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view src/http/modules/ngx_http_ssl_module.c @ 7047:3fef8c5caa75

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Proxy: split configured header names and values. Previously, each configured header was represented in one of two ways, depending on whether or not its value included any variables. If the value didn't include any variables, then it would be represented as as a single script that contained complete header line with HTTP/1.1 delimiters, i.e.: "Header: value\r\n" But if the value included any variables, then it would be represented as a series of three scripts: first contained header name and the ": " delimiter, second evaluated to header value, and third contained only "\r\n", i.e.: "Header: " "$value" "\r\n" This commit changes that, so that each configured header is represented as a series of two scripts: first contains only header name, and second contains (or evaluates to) only header value, i.e.: "Header" "$value" or "Header" "value" This not only makes things more consistent, but also allows header name and value to be accessed separately. Signed-off-by: Piotr Sikora <piotrsikora@google.com>
author Piotr Sikora <piotrsikora@google.com>
date Wed, 15 Mar 2017 15:55:35 -0700
parents 08dc60979133
children 2a288909abc6
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


typedef ngx_int_t (*ngx_ssl_variable_handler_pt)(ngx_connection_t *c,
    ngx_pool_t *pool, ngx_str_t *s);


#define NGX_DEFAULT_CIPHERS     "HIGH:!aNULL:!MD5"
#define NGX_DEFAULT_ECDH_CURVE  "auto"

#define NGX_HTTP_NPN_ADVERTISE  "\x08http/1.1"


#ifdef TLSEXT_TYPE_application_layer_protocol_negotiation
static int ngx_http_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn,
    const unsigned char **out, unsigned char *outlen,
    const unsigned char *in, unsigned int inlen, void *arg);
#endif

#ifdef TLSEXT_TYPE_next_proto_neg
static int ngx_http_ssl_npn_advertised(ngx_ssl_conn_t *ssl_conn,
    const unsigned char **out, unsigned int *outlen, void *arg);
#endif

static ngx_int_t ngx_http_ssl_static_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_ssl_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);

static ngx_int_t ngx_http_ssl_add_variables(ngx_conf_t *cf);
static void *ngx_http_ssl_create_srv_conf(ngx_conf_t *cf);
static char *ngx_http_ssl_merge_srv_conf(ngx_conf_t *cf,
    void *parent, void *child);

static char *ngx_http_ssl_enable(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_ssl_password_file(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_ssl_session_cache(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);

static ngx_int_t ngx_http_ssl_init(ngx_conf_t *cf);


static ngx_conf_bitmask_t  ngx_http_ssl_protocols[] = {
    { ngx_string("SSLv2"), NGX_SSL_SSLv2 },
    { ngx_string("SSLv3"), NGX_SSL_SSLv3 },
    { ngx_string("TLSv1"), NGX_SSL_TLSv1 },
    { ngx_string("TLSv1.1"), NGX_SSL_TLSv1_1 },
    { ngx_string("TLSv1.2"), NGX_SSL_TLSv1_2 },
    { ngx_string("TLSv1.3"), NGX_SSL_TLSv1_3 },
    { ngx_null_string, 0 }
};


static ngx_conf_enum_t  ngx_http_ssl_verify[] = {
    { ngx_string("off"), 0 },
    { ngx_string("on"), 1 },
    { ngx_string("optional"), 2 },
    { ngx_string("optional_no_ca"), 3 },
    { ngx_null_string, 0 }
};


static ngx_command_t  ngx_http_ssl_commands[] = {

    { ngx_string("ssl"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
      ngx_http_ssl_enable,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, enable),
      NULL },

    { ngx_string("ssl_certificate"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_array_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, certificates),
      NULL },

    { ngx_string("ssl_certificate_key"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_array_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, certificate_keys),
      NULL },

    { ngx_string("ssl_password_file"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_ssl_password_file,
      NGX_HTTP_SRV_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("ssl_dhparam"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, dhparam),
      NULL },

    { ngx_string("ssl_ecdh_curve"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, ecdh_curve),
      NULL },

    { ngx_string("ssl_protocols"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_1MORE,
      ngx_conf_set_bitmask_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, protocols),
      &ngx_http_ssl_protocols },

    { ngx_string("ssl_ciphers"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, ciphers),
      NULL },

    { ngx_string("ssl_buffer_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, buffer_size),
      NULL },

