ACL Optimization: inline currentAnswer() methods to reduce copying

[thirdparty/squid.git] / src / ssl / support.cc

/*
 * $Id$
 *
 * AUTHOR: Benno Rice
 * DEBUG: section 83    SSL accelerator support
 *
 * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from the
 *  Internet community.  Development is led by Duane Wessels of the
 *  National Laboratory for Applied Network Research and funded by the
 *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
 *  Duane Wessels and the University of California San Diego.  Please
 *  see the COPYRIGHT file for full details.  Squid incorporates
 *  software developed and/or copyrighted by other sources.  Please see
 *  the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "squid-old.h"

/* MS Visual Studio Projects are monolithic, so we need the following
 * #if to exclude the SSL code from compile process when not needed.
 */
#if USE_SSL

#include "fde.h"
#include "acl/FilledChecklist.h"
#include "ssl/ErrorDetail.h"
#include "ssl/support.h"
#include "ssl/gadgets.h"

/**
 \defgroup ServerProtocolSSLInternal Server-Side SSL Internals
 \ingroup ServerProtocolSSLAPI
 */

/// \ingroup ServerProtocolSSLInternal
static int
ssl_ask_password_cb(char *buf, int size, int rwflag, void *userdata)
{
    FILE *in;
    int len = 0;
    char cmdline[1024];

    snprintf(cmdline, sizeof(cmdline), "\"%s\" \"%s\"", Config.Program.ssl_password, (const char *)userdata);
    in = popen(cmdline, "r");

    if (fgets(buf, size, in))

        len = strlen(buf);

    while (len > 0 && (buf[len - 1] == '\n' || buf[len - 1] == '\r'))

        len--;

    buf[len] = '\0';

    pclose(in);

    return len;
}

/// \ingroup ServerProtocolSSLInternal
static void
ssl_ask_password(SSL_CTX * context, const char * prompt)
{
    if (Config.Program.ssl_password) {
        SSL_CTX_set_default_passwd_cb(context, ssl_ask_password_cb);
        SSL_CTX_set_default_passwd_cb_userdata(context, (void *)prompt);
    }
}

/// \ingroup ServerProtocolSSLInternal
static RSA *
ssl_temp_rsa_cb(SSL * ssl, int anInt, int keylen)
{
    static RSA *rsa_512 = NULL;
    static RSA *rsa_1024 = NULL;
    RSA *rsa = NULL;
    int newkey = 0;

    switch (keylen) {

    case 512:

        if (!rsa_512) {
            rsa_512 = RSA_generate_key(512, RSA_F4, NULL, NULL);
            newkey = 1;
        }

        rsa = rsa_512;
        break;

    case 1024:

        if (!rsa_1024) {
            rsa_1024 = RSA_generate_key(1024, RSA_F4, NULL, NULL);
            newkey = 1;
        }

        rsa = rsa_1024;
        break;

    default:
        debugs(83, 1, "ssl_temp_rsa_cb: Unexpected key length " << keylen);
        return NULL;
    }

    if (rsa == NULL) {
        debugs(83, 1, "ssl_temp_rsa_cb: Failed to generate key " << keylen);
        return NULL;
    }

    if (newkey) {
        if (do_debug(83, 5))
            PEM_write_RSAPrivateKey(debug_log, rsa, NULL, NULL, 0, NULL, NULL);

        debugs(83, 1, "Generated ephemeral RSA key of length " << keylen);
    }

    return rsa;
}

int Ssl::asn1timeToString(ASN1_TIME *tm, char *buf, int len)
{
    BIO *bio;
    int write = 0;
    bio = BIO_new(BIO_s_mem());
    if (bio) {
        if (ASN1_TIME_print(bio, tm))
            write = BIO_read(bio, buf, len-1);
        BIO_free(bio);
    }
    buf[write]='\0';
    return write;
}

int Ssl::matchX509CommonNames(X509 *peer_cert, void *check_data, int (*check_func)(void *check_data,  ASN1_STRING *cn_data))
{
    assert(peer_cert);

    X509_NAME *name = X509_get_subject_name(peer_cert);

    for (int i = X509_NAME_get_index_by_NID(name, NID_commonName, -1); i >= 0; i = X509_NAME_get_index_by_NID(name, NID_commonName, i)) {

        ASN1_STRING *cn_data = X509_NAME_ENTRY_get_data(X509_NAME_get_entry(name, i));

        if ( (*check_func)(check_data, cn_data) == 0)
            return 1;
    }

    STACK_OF(GENERAL_NAME) * altnames;
    altnames = (STACK_OF(GENERAL_NAME)*)X509_get_ext_d2i(peer_cert, NID_subject_alt_name, NULL, NULL);

    if (altnames) {
        int numalts = sk_GENERAL_NAME_num(altnames);
        for (int i = 0; i < numalts; i++) {
            const GENERAL_NAME *check = sk_GENERAL_NAME_value(altnames, i);
            if (check->type != GEN_DNS) {
                continue;
            }
            ASN1_STRING *cn_data = check->d.dNSName;

            if ( (*check_func)(check_data, cn_data) == 0)
                return 1;
        }
        sk_GENERAL_NAME_pop_free(altnames, GENERAL_NAME_free);
    }
    return 0;
}

static int check_domain( void *check_data, ASN1_STRING *cn_data)
{
    char cn[1024];
    const char *server = (const char *)check_data;

    if (cn_data->length > (int)sizeof(cn) - 1) {
        return 1; //if does not fit our buffer just ignore
    }
    memcpy(cn, cn_data->data, cn_data->length);
    cn[cn_data->length] = '\0';
    debugs(83, 4, "Verifying server domain " << server << " to certificate name/subjectAltName " << cn);
    return matchDomainName(server, cn[0] == '*' ? cn + 1 : cn);
}

bool Ssl::checkX509ServerValidity(X509 *cert, const char *server)
{
    return matchX509CommonNames(cert, (void *)server, check_domain);
}

