/* 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 , MIT License. * Additions Copyright (C) 2016 Stefan Schake, MIT License. */ #include "espressif/esp_common.h" #include "esp/uart.h" #include "esp/hwrand.h" #include #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" #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); }