/* http_get_mbedtls - HTTPS version of the http_get example, using mbed TLS. * * Retrieves a JSON response from the howsmyssl.com API via HTTPS over TLS v1.2. * * Validates the server's certificate using the root CA loaded (in PEM format) in cert.c. * * Adapted from the ssl_client1 example in mbedtls. * * Original Copyright (C) 2006-2015, ARM Limited, All Rights Reserved, Apache 2.0 License. * Additions Copyright (C) 2015 Angus Gratton, Apache 2.0 License. */ #include "espressif/esp_common.h" #include "espressif/sdk_private.h" #include #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" /* mbedtls/config.h MUST appear before all other mbedtls headers, or you'll get the default config. (Although mostly that isn't a big problem, you just might get errors at link time if functions don't exist.) */ #include "mbedtls/config.h" #include "mbedtls/net.h" #include "mbedtls/debug.h" #include "mbedtls/ssl.h" #include "mbedtls/entropy.h" #include "mbedtls/ctr_drbg.h" #include "mbedtls/error.h" #include "mbedtls/certs.h" #define WEB_SERVER "howsmyssl.com" #define WEB_PORT "443" #define WEB_URL "https://www.howsmyssl.com/a/check" #define GET_REQUEST "GET "WEB_URL" HTTP/1.1\n\n" /* Root cert for howsmyssl.com, stored in cert.c */ extern const char *server_root_cert; /* MBEDTLS_DEBUG_C disabled by default to save substantial bloating of * firmware, define it in * examples/http_get_mbedtls/include/mbedtls/config.h if you'd like * debugging output. */ #ifdef MBEDTLS_DEBUG_C /* Increase this value to see more TLS debug details, 0 prints nothing, 1 will print any errors, 4 will print _everything_ */ #define DEBUG_LEVEL 4 static void my_debug(void *ctx, int level, const char *file, int line, const char *str) { ((void) level); /* 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, so the firmware is bloated out by a few kb. But there's not a lot we can do about it... */ char *file_sep = rindex(file, '/'); if(file_sep) file = file_sep+1; printf("%s:%04d: %s", file, line, str); fflush(stdout); } #endif void http_get_task(void *pvParameters) { int successes = 0, failures = 0, ret; printf("HTTP get task starting...\n"); uint32_t flags; unsigned char buf[1024]; const char *pers = "ssl_client1"; mbedtls_entropy_context entropy; mbedtls_ctr_drbg_context ctr_drbg; mbedtls_ssl_context ssl; mbedtls_x509_crt cacert; mbedtls_ssl_config conf; mbedtls_net_context server_fd; /* * 0. Initialize the RNG and the session data */ mbedtls_ssl_init(&ssl); mbedtls_x509_crt_init(&cacert); mbedtls_ctr_drbg_init(&ctr_drbg); printf("\n . Seeding the random number generator..."); fflush(stdout); mbedtls_ssl_config_init(&conf); mbedtls_entropy_init(&entropy); if((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, (const unsigned char *) pers, strlen(pers))) != 0) { printf(" failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret); while(1) {} /* todo: replace with abort() */ } printf(" ok\n"); /* * 0. Initialize certificates */ printf(" . Loading the CA root certificate ..."); fflush(stdout); ret = mbedtls_x509_crt_parse(&cacert, (uint8_t*)server_root_cert, strlen(server_root_cert)+1); if(ret < 0) { printf(" failed\n ! mbedtls_x509_crt_parse returned -0x%x\n\n", -ret); while(1) {} /* todo: replace with abort() */ } printf(" ok (%d skipped)\n", ret); /* Hostname set here should match CN in server certificate */ if((ret = mbedtls_ssl_set_hostname(&ssl, WEB_SERVER)) != 0) { printf(" failed\n ! mbedtls_ssl_set_hostname returned %d\n\n", ret); while(1) {} /* todo: replace with abort() */ } /* * 2. Setup stuff */ printf(" . Setting up the SSL/TLS structure..."); fflush(stdout); if((ret = mbedtls_ssl_config_defaults(&conf, MBEDTLS_SSL_IS_CLIENT, MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT)) != 