    { ngx_string("ssl_verify_client"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, verify),
      &ngx_http_ssl_verify },

    { ngx_string("ssl_verify_depth"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, verify_depth),
      NULL },

    { ngx_string("ssl_client_certificate"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, client_certificate),
      NULL },

    { ngx_string("ssl_trusted_certificate"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, trusted_certificate),
      NULL },

    { ngx_string("ssl_prefer_server_ciphers"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, prefer_server_ciphers),
      NULL },

    { ngx_string("ssl_session_cache"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE12,
      ngx_http_ssl_session_cache,
      NGX_HTTP_SRV_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("ssl_session_tickets"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, session_tickets),
      NULL },

    { ngx_string("ssl_session_ticket_key"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_array_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, session_ticket_keys),
      NULL },

    { ngx_string("ssl_session_timeout"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_sec_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, session_timeout),
      NULL },

    { ngx_string("ssl_crl"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, crl),
      NULL },

    { ngx_string("ssl_stapling"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, stapling),
      NULL },

    { ngx_string("ssl_stapling_file"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, stapling_file),
      NULL },

    { ngx_string("ssl_stapling_responder"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, stapling_responder),
      NULL },

    { ngx_string("ssl_stapling_verify"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_ssl_srv_conf_t, stapling_verify),
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_ssl_module_ctx = {
    ngx_http_ssl_add_variables,            /* preconfiguration */
    ngx_http_ssl_init,                     /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    ngx_http_ssl_create_srv_conf,          /* create server configuration */
    ngx_http_ssl_merge_srv_conf,           /* merge server configuration */

    NULL,                                  /* create location configuration */
    NULL                                   /* merge location configuration */
};


ngx_module_t  ngx_http_ssl_module = {
    NGX_MODULE_V1,
    &ngx_http_ssl_module_ctx,              /* module context */
    ngx_http_ssl_commands,                 /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static ngx_http_variable_t  ngx_http_ssl_vars[] = {

    { ngx_string("ssl_protocol"), NULL, ngx_http_ssl_static_variable,
      (uintptr_t) ngx_ssl_get_protocol, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_cipher"), NULL, ngx_http_ssl_static_variable,
      (uintptr_t) ngx_ssl_get_cipher_name, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_ciphers"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_ciphers, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_curves"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_curves, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_session_id"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_session_id, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_session_reused"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_session_reused, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_server_name"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_server_name, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_cert"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_certificate, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_raw_cert"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_raw_certificate,
      NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_s_dn"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_subject_dn, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_i_dn"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_issuer_dn, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_s_dn_legacy"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_subject_dn_legacy, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_i_dn_legacy"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_issuer_dn_legacy, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_serial"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_serial_number, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_fingerprint"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_fingerprint, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_verify"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_client_verify, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_v_start"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_client_v_start, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_v_end"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_client_v_end, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_string("ssl_client_v_remain"), NULL, ngx_http_ssl_variable,
      (uintptr_t) ngx_ssl_get_client_v_remain, NGX_HTTP_VAR_CHANGEABLE, 0 },

    { ngx_null_string, NULL, NULL, 0, 0, 0 }
};


static ngx_str_t ngx_http_ssl_sess_id_ctx = ngx_string("HTTP");


#ifdef TLSEXT_TYPE_application_layer_protocol_negotiation

static int
ngx_http_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn, const unsigned char **out,
    unsigned char *outlen, const unsigned char *in, unsigned int inlen,
    void *arg)
{
    unsigned int            srvlen;
    unsigned char          *srv;
#if (NGX_DEBUG)
    unsigned int            i;
#endif
#if (NGX_HTTP_V2)
    ngx_http_connection_t  *hc;
#endif
#if (NGX_HTTP_V2 || NGX_DEBUG)
    ngx_connection_t       *c;

    c = ngx_ssl_get_connection(ssl_conn);
#endif

#if (NGX_DEBUG)
    for (i = 0; i < inlen; i += in[i] + 1) {
        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "SSL ALPN supported by client: %*s",
                       (size_t) in[i], &in[i + 1]);
    }
#endif

#if (NGX_HTTP_V2)
    hc = c->data;

    if (hc->addr_conf->http2) {
        srv =
           (unsigned char *) NGX_HTTP_V2_ALPN_ADVERTISE NGX_HTTP_NPN_ADVERTISE;
        srvlen = sizeof(NGX_HTTP_V2_ALPN_ADVERTISE NGX_HTTP_NPN_ADVERTISE) - 1;

