dtls-client.c

/*
 * Copyright (C) 2020 Dyne.org foundation
 *
 * This file is subject to the terms and conditions of the Affero GNU
 * General Public License (AGPL) version 3. See the file LICENSE for
 * more details.
 *
 */

#include <wolfssl/ssl.h>
#include <wolfssl/error-ssl.h>
#include <sock_tls.h>
#include <net/sock.h>

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

#include "log.h"

#define SERVER_PORT 11111
#define APP_DTLS_BUF_SIZE 64

extern const unsigned char server_cert[];
extern const unsigned long server_cert_len;

static sock_tls_t skv;
static sock_tls_t *sk = &skv;

static void usage(const char *cmd_name)
{
    LOG(LOG_ERROR, "Usage: %s <server-address>\n", cmd_name);
}

#ifdef MODULE_WOLFSSL_PSK
/* identity is OpenSSL testing default for openssl s_client, keep same */
static const char* kIdentityStr = "Client_identity";

static inline unsigned int my_psk_client_cb(WOLFSSL* ssl, const char* hint,
        char* identity, unsigned int id_max_len, unsigned char* key,
        unsigned int key_max_len)
{
    (void)ssl;
    (void)hint;
    (void)key_max_len;

    /* see internal.h MAX_PSK_ID_LEN for PSK identity limit */
    strncpy(identity, kIdentityStr, id_max_len);

    if (wolfSSL_GetVersion(ssl) < WOLFSSL_TLSV1_3) {
        /* test key in hex is 0x1a2b3c4d , in decimal 439,041,101 , we're using
           unsigned binary */
        key[0] = 0x1a;
        key[1] = 0x2b;
        key[2] = 0x3c;
        key[3] = 0x4d;

        return 4;   /* length of key in octets or 0 for error */
    }
    else {
        int i;
        int b = 0x01;

        for (i = 0; i < 32; i++, b += 0x22) {
            if (b >= 0x100)
                b = 0x01;
            key[i] = b;
        }

        return 32;   /* length of key in octets or 0 for error */
    }
}
#endif

int dtls_client(int argc, char **argv)
{
    int ret = 0;
    char buf[APP_DTLS_BUF_SIZE] = "Hello from DTLS client!";
    char *iface;
    char *addr_str;
    int connect_timeout = 0;
    const int max_connect_timeouts = 5;

    if (argc != 2) {
        usage(argv[0]);
        return -1;
    }

    addr_str = argv[1];
    sock_udp_ep_t local = SOCK_IPV6_EP_ANY;
    sock_udp_ep_t remote = SOCK_IPV6_EP_ANY;

    /* Parsing <address> */
    iface = ipv6_addr_split_iface(addr_str);
    if (!iface) {
        if (gnrc_netif_numof() == 1) {
            /* assign the single interface found in gnrc_netif_numof() */
            remote.netif = (uint16_t)gnrc_netif_iter(NULL)->pid;
        }
    }
    else {
        gnrc_netif_t *netif = gnrc_netif_get_by_pid(atoi(iface));
        if (netif == NULL) {
            LOG(LOG_ERROR, "ERROR: interface not valid\n");
            usage(argv[0]);
            return -1;
        }
        remote.netif = (uint16_t)netif->pid;
    }
    if (ipv6_addr_from_str((ipv6_addr_t *)remote.addr.ipv6, addr_str) == NULL) {
        LOG(LOG_ERROR, "ERROR: unable to parse destination address\n");
        usage(argv[0]);
        return -1;
    }
    remote.port = SERVER_PORT;
    if (sock_dtls_create(sk, &local, &remote, 0, wolfDTLSv1_2_client_method()) != 0) {
        LOG(LOG_ERROR, "ERROR: Unable to create DTLS sock\n");
        return -1;
    }

#ifndef MODULE_WOLFSSL_PSK
    /* Disable certificate validation from the client side */
    wolfSSL_CTX_set_verify(sk->ctx, SSL_VERIFY_NONE, 0);

    /* Load certificate file for the DTLS client */
    if (wolfSSL_CTX_use_certificate_buffer(sk->ctx, server_cert,
                server_cert_len, SSL_FILETYPE_ASN1 ) != SSL_SUCCESS)
    {
        LOG(LOG_ERROR, "Error loading cert buffer\n");
        return -1;
    }

#else /* !def MODULE_WOLFSSL_PSK */
    wolfSSL_CTX_set_psk_client_callback(sk->ctx, my_psk_client_cb);
#endif

    if (sock_dtls_session_create(sk) < 0)
        return -1;
    wolfSSL_dtls_set_timeout_init(sk->ssl, 5);
    LOG(LOG_INFO, "connecting to server...\n");
    /* attempt to connect until the connection is successful */
    do {
        ret = wolfSSL_connect(sk->ssl);
        if ((ret != SSL_SUCCESS)) {
            if(wolfSSL_get_error(sk->ssl, ret) == SOCKET_ERROR_E) {
                LOG(LOG_WARNING, "Socket error: reconnecting...\n");
                sock_dtls_session_destroy(sk);
                connect_timeout = 0;
                if (sock_dtls_session_create(sk) < 0)
                    return -1;
            }
            if ((wolfSSL_get_error(sk->ssl, ret) == WOLFSSL_ERROR_WANT_READ) &&
                    (connect_timeout++ >= max_connect_timeouts)) {
                LOG(LOG_WARNING, "Server not responding: reconnecting...\n");
                sock_dtls_session_destroy(sk);
                connect_timeout = 0;
                if (sock_dtls_session_create(sk) < 0)
                    return -1;
            }
        }
    } while(ret != SSL_SUCCESS);

    /* set remote endpoint */
    sock_dtls_set_endpoint(sk, &remote);

    /* send the hello message */
    wolfSSL_write(sk->ssl, buf, strlen(buf));

    /* wait for a reply, indefinitely */
    do {
        ret = wolfSSL_read(sk->ssl, buf, APP_DTLS_BUF_SIZE - 1);
        LOG(LOG_INFO, "wolfSSL_read returned %d\n", ret);
    } while (ret <= 0);
    buf[ret] = (char)0;
    LOG(LOG_INFO, "Received: '%s'\n", buf);

    /* Clean up and exit. */
    LOG(LOG_INFO, "Closing connection.\n");
    sock_dtls_session_destroy(sk);
    sock_dtls_close(sk);
    return 0;
}