lighttpd1.4/src/mod_openssl.c

#include "first.h"

#include <errno.h>
#include <string.h>
#include <unistd.h>

#ifndef USE_OPENSSL_KERBEROS
#ifndef OPENSSL_NO_KRB5
#define OPENSSL_NO_KRB5
#endif
#endif

#include "sys-crypto.h"

#include <openssl/ssl.h>
#include <openssl/bio.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/objects.h>
#include <openssl/pem.h>
#include <openssl/rand.h>
#ifndef OPENSSL_NO_DH
#include <openssl/dh.h>
#endif

#if ! defined OPENSSL_NO_TLSEXT && ! defined SSL_CTRL_SET_TLSEXT_HOSTNAME
#define OPENSSL_NO_TLSEXT
#endif

#if OPENSSL_VERSION_NUMBER >= 0x0090800fL
#ifndef OPENSSL_NO_ECDH
#include <openssl/ecdh.h>
#endif
#endif

#include "base.h"
#include "http_header.h"
#include "log.h"
#include "plugin.h"

typedef struct {
    SSL_CTX *ssl_ctx; /* not patched */
    /* SNI per host: with COMP_SERVER_SOCKET, COMP_HTTP_SCHEME, COMP_HTTP_HOST */
    EVP_PKEY *ssl_pemfile_pkey;
    X509 *ssl_pemfile_x509;
    STACK_OF(X509_NAME) *ssl_ca_file_cert_names;

    unsigned short ssl_verifyclient;
    unsigned short ssl_verifyclient_enforce;
    unsigned short ssl_verifyclient_depth;
    unsigned short ssl_verifyclient_export_cert;
    buffer *ssl_verifyclient_username;

    unsigned short ssl_disable_client_renegotiation;
    unsigned short ssl_read_ahead;
    unsigned short ssl_log_noise;

    /*(used only during startup; not patched)*/
    unsigned short ssl_enabled; /* only interesting for setting up listening sockets. don't use at runtime */
    unsigned short ssl_honor_cipher_order; /* determine SSL cipher in server-preferred order, not client-order */
    unsigned short ssl_empty_fragments; /* whether to not set SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS */
    unsigned short ssl_use_sslv2;
    unsigned short ssl_use_sslv3;
    buffer *ssl_pemfile;
    buffer *ssl_privkey;
    buffer *ssl_ca_file;
    buffer *ssl_ca_crl_file;
    buffer *ssl_ca_dn_file;
    buffer *ssl_cipher_list;
    buffer *ssl_dh_file;
    buffer *ssl_ec_curve;
    array *ssl_conf_cmd;
    buffer *ssl_acme_tls_1;
} plugin_config;

typedef struct {
    PLUGIN_DATA;
    plugin_config **config_storage;
} plugin_data;

static int ssl_is_init;
/* need assigned p->id for deep access of module handler_ctx for connection
 *   i.e. handler_ctx *hctx = con->plugin_ctx[plugin_data_singleton->id]; */
static plugin_data *plugin_data_singleton;
#define LOCAL_SEND_BUFSIZE (16 * 1024)
static char *local_send_buffer;

typedef struct {
    SSL *ssl;
    connection *con;
    short renegotiations; /* count of SSL_CB_HANDSHAKE_START */
    short close_notify;
    unsigned short request_env_patched;
    unsigned short alpn;
    plugin_config conf;
    server *srv;
} handler_ctx;


static handler_ctx *
handler_ctx_init (void)
{
    handler_ctx *hctx = calloc(1, sizeof(*hctx));
    force_assert(hctx);
    return hctx;
}


static void
handler_ctx_free (handler_ctx *hctx)
{
    if (hctx->ssl) SSL_free(hctx->ssl);
    free(hctx);
}


INIT_FUNC(mod_openssl_init)
{
    plugin_data_singleton = (plugin_data *)calloc(1, sizeof(plugin_data));
  #ifdef DEBUG_WOLFSSL
    wolfSSL_Debugging_ON();
  #endif
    return plugin_data_singleton;
}


