mbedtls_test.c

// To compile:
// cc -I./include mbedtls_test.c library/libmbedtls.a library/libmbedx509.a library/libmbedcrypto.a

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>

#include "mbedtls/net_sockets.h"
#include "mbedtls/ssl.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/error.h"
#include "mbedtls/version.h"
#include "mbedtls/x509.h"

#define HOSTNAME "google.com"

#define TRUST_PATH "/etc/ssl/cert.pem"

int main() {

    mbedtls_entropy_context entropy;
    mbedtls_entropy_init( &entropy );

    mbedtls_ctr_drbg_context ctr_drbg;
    mbedtls_ctr_drbg_init( &ctr_drbg );

    int result = mbedtls_ctr_drbg_seed(
        &ctr_drbg,
        mbedtls_entropy_func,
        &entropy,
        NULL, 0
    );
    assert(!result);
    printf("seeded entropy\n");

    mbedtls_net_context net_context;
    result = mbedtls_net_connect(&net_context, HOSTNAME, "443", 0);
    assert(!result);
    printf("mbedtls connected\n");

    mbedtls_ssl_config conf;

    mbedtls_ssl_config_init( &conf );

    result = mbedtls_ssl_config_defaults(
        &conf,
        MBEDTLS_SSL_IS_CLIENT,
        MBEDTLS_SSL_TRANSPORT_STREAM,
        MBEDTLS_SSL_PRESET_DEFAULT
    );
    assert(!result);

    mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );

    mbedtls_ssl_context ssl;
    mbedtls_ssl_init(&ssl);

    result = mbedtls_ssl_setup( &ssl, &conf );
    assert(!result);

    mbedtls_x509_crt cacert;
    mbedtls_x509_crt_init(&cacert);
    result = mbedtls_x509_crt_parse_file(&cacert, TRUST_PATH);
    assert(!result);
printf("trust loaded ok\n");

    mbedtls_ssl_conf_ca_chain(&conf, &cacert, NULL);

    result = mbedtls_ssl_set_hostname(&ssl, HOSTNAME);
    assert(!result);
printf("SNI set ok\n");

    mbedtls_ssl_set_bio(
        &ssl,
        &net_context,
        mbedtls_net_send,
        mbedtls_net_recv,
        mbedtls_net_recv_timeout
    );

    result = mbedtls_ssl_handshake(&ssl);
printf("handshake tried\n");

    if (result) {
        char errstr[200];
        mbedtls_strerror(result, errstr, sizeof(errstr));

        fprintf(stderr, "handshake: %s\n", errstr);
        return 1;
    }

    return 0;
}