programs/ssl/ssl_client1.c

/*
 *  SSL client demonstration program
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

#include "mbedtls/build_info.h"

#include "mbedtls/platform.h"

#if !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) ||      \
    !defined(MBEDTLS_NET_C) || !defined(MBEDTLS_SSL_CLI_C) ||           \
    !defined(MBEDTLS_PEM_PARSE_C) || !defined(MBEDTLS_X509_CRT_PARSE_C)
int main(void)
{
    mbedtls_printf("MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C and/or "
                   "MBEDTLS_NET_C and/or MBEDTLS_SSL_CLI_C and/or "
                   "MBEDTLS_PEM_PARSE_C and/or MBEDTLS_X509_CRT_PARSE_C "
                   "not defined.\n");
    mbedtls_exit(0);
}
#else

#include "mbedtls/net_sockets.h"
#include "mbedtls/debug.h"
#include "mbedtls/ssl.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/error.h"
#include "test/certs.h"

#include <string.h>

#define SERVER_PORT "4433"
#define SERVER_NAME "localhost"
#define GET_REQUEST "GET / HTTP/1.0\r\n\r\n"

#define DEBUG_LEVEL 1


static void my_debug(void *ctx, int level,
                     const char *file, int line,
                     const char *str)
{
    ((void) level);

    mbedtls_fprintf((FILE *) ctx, "%s:%04d: %s", file, line, str);
    fflush((FILE *) ctx);
}

int main(void)
{
    int ret = 1, len;
    int exit_code = MBEDTLS_EXIT_FAILURE;
    mbedtls_net_context server_fd;
    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_ssl_config conf;
    mbedtls_x509_crt cacert;

#if defined(MBEDTLS_DEBUG_C)
    mbedtls_debug_set_threshold(DEBUG_LEVEL);
#endif

    /*
     * 0. Initialize the RNG and the session data
     */
    mbedtls_net_init(&server_fd);
    mbedtls_ssl_init(&ssl);
    mbedtls_ssl_config_init(&conf);
    mbedtls_x509_crt_init(&cacert);
    mbedtls_ctr_drbg_init(&ctr_drbg);
    mbedtls_entropy_init(&entropy);

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_status_t status = psa_crypto_init();
    if (status != PSA_SUCCESS) {
        mbedtls_fprintf(stderr, "Failed to initialize PSA Crypto implementation: %d\n",
                        (int) status);
        goto exit;
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    mbedtls_printf("\n  . Seeding the random number generator...");
    fflush(stdout);


    if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
                                     (const unsigned char *) pers,
                                     strlen(pers))) != 0) {
        mbedtls_printf(" failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    /*
     * 0. Initialize certificates
     */
    mbedtls_printf("  . Loading the CA root certificate ...");
    fflush(stdout);

    ret = mbedtls_x509_crt_parse(&cacert, (const unsigned char *) mbedtls_test_cas_pem,
                                 mbedtls_test_cas_pem_len);
    if (ret < 0) {
        mbedtls_printf(" failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n",
                       (unsigned int) -ret);
        goto exit;
    }

    mbedtls_printf(" ok (%d skipped)\n", ret);

    /*
     * 1. Start the connection
     */
    mbedtls_printf("  . Connecting to tcp/%s/%s...", SERVER_NAME, SERVER_PORT);
    fflush(stdout);

    if ((ret = mbedtls_net_connect(&server_fd, SERVER_NAME,
                                   SERVER_PORT, MBEDTLS_NET_PROTO_TCP)) != 0) {
        mbedtls_printf(" failed\n  ! mbedtls_net_connect returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    /*
     * 2. Setup stuff
     */
    mbedtls_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) {
        mbedtls_printf(" failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    /* OPTIONAL is not optimal for security,
     * but makes interop easier in this simplified example */
    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);
    mbedtls_ssl_conf_dbg(&conf, my_debug, stdout);

    if ((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0) {
        mbedtls_printf(" failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret);
        goto exit;
    }

    if ((ret = mbedtls_ssl_set_hostname(&ssl, SERVER_NAME)) != 0) {
        mbedtls_printf(" failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_ssl_set_bio(&ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL);

    /*
     * 4. Handshake
     */
    mbedtls_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) {
            mbedtls_printf(" failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n",
                           (unsigned int) -ret);
            goto exit;
        }
    }

    mbedtls_printf(" ok\n");

    /*
     * 5. Verify the server certificate
     */
    mbedtls_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) {
#if !defined(MBEDTLS_X509_REMOVE_INFO)
        char vrfy_buf[512];
#endif

        mbedtls_printf(" failed\n");

#if !defined(MBEDTLS_X509_REMOVE_INFO)
        mbedtls_x509_crt_verify_info(vrfy_buf, sizeof(vrfy_buf), "  ! ", flags);

        mbedtls_printf("%s\n", vrfy_buf);
#endif
    } else {
        mbedtls_printf(" ok\n");
    }

    /*
     * 3. Write the GET request
     */
    mbedtls_printf("  > Write to server:");
    fflush(stdout);

    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) {
            mbedtls_printf(" failed\n  ! mbedtls_ssl_write returned %d\n\n", ret);
            goto exit;
        }
    }

    len = ret;
    mbedtls_printf(" %d bytes written\n\n%s", len, (char *) buf);

    /*
     * 7. Read the HTTP response
     */
    mbedtls_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) {
            mbedtls_printf("The return value %d from mbedtls_ssl_read() means that the server\n"
                           "closed the connection first. We're ok with that.\n",
                           MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY);
            break;
        }

        if (ret < 0) {
            mbedtls_printf("failed\n  ! mbedtls_ssl_read returned %d\n\n", ret);
            break;
        }

        if (ret == 0) {
            mbedtls_printf("\n\nEOF\n\n");
            break;
        }

        len = ret;
        mbedtls_printf(" %d bytes read\n\n%s", len, (char *) buf);
    } while (1);

    mbedtls_ssl_close_notify(&ssl);

    if (ret == 0 || ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
        exit_code = MBEDTLS_EXIT_SUCCESS;
    }

exit:

#ifdef MBEDTLS_ERROR_C
    if (exit_code != MBEDTLS_EXIT_SUCCESS) {
        char error_buf[100];
        mbedtls_strerror(ret, error_buf, 100);
        mbedtls_printf("Last error was: %d - %s\n\n", ret, error_buf);
    }
#endif

    mbedtls_net_free(&server_fd);
    mbedtls_x509_crt_free(&cacert);
    mbedtls_ssl_free(&ssl);
    mbedtls_ssl_config_free(&conf);
    mbedtls_ctr_drbg_free(&ctr_drbg);
    mbedtls_entropy_free(&entropy);
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    mbedtls_psa_crypto_free();
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    mbedtls_exit(exit_code);
}

#endif /* configuration allows running this program */