FREE_FUNC(mod_openssl_free)
{
    plugin_data *p = p_d;
    if (!p) return HANDLER_GO_ON;

    if (p->config_storage) {
        for (size_t i = 0; i < srv->config_context->used; ++i) {
            plugin_config *s = p->config_storage[i];
            int copy;
            if (NULL == s) continue;
            copy = s->ssl_enabled && buffer_string_is_empty(s->ssl_pemfile);
            buffer_free(s->ssl_pemfile);
            buffer_free(s->ssl_privkey);
            buffer_free(s->ssl_ca_file);
            buffer_free(s->ssl_ca_crl_file);
            buffer_free(s->ssl_ca_dn_file);
            buffer_free(s->ssl_cipher_list);
            buffer_free(s->ssl_dh_file);
            buffer_free(s->ssl_ec_curve);
            buffer_free(s->ssl_verifyclient_username);
            array_free(s->ssl_conf_cmd);
            buffer_free(s->ssl_acme_tls_1);

            if (copy) continue;
            SSL_CTX_free(s->ssl_ctx);
            EVP_PKEY_free(s->ssl_pemfile_pkey);
            X509_free(s->ssl_pemfile_x509);
            if (NULL != s->ssl_ca_file_cert_names)
                sk_X509_NAME_pop_free(s->ssl_ca_file_cert_names,X509_NAME_free);
        }
        for (size_t i = 0; i < srv->config_context->used; ++i) {
            plugin_config *s = p->config_storage[i];
            if (NULL == s) continue;

            free(s);
        }
        free(p->config_storage);
    }

    if (ssl_is_init) {
      #if OPENSSL_VERSION_NUMBER >= 0x10100000L \
       && !defined(LIBRESSL_VERSION_NUMBER)
        /*(OpenSSL libraries handle thread init and deinit)
         * https://github.com/openssl/openssl/pull/1048 */
      #else
        CRYPTO_cleanup_all_ex_data();
        ERR_free_strings();
       #if OPENSSL_VERSION_NUMBER >= 0x10000000L
        ERR_remove_thread_state(NULL);
       #else
        ERR_remove_state(0);
       #endif
        EVP_cleanup();
      #endif

        free(local_send_buffer);
    }

    free(p);

    return HANDLER_GO_ON;
}


static int
safer_X509_NAME_oneline(X509_NAME *name, char *buf, size_t sz)
{
    BIO *bio = BIO_new(BIO_s_mem());
    if (bio) {
        int len = X509_NAME_print_ex(bio, name, 0, XN_FLAG_ONELINE);
        BIO_gets(bio, buf, (int)sz); /*(may be truncated if len >= sz)*/
        BIO_free(bio);
        return len; /*return value has similar semantics to that of snprintf()*/
    }
    else {
        buf[0] = '\0';
        return -1;
    }
}


static void
ssl_info_callback (const SSL *ssl, int where, int ret)
{
    UNUSED(ret);

    if (0 != (where & SSL_CB_HANDSHAKE_START)) {
        handler_ctx *hctx = (handler_ctx *) SSL_get_app_data(ssl);
        if (hctx->renegotiations >= 0) ++hctx->renegotiations;
    }
  #ifdef TLS1_3_VERSION
    /* https://github.com/openssl/openssl/issues/5721
     * "TLSv1.3 unexpected InfoCallback after handshake completed" */
    if (0 != (where & SSL_CB_HANDSHAKE_DONE)) {
        /* SSL_version() is valid after initial handshake completed */
        if (SSL_version(ssl) >= TLS1_3_VERSION) {
            /* https://wiki.openssl.org/index.php/TLS1.3
             * "Renegotiation is not possible in a TLSv1.3 connection" */
            handler_ctx *hctx = (handler_ctx *) SSL_get_app_data(ssl);
            hctx->renegotiations = -1;
        }
    }
  #endif
}

/* https://wiki.openssl.org/index.php/Manual:SSL_CTX_set_verify(3)#EXAMPLES */
static int
verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
{
    char buf[256];
    X509 *err_cert;
    int err, depth;
    SSL *ssl;
    handler_ctx *hctx;
    server *srv;

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

    /*
     * Retrieve the pointer to the SSL of the connection currently treated
     * and the application specific data stored into the SSL object.
     */
    ssl = X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
    hctx = (handler_ctx *) SSL_get_app_data(ssl);
    srv = hctx->srv;

