core.c

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "apr.h"
#include "apr_strings.h"
#include "apr_lib.h"
#include "apr_fnmatch.h"
#include "apr_hash.h"
#include "apr_thread_proc.h"    /* for RLIMIT stuff */
#include "apr_random.h"

#define APR_WANT_IOVEC
#define APR_WANT_STRFUNC
#define APR_WANT_MEMFUNC
#include "apr_want.h"

#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_protocol.h" /* For index_of_response().  Grump. */
#include "http_request.h"
#include "http_vhost.h"
#include "http_main.h"     /* For the default_handler below... */
#include "http_log.h"
#include "util_md5.h"
#include "http_connection.h"
#include "apr_buckets.h"
#include "util_filter.h"
#include "util_ebcdic.h"
#include "util_mutex.h"
#include "util_time.h"
#include "mpm_common.h"
#include "scoreboard.h"
#include "mod_core.h"
#include "mod_proxy.h"
#include "ap_listen.h"

#include "mod_so.h" /* for ap_find_loaded_module_symbol */

#if defined(RLIMIT_CPU) || defined (RLIMIT_DATA) || defined (RLIMIT_VMEM) || defined(RLIMIT_AS) || defined (RLIMIT_NPROC)
#include "unixd.h"
#endif
#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif

/* LimitRequestBody handling */
#define AP_LIMIT_REQ_BODY_UNSET         ((apr_off_t) -1)
#define AP_DEFAULT_LIMIT_REQ_BODY       ((apr_off_t) 0)

/* LimitXMLRequestBody handling */
#define AP_LIMIT_UNSET                  ((long) -1)
#define AP_DEFAULT_LIMIT_XML_BODY       ((apr_size_t)1000000)

#define AP_MIN_SENDFILE_BYTES           (256)

/* maximum include nesting level */
#ifndef AP_MAX_INCLUDE_DEPTH
#define AP_MAX_INCLUDE_DEPTH            (128)
#endif

/* valid in core-conf, but not in runtime r->used_path_info */
#define AP_ACCEPT_PATHINFO_UNSET 3

#define AP_CONTENT_MD5_OFF   0
#define AP_CONTENT_MD5_ON    1
#define AP_CONTENT_MD5_UNSET 2

APR_HOOK_STRUCT(
    APR_HOOK_LINK(get_mgmt_items)
    APR_HOOK_LINK(insert_network_bucket)
)

AP_IMPLEMENT_HOOK_RUN_ALL(int, get_mgmt_items,
                          (apr_pool_t *p, const char *val, apr_hash_t *ht),
                          (p, val, ht), OK, DECLINED)

AP_IMPLEMENT_HOOK_RUN_FIRST(apr_status_t, insert_network_bucket,
                            (conn_rec *c, apr_bucket_brigade *bb,
                             apr_socket_t *socket),
                            (c, bb, socket), AP_DECLINED)

/* Server core module... This module provides support for really basic
 * server operations, including options and commands which control the
 * operation of other modules.  Consider this the bureaucracy module.
 *
 * The core module also defines handlers, etc., to handle just enough
 * to allow a server with the core module ONLY to actually serve documents.
 *
 * This file could almost be mod_core.c, except for the stuff which affects
 * the http_conf_globals.
 */

/* we know core's module_index is 0 */
#undef APLOG_MODULE_INDEX
#define APLOG_MODULE_INDEX AP_CORE_MODULE_INDEX

/* Handles for core filters */
AP_DECLARE_DATA ap_filter_rec_t *ap_subreq_core_filter_handle;
AP_DECLARE_DATA ap_filter_rec_t *ap_core_output_filter_handle;
AP_DECLARE_DATA ap_filter_rec_t *ap_content_length_filter_handle;
AP_DECLARE_DATA ap_filter_rec_t *ap_core_input_filter_handle;

/* Provide ap_document_root_check storage and default value = true */
AP_DECLARE_DATA int ap_document_root_check = 1;

/* magic pointer for ErrorDocument xxx "default" */
static char errordocument_default;

static apr_array_header_t *saved_server_config_defines = NULL;
static apr_table_t *server_config_defined_vars = NULL;