/// \ingroup ServerProtocolSSLInternal
static int
ssl_verify_cb(int ok, X509_STORE_CTX * ctx)
{
    // preserve original ctx->error before SSL_ calls can overwrite it
    Ssl::ssl_error_t error_no = ok ? SSL_ERROR_NONE : ctx->error;

    char buffer[256] = "";
    SSL *ssl = (SSL *)X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
    SSL_CTX *sslctx = SSL_get_SSL_CTX(ssl);
    const char *server = (const char *)SSL_get_ex_data(ssl, ssl_ex_index_server);
    void *dont_verify_domain = SSL_CTX_get_ex_data(sslctx, ssl_ctx_ex_index_dont_verify_domain);
    ACLChecklist *check = (ACLChecklist*)SSL_get_ex_data(ssl, ssl_ex_index_cert_error_check);
    X509 *peeked_cert = (X509 *)SSL_get_ex_data(ssl, ssl_ex_index_ssl_peeked_cert);
    X509 *peer_cert = ctx->cert;

    X509_NAME_oneline(X509_get_subject_name(peer_cert), buffer,
                      sizeof(buffer));

    if (ok) {
        debugs(83, 5, "SSL Certificate signature OK: " << buffer);

        if (server) {
            if (!Ssl::checkX509ServerValidity(peer_cert, server)) {
                debugs(83, 2, "SQUID_X509_V_ERR_DOMAIN_MISMATCH: Certificate " << buffer << " does not match domainname " << server);
                ok = 0;
                error_no = SQUID_X509_V_ERR_DOMAIN_MISMATCH;
            }
        }
    }

    if (ok && peeked_cert) {
        /*Check if the already peeked certificate match the new one*/
        if (X509_cmp(peer_cert, peeked_cert) != 0) {
            debugs(83, 2, "SQUID_X509_V_ERR_CERT_CHANGE: Certificate " << buffer << " does not match peeked certificate");
            ok = 0;
            error_no =  SQUID_X509_V_ERR_CERT_CHANGE;
        }
    }

    if (!ok) {
        Ssl::Errors *errNoList = static_cast<Ssl::Errors *>(SSL_get_ex_data(ssl, ssl_ex_index_ssl_error_sslerrno));
        if (!errNoList) {
            errNoList = new Ssl::Errors(error_no);
            if (!SSL_set_ex_data(ssl, ssl_ex_index_ssl_error_sslerrno,  (void *)errNoList)) {
                debugs(83, 2, "Failed to set ssl error_no in ssl_verify_cb: Certificate " << buffer);
                delete errNoList;
                errNoList = NULL;
            }
        }
        else // Append the err no to the SSL errors lists.
            errNoList->push_back_unique(error_no);

        if (const char *err_descr = Ssl::GetErrorDescr(error_no))
            debugs(83, 5, err_descr << ": " << buffer);
        else
            debugs(83, DBG_IMPORTANT, "SSL unknown certificate error " << error_no << " in " << buffer);

        if (check) {
            ACLFilledChecklist *filledCheck = Filled(check);
            assert(filledCheck->sslErrorList == NULL);
            filledCheck->sslErrorList = new Ssl::Errors(error_no);
            if (check->fastCheck() == ACCESS_ALLOWED) {
                debugs(83, 3, "bypassing SSL error " << error_no << " in " << buffer);
                ok = 1;
            } else {
                debugs(83, 5, "confirming SSL error " << error_no);
            }
            // Delete the ssl error list
            delete filledCheck->sslErrorList;
            filledCheck->sslErrorList = NULL;
        }
    }

    if (!dont_verify_domain && server) {}

    if (!ok && !SSL_get_ex_data(ssl, ssl_ex_index_ssl_error_detail) ) {

        // Find the broken certificate. It may be intermediate.
        X509 *broken_cert = peer_cert; // reasonable default if search fails
        // Our SQUID_X509_V_ERR_DOMAIN_MISMATCH implies peer_cert is at fault.
        if (error_no != SQUID_X509_V_ERR_DOMAIN_MISMATCH) {
            if (X509 *last_used_cert = X509_STORE_CTX_get_current_cert(ctx))
                broken_cert = last_used_cert;
        }

        Ssl::ErrorDetail *errDetail =
            new Ssl::ErrorDetail(error_no, peer_cert, broken_cert);

        if (!SSL_set_ex_data(ssl, ssl_ex_index_ssl_error_detail,  errDetail)) {
            debugs(83, 2, "Failed to set Ssl::ErrorDetail in ssl_verify_cb: Certificate " << buffer);
            delete errDetail;
        }
    }

    return ok;
}

/// \ingroup ServerProtocolSSLInternal
static struct ssl_option {
    const char *name;
    long value;
}

