ssl_fork_server.c

/*
 *  SSL server demonstration program using fork() for handling multiple clients
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#include "mbedtls/platform.h"

#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_CERTS_C) ||    \
    !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_SSL_TLS_C) || \
    !defined(MBEDTLS_SSL_SRV_C) || !defined(MBEDTLS_NET_C) ||     \
    !defined(MBEDTLS_RSA_C) || !defined(MBEDTLS_CTR_DRBG_C) ||    \
    !defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_TIMING_C) || \
    !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_PEM_PARSE_C)
int main(int argc, char *argv[])
{
    ((void) argc);
    ((void) argv);

    mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_CERTS_C and/or MBEDTLS_ENTROPY_C "
                   "and/or MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_SRV_C and/or "
                   "MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
                   "MBEDTLS_CTR_DRBG_C and/or MBEDTLS_X509_CRT_PARSE_C and/or "
                   "MBEDTLS_TIMING_C and/or MBEDTLS_PEM_PARSE_C not defined.\n");
    mbedtls_exit(0);
}
#elif defined(_WIN32)
int main(void)
{
    mbedtls_printf("_WIN32 defined. This application requires fork() and signals "
                   "to work correctly.\n");
    mbedtls_exit(0);
}
#else

#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/certs.h"
#include "mbedtls/x509.h"
#include "mbedtls/ssl.h"
#include "mbedtls/net_sockets.h"
#include "mbedtls/timing.h"

#include <string.h>
#include <signal.h>

#if !defined(_MSC_VER) || defined(EFIX64) || defined(EFI32)
#include <unistd.h>
#endif

#define HTTP_RESPONSE \
    "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n" \
    "<h2>Mbed TLS Test Server</h2>\r\n" \
    "<p>Successful connection using: %s</p>\r\n"

#define DEBUG_LEVEL 0


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, cnt = 0, pid;
    int exit_code = MBEDTLS_EXIT_FAILURE;
    mbedtls_net_context listen_fd, client_fd;
    unsigned char buf[1024];
    const char *pers = "ssl_fork_server";

    mbedtls_entropy_context entropy;
    mbedtls_ctr_drbg_context ctr_drbg;
    mbedtls_ssl_context ssl;
    mbedtls_ssl_config conf;
    mbedtls_x509_crt srvcert;
    mbedtls_pk_context pkey;

    mbedtls_net_init(&listen_fd);
    mbedtls_net_init(&client_fd);
    mbedtls_ssl_init(&ssl);
    mbedtls_ssl_config_init(&conf);
    mbedtls_entropy_init(&entropy);
    mbedtls_pk_init(&pkey);
    mbedtls_x509_crt_init(&srvcert);
    mbedtls_ctr_drbg_init(&ctr_drbg);

#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 */

    signal(SIGCHLD, SIG_IGN);

    /*
     * 0. Initial seeding of the RNG
     */
    mbedtls_printf("\n  . Initial seeding of the random 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!  mbedtls_ctr_drbg_seed returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    /*
     * 1. Load the certificates and private RSA key
     */
    mbedtls_printf("  . Loading the server cert. and key...");
    fflush(stdout);

    /*
     * This demonstration program uses embedded test certificates.
     * Instead, you may want to use mbedtls_x509_crt_parse_file() to read the
     * server and CA certificates, as well as mbedtls_pk_parse_keyfile().
     */
    ret = mbedtls_x509_crt_parse(&srvcert, (const unsigned char *) mbedtls_test_srv_crt,
                                 mbedtls_test_srv_crt_len);
    if (ret != 0) {
        mbedtls_printf(" failed!  mbedtls_x509_crt_parse returned %d\n\n", ret);
        goto exit;
    }

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

    ret =  mbedtls_pk_parse_key(&pkey, (const unsigned char *) mbedtls_test_srv_key,
                                mbedtls_test_srv_key_len, NULL, 0);
    if (ret != 0) {
        mbedtls_printf(" failed!  mbedtls_pk_parse_key returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    /*
     * 1b. Prepare SSL configuration
     */
    mbedtls_printf("  . Configuring SSL...");
    fflush(stdout);

    if ((ret = mbedtls_ssl_config_defaults(&conf,
                                           MBEDTLS_SSL_IS_SERVER,
                                           MBEDTLS_SSL_TRANSPORT_STREAM,
                                           MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
        mbedtls_printf(" failed!  mbedtls_ssl_config_defaults returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg);
    mbedtls_ssl_conf_dbg(&conf, my_debug, stdout);

    mbedtls_ssl_conf_ca_chain(&conf, srvcert.next, NULL);
    if ((ret = mbedtls_ssl_conf_own_cert(&conf, &srvcert, &pkey)) != 0) {
        mbedtls_printf(" failed!  mbedtls_ssl_conf_own_cert returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    /*
     * 2. Setup the listening TCP socket
     */
    mbedtls_printf("  . Bind on https://localhost:4433/ ...");
    fflush(stdout);

    if ((ret = mbedtls_net_bind(&listen_fd, NULL, "4433", MBEDTLS_NET_PROTO_TCP)) != 0) {
        mbedtls_printf(" failed!  mbedtls_net_bind returned %d\n\n", ret);
        goto exit;
    }

    mbedtls_printf(" ok\n");

    while (1) {
        /*
         * 3. Wait until a client connects
         */
        mbedtls_net_init(&client_fd);
        mbedtls_ssl_init(&ssl);

        mbedtls_printf("  . Waiting for a remote connection ...\n");
        fflush(stdout);

        if ((ret = mbedtls_net_accept(&listen_fd, &client_fd,
                                      NULL, 0, NULL)) != 0) {
            mbedtls_printf(" failed!  mbedtls_net_accept returned %d\n\n", ret);
            goto exit;
        }