AP_DECLARE_DATA int ap_main_state = AP_SQ_MS_INITIAL_STARTUP;
AP_DECLARE_DATA int ap_run_mode = AP_SQ_RM_UNKNOWN;
AP_DECLARE_DATA int ap_config_generation = 0;

static void *create_core_dir_config(apr_pool_t *a, char *dir)
{
    core_dir_config *conf;

    conf = (core_dir_config *)apr_pcalloc(a, sizeof(core_dir_config));

    /* conf->r and conf->d[_*] are initialized by dirsection() or left NULL */

    conf->opts = dir ? OPT_UNSET : OPT_UNSET|OPT_SYM_LINKS;
    conf->opts_add = conf->opts_remove = OPT_NONE;
    conf->override = OR_UNSET|OR_NONE;
    conf->override_opts = OPT_UNSET | OPT_ALL | OPT_SYM_OWNER | OPT_MULTI;

    conf->content_md5 = AP_CONTENT_MD5_UNSET;
    conf->accept_path_info = AP_ACCEPT_PATHINFO_UNSET;

    conf->use_canonical_name = USE_CANONICAL_NAME_UNSET;
    conf->use_canonical_phys_port = USE_CANONICAL_PHYS_PORT_UNSET;

    conf->hostname_lookups = HOSTNAME_LOOKUP_UNSET;

    /*
     * left as NULL (we use apr_pcalloc):
     * conf->limit_cpu = NULL;
     * conf->limit_mem = NULL;
     * conf->limit_nproc = NULL;
     * conf->sec_file = NULL;
     * conf->sec_if   = NULL;
     */

    conf->limit_req_body = AP_LIMIT_REQ_BODY_UNSET;
    conf->limit_xml_body = AP_LIMIT_UNSET;

    conf->server_signature = srv_sig_unset;

    conf->add_default_charset = ADD_DEFAULT_CHARSET_UNSET;
    conf->add_default_charset_name = DEFAULT_ADD_DEFAULT_CHARSET_NAME;

    /* Overriding all negotiation
     * Set NULL by apr_pcalloc:
     * conf->mime_type = NULL;
     * conf->handler = NULL;
     * conf->output_filters = NULL;
     * conf->input_filters = NULL;
     */

    /*
     * Flag for use of inodes in ETags.
     */
    conf->etag_bits = ETAG_UNSET;
    conf->etag_add = ETAG_UNSET;
    conf->etag_remove = ETAG_UNSET;

    conf->enable_mmap = ENABLE_MMAP_UNSET;
    conf->enable_sendfile = ENABLE_SENDFILE_UNSET;
    conf->allow_encoded_slashes = 0;
    conf->decode_encoded_slashes = 0;

    conf->max_ranges = AP_MAXRANGES_UNSET;
    conf->max_overlaps = AP_MAXRANGES_UNSET;
    conf->max_reversals = AP_MAXRANGES_UNSET;

    conf->cgi_pass_auth = AP_CGI_PASS_AUTH_UNSET;
    conf->qualify_redirect_url = AP_CORE_CONFIG_UNSET; 

    return (void *)conf;
}

static void *merge_core_dir_configs(apr_pool_t *a, void *basev, void *newv)
{
    core_dir_config *base = (core_dir_config *)basev;
    core_dir_config *new = (core_dir_config *)newv;
    core_dir_config *conf;

    /* Create this conf by duplicating the base, replacing elements
     * (or creating copies for merging) where new-> values exist.
     */
    conf = (core_dir_config *)apr_pmemdup(a, base, sizeof(core_dir_config));

    conf->d = new->d;
    conf->d_is_fnmatch = new->d_is_fnmatch;
    conf->d_components = new->d_components;
    conf->r = new->r;
    conf->refs = new->refs;
    conf->condition = new->condition;

    if (new->opts & OPT_UNSET) {
        /* there was no explicit setting of new->opts, so we merge
         * preserve the invariant (opts_add & opts_remove) == 0
         */
        conf->opts_add = (conf->opts_add & ~new->opts_remove) | new->opts_add;
        conf->opts_remove = (conf->opts_remove & ~new->opts_add)
                            | new->opts_remove;
        conf->opts = (conf->opts & ~conf->opts_remove) | conf->opts_add;

