/* 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.

 */

/*

 * Security options etc.

 *

 * Module derived from code originally written by Rob McCool

 *

 */

#include "apr_strings.h"

#include "apr_network_io.h"

#include "apr_md5.h"

#include "apr_hash.h"

#define APR_WANT_STRFUNC

#define APR_WANT_BYTEFUNC

#include "apr_want.h"

#include "ap_config.h"

#include "ap_provider.h"

#include "httpd.h"

#include "http_core.h"

#include "http_config.h"

#include "http_log.h"

#include "http_protocol.h"

#include "http_request.h"

#include "mod_auth.h"

#if APR_HAVE_NETINET_IN_H

#include <netinet/in.h>

#endif

/*

 * To save memory if the same subnets are used in hundres of vhosts, we store

 * each subnet only once and use this temporary hash to find it again.

 */

static apr_hash_t *parsed_subnets;

static apr_ipsubnet_t *localhost_v4;

#if APR_HAVE_IPV6

static apr_ipsubnet_t *localhost_v6;

#endif

static int in_domain(const char *domain, const char *what)

{

    int dl = strlen(domain);

    int wl = strlen(what);

    if ((wl - dl) >= 0) {

        if (strcasecmp(domain, &what[wl - dl]) != 0) {

            return 0;

        }

        /* Make sure we matched an *entire* subdomain --- if the user

         * said 'allow from good.com', we don't want people from nogood.com

         * to be able to get in.

         */

        if (wl == dl) {

            return 1;                /* matched whole thing */

        }

        else {

            return (domain[0] == '.' || what[wl - dl - 1] == '.');

        }

    }

    else {

        return 0;

    }

}

static const char *ip_parse_config(cmd_parms *cmd,

                                   const char *require_line,

                                   const void **parsed_require_line)

{

    const char *t, *w;

    int count = 0;

    apr_ipsubnet_t **ip;

    apr_pool_t *ptemp = cmd->temp_pool;

    apr_pool_t *p = cmd->pool;

    /* The 'ip' provider will allow the configuration to specify a list of

        ip addresses to check rather than a single address.  This is different

        from the previous host based syntax. */

    t = require_line;

    while ((w = ap_getword_conf(ptemp, &t)) && w[0])

        count++;

    if (count == 0)

        return "'require ip' requires an argument";

    ip = apr_pcalloc(p, sizeof(apr_ipsubnet_t *) * (count + 1));

    *parsed_require_line = ip;

    t = require_line;

    while ((w = ap_getword_conf(ptemp, &t)) && w[0]) {

        char *addr = apr_pstrdup(ptemp, w);

        char *mask;

        apr_status_t rv;

        if (parsed_subnets &&

            (*ip = apr_hash_get(parsed_subnets, w, APR_HASH_KEY_STRING)) != NULL)

        {

            /* we already have parsed this subnet */

            ip++;

            continue;

        }

        if ((mask = ap_strchr(addr, '/')))

            *mask++ = '\0';

        rv = apr_ipsubnet_create(ip, addr, mask, p);

        if(APR_STATUS_IS_EINVAL(rv)) {

            /* looked nothing like an IP address */

            return apr_psprintf(p, "ip address '%s' appears to be invalid", w);

        }

        else if (rv != APR_SUCCESS) {

            return apr_psprintf(p, "ip address '%s' appears to be invalid: %pm",

                                w, &rv;;

        }

        if (parsed_subnets)

            apr_hash_set(parsed_subnets, w, APR_HASH_KEY_STRING, *ip);

        ip++;

    }

    return NULL;

}

static authz_status ip_check_authorization(request_rec *r,

                                           const char *require_line,

                                           const void *parsed_require_line)

{

    /* apr_ipsubnet_test should accept const but doesn't */

    apr_ipsubnet_t **ip = (apr_ipsubnet_t **)parsed_require_line;

    while (*ip) {

        if (apr_ipsubnet_test(*ip, r->useragent_addr))

            return AUTHZ_GRANTED;

        ip++;