    /*
     * Catch a too long certificate chain. The depth limit set using
     * SSL_CTX_set_verify_depth() is by purpose set to "limit+1" so
     * that whenever the "depth>verify_depth" condition is met, we
     * have violated the limit and want to log this error condition.
     * We must do it here, because the CHAIN_TOO_LONG error would not
     * be found explicitly; only errors introduced by cutting off the
     * additional certificates would be logged.
     */
    if (depth > hctx->conf.ssl_verifyclient_depth) {
        preverify_ok = 0;
        err = X509_V_ERR_CERT_CHAIN_TOO_LONG;
        X509_STORE_CTX_set_error(ctx, err);
    }

    if (preverify_ok && 0 == depth
        && !buffer_string_is_empty(hctx->conf.ssl_ca_dn_file)
        && !buffer_string_is_empty(hctx->conf.ssl_ca_file)) {
        /* verify that client cert is issued by CA in ssl.ca-dn-file
         * if both ssl.ca-dn-file and ssl.ca-file were configured */
        STACK_OF(X509_NAME) * const names = hctx->conf.ssl_ca_file_cert_names;
        X509_NAME *issuer;
      #if OPENSSL_VERSION_NUMBER >= 0x10002000L
        err_cert = X509_STORE_CTX_get_current_cert(ctx);
      #else
        err_cert = ctx->current_cert;
      #endif
        if (NULL == err_cert) return !hctx->conf.ssl_verifyclient_enforce;
        issuer = X509_get_issuer_name(err_cert);
      #if 0 /*(?desirable/undesirable to have ssl_ca_file_cert_names sorted?)*/
        if (-1 != sk_X509_NAME_find(names, issuer))
            return preverify_ok; /* match */
      #else
        for (int i = 0, len = sk_X509_NAME_num(names); i < len; ++i) {
            if (0 == X509_NAME_cmp(sk_X509_NAME_value(names, i), issuer))
                return preverify_ok; /* match */
        }
      #endif

        preverify_ok = 0;
        err = X509_V_ERR_CERT_REJECTED;
        X509_STORE_CTX_set_error(ctx, err);
    }

    if (preverify_ok) {
        return preverify_ok;
    }

  #if OPENSSL_VERSION_NUMBER >= 0x10002000L
    err_cert = X509_STORE_CTX_get_current_cert(ctx);
  #else
    err_cert = ctx->current_cert;
  #endif
    if (NULL == err_cert) return !hctx->conf.ssl_verifyclient_enforce;
    safer_X509_NAME_oneline(X509_get_subject_name(err_cert),buf,sizeof(buf));
    log_error_write(srv, __FILE__, __LINE__, "SDSSSDSS",
                        "SSL: verify error:num=", err, ":",
                        X509_verify_cert_error_string(err), ":depth=", depth,
                        ":subject=", buf);

    /*
     * At this point, err contains the last verification error. We can use
     * it for something special
     */
    if (!preverify_ok && (err == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY ||
                          err == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT)) {
        safer_X509_NAME_oneline(X509_get_issuer_name(err_cert),buf,sizeof(buf));
        log_error_write(srv, __FILE__, __LINE__, "SS", "SSL: issuer=", buf);
    }

    return !hctx->conf.ssl_verifyclient_enforce;
}

#ifndef OPENSSL_NO_TLSEXT
static int mod_openssl_patch_connection (server *srv, connection *con, handler_ctx *hctx);

static int
mod_openssl_SNI (SSL *ssl, server *srv, handler_ctx *hctx, const char *servername, size_t len)
{
    if (len >= 1024) { /*(expecting < 256; TLSEXT_MAXLEN_host_name is 255)*/
        log_error(srv->errh, __FILE__, __LINE__,
                  "SSL: SNI name too long %.*s", (int)len, servername);
        return SSL_TLSEXT_ERR_ALERT_FATAL;
    }

    /* use SNI to patch mod_openssl config and then reset COMP_HTTP_HOST */
    connection * const con = hctx->con;
    buffer_copy_string_len(con->uri.authority, servername, len);
    buffer_to_lower(con->uri.authority);
  #if 0
    /*(con->uri.authority used below for configuration before request read;
     * revisit for h2)*/
    if (0 != http_request_host_policy(con, con->uri.authority, con->uri.scheme))
        return SSL_TLSEXT_ERR_ALERT_FATAL;
  #endif

    con->conditional_is_valid |= (1 << COMP_HTTP_SCHEME)
                              |  (1 << COMP_HTTP_HOST);
    mod_openssl_patch_connection(srv, con, hctx);
    /* reset COMP_HTTP_HOST so that conditions re-run after request hdrs read */
    /*(done in response.c:config_cond_cache_reset() after request hdrs read)*/
    /*config_cond_cache_reset_item(con, COMP_HTTP_HOST);*/
    /*buffer_clear(con->uri.authority);*/

    if (NULL == hctx->conf.ssl_pemfile_x509
        || NULL == hctx->conf.ssl_pemfile_pkey) {
        /* x509/pkey available <=> pemfile was set <=> pemfile got patched:
         * so this should never happen, unless you nest $SERVER["socket"] */
        log_error_write(srv, __FILE__, __LINE__, "ssb", "SSL:",
                        "no certificate/private key for TLS server name",
                        con->uri.authority);
        return SSL_TLSEXT_ERR_ALERT_FATAL;
    }