ssl_options[] = {

#if SSL_OP_MICROSOFT_SESS_ID_BUG
    {
        "MICROSOFT_SESS_ID_BUG", SSL_OP_MICROSOFT_SESS_ID_BUG
    },
#endif
#if SSL_OP_NETSCAPE_CHALLENGE_BUG
    {
        "NETSCAPE_CHALLENGE_BUG", SSL_OP_NETSCAPE_CHALLENGE_BUG
    },
#endif
#if SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
    {
        "NETSCAPE_REUSE_CIPHER_CHANGE_BUG", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
    },
#endif
#if SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
    {
        "SSLREF2_REUSE_CERT_TYPE_BUG", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
    },
#endif
#if SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
    {
        "MICROSOFT_BIG_SSLV3_BUFFER", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
    },
#endif
#if SSL_OP_MSIE_SSLV2_RSA_PADDING
    {
        "MSIE_SSLV2_RSA_PADDING", SSL_OP_MSIE_SSLV2_RSA_PADDING
    },
#endif
#if SSL_OP_SSLEAY_080_CLIENT_DH_BUG
    {
        "SSLEAY_080_CLIENT_DH_BUG", SSL_OP_SSLEAY_080_CLIENT_DH_BUG
    },
#endif
#if SSL_OP_TLS_D5_BUG
    {
        "TLS_D5_BUG", SSL_OP_TLS_D5_BUG
    },
#endif
#if SSL_OP_TLS_BLOCK_PADDING_BUG
    {
        "TLS_BLOCK_PADDING_BUG", SSL_OP_TLS_BLOCK_PADDING_BUG
    },
#endif
#if SSL_OP_TLS_ROLLBACK_BUG
    {
        "TLS_ROLLBACK_BUG", SSL_OP_TLS_ROLLBACK_BUG
    },
#endif
#if SSL_OP_ALL
    {
        "ALL", (long)SSL_OP_ALL
    },
#endif
#if SSL_OP_SINGLE_DH_USE
    {
        "SINGLE_DH_USE", SSL_OP_SINGLE_DH_USE
    },
#endif
#if SSL_OP_EPHEMERAL_RSA
    {
        "EPHEMERAL_RSA", SSL_OP_EPHEMERAL_RSA
    },
#endif
#if SSL_OP_PKCS1_CHECK_1
    {
        "PKCS1_CHECK_1", SSL_OP_PKCS1_CHECK_1
    },
#endif
#if SSL_OP_PKCS1_CHECK_2
    {
        "PKCS1_CHECK_2", SSL_OP_PKCS1_CHECK_2
    },
#endif
#if SSL_OP_NETSCAPE_CA_DN_BUG
    {
        "NETSCAPE_CA_DN_BUG", SSL_OP_NETSCAPE_CA_DN_BUG
    },
#endif
#if SSL_OP_NON_EXPORT_FIRST
    {
        "NON_EXPORT_FIRST", SSL_OP_NON_EXPORT_FIRST
    },
#endif
#if SSL_OP_CIPHER_SERVER_PREFERENCE
    {
        "CIPHER_SERVER_PREFERENCE", SSL_OP_CIPHER_SERVER_PREFERENCE
    },
#endif
#if SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG
    {
        "NETSCAPE_DEMO_CIPHER_CHANGE_BUG", SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG
    },
#endif
#if SSL_OP_NO_SSLv2
    {
        "NO_SSLv2", SSL_OP_NO_SSLv2
    },
#endif
#if SSL_OP_NO_SSLv3
    {
        "NO_SSLv3", SSL_OP_NO_SSLv3
    },
#endif
#if SSL_OP_NO_TLSv1
    {
        "NO_TLSv1", SSL_OP_NO_TLSv1
    },
#endif
    {
        "", 0
    },
    {
        NULL, 0
    }
};

/// \ingroup ServerProtocolSSLInternal
static long
ssl_parse_options(const char *options)
{
    long op = 0;
    char *tmp;
    char *option;

    if (!options)
        goto no_options;

    tmp = xstrdup(options);

    option = strtok(tmp, ":,");

    while (option) {

        struct ssl_option *opt = NULL, *opttmp;
        long value = 0;
        enum {
            MODE_ADD, MODE_REMOVE
        } mode;

        switch (*option) {

        case '!':

        case '-':
            mode = MODE_REMOVE;
            option++;
            break;

        case '+':
            mode = MODE_ADD;
            option++;
            break;

        default:
            mode = MODE_ADD;
            break;
        }

        for (opttmp = ssl_options; opttmp->name; opttmp++) {
            if (strcmp(opttmp->name, option) == 0) {
                opt = opttmp;
                break;
            }
        }

        if (opt)
            value = opt->value;
        else if (strncmp(option, "0x", 2) == 0) {
            /* Special case.. hex specification */
            value = strtol(option + 2, NULL, 16);
        } else {
            fatalf("Unknown SSL option '%s'", option);
            value = 0;		/* Keep GCC happy */
        }

        switch (mode) {

        case MODE_ADD:
            op |= value;
            break;

        case MODE_REMOVE:
            op &= ~value;
            break;
        }

        option = strtok(NULL, ":,");
    }

    safe_free(tmp);

no_options:
    return op;
}

/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_NO_DEFAULT_CA		(1<<0)
/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_DELAYED_AUTH		(1<<1)
/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_DONT_VERIFY_PEER	(1<<2)
/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_DONT_VERIFY_DOMAIN	(1<<3)
/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_NO_SESSION_REUSE	(1<<4)
/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_VERIFY_CRL		(1<<5)
/// \ingroup ServerProtocolSSLInternal
#define SSL_FLAG_VERIFY_CRL_ALL		(1<<6)

/// \ingroup ServerProtocolSSLInternal
static long
ssl_parse_flags(const char *flags)
{
    long fl = 0;
    char *tmp;
    char *flag;

    if (!flags)
        return 0;

    tmp = xstrdup(flags);

    flag = strtok(tmp, ":,");

    while (flag) {
        if (strcmp(flag, "NO_DEFAULT_CA") == 0)
            fl |= SSL_FLAG_NO_DEFAULT_CA;
        else if (strcmp(flag, "DELAYED_AUTH") == 0)
            fl |= SSL_FLAG_DELAYED_AUTH;
        else if (strcmp(flag, "DONT_VERIFY_PEER") == 0)
            fl |= SSL_FLAG_DONT_VERIFY_PEER;
        else if (strcmp(flag, "DONT_VERIFY_DOMAIN") == 0)
            fl |= SSL_FLAG_DONT_VERIFY_DOMAIN;
        else if (strcmp(flag, "NO_SESSION_REUSE") == 0)
            fl |= SSL_FLAG_NO_SESSION_REUSE;