        /* If Includes was enabled with exec in the base config, but
         * was enabled without exec in the new config, then disable
         * exec in the merged set. */
        if (((base->opts & (OPT_INCLUDES|OPT_INC_WITH_EXEC))
             == (OPT_INCLUDES|OPT_INC_WITH_EXEC))
            && ((new->opts & (OPT_INCLUDES|OPT_INC_WITH_EXEC))
                == OPT_INCLUDES)) {
            conf->opts &= ~OPT_INC_WITH_EXEC;
        }
    }
    else {
        /* otherwise we just copy, because an explicit opts setting
         * overrides all earlier +/- modifiers
         */
        conf->opts = new->opts;
        conf->opts_add = new->opts_add;
        conf->opts_remove = new->opts_remove;
    }

    if (!(new->override & OR_UNSET)) {
        conf->override = new->override;
    }

    if (!(new->override_opts & OPT_UNSET)) {
        conf->override_opts = new->override_opts;
    }

    if (new->override_list != NULL) {
        conf->override_list = new->override_list;
    }

    if (conf->response_code_exprs == NULL) {
        conf->response_code_exprs = new->response_code_exprs;
    }
    else if (new->response_code_exprs != NULL) {
        conf->response_code_exprs = apr_hash_overlay(a,
                new->response_code_exprs, conf->response_code_exprs);
    }
    /* Otherwise we simply use the base->response_code_exprs array
     */

    if (new->hostname_lookups != HOSTNAME_LOOKUP_UNSET) {
        conf->hostname_lookups = new->hostname_lookups;
    }

    if (new->content_md5 != AP_CONTENT_MD5_UNSET) {
        conf->content_md5 = new->content_md5;
    }

    if (new->accept_path_info != AP_ACCEPT_PATHINFO_UNSET) {
        conf->accept_path_info = new->accept_path_info;
    }

    if (new->use_canonical_name != USE_CANONICAL_NAME_UNSET) {
        conf->use_canonical_name = new->use_canonical_name;
    }

    if (new->use_canonical_phys_port != USE_CANONICAL_PHYS_PORT_UNSET) {
        conf->use_canonical_phys_port = new->use_canonical_phys_port;
    }

#ifdef RLIMIT_CPU
    if (new->limit_cpu) {
        conf->limit_cpu = new->limit_cpu;
    }
#endif

#if defined(RLIMIT_DATA) || defined(RLIMIT_VMEM) || defined(RLIMIT_AS)
    if (new->limit_mem) {
        conf->limit_mem = new->limit_mem;
    }
#endif

#ifdef RLIMIT_NPROC
    if (new->limit_nproc) {
        conf->limit_nproc = new->limit_nproc;
    }
#endif

    if (new->limit_req_body != AP_LIMIT_REQ_BODY_UNSET) {
        conf->limit_req_body = new->limit_req_body;
    }

    if (new->limit_xml_body != AP_LIMIT_UNSET)
        conf->limit_xml_body = new->limit_xml_body;

    if (!conf->sec_file) {
        conf->sec_file = new->sec_file;
    }
    else if (new->sec_file) {
        /* If we merge, the merge-result must have its own array
         */
        conf->sec_file = apr_array_append(a, base->sec_file, new->sec_file);
    }
    /* Otherwise we simply use the base->sec_file array
     */

    if (!conf->sec_if) {
        conf->sec_if = new->sec_if;
    }
    else if (new->sec_if) {
        /* If we merge, the merge-result must have its own array
         */
        conf->sec_if = apr_array_append(a, base->sec_if, new->sec_if);
    }
    /* Otherwise we simply use the base->sec_if array
     */

    if (new->server_signature != srv_sig_unset) {
        conf->server_signature = new->server_signature;
    }

    if (new->add_default_charset != ADD_DEFAULT_CHARSET_UNSET) {
        conf->add_default_charset = new->add_default_charset;
        conf->add_default_charset_name = new->add_default_charset_name;
    }

    /* Overriding all negotiation
     */
    if (new->mime_type) {
        conf->mime_type = new->mime_type;
    }

    if (new->handler) {
        conf->handler = new->handler;
    }
    if (new->expr_handler) {
        conf->expr_handler = new->expr_handler;
    }

    if (new->output_filters) {
        conf->output_filters = new->output_filters;
    }

    if (new->input_filters) {
        conf->input_filters = new->input_filters;
    }