    /* first set certificate!
     * setting private key checks whether certificate matches it */
    if (1 != SSL_use_certificate(ssl, hctx->conf.ssl_pemfile_x509)) {
        log_error_write(srv, __FILE__, __LINE__, "ssb:s", "SSL:",
                        "failed to set certificate for TLS server name",
                        con->uri.authority,
                        ERR_error_string(ERR_get_error(), NULL));
        return SSL_TLSEXT_ERR_ALERT_FATAL;
    }

    if (1 != SSL_use_PrivateKey(ssl, hctx->conf.ssl_pemfile_pkey)) {
        log_error_write(srv, __FILE__, __LINE__, "ssb:s", "SSL:",
                        "failed to set private key for TLS server name",
                        con->uri.authority,
                        ERR_error_string(ERR_get_error(), NULL));
        return SSL_TLSEXT_ERR_ALERT_FATAL;
    }

    if (hctx->conf.ssl_verifyclient) {
        int mode;
        if (NULL == hctx->conf.ssl_ca_file_cert_names) {
            log_error_write(srv, __FILE__, __LINE__, "ssb:s", "SSL:",
                            "can't verify client without ssl.ca-file "
                            "or ssl.ca-dn-file for TLS server name",
                            con->uri.authority,
                            ERR_error_string(ERR_get_error(), NULL));
            return SSL_TLSEXT_ERR_ALERT_FATAL;
        }

        SSL_set_client_CA_list(
          ssl, SSL_dup_CA_list(hctx->conf.ssl_ca_file_cert_names));
        /* forcing verification here is really not that useful
         * -- a client could just connect without SNI */
        mode = SSL_VERIFY_PEER;
        if (hctx->conf.ssl_verifyclient_enforce) {
            mode |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
        }
        SSL_set_verify(ssl, mode, verify_callback);
        SSL_set_verify_depth(ssl, hctx->conf.ssl_verifyclient_depth + 1);
    } else {
        SSL_set_verify(ssl, SSL_VERIFY_NONE, NULL);
    }

    return SSL_TLSEXT_ERR_OK;
}

#ifdef SSL_CLIENT_HELLO_SUCCESS
static int
mod_openssl_client_hello_cb (SSL *ssl, int *al, void *srv)
{
    handler_ctx *hctx = (handler_ctx *) SSL_get_app_data(ssl);
    buffer_copy_string(hctx->con->uri.scheme, "https");

    const unsigned char *name;
    size_t len, slen;
    if (!SSL_client_hello_get0_ext(ssl, TLSEXT_TYPE_server_name, &name, &len)) {
        return SSL_CLIENT_HELLO_SUCCESS; /* client did not provide SNI */
    }

    /* expecting single element in the server_name extension; parse first one */
    if (len > 5
        && (size_t)((name[0] << 8) + name[1]) == len-2
        && name[2] == TLSEXT_TYPE_server_name
        && (slen = (name[3] << 8) + name[4]) <= len-5) { /*(first)*/
        int rc = mod_openssl_SNI(ssl, srv, hctx, (const char *)name+5, slen);
        if (rc == SSL_TLSEXT_ERR_OK)
            return SSL_CLIENT_HELLO_SUCCESS;
    }

    *al = TLS1_AD_UNRECOGNIZED_NAME;
    return SSL_CLIENT_HELLO_ERROR;
}
#else
static int
network_ssl_servername_callback (SSL *ssl, int *al, server *srv)
{
    handler_ctx *hctx = (handler_ctx *) SSL_get_app_data(ssl);
    buffer_copy_string(hctx->con->uri.scheme, "https");
    UNUSED(al);

    const char *servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
    return (NULL != servername)
      ? mod_openssl_SNI(ssl, srv, hctx, servername, strlen(servername))
      : SSL_TLSEXT_ERR_NOACK; /* client did not provide SNI */
}
#endif
#endif


static X509 *
x509_load_pem_file (server *srv, const char *file)
{
    BIO *in;
    X509 *x = NULL;

    in = BIO_new(BIO_s_file());
    if (NULL == in) {
        log_error_write(srv, __FILE__, __LINE__, "S",
                        "SSL: BIO_new(BIO_s_file()) failed");
        goto error;
    }

    if (BIO_read_filename(in,file) <= 0) {
        log_error_write(srv, __FILE__, __LINE__, "SSS",
                        "SSL: BIO_read_filename('", file,"') failed");
        goto error;
    }

    x = PEM_read_bio_X509(in, NULL, NULL, NULL);
    if (NULL == x) {
        log_error_write(srv, __FILE__, __LINE__, "SSS",
                        "SSL: couldn't read X509 certificate from '", file,"'");
        goto error;
    }