#if X509_V_FLAG_CRL_CHECK

        else if (strcmp(flag, "VERIFY_CRL") == 0)
            fl |= SSL_FLAG_VERIFY_CRL;
        else if (strcmp(flag, "VERIFY_CRL_ALL") == 0)
            fl |= SSL_FLAG_VERIFY_CRL_ALL;

#endif

        else
            fatalf("Unknown ssl flag '%s'", flag);

        flag = strtok(NULL, ":,");
    }

    safe_free(tmp);
    return fl;
}

// "dup" function for SSL_get_ex_new_index("cert_err_check")
static int
ssl_dupAclChecklist(CRYPTO_EX_DATA *, CRYPTO_EX_DATA *, void *,
                    int, long, void *)
{
    // We do not support duplication of ACLCheckLists.
    // If duplication is needed, we can count copies with cbdata.
    assert(false);
    return 0;
}

// "free" function for SSL_get_ex_new_index("cert_err_check")
static void
ssl_freeAclChecklist(void *, void *ptr, CRYPTO_EX_DATA *,
                     int, long, void *)
{
    delete static_cast<ACLChecklist *>(ptr); // may be NULL
}

// "free" function for SSL_get_ex_new_index("ssl_error_detail")
static void
ssl_free_ErrorDetail(void *, void *ptr, CRYPTO_EX_DATA *,
                     int, long, void *)
{
    Ssl::ErrorDetail  *errDetail = static_cast <Ssl::ErrorDetail *>(ptr);
    delete errDetail;
}

static void
ssl_free_SslErrNoList(void *, void *ptr, CRYPTO_EX_DATA *,
                     int, long, void *)
{
    Ssl::Errors *errNo = static_cast <Ssl::Errors *>(ptr);
    delete errNo;
}

// "free" function for X509 certificates
static void
ssl_free_X509(void *, void *ptr, CRYPTO_EX_DATA *,
                     int, long, void *)
{
    X509  *cert = static_cast <X509 *>(ptr);
    X509_free(cert);
}

/// \ingroup ServerProtocolSSLInternal
static void
ssl_initialize(void)
{
    static int ssl_initialized = 0;

    if (!ssl_initialized) {
        ssl_initialized = 1;
        SSL_load_error_strings();
        SSLeay_add_ssl_algorithms();
#if HAVE_OPENSSL_ENGINE_H

        if (Config.SSL.ssl_engine) {
            ENGINE *e;

            if (!(e = ENGINE_by_id(Config.SSL.ssl_engine))) {
                fatalf("Unable to find SSL engine '%s'\n", Config.SSL.ssl_engine);
            }

            if (!ENGINE_set_default(e, ENGINE_METHOD_ALL)) {
                int ssl_error = ERR_get_error();
                fatalf("Failed to initialise SSL engine: %s\n",
                       ERR_error_string(ssl_error, NULL));
            }
        }

#else
        if (Config.SSL.ssl_engine) {
            fatalf("Your OpenSSL has no SSL engine support\n");
        }

#endif

    }

    ssl_ex_index_server = SSL_get_ex_new_index(0, (void *) "server", NULL, NULL, NULL);
    ssl_ctx_ex_index_dont_verify_domain = SSL_CTX_get_ex_new_index(0, (void *) "dont_verify_domain", NULL, NULL, NULL);
    ssl_ex_index_cert_error_check = SSL_get_ex_new_index(0, (void *) "cert_error_check", NULL, &ssl_dupAclChecklist, &ssl_freeAclChecklist);
    ssl_ex_index_ssl_error_detail = SSL_get_ex_new_index(0, (void *) "ssl_error_detail", NULL, NULL, &ssl_free_ErrorDetail);
    ssl_ex_index_ssl_peeked_cert  = SSL_get_ex_new_index(0, (void *) "ssl_peeked_cert", NULL, NULL, &ssl_free_X509);
    ssl_ex_index_ssl_error_sslerrno =  SSL_get_ex_new_index(0, (void *) "ssl_error_sslerrno", NULL, NULL, &ssl_free_SslErrNoList);
}

/// \ingroup ServerProtocolSSLInternal
static int
ssl_load_crl(SSL_CTX *sslContext, const char *CRLfile)
{
    X509_STORE *st = SSL_CTX_get_cert_store(sslContext);
    X509_CRL *crl;
    BIO *in = BIO_new_file(CRLfile, "r");
    int count = 0;

    if (!in) {
        debugs(83, 2, "WARNING: Failed to open CRL file '" << CRLfile << "'");
        return 0;
    }

    while ((crl = PEM_read_bio_X509_CRL(in,NULL,NULL,NULL))) {
        if (!X509_STORE_add_crl(st, crl))
            debugs(83, 2, "WARNING: Failed to add CRL from file '" << CRLfile << "'");
        else
            count++;

        X509_CRL_free(crl);
    }

    BIO_free(in);
    return count;
}

SSL_CTX *
sslCreateServerContext(const char *certfile, const char *keyfile, int version, const char *cipher, const char *options, const char *flags, const char *clientCA, const char *CAfile, const char *CApath, const char *CRLfile, const char *dhfile, const char *context)
{
    int ssl_error;
#if OPENSSL_VERSION_NUMBER < 0x00909000L
    SSL_METHOD *method;
#else
    const SSL_METHOD *method;
#endif
    SSL_CTX *sslContext;
    long fl = ssl_parse_flags(flags);

    ssl_initialize();

    if (!keyfile)
        keyfile = certfile;

    if (!certfile)
        certfile = keyfile;

    if (!CAfile)
        CAfile = clientCA;

    if (!certfile) {
        debugs(83, DBG_CRITICAL, "ERROR: No certificate file");
        return NULL;
    }