0) { printf(" failed\n ! mbedtls_ssl_config_defaults returned %d\n\n", ret); goto exit; } printf(" ok\n"); /* OPTIONAL is not optimal for security, in this example it will print a warning if CA verification fails but it will continue to connect. */ mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_OPTIONAL); mbedtls_ssl_conf_ca_chain(&conf, &cacert, NULL); mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg); #ifdef MBEDTLS_DEBUG_C mbedtls_debug_set_threshold(DEBUG_LEVEL); mbedtls_ssl_conf_dbg(&conf, my_debug, stdout); #endif if((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0) { printf(" failed\n ! mbedtls_ssl_setup returned %d\n\n", ret); goto exit; } /* Wait until we can resolve the DNS for the server, as an indication our network is probably working... */ printf("Waiting for server DNS to resolve... "); fflush(stdout); err_t dns_err; ip_addr_t host_ip; do { vTaskDelay(500 / portTICK_RATE_MS); dns_err = netconn_gethostbyname(WEB_SERVER, &host_ip); } while(dns_err != ERR_OK); printf("done.\n"); while(1) { mbedtls_net_init(&server_fd); printf("top of loop, free heap = %u\n", xPortGetFreeHeapSize()); /* * 1. Start the connection */ printf(" . Connecting to %s:%s...", WEB_SERVER, WEB_PORT); fflush(stdout); if((ret = mbedtls_net_connect(&server_fd, WEB_SERVER, WEB_PORT, MBEDTLS_NET_PROTO_TCP)) != 0) { printf(" failed\n ! mbedtls_net_connect returned %d\n\n", ret); goto exit; } printf(" ok\n"); mbedtls_ssl_set_bio(&ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL); /* * 4. Handshake */ printf(" . Performing the SSL/TLS handshake..."); fflush(stdout); while((ret = mbedtls_ssl_handshake(&ssl)) != 0) { if(ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) { printf(" failed\n ! mbedtls_ssl_handshake returned -0x%x\n\n", -ret); goto exit; } } printf(" ok\n"); /* * 5. Verify the server certificate */ printf(" . Verifying peer X.509 certificate..."); /* In real life, we probably want to bail out when ret != 0 */ if((flags = mbedtls_ssl_get_verify_result(&ssl)) != 0) { char vrfy_buf[512]; printf(" failed\n"); mbedtls_x509_crt_verify_info(vrfy_buf, sizeof(vrfy_buf), " ! ", flags); printf("%s\n", vrfy_buf); } else printf(" ok\n"); /* * 3. Write the GET request */ printf(" > Write to server:"); fflush(stdout); int len = sprintf((char *) buf, GET_REQUEST); while((ret = mbedtls_ssl_write(&ssl, buf, len)) <= 0) { if(ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) { printf(" failed\n ! mbedtls_ssl_write returned %d\n\n", ret); goto exit; } } len = ret; printf(" %d bytes written\n\n%s", len, (char *) buf); /* * 7. Read the HTTP response */ printf(" < Read from server:"); fflush(stdout); do { len = sizeof(buf) - 1; memset(buf, 0, sizeof(buf)); ret = mbedtls_ssl_read(&ssl, buf, len); if(ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE) continue; if(ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) { ret = 0; break; } if(ret < 0) { printf("failed\n ! mbedtls_ssl_read returned %d\n\n", ret); break; } if(ret == 0) { printf("\n\nEOF\n\n"); break; } len = ret; printf(" %d bytes read\n\n%s", len, (char *) buf); } while(1); mbedtls_ssl_close_notify(&ssl); exit: mbedtls_ssl_session_reset(&ssl); mbedtls_net_free(&server_fd); if(ret != 0) { char error_buf[100]; mbedtls_strerror(ret, error_buf, 100); printf("\n\nLast error was: %d - %s\n\n", ret, error_buf); failures++; } else { successes++; } printf("\n\nsuccesses = %d failures = %d\n", successes, failures); for(int countdown = successes ? 10 : 5; countdown >= 0; countdown--) { printf("%d... ", countdown); fflush(stdout); vTaskDelay(1000 / portTICK_RATE_MS); } printf("\nStarting again!\n"); } } void user_init(void) { 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, (signed char *)"get_task", 2048, NULL, 2, NULL); }