    BIO_free(in);
    return x;

error:
    if (NULL != in) BIO_free(in);
    return NULL;
}


static EVP_PKEY *
evp_pkey_load_pem_file (server *srv, const char *file)
{
    BIO *in;
    EVP_PKEY *x = NULL;

    in = BIO_new(BIO_s_file());
    if (NULL == in) {
        log_error_write(srv, __FILE__, __LINE__, "s",
                        "SSL: BIO_new(BIO_s_file()) failed");
        goto error;
    }

    if (BIO_read_filename(in,file) <= 0) {
        log_error_write(srv, __FILE__, __LINE__, "SSS",
                        "SSL: BIO_read_filename('", file,"') failed");
        goto error;
    }

    x = PEM_read_bio_PrivateKey(in, NULL, NULL, NULL);
    if (NULL == x) {
        log_error_write(srv, __FILE__, __LINE__, "SSS",
                        "SSL: couldn't read private key from '", file,"'");
        goto error;
    }

    BIO_free(in);
    return x;

error:
    if (NULL != in) BIO_free(in);
    return NULL;
}


static int
network_openssl_load_pemfile (server *srv, plugin_config *s, size_t ndx)
{
  #ifdef OPENSSL_NO_TLSEXT
    data_config *dc = (data_config *)srv->config_context->data[ndx];
    if ((ndx > 0 && (COMP_SERVER_SOCKET != dc->comp
                     || dc->cond != CONFIG_COND_EQ)) || !s->ssl_enabled) {
        log_error_write(srv, __FILE__, __LINE__, "ss", "SSL:",
                        "ssl.pemfile only works in SSL socket binding context "
                        "as openssl version does not support TLS extensions");
        return -1;
    }
  #else
    UNUSED(ndx);
  #endif

    s->ssl_pemfile_x509 = x509_load_pem_file(srv, s->ssl_pemfile->ptr);
    if (NULL == s->ssl_pemfile_x509) return -1;
    s->ssl_pemfile_pkey = !buffer_string_is_empty(s->ssl_privkey)
      ? evp_pkey_load_pem_file(srv, s->ssl_privkey->ptr)
      : evp_pkey_load_pem_file(srv, s->ssl_pemfile->ptr);
    if (NULL == s->ssl_pemfile_pkey) return -1;

    if (!X509_check_private_key(s->ssl_pemfile_x509, s->ssl_pemfile_pkey)) {
        log_error_write(srv, __FILE__, __LINE__, "sssbb", "SSL:",
                        "Private key does not match the certificate public key,"
                        " reason:", ERR_error_string(ERR_get_error(), NULL),
                        s->ssl_pemfile, s->ssl_privkey);
        return -1;
    }

    return 0;
}


#ifndef OPENSSL_NO_TLSEXT

#if OPENSSL_VERSION_NUMBER >= 0x10002000

static int
mod_openssl_acme_tls_1 (SSL *ssl, handler_ctx *hctx)
{
    server *srv = hctx->srv;
    buffer *b = srv->tmp_buf;
    buffer *name = hctx->con->uri.authority;
    X509 *ssl_pemfile_x509 = NULL;
    EVP_PKEY *ssl_pemfile_pkey = NULL;
    size_t len;
    int rc = SSL_TLSEXT_ERR_ALERT_FATAL;

    /* check if acme-tls/1 protocol is enabled (path to dir of cert(s) is set)*/
    if (buffer_string_is_empty(hctx->conf.ssl_acme_tls_1))
        return SSL_TLSEXT_ERR_NOACK; /*(reuse value here for not-configured)*/
    buffer_copy_buffer(b, hctx->conf.ssl_acme_tls_1);
    buffer_append_slash(b);