    switch (version) {

    case 2:
#ifndef OPENSSL_NO_SSL2
        debugs(83, 5, "Using SSLv2.");
        method = SSLv2_server_method();
#else
        debugs(83, DBG_IMPORTANT, "SSLv2 is not available in this Proxy.");
        return NULL;
#endif
        break;

    case 3:
        debugs(83, 5, "Using SSLv3.");
        method = SSLv3_server_method();
        break;

    case 4:
        debugs(83, 5, "Using TLSv1.");
        method = TLSv1_server_method();
        break;

    case 1:

    default:
        debugs(83, 5, "Using SSLv2/SSLv3.");
        method = SSLv23_server_method();
        break;
    }

    sslContext = SSL_CTX_new(method);

    if (sslContext == NULL) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_CRITICAL, "ERROR: Failed to allocate SSL context: " << ERR_error_string(ssl_error, NULL));
        return NULL;
    }

    SSL_CTX_set_options(sslContext, ssl_parse_options(options));

    if (context && *context) {
        SSL_CTX_set_session_id_context(sslContext, (const unsigned char *)context, strlen(context));
    }

    if (fl & SSL_FLAG_NO_SESSION_REUSE) {
        SSL_CTX_set_session_cache_mode(sslContext, SSL_SESS_CACHE_OFF);
    }

    if (Config.SSL.unclean_shutdown) {
        debugs(83, 5, "Enabling quiet SSL shutdowns (RFC violation).");

        SSL_CTX_set_quiet_shutdown(sslContext, 1);
    }

    if (cipher) {
        debugs(83, 5, "Using chiper suite " << cipher << ".");

        if (!SSL_CTX_set_cipher_list(sslContext, cipher)) {
            ssl_error = ERR_get_error();
            debugs(83, DBG_CRITICAL, "ERROR: Failed to set SSL cipher suite '" << cipher << "': " << ERR_error_string(ssl_error, NULL));
            SSL_CTX_free(sslContext);
            return NULL;
        }
    }

    debugs(83, DBG_IMPORTANT, "Using certificate in " << certfile);

    if (!SSL_CTX_use_certificate_chain_file(sslContext, certfile)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_CRITICAL, "ERROR: Failed to acquire SSL certificate '" << certfile << "': " << ERR_error_string(ssl_error, NULL));
        SSL_CTX_free(sslContext);
        return NULL;
    }

    debugs(83, DBG_IMPORTANT, "Using private key in " << keyfile);
    ssl_ask_password(sslContext, keyfile);

    if (!SSL_CTX_use_PrivateKey_file(sslContext, keyfile, SSL_FILETYPE_PEM)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_CRITICAL, "ERROR: Failed to acquire SSL private key '" << keyfile << "': " << ERR_error_string(ssl_error, NULL));
        SSL_CTX_free(sslContext);
        return NULL;
    }

    debugs(83, 5, "Comparing private and public SSL keys.");

    if (!SSL_CTX_check_private_key(sslContext)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_CRITICAL, "ERROR: SSL private key '" << certfile << "' does not match public key '" <<
               keyfile << "': " << ERR_error_string(ssl_error, NULL));
        SSL_CTX_free(sslContext);
        return NULL;
    }

    debugs(83, 9, "Setting RSA key generation callback.");
    SSL_CTX_set_tmp_rsa_callback(sslContext, ssl_temp_rsa_cb);

    debugs(83, 9, "Setting CA certificate locations.");

    if ((CAfile || CApath) && !SSL_CTX_load_verify_locations(sslContext, CAfile, CApath)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_IMPORTANT, "WARNING: Ignoring error setting CA certificate locations: " << ERR_error_string(ssl_error, NULL));
    }

    if (!(fl & SSL_FLAG_NO_DEFAULT_CA) &&
            !SSL_CTX_set_default_verify_paths(sslContext)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_IMPORTANT, "WARNING: Ignoring error setting default CA certificate location: " << ERR_error_string(ssl_error, NULL));
    }

    if (clientCA) {
        STACK_OF(X509_NAME) *cert_names;
        debugs(83, 9, "Set client certifying authority list.");
        cert_names = SSL_load_client_CA_file(clientCA);

        if (cert_names == NULL) {
            debugs(83, DBG_IMPORTANT, "ERROR: loading the client CA certificates from '" << clientCA << "\': " << ERR_error_string(ERR_get_error(),NULL));
            SSL_CTX_free(sslContext);
            return NULL;
        }

        ERR_clear_error();
        SSL_CTX_set_client_CA_list(sslContext, cert_names);

        if (fl & SSL_FLAG_DELAYED_AUTH) {
            debugs(83, 9, "Not requesting client certificates until acl processing requires one");
            SSL_CTX_set_verify(sslContext, SSL_VERIFY_NONE, NULL);
        } else {
            debugs(83, 9, "Requiring client certificates.");
            SSL_CTX_set_verify(sslContext, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, ssl_verify_cb);
        }

        if (CRLfile) {
            ssl_load_crl(sslContext, CRLfile);
            fl |= SSL_FLAG_VERIFY_CRL;
        }

#if X509_V_FLAG_CRL_CHECK
        if (fl & SSL_FLAG_VERIFY_CRL_ALL)
            X509_STORE_set_flags(SSL_CTX_get_cert_store(sslContext), X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
        else if (fl & SSL_FLAG_VERIFY_CRL)
            X509_STORE_set_flags(SSL_CTX_get_cert_store(sslContext), X509_V_FLAG_CRL_CHECK);