    /*
     * Now merge the setting of the FileETag directive.
     */
    if (new->etag_bits == ETAG_UNSET) {
        conf->etag_add =
            (conf->etag_add & (~ new->etag_remove)) | new->etag_add;
        conf->etag_remove =
            (conf->etag_remove & (~ new->etag_add)) | new->etag_remove;
        conf->etag_bits =
            (conf->etag_bits & (~ conf->etag_remove)) | conf->etag_add;
    }
    else {
        conf->etag_bits = new->etag_bits;
        conf->etag_add = new->etag_add;
        conf->etag_remove = new->etag_remove;
    }

    if (conf->etag_bits != ETAG_NONE) {
        conf->etag_bits &= (~ ETAG_NONE);
    }

    if (new->enable_mmap != ENABLE_MMAP_UNSET) {
        conf->enable_mmap = new->enable_mmap;
    }

    if (new->enable_sendfile != ENABLE_SENDFILE_UNSET) {
        conf->enable_sendfile = new->enable_sendfile;
    }

    conf->allow_encoded_slashes = new->allow_encoded_slashes;
    conf->decode_encoded_slashes = new->decode_encoded_slashes;

    if (new->log) {
        if (!conf->log) {
            conf->log = new->log;
        }
        else {
            conf->log = ap_new_log_config(a, new->log);
            ap_merge_log_config(base->log, conf->log);
        }
    }

    conf->max_ranges = new->max_ranges != AP_MAXRANGES_UNSET ? new->max_ranges : base->max_ranges;
    conf->max_overlaps = new->max_overlaps != AP_MAXRANGES_UNSET ? new->max_overlaps : base->max_overlaps;
    conf->max_reversals = new->max_reversals != AP_MAXRANGES_UNSET ? new->max_reversals : base->max_reversals;

    conf->cgi_pass_auth = new->cgi_pass_auth != AP_CGI_PASS_AUTH_UNSET ? new->cgi_pass_auth : base->cgi_pass_auth;

    if (new->cgi_var_rules) {
        if (!conf->cgi_var_rules) {
            conf->cgi_var_rules = new->cgi_var_rules;
        }
        else {
            conf->cgi_var_rules = apr_hash_overlay(a, new->cgi_var_rules, conf->cgi_var_rules);
        }
    }

    AP_CORE_MERGE_FLAG(qualify_redirect_url, conf, base, new);

    return (void*)conf;
}

#if APR_HAS_SO_ACCEPTFILTER
#ifndef ACCEPT_FILTER_NAME
#define ACCEPT_FILTER_NAME "httpready"
#ifdef __FreeBSD_version
#if __FreeBSD_version < 411000 /* httpready broken before 4.1.1 */
#undef ACCEPT_FILTER_NAME
#define ACCEPT_FILTER_NAME "dataready"
#endif
#endif
#endif
#endif

static void *create_core_server_config(apr_pool_t *a, server_rec *s)
{
    core_server_config *conf;
    int is_virtual = s->is_virtual;

    conf = (core_server_config *)apr_pcalloc(a, sizeof(core_server_config));

    /* global-default / global-only settings */

    if (!is_virtual) {
        conf->ap_document_root = DOCUMENT_LOCATION;
        conf->access_name = DEFAULT_ACCESS_FNAME;

        /* A mapping only makes sense in the global context */
        conf->accf_map = apr_table_make(a, 5);
#if APR_HAS_SO_ACCEPTFILTER
        apr_table_setn(conf->accf_map, "http", ACCEPT_FILTER_NAME);
        apr_table_setn(conf->accf_map, "https", "dataready");
#elif defined(WIN32)
        /* 'data' is disabled on Windows due to a DoS vuln (PR 59970) */
        apr_table_setn(conf->accf_map, "http", "connect");
        apr_table_setn(conf->accf_map, "https", "connect");
#else
        apr_table_setn(conf->accf_map, "http", "data");
        apr_table_setn(conf->accf_map, "https", "data");
#endif
    }
    /* pcalloc'ed - we have NULL's/0's
    else ** is_virtual ** {
        conf->ap_document_root = NULL;
        conf->access_name = NULL;
        conf->accf_map = NULL;
    }
     */