    /* check if SNI set server name (required for acme-tls/1 protocol)
     * and perform simple path checks for no '/'
     * and no leading '.' (e.g. ignore "." or ".." or anything beginning '.') */
    if (buffer_string_is_empty(name))   return rc;
    if (NULL != strchr(name->ptr, '/')) return rc;
    if (name->ptr[0] == '.')            return rc;
  #if 0
    if (0 != http_request_host_policy(hctx->con, name, hctx->con->uri.scheme))
        return rc;
  #endif
    buffer_append_string_buffer(b, name);
    len = buffer_string_length(b);

    do {
        buffer_append_string_len(b, CONST_STR_LEN(".crt.pem"));
        ssl_pemfile_x509 = x509_load_pem_file(srv, b->ptr);
        if (NULL == ssl_pemfile_x509) {
            log_error_write(srv, __FILE__, __LINE__, "ssb", "SSL:",
                            "Failed to load acme-tls/1 pemfile:", b);
            break;
        }

        buffer_string_set_length(b, len); /*(remove ".crt.pem")*/
        buffer_append_string_len(b, CONST_STR_LEN(".key.pem"));
        ssl_pemfile_pkey = evp_pkey_load_pem_file(srv, b->ptr);
        if (NULL == ssl_pemfile_pkey) {
            log_error_write(srv, __FILE__, __LINE__, "ssb", "SSL:",
                            "Failed to load acme-tls/1 pemfile:", b);
            break;
        }

      #if 0 /* redundant with below? */
        if (!X509_check_private_key(ssl_pemfile_x509, ssl_pemfile_pkey)) {
            log_error_write(srv, __FILE__, __LINE__, "sssb", "SSL:",
               "Private key does not match acme-tls/1 certificate public key,"
               " reason:" ERR_error_string(ERR_get_error(), NULL), b);
            break;
        }
      #endif

        /* first set certificate!
         * setting private key checks whether certificate matches it */
        if (1 != SSL_use_certificate(ssl, ssl_pemfile_x509)) {
            log_error_write(srv, __FILE__, __LINE__, "ssb:s", "SSL:",
              "failed to set acme-tls/1 certificate for TLS server name",
              name, ERR_error_string(ERR_get_error(), NULL));
            break;
        }

        if (1 != SSL_use_PrivateKey(ssl, ssl_pemfile_pkey)) {
            log_error_write(srv, __FILE__, __LINE__, "ssb:s", "SSL:",
              "failed to set acme-tls/1 private key for TLS server name",
              name, ERR_error_string(ERR_get_error(), NULL));
            break;
        }

        rc = SSL_TLSEXT_ERR_OK;
    } while (0);

    if (ssl_pemfile_pkey) EVP_PKEY_free(ssl_pemfile_pkey);
    if (ssl_pemfile_x509) X509_free(ssl_pemfile_x509);

    return rc;
}

enum {
  MOD_OPENSSL_ALPN_HTTP11      = 1
 ,MOD_OPENSSL_ALPN_HTTP10      = 2
 ,MOD_OPENSSL_ALPN_H2          = 3
 ,MOD_OPENSSL_ALPN_ACME_TLS_1  = 4
};

/* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids */
static int
mod_openssl_alpn_select_cb (SSL *ssl, const unsigned char **out, unsigned char *outlen, const unsigned char *in, unsigned int inlen, void *arg)
{
    handler_ctx *hctx = (handler_ctx *) SSL_get_app_data(ssl);
    unsigned short proto;
    UNUSED(arg);

    for (unsigned int i = 0, n; i < inlen; i += n) {
        n = in[i++];
        if (i+n > inlen || 0 == n) break;
        switch (n) {
         #if 0
          case 2:  /* "h2" */
            if (in[i] == 'h' && in[i+1] == '2') {
                proto = MOD_OPENSSL_ALPN_H2;
                break;
            }
            continue;
         #endif
          case 8:  /* "http/1.1" "http/1.0" */
            if (0 == memcmp(in+i, "http/1.", 7)) {
                if (in[i+7] == '1') {
                    proto = MOD_OPENSSL_ALPN_HTTP11;
                    break;
                }
                if (in[i+7] == '0') {
                    proto = MOD_OPENSSL_ALPN_HTTP10;
                    break;
                }
            }
            continue;
          case 10: /* "acme-tls/1" */
            if (0 == memcmp(in+i, "acme-tls/1", 10)) {
                int rc = mod_openssl_acme_tls_1(ssl, hctx);
                if (rc == SSL_TLSEXT_ERR_OK) {
                    proto = MOD_OPENSSL_ALPN_ACME_TLS_1;
                    break;
                }
                /* (use SSL_TLSEXT_ERR_NOACK for not-configured) */
                if (rc == SSL_TLSEXT_ERR_NOACK) continue;
                return rc;
            }
            continue;
          default:
            continue;
        }

        hctx->alpn = proto;
        *out = in+i;
        *outlen = n;
        return SSL_TLSEXT_ERR_OK;
    }