#endif

    } else {
        debugs(83, 9, "Not requiring any client certificates");
        SSL_CTX_set_verify(sslContext, SSL_VERIFY_NONE, NULL);
    }

    if (dhfile) {
        FILE *in = fopen(dhfile, "r");
        DH *dh = NULL;
        int codes;

        if (in) {
            dh = PEM_read_DHparams(in, NULL, NULL, NULL);
            fclose(in);
        }

        if (!dh)
            debugs(83, DBG_IMPORTANT, "WARNING: Failed to read DH parameters '" << dhfile << "'");
        else if (dh && DH_check(dh, &codes) == 0) {
            if (codes) {
                debugs(83, DBG_IMPORTANT, "WARNING: Failed to verify DH parameters '" << dhfile  << "' (" << std::hex << codes  << ")");
                DH_free(dh);
                dh = NULL;
            }
        }

        if (dh)
            SSL_CTX_set_tmp_dh(sslContext, dh);
    }

    if (fl & SSL_FLAG_DONT_VERIFY_DOMAIN)
        SSL_CTX_set_ex_data(sslContext, ssl_ctx_ex_index_dont_verify_domain, (void *) -1);

    return sslContext;
}

SSL_CTX *
sslCreateClientContext(const char *certfile, const char *keyfile, int version, const char *cipher, const char *options, const char *flags, const char *CAfile, const char *CApath, const char *CRLfile)
{
    int ssl_error;
#if OPENSSL_VERSION_NUMBER < 0x00909000L
    SSL_METHOD *method;
#else
    const SSL_METHOD *method;
#endif
    SSL_CTX *sslContext;
    long fl = ssl_parse_flags(flags);

    ssl_initialize();

    if (!keyfile)
        keyfile = certfile;

    if (!certfile)
        certfile = keyfile;

    switch (version) {

    case 2:
#ifndef OPENSSL_NO_SSL2
        debugs(83, 5, "Using SSLv2.");
        method = SSLv2_client_method();
#else
        debugs(83, DBG_IMPORTANT, "SSLv2 is not available in this Proxy.");
        return NULL;
#endif
        break;

    case 3:
        debugs(83, 5, "Using SSLv3.");
        method = SSLv3_client_method();
        break;

    case 4:
        debugs(83, 5, "Using TLSv1.");
        method = TLSv1_client_method();
        break;

    case 1:

    default:
        debugs(83, 5, "Using SSLv2/SSLv3.");
        method = SSLv23_client_method();
        break;
    }

    sslContext = SSL_CTX_new(method);

    if (sslContext == NULL) {
        ssl_error = ERR_get_error();
        fatalf("Failed to allocate SSL context: %s\n",
               ERR_error_string(ssl_error, NULL));
    }

    SSL_CTX_set_options(sslContext, ssl_parse_options(options));

    if (cipher) {
        debugs(83, 5, "Using chiper suite " << cipher << ".");

        if (!SSL_CTX_set_cipher_list(sslContext, cipher)) {
            ssl_error = ERR_get_error();
            fatalf("Failed to set SSL cipher suite '%s': %s\n",
                   cipher, ERR_error_string(ssl_error, NULL));
        }
    }

    if (certfile) {
        debugs(83, 1, "Using certificate in " << certfile);

        if (!SSL_CTX_use_certificate_chain_file(sslContext, certfile)) {
            ssl_error = ERR_get_error();
            fatalf("Failed to acquire SSL certificate '%s': %s\n",
                   certfile, ERR_error_string(ssl_error, NULL));
        }

        debugs(83, 1, "Using private key in " << keyfile);
        ssl_ask_password(sslContext, keyfile);

        if (!SSL_CTX_use_PrivateKey_file(sslContext, keyfile, SSL_FILETYPE_PEM)) {
            ssl_error = ERR_get_error();
            fatalf("Failed to acquire SSL private key '%s': %s\n",
                   keyfile, ERR_error_string(ssl_error, NULL));
        }

        debugs(83, 5, "Comparing private and public SSL keys.");

        if (!SSL_CTX_check_private_key(sslContext)) {
            ssl_error = ERR_get_error();
            fatalf("SSL private key '%s' does not match public key '%s': %s\n",
                   certfile, keyfile, ERR_error_string(ssl_error, NULL));
        }
    }

    debugs(83, 9, "Setting RSA key generation callback.");
    SSL_CTX_set_tmp_rsa_callback(sslContext, ssl_temp_rsa_cb);

    if (fl & SSL_FLAG_DONT_VERIFY_PEER) {
        debugs(83, 2, "NOTICE: Peer certificates are not verified for validity!");
        SSL_CTX_set_verify(sslContext, SSL_VERIFY_NONE, NULL);
    } else {
        debugs(83, 9, "Setting certificate verification callback.");
        SSL_CTX_set_verify(sslContext, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, ssl_verify_cb);
    }

    debugs(83, 9, "Setting CA certificate locations.");

    if ((CAfile || CApath) && !SSL_CTX_load_verify_locations(sslContext, CAfile, CApath)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_IMPORTANT, "WARNING: Ignoring error setting CA certificate locations: " << ERR_error_string(ssl_error, NULL));
    }

    if (CRLfile) {
        ssl_load_crl(sslContext, CRLfile);
        fl |= SSL_FLAG_VERIFY_CRL;
    }

#if X509_V_FLAG_CRL_CHECK
    if (fl & SSL_FLAG_VERIFY_CRL_ALL)
        X509_STORE_set_flags(SSL_CTX_get_cert_store(sslContext), X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
    else if (fl & SSL_FLAG_VERIFY_CRL)
        X509_STORE_set_flags(SSL_CTX_get_cert_store(sslContext), X509_V_FLAG_CRL_CHECK);

#endif

    if (!(fl & SSL_FLAG_NO_DEFAULT_CA) &&
            !SSL_CTX_set_default_verify_paths(sslContext)) {
        ssl_error = ERR_get_error();
        debugs(83, DBG_IMPORTANT, "WARNING: Ignoring error setting default CA certificate location: " << ERR_error_string(ssl_error, NULL));
    }

    return sslContext;
}

/// \ingroup ServerProtocolSSLInternal
int
ssl_read_method(int fd, char *buf, int len)
{
    SSL *ssl = fd_table[fd].ssl;
    int i;