    /* initialization, no special case for global context */

    conf->sec_dir = apr_array_make(a, 40, sizeof(ap_conf_vector_t *));
    conf->sec_url = apr_array_make(a, 40, sizeof(ap_conf_vector_t *));

    /* pcalloc'ed - we have NULL's/0's
    conf->gprof_dir = NULL;

    ** recursion stopper; 0 == unset
    conf->redirect_limit = 0;
    conf->subreq_limit = 0;

    conf->protocol = NULL;
     */

    conf->trace_enable = AP_TRACE_UNSET;

    conf->protocols = apr_array_make(a, 5, sizeof(const char *));
    conf->protocols_honor_order = -1;
    
    return (void *)conf;
}

static void *merge_core_server_configs(apr_pool_t *p, void *basev, void *virtv)
{
    core_server_config *base = (core_server_config *)basev;
    core_server_config *virt = (core_server_config *)virtv;
    core_server_config *conf = (core_server_config *)
                               apr_pmemdup(p, base, sizeof(core_server_config));

    if (virt->ap_document_root)
        conf->ap_document_root = virt->ap_document_root;

    if (virt->access_name)
        conf->access_name = virt->access_name;

    /* XXX optimize to keep base->sec_ pointers if virt->sec_ array is empty */
    conf->sec_dir = apr_array_append(p, base->sec_dir, virt->sec_dir);
    conf->sec_url = apr_array_append(p, base->sec_url, virt->sec_url);

    if (virt->redirect_limit)
        conf->redirect_limit = virt->redirect_limit;

    if (virt->subreq_limit)
        conf->subreq_limit = virt->subreq_limit;

    if (virt->trace_enable != AP_TRACE_UNSET)
        conf->trace_enable = virt->trace_enable;

    if (virt->http09_enable != AP_HTTP09_UNSET)
        conf->http09_enable = virt->http09_enable;

    if (virt->http_conformance != AP_HTTP_CONFORMANCE_UNSET)
        conf->http_conformance = virt->http_conformance;

    if (virt->http_methods != AP_HTTP_METHODS_UNSET)
        conf->http_methods = virt->http_methods;

    /* no action for virt->accf_map, not allowed per-vhost */

    if (virt->protocol)
        conf->protocol = virt->protocol;

    if (virt->gprof_dir)
        conf->gprof_dir = virt->gprof_dir;

    if (virt->error_log_format)
        conf->error_log_format = virt->error_log_format;

    if (virt->error_log_conn)
        conf->error_log_conn = virt->error_log_conn;

    if (virt->error_log_req)
        conf->error_log_req = virt->error_log_req;

    conf->merge_trailers = (virt->merge_trailers != AP_MERGE_TRAILERS_UNSET)
                           ? virt->merge_trailers
                           : base->merge_trailers;

    conf->protocols = ((virt->protocols->nelts > 0)? 
                       virt->protocols : base->protocols);
    conf->protocols_honor_order = ((virt->protocols_honor_order < 0)?
                                       base->protocols_honor_order :
                                       virt->protocols_honor_order);
    
    return conf;
}

/* Add per-directory configuration entry (for <directory> section);
 * these are part of the core server config.
 */

AP_CORE_DECLARE(void) ap_add_per_dir_conf(server_rec *s, void *dir_config)
{
    core_server_config *sconf = ap_get_core_module_config(s->module_config);
    void **new_space = (void **)apr_array_push(sconf->sec_dir);

    *new_space = dir_config;
}

AP_CORE_DECLARE(void) ap_add_per_url_conf(server_rec *s, void *url_config)
{
    core_server_config *sconf = ap_get_core_module_config(s->module_config);
    void **new_space = (void **)apr_array_push(sconf->sec_url);

    *new_space = url_config;
}

AP_CORE_DECLARE(void) ap_add_file_conf(apr_pool_t *p, core_dir_config *conf,
                                       void *url_config)
{
    void **new_space;

    if (!conf->sec_file)
        conf->sec_file = apr_array_make(p, 2, sizeof(ap_conf_vector_t *));

    new_space = (void **)apr_array_push(conf->sec_file);
    *new_space = url_config;
}

