Add BearSSL extra (#340)

Add BearSSL extra + http_get example, TLS server example

.gitmodules

@@ -19,6 +19,9 @@
 [submodule "tests/fs-test"]
 	path = tests/fs-test
 	url = https://github.com/sheinz/fs-test
+[submodule "extras/bearssl/BearSSL"]
+	path = extras/bearssl/BearSSL
+	url = https://www.bearssl.org/git/BearSSL
 [submodule "extras/http-parser/http-parser"]
 	path = extras/http-parser/http-parser
 	url = https://github.com/nodejs/http-parser

examples/http_get_bearssl/Makefile

@@ -0,0 +1,6 @@
+PROGRAM=http_get_bearssl
+EXTRA_COMPONENTS = extras/bearssl
+
+EXTRA_CFLAGS +=-DCONFIG_EPOCH_TIME=$(shell date --utc '+%s')
+
+include ../../common.mk

examples/http_get_bearssl/http_get_bearssl.c

@@ -0,0 +1,342 @@
+/* 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 <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);
+}

examples/tls_server_bearssl/Makefile

@@ -0,0 +1,4 @@
+PROGRAM=tls_server_bearssl
+EXTRA_COMPONENTS = extras/bearssl
+
+include ../../common.mk