        /*
         * 3.5. Forking server thread
         */

        mbedtls_printf("  . Forking to handle connection ...");
        fflush(stdout);

        pid = fork();

        if (pid < 0) {
            mbedtls_printf(" failed!  fork returned %d\n\n", pid);
            goto exit;
        }

        if (pid != 0) {
            mbedtls_printf(" ok\n");
            mbedtls_net_close(&client_fd);

            if ((ret = mbedtls_ctr_drbg_reseed(&ctr_drbg,
                                               (const unsigned char *) "parent",
                                               6)) != 0) {
                mbedtls_printf(" failed!  mbedtls_ctr_drbg_reseed returned %d\n\n", ret);
                goto exit;
            }

            continue;
        }

        mbedtls_net_close(&listen_fd);

        pid = getpid();

        /*
         * 4. Setup stuff
         */
        mbedtls_printf("pid %d: Setting up the SSL data.\n", pid);
        fflush(stdout);

        if ((ret = mbedtls_ctr_drbg_reseed(&ctr_drbg,
                                           (const unsigned char *) "child",
                                           5)) != 0) {
            mbedtls_printf(
                "pid %d: SSL setup failed!  mbedtls_ctr_drbg_reseed returned %d\n\n",
                pid, ret);
            goto exit;
        }

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

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

        mbedtls_printf("pid %d: SSL setup ok\n", pid);

        /*
         * 5. Handshake
         */
        mbedtls_printf("pid %d: Performing the SSL/TLS handshake.\n", pid);
        fflush(stdout);

        while ((ret = mbedtls_ssl_handshake(&ssl)) != 0) {
            if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
                mbedtls_printf(
                    "pid %d: SSL handshake failed!  mbedtls_ssl_handshake returned %d\n\n",
                    pid, ret);
                goto exit;
            }
        }

        mbedtls_printf("pid %d: SSL handshake ok\n", pid);

        /*
         * 6. Read the HTTP Request
         */
        mbedtls_printf("pid %d: Start reading from client.\n", pid);
        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 <= 0) {
                switch (ret) {
                    case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
                        mbedtls_printf("pid %d: connection was closed gracefully\n", pid);
                        break;

                    case MBEDTLS_ERR_NET_CONN_RESET:
                        mbedtls_printf("pid %d: connection was reset by peer\n", pid);
                        break;

                    default:
                        mbedtls_printf("pid %d: mbedtls_ssl_read returned %d\n", pid, ret);
                        break;
                }

                break;
            }

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

            if (ret > 0) {
                break;
            }
        } while (1);

        /*
         * 7. Write the 200 Response
         */
        mbedtls_printf("pid %d: Start writing to client.\n", pid);
        fflush(stdout);

        len = sprintf((char *) buf, HTTP_RESPONSE,
                      mbedtls_ssl_get_ciphersuite(&ssl));

        while (cnt++ < 100) {
            while ((ret = mbedtls_ssl_write(&ssl, buf, len)) <= 0) {
                if (ret == MBEDTLS_ERR_NET_CONN_RESET) {
                    mbedtls_printf(
                        "pid %d: Write failed!  peer closed the connection\n\n", pid);
                    goto exit;
                }

                if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
                    mbedtls_printf(
                        "pid %d: Write failed!  mbedtls_ssl_write returned %d\n\n",
                        pid, ret);
                    goto exit;
                }
            }
            len = ret;
            mbedtls_printf("pid %d: %d bytes written\n\n%s\n", pid, len, (char *) buf);

            mbedtls_net_usleep(1000000);
        }

        mbedtls_ssl_close_notify(&ssl);
        goto exit;
    }

    exit_code = MBEDTLS_EXIT_SUCCESS;

exit:
    mbedtls_net_free(&client_fd);
    mbedtls_net_free(&listen_fd);
    mbedtls_x509_crt_free(&srvcert);
    mbedtls_pk_free(&pkey);
    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 */

#if defined(_WIN32)
    mbedtls_printf("  Press Enter to exit this program.\n");
    fflush(stdout); getchar();
#endif

    mbedtls_exit(exit_code);
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_CERTS_C && MBEDTLS_ENTROPY_C &&
          MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_SRV_C && MBEDTLS_NET_C &&
          MBEDTLS_RSA_C && MBEDTLS_CTR_DRBG_C && MBEDTLS_PEM_PARSE_C &&
          ! _WIN32 */