AP_CORE_DECLARE(const char *) ap_add_if_conf(apr_pool_t *p,
                                             core_dir_config *conf,
                                             void *if_config)
{
    void **new_space;
    core_dir_config *new = ap_get_module_config(if_config, &core_module);

    if (!conf->sec_if) {
        conf->sec_if = apr_array_make(p, 2, sizeof(ap_conf_vector_t *));
    }
    if (new->condition_ifelse & AP_CONDITION_ELSE) {
        int have_if = 0;
        if (conf->sec_if->nelts > 0) {
            core_dir_config *last;
            ap_conf_vector_t *lastelt = APR_ARRAY_IDX(conf->sec_if,
                                                      conf->sec_if->nelts - 1,
                                                      ap_conf_vector_t *);
            last = ap_get_module_config(lastelt, &core_module);
            if (last->condition_ifelse & AP_CONDITION_IF)
                have_if = 1;
        }
        if (!have_if)
            return "<Else> or <ElseIf> section without previous <If> or "
                   "<ElseIf> section in same scope";
    }

    new_space = (void **)apr_array_push(conf->sec_if);
    *new_space = if_config;
    return NULL;
}


/* We need to do a stable sort, qsort isn't stable.  So to make it stable
 * we'll be maintaining the original index into the list, and using it
 * as the minor key during sorting.  The major key is the number of
 * components (where the root component is zero).
 */
struct reorder_sort_rec {
    ap_conf_vector_t *elt;
    int orig_index;
};

static int reorder_sorter(const void *va, const void *vb)
{
    const struct reorder_sort_rec *a = va;
    const struct reorder_sort_rec *b = vb;
    core_dir_config *core_a;
    core_dir_config *core_b;

    core_a = ap_get_core_module_config(a->elt);
    core_b = ap_get_core_module_config(b->elt);

    /* a regex always sorts after a non-regex
     */
    if (!core_a->r && core_b->r) {
        return -1;
    }
    else if (core_a->r && !core_b->r) {
        return 1;
    }

    /* we always sort next by the number of components
     */
    if (core_a->d_components < core_b->d_components) {
        return -1;
    }
    else if (core_a->d_components > core_b->d_components) {
        return 1;
    }

    /* They have the same number of components, we now have to compare
     * the minor key to maintain the original order (from the config.)
     */
    return a->orig_index - b->orig_index;
}

void ap_core_reorder_directories(apr_pool_t *p, server_rec *s)
{
    core_server_config *sconf;
    apr_array_header_t *sec_dir;
    struct reorder_sort_rec *sortbin;
    int nelts;
    ap_conf_vector_t **elts;
    int i;
    apr_pool_t *tmp;

    sconf = ap_get_core_module_config(s->module_config);
    sec_dir = sconf->sec_dir;
    nelts = sec_dir->nelts;
    elts = (ap_conf_vector_t **)sec_dir->elts;

    if (!nelts) {
        /* simple case of already being sorted... */
        /* We're not checking this condition to be fast... we're checking
         * it to avoid trying to palloc zero bytes, which can trigger some
         * memory debuggers to barf
         */
        return;
    }

    /* we have to allocate tmp space to do a stable sort */
    apr_pool_create(&tmp, p);
    sortbin = apr_palloc(tmp, sec_dir->nelts * sizeof(*sortbin));
    for (i = 0; i < nelts; ++i) {
        sortbin[i].orig_index = i;
        sortbin[i].elt = elts[i];
    }

    qsort(sortbin, nelts, sizeof(*sortbin), reorder_sorter);

    /* and now copy back to the original array */
    for (i = 0; i < nelts; ++i) {
        elts[i] = sortbin[i].elt;
    }

    apr_pool_destroy(tmp);
}

/*****************************************************************
 *
 * There are some elements of the core config structures in which
 * other modules have a legitimate interest (this is ugly, but necessary
 * to preserve NCSA back-compatibility).  So, we have a bunch of accessors
 * here...
 */

