openssl/apps/s_cb.c

/* apps/s_cb.c - callback functions used by s_client, s_server, and s_time */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */
/* ====================================================================
 * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include <stdlib.h>
#define USE_SOCKETS
#define NON_MAIN
#include "apps.h"
#undef NON_MAIN
#undef USE_SOCKETS
#include <openssl/err.h>
#include <openssl/rand.h>
#include <openssl/x509.h>
#include <openssl/ssl.h>
#include "s_apps.h"

#define COOKIE_SECRET_LENGTH    16

int verify_depth = 0;
int verify_error = X509_V_OK;
int verify_return_error = 0;
unsigned char cookie_secret[COOKIE_SECRET_LENGTH];
int cookie_initialized = 0;

int MS_CALLBACK verify_callback(int ok, X509_STORE_CTX *ctx)
{
    X509 *err_cert;
    int err, depth;

    err_cert = X509_STORE_CTX_get_current_cert(ctx);
    err = X509_STORE_CTX_get_error(ctx);
    depth = X509_STORE_CTX_get_error_depth(ctx);

    BIO_printf(bio_err, "depth=%d ", depth);
    if (err_cert) {
        X509_NAME_print_ex(bio_err, X509_get_subject_name(err_cert),
                           0, XN_FLAG_ONELINE);
        BIO_puts(bio_err, "\n");
    } else
        BIO_puts(bio_err, "<no cert>\n");
    if (!ok) {
        BIO_printf(bio_err, "verify error:num=%d:%s\n", err,
                   X509_verify_cert_error_string(err));
        if (verify_depth >= depth) {
            if (!verify_return_error)
                ok = 1;
            verify_error = X509_V_OK;
        } else {
            ok = 0;
            verify_error = X509_V_ERR_CERT_CHAIN_TOO_LONG;
        }
    }
    switch (err) {
    case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
        BIO_puts(bio_err, "issuer= ");
        X509_NAME_print_ex(bio_err, X509_get_issuer_name(err_cert),
                           0, XN_FLAG_ONELINE);
        BIO_puts(bio_err, "\n");
        break;
    case X509_V_ERR_CERT_NOT_YET_VALID:
    case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
        BIO_printf(bio_err, "notBefore=");
        ASN1_TIME_print(bio_err, X509_get_notBefore(err_cert));
        BIO_printf(bio_err, "\n");
        break;
    case X509_V_ERR_CERT_HAS_EXPIRED:
    case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
        BIO_printf(bio_err, "notAfter=");
        ASN1_TIME_print(bio_err, X509_get_notAfter(err_cert));
        BIO_printf(bio_err, "\n");
        break;
    case X509_V_ERR_NO_EXPLICIT_POLICY:
        policies_print(bio_err, ctx);
        break;
    }
    if (err == X509_V_OK && ok == 2)
        policies_print(bio_err, ctx);

    BIO_printf(bio_err, "verify return:%d\n", ok);
    return (ok);
}

int set_cert_stuff(SSL_CTX *ctx, char *cert_file, char *key_file)
{
    if (cert_file != NULL) {
        /*-
        SSL *ssl;
        X509 *x509;
        */

        if (SSL_CTX_use_certificate_file(ctx, cert_file,
                                         SSL_FILETYPE_PEM) <= 0) {
            BIO_printf(bio_err, "unable to get certificate from '%s'\n",
                       cert_file);
            ERR_print_errors(bio_err);
            return (0);
        }
        if (key_file == NULL)
            key_file = cert_file;
        if (SSL_CTX_use_PrivateKey_file(ctx, key_file, SSL_FILETYPE_PEM) <= 0) {
            BIO_printf(bio_err, "unable to get private key from '%s'\n",
                       key_file);
            ERR_print_errors(bio_err);
            return (0);
        }

        /*-
        In theory this is no longer needed
        ssl=SSL_new(ctx);
        x509=SSL_get_certificate(ssl);

        if (x509 != NULL) {
                EVP_PKEY *pktmp;
                pktmp = X509_get_pubkey(x509);
                EVP_PKEY_copy_parameters(pktmp,
                                        SSL_get_privatekey(ssl));
                EVP_PKEY_free(pktmp);
        }
        SSL_free(ssl);
        */