  #if OPENSSL_VERSION_NUMBER < 0x10100000L
    return SSL_TLSEXT_ERR_NOACK;
  #else
    return SSL_TLSEXT_ERR_ALERT_FATAL;
  #endif
}

#endif /* OPENSSL_VERSION_NUMBER >= 0x10002000 */

#endif /* OPENSSL_NO_TLSEXT */


static int
network_openssl_ssl_conf_cmd (server *srv, plugin_config *s)
{
  #ifdef SSL_CONF_FLAG_CMDLINE

    int rc = 0;
    const data_string *ds;
    SSL_CONF_CTX * const cctx = SSL_CONF_CTX_new();
    SSL_CONF_CTX_set_ssl_ctx(cctx, s->ssl_ctx);
    SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_FILE
                               | SSL_CONF_FLAG_SERVER
                               | SSL_CONF_FLAG_SHOW_ERRORS
                               | SSL_CONF_FLAG_CERTIFICATE);

    /* always disable null and export ciphers */
    ds = (const data_string *)
      array_get_element_klen(s->ssl_conf_cmd,
                             CONST_STR_LEN("CipherString"));
    if (NULL != ds) {
        buffer_append_string_len(ds->value,
                                 CONST_STR_LEN(":!aNULL:!eNULL:!EXP"));
    }

    for (size_t i = 0; i < s->ssl_conf_cmd->used; ++i) {
        ds = (data_string *)s->ssl_conf_cmd->data[i];
        ERR_clear_error();
        if (SSL_CONF_cmd(cctx, ds->key.ptr, ds->value->ptr) <= 0) {
            log_error_write(srv, __FILE__, __LINE__, "ssbbss", "SSL:",
                            "SSL_CONF_cmd", &ds->key, ds->value, ":",
                            ERR_error_string(ERR_get_error(), NULL));
            rc = -1;
            break;
        }
    }

    if (0 == rc && 1 != SSL_CONF_CTX_finish(cctx)) {
        log_error_write(srv, __FILE__, __LINE__, "sss", "SSL:",
                        "SSL_CONF_CTX_finish():",
                        ERR_error_string(ERR_get_error(), NULL));
        rc = -1;
    }

    SSL_CONF_CTX_free(cctx);
    return rc;

  #else

    UNUSED(s);
    log_error_write(srv, __FILE__, __LINE__, "ss", "SSL:",
                    "ssl.openssl.ssl-conf-cmd not available; ignored");
    return 0;

  #endif
}


static int
network_init_ssl (server *srv, void *p_d)
{
    plugin_data *p = p_d;

  #ifndef OPENSSL_NO_DH
   /* 1024-bit MODP Group with 160-bit prime order subgroup (RFC5114)
    * -----BEGIN DH PARAMETERS-----
    * MIIBDAKBgQCxC4+WoIDgHd6S3l6uXVTsUsmfvPsGo8aaap3KUtI7YWBz4oZ1oj0Y
    * mDjvHi7mUsAT7LSuqQYRIySXXDzUm4O/rMvdfZDEvXCYSI6cIZpzck7/1vrlZEc4
    * +qMaT/VbzMChUa9fDci0vUW/N982XBpl5oz9p21NpwjfH7K8LkpDcQKBgQCk0cvV
    * w/00EmdlpELvuZkF+BBN0lisUH/WQGz/FCZtMSZv6h5cQVZLd35pD1UE8hMWAhe0
    * sBuIal6RVH+eJ0n01/vX07mpLuGQnQ0iY/gKdqaiTAh6CR9THb8KAWm2oorWYqTR
    * jnOvoy13nVkY0IvIhY9Nzvl8KiSFXm7rIrOy5QICAKA=
    * -----END DH PARAMETERS-----
    */