AP_DECLARE(int) ap_allow_options(request_rec *r)
{
    core_dir_config *conf =
      (core_dir_config *)ap_get_core_module_config(r->per_dir_config);

    return conf->opts;
}

AP_DECLARE(int) ap_allow_overrides(request_rec *r)
{
    core_dir_config *conf;
    conf = (core_dir_config *)ap_get_core_module_config(r->per_dir_config);

    return conf->override;
}

/*
 * Optional function coming from mod_authn_core, used for
 * retrieving the type of autorization
 */
static APR_OPTIONAL_FN_TYPE(authn_ap_auth_type) *authn_ap_auth_type;

AP_DECLARE(const char *) ap_auth_type(request_rec *r)
{
    if (authn_ap_auth_type) {
        return authn_ap_auth_type(r);
    }
    return NULL;
}

/*
 * Optional function coming from mod_authn_core, used for
 * retrieving the authorization realm
 */
static APR_OPTIONAL_FN_TYPE(authn_ap_auth_name) *authn_ap_auth_name;

AP_DECLARE(const char *) ap_auth_name(request_rec *r)
{
    if (authn_ap_auth_name) {
        return authn_ap_auth_name(r);
    }
    return NULL;
}

/*
 * Optional function coming from mod_access_compat, used to determine how
   access control interacts with authentication/authorization
 */
static APR_OPTIONAL_FN_TYPE(access_compat_ap_satisfies) *access_compat_ap_satisfies;

AP_DECLARE(int) ap_satisfies(request_rec *r)
{
    if (access_compat_ap_satisfies) {
        return access_compat_ap_satisfies(r);
    }
    return SATISFY_NOSPEC;
}

AP_DECLARE(const char *) ap_document_root(request_rec *r) /* Don't use this! */
{
    core_server_config *sconf;
    core_request_config *rconf = ap_get_core_module_config(r->request_config);
    if (rconf->document_root)
        return rconf->document_root;
    sconf = ap_get_core_module_config(r->server->module_config);
    return sconf->ap_document_root;
}

AP_DECLARE(const char *) ap_context_prefix(request_rec *r)
{
    core_request_config *conf = ap_get_core_module_config(r->request_config);
    if (conf->context_prefix)
        return conf->context_prefix;
    else
        return "";
}

AP_DECLARE(const char *) ap_context_document_root(request_rec *r)
{
    core_request_config *conf = ap_get_core_module_config(r->request_config);
    if (conf->context_document_root)
        return conf->context_document_root;
    else
        return ap_document_root(r);
}

AP_DECLARE(void) ap_set_document_root(request_rec *r, const char *document_root)
{
    core_request_config *conf = ap_get_core_module_config(r->request_config);
    conf->document_root = document_root;
}

AP_DECLARE(void) ap_set_context_info(request_rec *r, const char *context_prefix,
                                     const char *context_document_root)
{
    core_request_config *conf = ap_get_core_module_config(r->request_config);
    if (context_prefix)
        conf->context_prefix = context_prefix;
    if (context_document_root)
        conf->context_document_root = context_document_root;
}

/* Should probably just get rid of this... the only code that cares is
 * part of the core anyway (and in fact, it isn't publicised to other
 * modules).
 */

char *ap_response_code_string(request_rec *r, int error_index)
{
    core_dir_config *dirconf;
    core_request_config *reqconf = ap_get_core_module_config(r->request_config);
    const char *err;
    const char *response;
    ap_expr_info_t *expr;

    /* check for string registered via ap_custom_response() first */
    if (reqconf->response_code_strings != NULL
            && reqconf->response_code_strings[error_index] != NULL) {
        return reqconf->response_code_strings[error_index];
    }

    /* check for string specified via ErrorDocument */
    dirconf = ap_get_core_module_config(r->per_dir_config);

    if (!dirconf->response_code_exprs) {
        return NULL;
    }

    expr = apr_hash_get(dirconf->response_code_exprs, &error_index,
            sizeof(error_index));
    if (!expr) {
        return NULL;
    }

    /* special token to indicate revert back to default */
    if ((char *) expr == &errordocument_default) {
        return NULL;
    }

    err = NULL;
    response = ap_expr_str_exec(r, expr, &err);
    if (err) {
        ap_log_rerror(
                APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02841) "core: ErrorDocument: can't "
                "evaluate require expression: %s", err);
        return NULL;
    }