    } else
#endif
    {
        srv = (unsigned char *) NGX_HTTP_NPN_ADVERTISE;
        srvlen = sizeof(NGX_HTTP_NPN_ADVERTISE) - 1;
    }

    if (SSL_select_next_proto((unsigned char **) out, outlen, srv, srvlen,
                              in, inlen)
        != OPENSSL_NPN_NEGOTIATED)
    {
        return SSL_TLSEXT_ERR_NOACK;
    }

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "SSL ALPN selected: %*s", (size_t) *outlen, *out);

    return SSL_TLSEXT_ERR_OK;
}

#endif


#ifdef TLSEXT_TYPE_next_proto_neg

static int
ngx_http_ssl_npn_advertised(ngx_ssl_conn_t *ssl_conn,
    const unsigned char **out, unsigned int *outlen, void *arg)
{
#if (NGX_HTTP_V2 || NGX_DEBUG)
    ngx_connection_t  *c;

    c = ngx_ssl_get_connection(ssl_conn);
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "SSL NPN advertised");
#endif

#if (NGX_HTTP_V2)
    {
    ngx_http_connection_t  *hc;

    hc = c->data;

    if (hc->addr_conf->http2) {
        *out =
            (unsigned char *) NGX_HTTP_V2_NPN_ADVERTISE NGX_HTTP_NPN_ADVERTISE;
        *outlen = sizeof(NGX_HTTP_V2_NPN_ADVERTISE NGX_HTTP_NPN_ADVERTISE) - 1;

        return SSL_TLSEXT_ERR_OK;
    }
    }
#endif

    *out = (unsigned char *) NGX_HTTP_NPN_ADVERTISE;
    *outlen = sizeof(NGX_HTTP_NPN_ADVERTISE) - 1;

    return SSL_TLSEXT_ERR_OK;
}

#endif


static ngx_int_t
ngx_http_ssl_static_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_ssl_variable_handler_pt  handler = (ngx_ssl_variable_handler_pt) data;

    size_t     len;
    ngx_str_t  s;

    if (r->connection->ssl) {

        (void) handler(r->connection, NULL, &s);

        v->data = s.data;

        for (len = 0; v->data[len]; len++) { /* void */ }

        v->len = len;
        v->valid = 1;
        v->no_cacheable = 0;
        v->not_found = 0;

        return NGX_OK;
    }

    v->not_found = 1;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssl_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v,
    uintptr_t data)
{
    ngx_ssl_variable_handler_pt  handler = (ngx_ssl_variable_handler_pt) data;

    ngx_str_t  s;

    if (r->connection->ssl) {

        if (handler(r->connection, r->pool, &s) != NGX_OK) {
            return NGX_ERROR;
        }

        v->len = s.len;
        v->data = s.data;

        if (v->len) {
            v->valid = 1;
            v->no_cacheable = 0;
            v->not_found = 0;

            return NGX_OK;
        }
    }

    v->not_found = 1;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssl_add_variables(ngx_conf_t *cf)
{
    ngx_http_variable_t  *var, *v;

    for (v = ngx_http_ssl_vars; v->name.len; v++) {
        var = ngx_http_add_variable(cf, &v->name, v->flags);
        if (var == NULL) {
            return NGX_ERROR;
        }

        var->get_handler = v->get_handler;
        var->data = v->data;
    }

    return NGX_OK;
}


static void *
ngx_http_ssl_create_srv_conf(ngx_conf_t *cf)
{
    ngx_http_ssl_srv_conf_t  *sscf;

    sscf = ngx_pcalloc(cf->pool, sizeof(ngx_http_ssl_srv_conf_t));
    if (sscf == NULL) {
        return NULL;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     sscf->protocols = 0;
     *     sscf->dhparam = { 0, NULL };
     *     sscf->ecdh_curve = { 0, NULL };
     *     sscf->client_certificate = { 0, NULL };
     *     sscf->trusted_certificate = { 0, NULL };
     *     sscf->crl = { 0, NULL };
     *     sscf->ciphers = { 0, NULL };
     *     sscf->shm_zone = NULL;
     *     sscf->stapling_file = { 0, NULL };
     *     sscf->stapling_responder = { 0, NULL };
     */