        /*
         * If we are using DSA, we can copy the parameters from the private
         * key
         */

        /*
         * Now we know that a key and cert have been set against the SSL
         * context
         */
        if (!SSL_CTX_check_private_key(ctx)) {
            BIO_printf(bio_err,
                       "Private key does not match the certificate public key\n");
            return (0);
        }
    }
    return (1);
}

int set_cert_key_stuff(SSL_CTX *ctx, X509 *cert, EVP_PKEY *key)
{
    if (cert == NULL)
        return 1;
    if (SSL_CTX_use_certificate(ctx, cert) <= 0) {
        BIO_printf(bio_err, "error setting certificate\n");
        ERR_print_errors(bio_err);
        return 0;
    }
    if (SSL_CTX_use_PrivateKey(ctx, key) <= 0) {
        BIO_printf(bio_err, "error setting private key\n");
        ERR_print_errors(bio_err);
        return 0;
    }

    /*
     * Now we know that a key and cert have been set against the SSL context
     */
    if (!SSL_CTX_check_private_key(ctx)) {
        BIO_printf(bio_err,
                   "Private key does not match the certificate public key\n");
        return 0;
    }
    return 1;
}

long MS_CALLBACK bio_dump_callback(BIO *bio, int cmd, const char *argp,
                                   int argi, long argl, long ret)
{
    BIO *out;

    out = (BIO *)BIO_get_callback_arg(bio);
    if (out == NULL)
        return (ret);

    if (cmd == (BIO_CB_READ | BIO_CB_RETURN)) {
        BIO_printf(out, "read from %p [%p] (%lu bytes => %ld (0x%lX))\n",
                   (void *)bio, argp, (unsigned long)argi, ret, ret);
        BIO_dump(out, argp, (int)ret);
        return (ret);
    } else if (cmd == (BIO_CB_WRITE | BIO_CB_RETURN)) {
        BIO_printf(out, "write to %p [%p] (%lu bytes => %ld (0x%lX))\n",
                   (void *)bio, argp, (unsigned long)argi, ret, ret);
        BIO_dump(out, argp, (int)ret);
    }
    return (ret);
}

void MS_CALLBACK apps_ssl_info_callback(const SSL *s, int where, int ret)
{
    const char *str;
    int w;

    w = where & ~SSL_ST_MASK;

    if (w & SSL_ST_CONNECT)
        str = "SSL_connect";
    else if (w & SSL_ST_ACCEPT)
        str = "SSL_accept";
    else
        str = "undefined";

    if (where & SSL_CB_LOOP) {
        BIO_printf(bio_err, "%s:%s\n", str, SSL_state_string_long(s));
    } else if (where & SSL_CB_ALERT) {
        str = (where & SSL_CB_READ) ? "read" : "write";
        BIO_printf(bio_err, "SSL3 alert %s:%s:%s\n",
                   str,
                   SSL_alert_type_string_long(ret),
                   SSL_alert_desc_string_long(ret));
    } else if (where & SSL_CB_EXIT) {
        if (ret == 0)
            BIO_printf(bio_err, "%s:failed in %s\n",
                       str, SSL_state_string_long(s));
        else if (ret < 0) {
            BIO_printf(bio_err, "%s:error in %s\n",
                       str, SSL_state_string_long(s));
        }
    }
}

void MS_CALLBACK msg_cb(int write_p, int version, int content_type,
                        const void *buf, size_t len, SSL *ssl, void *arg)
{
    BIO *bio = arg;
    const char *str_write_p, *str_version, *str_content_type =
        "", *str_details1 = "", *str_details2 = "";

    str_write_p = write_p ? ">>>" : "<<<";

    switch (version) {
    case SSL2_VERSION:
        str_version = "SSL 2.0";
        break;
    case SSL3_VERSION:
        str_version = "SSL 3.0 ";
        break;
    case TLS1_VERSION:
        str_version = "TLS 1.0 ";
        break;
    case DTLS1_VERSION:
        str_version = "DTLS 1.0 ";
        break;
    case DTLS1_BAD_VER:
        str_version = "DTLS 1.0 (bad) ";
        break;
    default:
        str_version = "???";
    }

