ssl_client1.c

/*
 *  SSL client demonstration program
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include "mbedtls/build_info.h"

#include "mbedtls/platform.h"

#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) ||     \
    !defined(MBEDTLS_SSL_TLS_C) || !defined(MBEDTLS_SSL_CLI_C) ||    \
    !defined(MBEDTLS_NET_C) || !defined(MBEDTLS_RSA_C) ||            \
    !defined(MBEDTLS_PEM_PARSE_C) || !defined(MBEDTLS_CTR_DRBG_C) || \
    !defined(MBEDTLS_X509_CRT_PARSE_C)
int main( void )
{
    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
           "MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_CLI_C and/or "
           "MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
           "MBEDTLS_CTR_DRBG_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_printf( "\n  . Seeding the random number generator..." );
    fflush( stdout );

    mbedtls_entropy_init( &entropy );
    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 )
            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 );

    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 );

    mbedtls_exit( exit_code );
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_SSL_TLS_C &&
          MBEDTLS_SSL_CLI_C && MBEDTLS_NET_C && MBEDTLS_RSA_C &&
          MBEDTLS_PEM_PARSE_C && MBEDTLS_CTR_DRBG_C && MBEDTLS_X509_CRT_PARSE_C */