    /* alas, duplication required as we return not-const */
    return apr_pstrdup(r->pool, response);
}


/* Code from Harald Hanche-Olsen <hanche@imf.unit.no> */
static APR_INLINE int do_double_reverse (int double_reverse,
                                         const char *remote_host,
                                         apr_sockaddr_t *client_addr,
                                         apr_pool_t *pool)
{
    apr_sockaddr_t *sa;
    apr_status_t rv;

    if (double_reverse) {
        /* already done */
        return double_reverse;
    }

    if (remote_host == NULL || remote_host[0] == '\0') {
        /* single reverse failed, so don't bother */
        return -1;
    }

    rv = apr_sockaddr_info_get(&sa, remote_host, APR_UNSPEC, 0, 0, pool);
    if (rv == APR_SUCCESS) {
        while (sa) {
            if (apr_sockaddr_equal(sa, client_addr)) {
                return 1;
            }

            sa = sa->next;
        }
    }

    return -1;
}

AP_DECLARE(const char *) ap_get_remote_host(conn_rec *conn, void *dir_config,
                                            int type, int *str_is_ip)
{
    int hostname_lookups;
    int ignored_str_is_ip;

    if (!str_is_ip) { /* caller doesn't want to know */
        str_is_ip = &ignored_str_is_ip;
    }
    *str_is_ip = 0;

    /* If we haven't checked the host name, and we want to */
    if (dir_config) {
        hostname_lookups = ((core_dir_config *)ap_get_core_module_config(dir_config))
                           ->hostname_lookups;

        if (hostname_lookups == HOSTNAME_LOOKUP_UNSET) {
            hostname_lookups = HOSTNAME_LOOKUP_OFF;
        }
    }
    else {
        /* the default */
        hostname_lookups = HOSTNAME_LOOKUP_OFF;
    }

    if (type != REMOTE_NOLOOKUP
        && conn->remote_host == NULL
        && (type == REMOTE_DOUBLE_REV
        || hostname_lookups != HOSTNAME_LOOKUP_OFF)) {

        if (apr_getnameinfo(&conn->remote_host, conn->client_addr, 0)
            == APR_SUCCESS) {
            ap_str_tolower(conn->remote_host);

            if (hostname_lookups == HOSTNAME_LOOKUP_DOUBLE) {
                conn->double_reverse = do_double_reverse(conn->double_reverse,
                                                         conn->remote_host,
                                                         conn->client_addr,
                                                         conn->pool);
                if (conn->double_reverse != 1) {
                    conn->remote_host = NULL;
                }
            }
        }

        /* if failed, set it to the NULL string to indicate error */
        if (conn->remote_host == NULL) {
            conn->remote_host = "";
        }
    }

    if (type == REMOTE_DOUBLE_REV) {
        conn->double_reverse = do_double_reverse(conn->double_reverse,
                                                 conn->remote_host,
                                                 conn->client_addr, conn->pool);
        if (conn->double_reverse == -1) {
            return NULL;
        }
    }

    /*
     * Return the desired information; either the remote DNS name, if found,
     * or either NULL (if the hostname was requested) or the IP address
     * (if any identifier was requested).
     */
    if (conn->remote_host != NULL && conn->remote_host[0] != '\0') {
        return conn->remote_host;
    }
    else {
        if (type == REMOTE_HOST || type == REMOTE_DOUBLE_REV) {
            return NULL;
        }
        else {
            *str_is_ip = 1;
            return conn->client_ip;
        }
    }
}

AP_DECLARE(const char *) ap_get_useragent_host(request_rec *r,
                                               int type, int *str_is_ip)
{
    conn_rec *conn = r->connection;
    int hostname_lookups;
    int ignored_str_is_ip;

    /* Guard here when examining the host before the read_request hook
     * has populated an r->useragent_addr
     */
    if (!r->useragent_addr || (r->useragent_addr == conn->client_addr)) {
        return ap_get_remote_host(conn, r->per_dir_config, type, str_is_ip);
    }

    if (!str_is_ip) { /* caller doesn't want to know */
        str_is_ip = &ignored_str_is_ip;
    }