#if DONT_DO_THIS

    if (!SSL_is_init_finished(ssl)) {
        errno = ENOTCONN;
        return -1;
    }

#endif

    i = SSL_read(ssl, buf, len);

    if (i > 0 && SSL_pending(ssl) > 0) {
        debugs(83, 2, "SSL FD " << fd << " is pending");
        fd_table[fd].flags.read_pending = 1;
    } else
        fd_table[fd].flags.read_pending = 0;

    return i;
}

/// \ingroup ServerProtocolSSLInternal
int
ssl_write_method(int fd, const char *buf, int len)
{
    SSL *ssl = fd_table[fd].ssl;
    int i;

    if (!SSL_is_init_finished(ssl)) {
        errno = ENOTCONN;
        return -1;
    }

    i = SSL_write(ssl, buf, len);

    return i;
}

void
ssl_shutdown_method(SSL *ssl)
{
    SSL_shutdown(ssl);
}

/// \ingroup ServerProtocolSSLInternal
static const char *
ssl_get_attribute(X509_NAME * name, const char *attribute_name)
{
    static char buffer[1024];
    int nid;

    buffer[0] = '\0';

    if (strcmp(attribute_name, "DN") == 0) {
        X509_NAME_oneline(name, buffer, sizeof(buffer));
        goto done;
    }

    nid = OBJ_txt2nid((char *) attribute_name);

    if (nid == 0) {
        debugs(83, 1, "WARNING: Unknown SSL attribute name '" << attribute_name << "'");
        return NULL;
    }

    X509_NAME_get_text_by_NID(name, nid, buffer, sizeof(buffer));

done:
    return *buffer ? buffer : NULL;
}

/// \ingroup ServerProtocolSSLInternal
const char *
sslGetUserAttribute(SSL * ssl, const char *attribute_name)
{
    X509 *cert;
    X509_NAME *name;
    const char *ret;

    if (!ssl)
        return NULL;

    cert = SSL_get_peer_certificate(ssl);

    if (!cert)
        return NULL;

    name = X509_get_subject_name(cert);

    ret = ssl_get_attribute(name, attribute_name);

    X509_free(cert);

    return ret;
}

/// \ingroup ServerProtocolSSLInternal
const char *
sslGetCAAttribute(SSL * ssl, const char *attribute_name)
{
    X509 *cert;
    X509_NAME *name;
    const char *ret;

    if (!ssl)
        return NULL;

    cert = SSL_get_peer_certificate(ssl);

    if (!cert)
        return NULL;

    name = X509_get_issuer_name(cert);

    ret = ssl_get_attribute(name, attribute_name);

    X509_free(cert);

    return ret;
}

const char *
sslGetUserEmail(SSL * ssl)
{
    return sslGetUserAttribute(ssl, "emailAddress");
}

const char *
sslGetUserCertificatePEM(SSL *ssl)
{
    X509 *cert;
    BIO *mem;
    static char *str = NULL;
    char *ptr;
    long len;

    safe_free(str);

    if (!ssl)
        return NULL;

    cert = SSL_get_peer_certificate(ssl);

    if (!cert)
        return NULL;

    mem = BIO_new(BIO_s_mem());

    PEM_write_bio_X509(mem, cert);


    len = BIO_get_mem_data(mem, &ptr);

    str = (char *)xmalloc(len + 1);

    memcpy(str, ptr, len);

    str[len] = '\0';

    X509_free(cert);

    BIO_free(mem);

    return str;
}

const char *
sslGetUserCertificateChainPEM(SSL *ssl)
{
    STACK_OF(X509) *chain;
    BIO *mem;
    static char *str = NULL;
    char *ptr;
    long len;
    int i;

    safe_free(str);

    if (!ssl)
        return NULL;

    chain = SSL_get_peer_cert_chain(ssl);

    if (!chain)
        return sslGetUserCertificatePEM(ssl);

    mem = BIO_new(BIO_s_mem());

    for (i = 0; i < sk_X509_num(chain); i++) {
        X509 *cert = sk_X509_value(chain, i);
        PEM_write_bio_X509(mem, cert);
    }

    len = BIO_get_mem_data(mem, &ptr);

    str = (char *)xmalloc(len + 1);
    memcpy(str, ptr, len);
    str[len] = '\0';

    BIO_free(mem);

    return str;
}

/// \ingroup ServerProtocolSSLInternal
/// Create SSL context and apply ssl certificate and private key to it.
static SSL_CTX * createSSLContext(Ssl::X509_Pointer & x509, Ssl::EVP_PKEY_Pointer & pkey)
{
    Ssl::SSL_CTX_Pointer sslContext(SSL_CTX_new(SSLv23_server_method()));

    if (!SSL_CTX_use_certificate(sslContext.get(), x509.get()))
        return NULL;

    if (!SSL_CTX_use_PrivateKey(sslContext.get(), pkey.get()))
        return NULL;
    return sslContext.release();
}