    if (version == SSL2_VERSION) {
        str_details1 = "???";

        if (len > 0) {
            switch (((const unsigned char *)buf)[0]) {
            case 0:
                str_details1 = ", ERROR:";
                str_details2 = " ???";
                if (len >= 3) {
                    unsigned err =
                        (((const unsigned char *)buf)[1] << 8) +
                        ((const unsigned char *)buf)[2];

                    switch (err) {
                    case 0x0001:
                        str_details2 = " NO-CIPHER-ERROR";
                        break;
                    case 0x0002:
                        str_details2 = " NO-CERTIFICATE-ERROR";
                        break;
                    case 0x0004:
                        str_details2 = " BAD-CERTIFICATE-ERROR";
                        break;
                    case 0x0006:
                        str_details2 = " UNSUPPORTED-CERTIFICATE-TYPE-ERROR";
                        break;
                    }
                }

                break;
            case 1:
                str_details1 = ", CLIENT-HELLO";
                break;
            case 2:
                str_details1 = ", CLIENT-MASTER-KEY";
                break;
            case 3:
                str_details1 = ", CLIENT-FINISHED";
                break;
            case 4:
                str_details1 = ", SERVER-HELLO";
                break;
            case 5:
                str_details1 = ", SERVER-VERIFY";
                break;
            case 6:
                str_details1 = ", SERVER-FINISHED";
                break;
            case 7:
                str_details1 = ", REQUEST-CERTIFICATE";
                break;
            case 8:
                str_details1 = ", CLIENT-CERTIFICATE";
                break;
            }
        }
    }

    if (version == SSL3_VERSION ||
        version == TLS1_VERSION ||
        version == DTLS1_VERSION || version == DTLS1_BAD_VER) {
        switch (content_type) {
        case 20:
            str_content_type = "ChangeCipherSpec";
            break;
        case 21:
            str_content_type = "Alert";
            break;
        case 22:
            str_content_type = "Handshake";
            break;
        }

        if (content_type == 21) { /* Alert */
            str_details1 = ", ???";

            if (len == 2) {
                switch (((const unsigned char *)buf)[0]) {
                case 1:
                    str_details1 = ", warning";
                    break;
                case 2:
                    str_details1 = ", fatal";
                    break;
                }

                str_details2 = " ???";
                switch (((const unsigned char *)buf)[1]) {
                case 0:
                    str_details2 = " close_notify";
                    break;
                case 10:
                    str_details2 = " unexpected_message";
                    break;
                case 20:
                    str_details2 = " bad_record_mac";
                    break;
                case 21:
                    str_details2 = " decryption_failed";
                    break;
                case 22:
                    str_details2 = " record_overflow";
                    break;
                case 30:
                    str_details2 = " decompression_failure";
                    break;
                case 40:
                    str_details2 = " handshake_failure";
                    break;
                case 42:
                    str_details2 = " bad_certificate";
                    break;
                case 43:
                    str_details2 = " unsupported_certificate";
                    break;
                case 44:
                    str_details2 = " certificate_revoked";
                    break;
                case 45:
                    str_details2 = " certificate_expired";
                    break;
                case 46:
                    str_details2 = " certificate_unknown";
                    break;
                case 47:
                    str_details2 = " illegal_parameter";
                    break;
                case 48:
                    str_details2 = " unknown_ca";
                    break;
                case 49:
                    str_details2 = " access_denied";
                    break;
                case 50:
                    str_details2 = " decode_error";
                    break;
                case 51:
                    str_details2 = " decrypt_error";
                    break;
                case 60:
                    str_details2 = " export_restriction";
                    break;
                case 70:
                    str_details2 = " protocol_version";
                    break;
                case 71:
                    str_details2 = " insufficient_security";
                    break;
                case 80:
                    str_details2 = " internal_error";
                    break;
                case 90:
                    str_details2 = " user_canceled";
                    break;
                case 100:
                    str_details2 = " no_renegotiation";
                    break;
                case 110:
                    str_details2 = " unsupported_extension";
                    break;
                case 111:
                    str_details2 = " certificate_unobtainable";
                    break;
                case 112:
                    str_details2 = " unrecognized_name";
                    break;
                case 113:
                    str_details2 = " bad_certificate_status_response";
                    break;
                case 114:
                    str_details2 = " bad_certificate_hash_value";
                    break;
                }
            }
        }

