap after TLS %u\n", xPortGetFreeHeapSize());
+    log_i("Free heap after TLS %u", xPortGetFreeHeapSize());
 
     return ssl_client->socket;
 }
@@ -285,7 +191,7 @@ int start_ssl_client(sslclient_context *ssl_client, uint32_t ipAddress, uint32_t
 
 void stop_ssl_socket(sslclient_context *ssl_client, const char *rootCABuff, const char *cli_cert, const char *cli_key)
 {
-    DEBUG_PRINT( "\nCleaning SSL connection.\n");
+    log_i("Cleaning SSL connection.");
 
     if (ssl_client->socket >= 0) {
         close(ssl_client->socket);
@@ -313,13 +219,12 @@ void stop_ssl_socket(sslclient_context *ssl_client, const char *rootCABuff, cons
 
 int data_to_read(sslclient_context *ssl_client)
 {
-
     int ret, res;
     ret = mbedtls_ssl_read(&ssl_client->ssl_ctx, NULL, 0);
-    //printf("RET: %i\n",ret);   //for low level debug
+    //log_e("RET: %i",ret);   //for low level debug
     res = mbedtls_ssl_get_bytes_avail(&ssl_client->ssl_ctx);
-    //printf("RES: %i\n",res);
-    if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret < 0 && ret != -76) { //RC:76 sockets is not connected
+    //log_e("RES: %i",res);
+    if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret < 0 && ret != -76) {
         return handle_error(ret);
     }
 
@@ -327,33 +232,30 @@ int data_to_read(sslclient_context *ssl_client)
 }
 
 
-
 int send_ssl_data(sslclient_context *ssl_client, const uint8_t *data, uint16_t len)
 {
-    //DEBUG_PRINT( "Writing HTTP request...\n");  //for low level debug
+    //log_i("Writing HTTP request...");  //for low level debug
     int ret = -1;
 
     while ((ret = mbedtls_ssl_write(&ssl_client->ssl_ctx, data, len)) <= 0) {
-        if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret != -76) { //RC:76 sockets is not connected
+        if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret != -76) {
             return handle_error(ret);
-				  
         }
     }
 
     len = ret;
-    //DEBUG_PRINT( "%d bytes written\n", len);  //for low level debug
+    //log_i("%d bytes written", len);  //for low level debug
     return ret;
 }
 
 
-
 int get_ssl_receive(sslclient_context *ssl_client, uint8_t *data, int length)
 {
-    //DEBUG_PRINT( "Reading HTTP response...\n");   //for low level debug
+    //log_i( "Reading HTTP response...");   //for low level debug
     int ret = -1;
 
     ret = mbedtls_ssl_read(&ssl_client->ssl_ctx, data, length);
 
-    //DEBUG_PRINT( "%d bytes readed\n", ret);   //for low level debug
+    //log_i( "%d bytes readed", ret);   //for low level debug
     return ret;
 }