    static const unsigned char dh1024_p[]={
        0xB1,0x0B,0x8F,0x96,0xA0,0x80,0xE0,0x1D,0xDE,0x92,0xDE,0x5E,
        0xAE,0x5D,0x54,0xEC,0x52,0xC9,0x9F,0xBC,0xFB,0x06,0xA3,0xC6,
        0x9A,0x6A,0x9D,0xCA,0x52,0xD2,0x3B,0x61,0x60,0x73,0xE2,0x86,
        0x75,0xA2,0x3D,0x18,0x98,0x38,0xEF,0x1E,0x2E,0xE6,0x52,0xC0,
        0x13,0xEC,0xB4,0xAE,0xA9,0x06,0x11,0x23,0x24,0x97,0x5C,0x3C,
        0xD4,0x9B,0x83,0xBF,0xAC,0xCB,0xDD,0x7D,0x90,0xC4,0xBD,0x70,
        0x98,0x48,0x8E,0x9C,0x21,0x9A,0x73,0x72,0x4E,0xFF,0xD6,0xFA,
        0xE5,0x64,0x47,0x38,0xFA,0xA3,0x1A,0x4F,0xF5,0x5B,0xCC,0xC0,
        0xA1,0x51,0xAF,0x5F,0x0D,0xC8,0xB4,0xBD,0x45,0xBF,0x37,0xDF,
        0x36,0x5C,0x1A,0x65,0xE6,0x8C,0xFD,0xA7,0x6D,0x4D,0xA7,0x08,
        0xDF,0x1F,0xB2,0xBC,0x2E,0x4A,0x43,0x71,
    };

    static const unsigned char dh1024_g[]={
        0xA4,0xD1,0xCB,0xD5,0xC3,0xFD,0x34,0x12,0x67,0x65,0xA4,0x42,
        0xEF,0xB9,0x99,0x05,0xF8,0x10,0x4D,0xD2,0x58,0xAC,0x50,0x7F,
        0xD6,0x40,0x6C,0xFF,0x14,0x26,0x6D,0x31,0x26,0x6F,0xEA,0x1E,
        0x5C,0x41,0x56,0x4B,0x77,0x7E,0x69,0x0F,0x55,0x04,0xF2,0x13,
        0x16,0x02,0x17,0xB4,0xB0,0x1B,0x88,0x6A,0x5E,0x91,0x54,0x7F,
        0x9E,0x27,0x49,0xF4,0xD7,0xFB,0xD7,0xD3,0xB9,0xA9,0x2E,0xE1,
        0x90,0x9D,0x0D,0x22,0x63,0xF8,0x0A,0x76,0xA6,0xA2,0x4C,0x08,
        0x7A,0x09,0x1F,0x53,0x1D,0xBF,0x0A,0x01,0x69,0xB6,0xA2,0x8A,
        0xD6,0x62,0xA4,0xD1,0x8E,0x73,0xAF,0xA3,0x2D,0x77,0x9D,0x59,
        0x18,0xD0,0x8B,0xC8,0x85,0x8F,0x4D,0xCE,0xF9,0x7C,0x2A,0x24,
        0x85,0x5E,0x6E,0xEB,0x22,0xB3,0xB2,0xE5,
    };
  #endif

    /* load SSL certificates */
    for (size_t i = 0; i < srv->config_context->used; ++i) {
        plugin_config *s = p->config_storage[i];
      #ifndef SSL_OP_NO_COMPRESSION
      #define SSL_OP_NO_COMPRESSION 0
      #endif
      #ifndef SSL_MODE_RELEASE_BUFFERS    /* OpenSSL >= 1.0.0 */
      #define SSL_MODE_RELEASE_BUFFERS 0
      #endif
        long ssloptions = SSL_OP_ALL
                        | SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
                        | SSL_OP_NO_COMPRESSION;

        if (s->ssl_enabled) {
            if (buffer_string_is_empty(s->ssl_pemfile)) {
                /* inherit ssl settings from global scope
                 * (if only ssl.engine = "enable" and no other ssl.* settings)*/
                if (0 != i && p->config_storage[0]->ssl_enabled) {
                    s->ssl_ctx = p->config_storage[0]->ssl_ctx;
                    continue;
                }
                /* PEM file is require */
                log_error_write(srv, __FILE__, __LINE__, "s",
                                "ssl.pemfile has to be set "
                                "when ssl.engine = \"enable\"");
                return -1;
            }
        }

        if (buffer_string_is_empty(s->ssl_pemfile)
            && buffer_string_is_empty(s->ssl_ca_dn_file)
            && buffer_string_is_empty(s->ssl_ca_file)) continue;

        if (ssl_is_init == 0) {
          #if OPENSSL_VERSION_NUMBER >= 0x10100000L \
           && !defined(LIBRESSL_VERSION_NUMBER)
            OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS
                            |OPENSSL_INIT_LOAD_CRYPTO_STRINGS,NULL);
            OPENSSL_init_crypto(OPENSSL_INIT_ADD_ALL_CIPHERS
                               |OPENSSL_INIT_ADD_ALL_DIGESTS
                               |OPENSSL_INIT_LOAD_CONFIG, NULL);
          #else
            SSL_load_error_strings();
            SSL_library_init();
            OpenSSL_add_all_algorithms();
          #endif
            ssl_is_init = 1;