        if (content_type == 22) { /* Handshake */
            str_details1 = "???";

            if (len > 0) {
                switch (((const unsigned char *)buf)[0]) {
                case 0:
                    str_details1 = ", HelloRequest";
                    break;
                case 1:
                    str_details1 = ", ClientHello";
                    break;
                case 2:
                    str_details1 = ", ServerHello";
                    break;
                case 3:
                    str_details1 = ", HelloVerifyRequest";
                    break;
                case 11:
                    str_details1 = ", Certificate";
                    break;
                case 12:
                    str_details1 = ", ServerKeyExchange";
                    break;
                case 13:
                    str_details1 = ", CertificateRequest";
                    break;
                case 14:
                    str_details1 = ", ServerHelloDone";
                    break;
                case 15:
                    str_details1 = ", CertificateVerify";
                    break;
                case 16:
                    str_details1 = ", ClientKeyExchange";
                    break;
                case 20:
                    str_details1 = ", Finished";
                    break;
                }
            }
        }
    }

    BIO_printf(bio, "%s %s%s [length %04lx]%s%s\n", str_write_p, str_version,
               str_content_type, (unsigned long)len, str_details1,
               str_details2);

    if (len > 0) {
        size_t num, i;

        BIO_printf(bio, "   ");
        num = len;
#if 0
        if (num > 16)
            num = 16;
#endif
        for (i = 0; i < num; i++) {
            if (i % 16 == 0 && i > 0)
                BIO_printf(bio, "\n   ");
            BIO_printf(bio, " %02x", ((const unsigned char *)buf)[i]);
        }
        if (i < len)
            BIO_printf(bio, " ...");
        BIO_printf(bio, "\n");
    }
    (void)BIO_flush(bio);
}

void MS_CALLBACK tlsext_cb(SSL *s, int client_server, int type,
                           unsigned char *data, int len, void *arg)
{
    BIO *bio = arg;
    char *extname;

    switch (type) {
    case TLSEXT_TYPE_server_name:
        extname = "server name";
        break;

    case TLSEXT_TYPE_max_fragment_length:
        extname = "max fragment length";
        break;

    case TLSEXT_TYPE_client_certificate_url:
        extname = "client certificate URL";
        break;

    case TLSEXT_TYPE_trusted_ca_keys:
        extname = "trusted CA keys";
        break;

    case TLSEXT_TYPE_truncated_hmac:
        extname = "truncated HMAC";
        break;

    case TLSEXT_TYPE_status_request:
        extname = "status request";
        break;

    case TLSEXT_TYPE_elliptic_curves:
        extname = "elliptic curves";
        break;

    case TLSEXT_TYPE_ec_point_formats:
        extname = "EC point formats";
        break;

    case TLSEXT_TYPE_session_ticket:
        extname = "server ticket";
        break;

    case TLSEXT_TYPE_renegotiate:
        extname = "renegotiate";
        break;

#ifdef TLSEXT_TYPE_opaque_prf_input
    case TLSEXT_TYPE_opaque_prf_input:
        extname = "opaque PRF input";
        break;
#endif

    default:
        extname = "unknown";
        break;

    }

    BIO_printf(bio, "TLS %s extension \"%s\" (id=%d), len=%d\n",
               client_server ? "server" : "client", extname, type, len);
    BIO_dump(bio, (char *)data, len);
    (void)BIO_flush(bio);
}

int MS_CALLBACK generate_cookie_callback(SSL *ssl, unsigned char *cookie,
                                         unsigned int *cookie_len)
{
    unsigned char *buffer, result[EVP_MAX_MD_SIZE];
    unsigned int length, resultlength;
    union {
        struct sockaddr sa;
        struct sockaddr_in s4;
#if OPENSSL_USE_IPV6
        struct sockaddr_in6 s6;
#endif
    } peer;

    /* Initialize a random secret */
    if (!cookie_initialized) {
        if (!RAND_bytes(cookie_secret, COOKIE_SECRET_LENGTH)) {
            BIO_printf(bio_err, "error setting random cookie secret\n");
            return 0;
        }
        cookie_initialized = 1;
    }