    sscf->enable = NGX_CONF_UNSET;
    sscf->prefer_server_ciphers = NGX_CONF_UNSET;
    sscf->buffer_size = NGX_CONF_UNSET_SIZE;
    sscf->verify = NGX_CONF_UNSET_UINT;
    sscf->verify_depth = NGX_CONF_UNSET_UINT;
    sscf->certificates = NGX_CONF_UNSET_PTR;
    sscf->certificate_keys = NGX_CONF_UNSET_PTR;
    sscf->passwords = NGX_CONF_UNSET_PTR;
    sscf->builtin_session_cache = NGX_CONF_UNSET;
    sscf->session_timeout = NGX_CONF_UNSET;
    sscf->session_tickets = NGX_CONF_UNSET;
    sscf->session_ticket_keys = NGX_CONF_UNSET_PTR;
    sscf->stapling = NGX_CONF_UNSET;
    sscf->stapling_verify = NGX_CONF_UNSET;

    return sscf;
}


static char *
ngx_http_ssl_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_ssl_srv_conf_t *prev = parent;
    ngx_http_ssl_srv_conf_t *conf = child;

    ngx_pool_cleanup_t  *cln;

    if (conf->enable == NGX_CONF_UNSET) {
        if (prev->enable == NGX_CONF_UNSET) {
            conf->enable = 0;

        } else {
            conf->enable = prev->enable;
            conf->file = prev->file;
            conf->line = prev->line;
        }
    }

    ngx_conf_merge_value(conf->session_timeout,
                         prev->session_timeout, 300);

    ngx_conf_merge_value(conf->prefer_server_ciphers,
                         prev->prefer_server_ciphers, 0);

    ngx_conf_merge_bitmask_value(conf->protocols, prev->protocols,
                         (NGX_CONF_BITMASK_SET|NGX_SSL_TLSv1
                          |NGX_SSL_TLSv1_1|NGX_SSL_TLSv1_2));

    ngx_conf_merge_size_value(conf->buffer_size, prev->buffer_size,
                         NGX_SSL_BUFSIZE);

    ngx_conf_merge_uint_value(conf->verify, prev->verify, 0);
    ngx_conf_merge_uint_value(conf->verify_depth, prev->verify_depth, 1);

    ngx_conf_merge_ptr_value(conf->certificates, prev->certificates, NULL);
    ngx_conf_merge_ptr_value(conf->certificate_keys, prev->certificate_keys,
                         NULL);

    ngx_conf_merge_ptr_value(conf->passwords, prev->passwords, NULL);

    ngx_conf_merge_str_value(conf->dhparam, prev->dhparam, "");

    ngx_conf_merge_str_value(conf->client_certificate, prev->client_certificate,
                         "");
    ngx_conf_merge_str_value(conf->trusted_certificate,
                         prev->trusted_certificate, "");
    ngx_conf_merge_str_value(conf->crl, prev->crl, "");

    ngx_conf_merge_str_value(conf->ecdh_curve, prev->ecdh_curve,
                         NGX_DEFAULT_ECDH_CURVE);

    ngx_conf_merge_str_value(conf->ciphers, prev->ciphers, NGX_DEFAULT_CIPHERS);

    ngx_conf_merge_value(conf->stapling, prev->stapling, 0);
    ngx_conf_merge_value(conf->stapling_verify, prev->stapling_verify, 0);
    ngx_conf_merge_str_value(conf->stapling_file, prev->stapling_file, "");
    ngx_conf_merge_str_value(conf->stapling_responder,
                         prev->stapling_responder, "");

    conf->ssl.log = cf->log;

    if (conf->enable) {

        if (conf->certificates == NULL) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate\" is defined for "
                          "the \"ssl\" directive in %s:%ui",
                          conf->file, conf->line);
            return NGX_CONF_ERROR;
        }

        if (conf->certificate_keys == NULL) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate_key\" is defined for "
                          "the \"ssl\" directive in %s:%ui",
                          conf->file, conf->line);
            return NGX_CONF_ERROR;
        }

        if (conf->certificate_keys->nelts < conf->certificates->nelts) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate_key\" is defined "
                          "for certificate \"%V\" and "
                          "the \"ssl\" directive in %s:%ui",
                          ((ngx_str_t *) conf->certificates->elts)
                          + conf->certificates->nelts - 1,
                          conf->file, conf->line);
            return NGX_CONF_ERROR;
        }