SSL_CTX * Ssl::generateSslContextUsingPkeyAndCertFromMemory(const char * data)
{
    Ssl::X509_Pointer cert;
    Ssl::EVP_PKEY_Pointer pkey;
    if (!readCertAndPrivateKeyFromMemory(cert, pkey, data))
        return NULL;

    if (!cert || !pkey)
        return NULL;

    return createSSLContext(cert, pkey);
}

SSL_CTX * Ssl::generateSslContext(CertificateProperties const &properties)
{
    Ssl::X509_Pointer cert;
    Ssl::EVP_PKEY_Pointer pkey;
    if (!generateSslCertificate(cert, pkey, properties))
        return NULL;

    if (!cert)
        return NULL;

    if (!pkey)
        return NULL;

    return createSSLContext(cert, pkey);
}

bool Ssl::verifySslCertificate(SSL_CTX * sslContext, CertificateProperties const &properties)
{
    // Temporary ssl for getting X509 certificate from SSL_CTX.
    Ssl::SSL_Pointer ssl(SSL_new(sslContext));
    X509 * cert = SSL_get_certificate(ssl.get());
    ASN1_TIME * time_notBefore = X509_get_notBefore(cert);
    ASN1_TIME * time_notAfter = X509_get_notAfter(cert);
    bool ret = (X509_cmp_current_time(time_notBefore) < 0 && X509_cmp_current_time(time_notAfter) > 0);
    if (!ret)
        return false;

    return certificateMatchesProperties(cert, properties);
}

bool
Ssl::setClientSNI(SSL *ssl, const char *fqdn)
{
    //The SSL_CTRL_SET_TLSEXT_HOSTNAME is a openssl macro which indicates
    // if the TLS servername extension (SNI) is enabled in openssl library.
#if defined(SSL_CTRL_SET_TLSEXT_HOSTNAME)
    if (!SSL_set_tlsext_host_name(ssl, fqdn)) {
        const int ssl_error = ERR_get_error();
        debugs(83, 3,  "WARNING: unable to set TLS servername extension (SNI): " <<
               ERR_error_string(ssl_error, NULL) << "\n");
        return false;
    }
    return true;
#else
    debugs(83, 7,  "no support for TLS servername extension (SNI)\n");
    return false;
#endif
}

void Ssl::addChainToSslContext(SSL_CTX *sslContext, STACK_OF(X509) *chain)
{
    if (!chain)
        return;

    for (int i = 0; i < sk_X509_num(chain); i++) {
        X509 *cert = sk_X509_value(chain, i);
        if (SSL_CTX_add_extra_chain_cert(sslContext, cert)) {
            // increase the certificate lock
            CRYPTO_add(&(cert->references),1,CRYPTO_LOCK_X509);
        } else {
            const int ssl_error = ERR_get_error();
            debugs(83, DBG_IMPORTANT, "WARNING: can not add certificate to SSL context chain: " << ERR_error_string(ssl_error, NULL));
        }
    }
}

/**
 \ingroup ServerProtocolSSLInternal
 * Read certificate from file.
 * See also: static readSslX509Certificate function, gadgets.cc file
 */
static X509 * readSslX509CertificatesChain(char const * certFilename,  STACK_OF(X509)* chain)
{
    if (!certFilename)
        return NULL;
    Ssl::BIO_Pointer bio(BIO_new(BIO_s_file_internal()));
    if (!bio)
        return NULL;
    if (!BIO_read_filename(bio.get(), certFilename))
        return NULL;
    X509 *certificate = PEM_read_bio_X509(bio.get(), NULL, NULL, NULL);

    if (certificate && chain) {

        if (X509_check_issued(certificate, certificate) == X509_V_OK)
            debugs(83, 5, "Certificate is self-signed, will not be chained");
        else {
            if (sk_X509_push(chain, certificate))
                CRYPTO_add(&(certificate->references), 1, CRYPTO_LOCK_X509);
            else
                debugs(83, DBG_IMPORTANT, "WARNING: unable to add signing certificate to cert chain");
            // and add to the chain any certificate loaded from the file
            while (X509 *ca = PEM_read_bio_X509(bio.get(), NULL, NULL, NULL)) {
                if (!sk_X509_push(chain, ca))
                    debugs(83, DBG_IMPORTANT, "WARNING: unable to add CA certificate to cert chain");
            }
        }
    }

    return certificate;
}

void Ssl::readCertChainAndPrivateKeyFromFiles(X509_Pointer & cert, EVP_PKEY_Pointer & pkey, X509_STACK_Pointer & chain, char const * certFilename, char const * keyFilename)
{
    if (keyFilename == NULL)
        keyFilename = certFilename;
    if (!chain)
        chain.reset(sk_X509_new_null());
    if (!chain)
        debugs(83, DBG_IMPORTANT, "WARNING: unable to allocate memory for cert chain");
    pkey.reset(readSslPrivateKey(keyFilename, ssl_ask_password_cb));
    cert.reset(readSslX509CertificatesChain(certFilename, chain.get()));
    if (!pkey || !cert || !X509_check_private_key(cert.get(), pkey.get())) {
        pkey.reset(NULL);
        cert.reset(NULL);
    }
}

bool Ssl::generateUntrustedCert(X509_Pointer &untrustedCert, EVP_PKEY_Pointer &untrustedPkey, X509_Pointer const  &cert, EVP_PKEY_Pointer const & pkey)
{
    // Generate the self-signed certificate, using a hard-coded subject prefix
    Ssl::CertificateProperties certProperties;
    if (const char *cn = CommonHostName(cert.get())) {
        certProperties.commonName = "Not trusted by \"";
        certProperties.commonName += cn;
        certProperties.commonName += "\"";
    }
    else if (const char *org = getOrganization(cert.get())) {
        certProperties.commonName =  "Not trusted by \"";
        certProperties.commonName += org;
        certProperties.commonName += "\"";
    }
    else
        certProperties.commonName =  "Not trusted";
    certProperties.setCommonName = true;
    // O, OU, and other CA subject fields will be mimicked
    // Expiration date and other common properties will be mimicked
    certProperties.signAlgorithm = Ssl::algSignSelf;
    certProperties.signWithPkey.resetAndLock(pkey.get());
    certProperties.mimicCert.resetAndLock(cert.get());
    return Ssl::generateSslCertificate(untrustedCert, untrustedPkey, certProperties);
}

#endif /* USE_SSL */