    }

    /* authz_core will log the require line and the result at DEBUG */

    return AUTHZ_DENIED;

}

static authz_status host_check_authorization(request_rec *r,

                                             const char *require_line,

                                             const void *parsed_require_line)

{

    const char *t, *w;

    const char *remotehost = NULL;

    int remotehost_is_ip;

    remotehost = ap_get_useragent_host(r, REMOTE_DOUBLE_REV, &remotehost_is_ip);

    if ((remotehost == NULL) || remotehost_is_ip) {

        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01753)

                      "access check of '%s' to %s failed, reason: unable to get the "

                      "remote host name", require_line, r->uri);

    }

    else {

        const char *err = NULL;

        const ap_expr_info_t *expr = parsed_require_line;

        const char *require;

        require = ap_expr_str_exec(r, expr, &err;;

        if (err) {

            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02593)

                          "authz_host authorize: require host: Can't "

                          "evaluate require expression: %s", err);

            return AUTHZ_DENIED;

        }

        /* The 'host' provider will allow the configuration to specify a list of

            host names to check rather than a single name.  This is different

            from the previous host based syntax. */

        t = require;

        /* '#' is not a valid hostname character and admin could

         * specify 'Require host localhost# Add example.com later'. We

         * should not grant access to 'example.com' in that case. */

        w = ap_strchr_c(t, '#');

        if (w) {

            if (w == t) {

                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10120)

                              "authz_host authorize: dubious empty "

                              "'Require host %s' with only comment", t);

                return AUTHZ_DENIED;

            }

            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(10121)

                          "authz_host authorize: ignoring comment in "

                          "'Require host %s'", t);

            /* Truncate the string at the #. */

            t = apr_pstrmemdup(r->pool, t, w - t);

        }

        while ((w = ap_getword_conf(r->pool, &t)) && w[0]) {

            if (in_domain(w, remotehost)) {

                return AUTHZ_GRANTED;

            }

        }

    }

    /* authz_core will log the require line and the result at DEBUG */

    return AUTHZ_DENIED;

}

static authz_status

forward_dns_check_authorization(request_rec *r,

                                const char *require_line,

                                const void *parsed_require_line)

{

    const char *err = NULL;

    const ap_expr_info_t *expr = parsed_require_line;

    const char *require, *t;

    char *w;

    /* the require line is an expression, which is evaluated now. */

    require = ap_expr_str_exec(r, expr, &err;;

    if (err) {

      ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(03354)

                    "authz_host authorize: require forward-dns: "

                    "Can't evaluate require expression: %s", err);

      return AUTHZ_DENIED;

    }

    /* tokenize expected list of names */

    t = require;

    while ((w = ap_getword_conf(r->pool, &t)) && w[0]) {

        apr_sockaddr_t *sa;

        apr_status_t rv;

        char *hash_ptr;

        /* stop on apache configuration file comments */

        if ((hash_ptr = ap_strchr(w, '#'))) {

            if (hash_ptr == w) {

                break;

            }

            *hash_ptr = '\0';

        }

        /* does the client ip match one of the names? */

        rv = apr_sockaddr_info_get(&sa, w, APR_UNSPEC, 0, 0, r->pool);

        if (rv == APR_SUCCESS) {

            while (sa) {

                int match = apr_sockaddr_equal(sa, r->useragent_addr);

                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(03355)

                              "access check for %s as '%s': %s",

                              r->useragent_ip, w, match? "yes": "no");

                if (match) {

                    return AUTHZ_GRANTED;

                }

                sa = sa->next;

            }

        }

        else {

            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(03356)

                          "No sockaddr info for \"%s\"", w);

        }

        /* stop processing, we are in a comment */

        if (hash_ptr) {

            break;

        }

    }

    return AUTHZ_DENIED;

}

static authz_status local_check_authorization(request_rec *r,

                                              const char *require_line,

                                              const void *parsed_require_line)