    } else {

        if (conf->certificates == NULL) {
            return NGX_CONF_OK;
        }

        if (conf->certificate_keys == NULL
            || conf->certificate_keys->nelts < conf->certificates->nelts)
        {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate_key\" is defined "
                          "for certificate \"%V\"",
                          ((ngx_str_t *) conf->certificates->elts)
                          + conf->certificates->nelts - 1);
            return NGX_CONF_ERROR;
        }
    }

    if (ngx_ssl_create(&conf->ssl, conf->protocols, conf) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME

    if (SSL_CTX_set_tlsext_servername_callback(conf->ssl.ctx,
                                               ngx_http_ssl_servername)
        == 0)
    {
        ngx_log_error(NGX_LOG_WARN, cf->log, 0,
            "nginx was built with SNI support, however, now it is linked "
            "dynamically to an OpenSSL library which has no tlsext support, "
            "therefore SNI is not available");
    }

#endif

#ifdef TLSEXT_TYPE_application_layer_protocol_negotiation
    SSL_CTX_set_alpn_select_cb(conf->ssl.ctx, ngx_http_ssl_alpn_select, NULL);
#endif

#ifdef TLSEXT_TYPE_next_proto_neg
    SSL_CTX_set_next_protos_advertised_cb(conf->ssl.ctx,
                                          ngx_http_ssl_npn_advertised, NULL);
#endif

    cln = ngx_pool_cleanup_add(cf->pool, 0);
    if (cln == NULL) {
        return NGX_CONF_ERROR;
    }

    cln->handler = ngx_ssl_cleanup_ctx;
    cln->data = &conf->ssl;

    if (ngx_ssl_certificates(cf, &conf->ssl, conf->certificates,
                             conf->certificate_keys, conf->passwords)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    if (ngx_ssl_ciphers(cf, &conf->ssl, &conf->ciphers,
                        conf->prefer_server_ciphers)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    conf->ssl.buffer_size = conf->buffer_size;

    if (conf->verify) {

        if (conf->client_certificate.len == 0 && conf->verify != 3) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no ssl_client_certificate for ssl_client_verify");
            return NGX_CONF_ERROR;
        }

        if (ngx_ssl_client_certificate(cf, &conf->ssl,
                                       &conf->client_certificate,
                                       conf->verify_depth)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }
    }

    if (ngx_ssl_trusted_certificate(cf, &conf->ssl,
                                    &conf->trusted_certificate,
                                    conf->verify_depth)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    if (ngx_ssl_crl(cf, &conf->ssl, &conf->crl) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    if (ngx_ssl_dhparam(cf, &conf->ssl, &conf->dhparam) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    if (ngx_ssl_ecdh_curve(cf, &conf->ssl, &conf->ecdh_curve) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    ngx_conf_merge_value(conf->builtin_session_cache,
                         prev->builtin_session_cache, NGX_SSL_NONE_SCACHE);

    if (conf->shm_zone == NULL) {
        conf->shm_zone = prev->shm_zone;
    }

    if (ngx_ssl_session_cache(&conf->ssl, &ngx_http_ssl_sess_id_ctx,
                              conf->builtin_session_cache,
                              conf->shm_zone, conf->session_timeout)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    ngx_conf_merge_value(conf->session_tickets, prev->session_tickets, 1);

#ifdef SSL_OP_NO_TICKET
    if (!conf->session_tickets) {
        SSL_CTX_set_options(conf->ssl.ctx, SSL_OP_NO_TICKET);
    }
#endif

    ngx_conf_merge_ptr_value(conf->session_ticket_keys,
                         prev->session_ticket_keys, NULL);

    if (ngx_ssl_session_ticket_keys(cf, &conf->ssl, conf->session_ticket_keys)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    if (conf->stapling) {

        if (ngx_ssl_stapling(cf, &conf->ssl, &conf->stapling_file,
                             &conf->stapling_responder, conf->stapling_verify)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }

    }

    return NGX_CONF_OK;
}


static char *
ngx_http_ssl_enable(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_ssl_srv_conf_t *sscf = conf;

    char  *rv;

    rv = ngx_conf_set_flag_slot(cf, cmd, conf);

    if (rv != NGX_CONF_OK) {
        return rv;
    }

    sscf->file = cf->conf_file->file.name.data;
    sscf->line = cf->conf_file->line;

    return NGX_CONF_OK;
}


static char *
ngx_http_ssl_password_file(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_ssl_srv_conf_t *sscf = conf;

    ngx_str_t  *value;

    if (sscf->passwords != NGX_CONF_UNSET_PTR) {
        return "is duplicate";
    }

    value = cf->args->elts;

    sscf->passwords = ngx_ssl_read_password_file(cf, &value[1]);

    if (sscf->passwords == NULL) {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_ssl_session_cache(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_ssl_srv_conf_t *sscf = conf;

    size_t       len;
    ngx_str_t   *value, name, size;
    ngx_int_t    n;
    ngx_uint_t   i, j;

    value = cf->args->elts;

    for (i = 1; i < cf->args->nelts; i++) {

        if (ngx_strcmp(value[i].data, "off") == 0) {
            sscf->builtin_session_cache = NGX_SSL_NO_SCACHE;
            continue;
        }

        if (ngx_strcmp(value[i].data, "none") == 0) {
            sscf->builtin_session_cache = NGX_SSL_NONE_SCACHE;
            continue;
        }

        if (ngx_strcmp(value[i].data, "builtin") == 0) {
            sscf->builtin_session_cache = NGX_SSL_DFLT_BUILTIN_SCACHE;
            continue;
        }

        if (value[i].len > sizeof("builtin:") - 1
            && ngx_strncmp(value[i].data, "builtin:", sizeof("builtin:") - 1)
               == 0)
        {
            n = ngx_atoi(value[i].data + sizeof("builtin:") - 1,
                         value[i].len - (sizeof("builtin:") - 1));

            if (n == NGX_ERROR) {
                goto invalid;
            }

            sscf->builtin_session_cache = n;

            continue;
        }

        if (value[i].len > sizeof("shared:") - 1
            && ngx_strncmp(value[i].data, "shared:", sizeof("shared:") - 1)
               == 0)
        {
            len = 0;

            for (j = sizeof("shared:") - 1; j < value[i].len; j++) {
                if (value[i].data[j] == ':') {
                    break;
                }

                len++;
            }

            if (len == 0) {
                goto invalid;
            }

            name.len = len;
            name.data = value[i].data + sizeof("shared:") - 1;

            size.len = value[i].len - j - 1;
            size.data = name.data + len + 1;

            n = ngx_parse_size(&size);

            if (n == NGX_ERROR) {
                goto invalid;
            }

            if (n < (ngx_int_t) (8 * ngx_pagesize)) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "session cache \"%V\" is too small",
                                   &value[i]);

                return NGX_CONF_ERROR;
            }

            sscf->shm_zone = ngx_shared_memory_add(cf, &name, n,
                                                   &ngx_http_ssl_module);
            if (sscf->shm_zone == NULL) {
                return NGX_CONF_ERROR;
            }

            sscf->shm_zone->init = ngx_ssl_session_cache_init;

            continue;
        }

        goto invalid;
    }

    if (sscf->shm_zone && sscf->builtin_session_cache == NGX_CONF_UNSET) {
        sscf->builtin_session_cache = NGX_SSL_NO_BUILTIN_SCACHE;
    }

    return NGX_CONF_OK;

invalid:

    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "invalid session cache \"%V\"", &value[i]);

    return NGX_CONF_ERROR;
}


static ngx_int_t
ngx_http_ssl_init(ngx_conf_t *cf)
{
    ngx_uint_t                   s;
    ngx_http_ssl_srv_conf_t     *sscf;
    ngx_http_core_loc_conf_t    *clcf;
    ngx_http_core_srv_conf_t   **cscfp;
    ngx_http_core_main_conf_t   *cmcf;

    cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
    cscfp = cmcf->servers.elts;

    for (s = 0; s < cmcf->servers.nelts; s++) {

        sscf = cscfp[s]->ctx->srv_conf[ngx_http_ssl_module.ctx_index];

        if (sscf->ssl.ctx == NULL || !sscf->stapling) {
            continue;
        }

        clcf = cscfp[s]->ctx->loc_conf[ngx_http_core_module.ctx_index];

        if (ngx_ssl_stapling_resolver(cf, &sscf->ssl, clcf->resolver,
                                      clcf->resolver_timeout)
            != NGX_OK)
        {
            return NGX_ERROR;
        }
    }

    return NGX_OK;
}