    /* Read peer information */
    (void)BIO_dgram_get_peer(SSL_get_rbio(ssl), &peer);

    /* Create buffer with peer's address and port */
    length = 0;
    switch (peer.sa.sa_family) {
    case AF_INET:
        length += sizeof(struct in_addr);
        length += sizeof(peer.s4.sin_port);
        break;
#if OPENSSL_USE_IPV6
    case AF_INET6:
        length += sizeof(struct in6_addr);
        length += sizeof(peer.s6.sin6_port);
        break;
#endif
    default:
        OPENSSL_assert(0);
        break;
    }
    buffer = OPENSSL_malloc(length);

    if (buffer == NULL) {
        BIO_printf(bio_err, "out of memory\n");
        return 0;
    }

    switch (peer.sa.sa_family) {
    case AF_INET:
        memcpy(buffer, &peer.s4.sin_port, sizeof(peer.s4.sin_port));
        memcpy(buffer + sizeof(peer.s4.sin_port),
               &peer.s4.sin_addr, sizeof(struct in_addr));
        break;
#if OPENSSL_USE_IPV6
    case AF_INET6:
        memcpy(buffer, &peer.s6.sin6_port, sizeof(peer.s6.sin6_port));
        memcpy(buffer + sizeof(peer.s6.sin6_port),
               &peer.s6.sin6_addr, sizeof(struct in6_addr));
        break;
#endif
    default:
        OPENSSL_assert(0);
        break;
    }

    /* Calculate HMAC of buffer using the secret */
    HMAC(EVP_sha1(), cookie_secret, COOKIE_SECRET_LENGTH,
         buffer, length, result, &resultlength);
    OPENSSL_free(buffer);

    memcpy(cookie, result, resultlength);
    *cookie_len = resultlength;

    return 1;
}

int MS_CALLBACK verify_cookie_callback(SSL *ssl, unsigned char *cookie,
                                       unsigned int cookie_len)
{
    unsigned char *buffer, result[EVP_MAX_MD_SIZE];
    unsigned int length, resultlength;
    union {
        struct sockaddr sa;
        struct sockaddr_in s4;
#if OPENSSL_USE_IPV6
        struct sockaddr_in6 s6;
#endif
    } peer;

    /* If secret isn't initialized yet, the cookie can't be valid */
    if (!cookie_initialized)
        return 0;

    /* Read peer information */
    (void)BIO_dgram_get_peer(SSL_get_rbio(ssl), &peer);

    /* Create buffer with peer's address and port */
    length = 0;
    switch (peer.sa.sa_family) {
    case AF_INET:
        length += sizeof(struct in_addr);
        length += sizeof(peer.s4.sin_port);
        break;
#if OPENSSL_USE_IPV6
    case AF_INET6:
        length += sizeof(struct in6_addr);
        length += sizeof(peer.s6.sin6_port);
        break;
#endif
    default:
        OPENSSL_assert(0);
        break;
    }
    buffer = OPENSSL_malloc(length);

    if (buffer == NULL) {
        BIO_printf(bio_err, "out of memory\n");
        return 0;
    }

    switch (peer.sa.sa_family) {
    case AF_INET:
        memcpy(buffer, &peer.s4.sin_port, sizeof(peer.s4.sin_port));
        memcpy(buffer + sizeof(peer.s4.sin_port),
               &peer.s4.sin_addr, sizeof(struct in_addr));
        break;
#if OPENSSL_USE_IPV6
    case AF_INET6:
        memcpy(buffer, &peer.s6.sin6_port, sizeof(peer.s6.sin6_port));
        memcpy(buffer + sizeof(peer.s6.sin6_port),
               &peer.s6.sin6_addr, sizeof(struct in6_addr));
        break;
#endif
    default:
        OPENSSL_assert(0);
        break;
    }

    /* Calculate HMAC of buffer using the secret */
    HMAC(EVP_sha1(), cookie_secret, COOKIE_SECRET_LENGTH,
         buffer, length, result, &resultlength);
    OPENSSL_free(buffer);

    if (cookie_len == resultlength
        && memcmp(result, cookie, resultlength) == 0)
        return 1;

    return 0;
}