{

     if (   apr_sockaddr_equal(r->connection->local_addr,

                               r->useragent_addr)

         || apr_ipsubnet_test(localhost_v4, r->useragent_addr)

#if APR_HAVE_IPV6

         || apr_ipsubnet_test(localhost_v6, r->useragent_addr)

#endif

        )

     {

        return AUTHZ_GRANTED;

     }

     return AUTHZ_DENIED;

}

static const char *host_parse_config(cmd_parms *cmd, const char *require_line,

                                     const void **parsed_require_line)

{

    const char *expr_err = NULL;

    ap_expr_info_t *expr;

    expr = ap_expr_parse_cmd(cmd, require_line, AP_EXPR_FLAG_STRING_RESULT,

            &expr_err, NULL);

    if (expr_err)

        return apr_pstrcat(cmd->temp_pool,

                           "Cannot parse expression in require line: ",

                           expr_err, NULL);

    *parsed_require_line = expr;

    return NULL;

}

static const authz_provider authz_ip_provider =

{

    &ip_check_authorization,

    &ip_parse_config,

};

static const authz_provider authz_host_provider =

{

    &host_check_authorization,

    &host_parse_config,

};

static const authz_provider authz_forward_dns_provider =

{

    &forward_dns_check_authorization,

    &host_parse_config,

};

static const authz_provider authz_local_provider =

{

    &local_check_authorization,

    NULL,

};

static int authz_host_pre_config(apr_pool_t *p, apr_pool_t *plog,

                                 apr_pool_t *ptemp)

{

    /* we only use this hash in the parse config phase, ptemp is enough */

    parsed_subnets = apr_hash_make(ptemp);

    apr_ipsubnet_create(&localhost_v4, "127.0.0.0", "8", p);

    apr_hash_set(parsed_subnets, "127.0.0.0/8", APR_HASH_KEY_STRING, localhost_v4);

#if APR_HAVE_IPV6

    apr_ipsubnet_create(&localhost_v6, "::1", NULL, p);

    apr_hash_set(parsed_subnets, "::1", APR_HASH_KEY_STRING, localhost_v6);

#endif

    return OK;

}

static int authz_host_post_config(apr_pool_t *p, apr_pool_t *plog,

                                  apr_pool_t *ptemp, server_rec *s)

{

    /* make sure we don't use this during .htaccess parsing */

    parsed_subnets = NULL;

    return OK;

}

static void register_hooks(apr_pool_t *p)

{

    ap_hook_pre_config(authz_host_pre_config, NULL, NULL, APR_HOOK_MIDDLE);

    ap_hook_post_config(authz_host_post_config, NULL, NULL, APR_HOOK_MIDDLE);

    ap_register_auth_provider(p, AUTHZ_PROVIDER_GROUP, "ip",

                              AUTHZ_PROVIDER_VERSION,

                              &authz_ip_provider, AP_AUTH_INTERNAL_PER_CONF);

    ap_register_auth_provider(p, AUTHZ_PROVIDER_GROUP, "host",

                              AUTHZ_PROVIDER_VERSION,

                              &authz_host_provider, AP_AUTH_INTERNAL_PER_CONF);

    ap_register_auth_provider(p, AUTHZ_PROVIDER_GROUP, "forward-dns",

                              AUTHZ_PROVIDER_VERSION,

                              &authz_forward_dns_provider,

                              AP_AUTH_INTERNAL_PER_CONF);

    ap_register_auth_provider(p, AUTHZ_PROVIDER_GROUP, "local",

                              AUTHZ_PROVIDER_VERSION,

                              &authz_local_provider, AP_AUTH_INTERNAL_PER_CONF);

}

AP_DECLARE_MODULE(authz_host) =

{

    STANDARD20_MODULE_STUFF,

    NULL,                           /* dir config creater */

    NULL,                           /* dir merger --- default is to override */

    NULL,                           /* server config */

    NULL,                           /* merge server config */

    NULL,

    register_hooks                  /* register hooks */

};