mod_actions.c

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/* 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.
 */

/*
 * mod_actions.c: executes scripts based on MIME type or HTTP method
 *
 * by Alexei Kosut; based on mod_cgi.c, mod_mime.c and mod_includes.c,
 * adapted by rst from original NCSA code by Rob McCool
 *
 * Usage instructions:
 *
 * Action mime/type /cgi-bin/script
 * 
 * will activate /cgi-bin/script when a file of content type mime/type is 
 * requested. It sends the URL and file path of the requested document using 
 * the standard CGI PATH_INFO and PATH_TRANSLATED environment variables.
 *
 * Script PUT /cgi-bin/script
 *
 * will activate /cgi-bin/script when a request is received with the
 * HTTP method "PUT".  The available method names are defined in httpd.h.
 * If the method is GET, the script will only be activated if the requested
 * URI includes query information (stuff after a ?-mark).
 */

#include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_main.h"
#include "http_log.h"
#include "util_script.h"

typedef struct {
    char *method;
    char *script;
} xmethod_t;

/*
 * HTTP methods are case-sensitive, so we can't use a table structure to
 * track extension method mappings -- table keys are case-INsensitive.
 */
typedef struct {
    table *action_types;       /* Added with Action... */
    char *scripted[METHODS];   /* Added with Script... */
    array_header *xmethods;    /* Added with Script -- extension methods */
} action_dir_config;

module action_module;

static void *create_action_dir_config(pool *p, char *dummy)
{
    action_dir_config *new =
	(action_dir_config *) ap_palloc(p, sizeof(action_dir_config));

    new->action_types = ap_make_table(p, 4);
    memset(new->scripted, 0, sizeof(new->scripted));
    new->xmethods = ap_make_array(p, 4, sizeof(xmethod_t));
    return new;
}

static void *merge_action_dir_configs(pool *p, void *basev, void *addv)
{
    action_dir_config *base = (action_dir_config *) basev;
    action_dir_config *add = (action_dir_config *) addv;
    action_dir_config *new = (action_dir_config *) ap_palloc(p,
                                  sizeof(action_dir_config));
    int i;

    new->action_types = ap_overlay_tables(p, add->action_types,
				       base->action_types);

    for (i = 0; i < METHODS; ++i) {
        new->scripted[i] = add->scripted[i] ? add->scripted[i]
                                            : base->scripted[i];
    }
    new->xmethods = ap_append_arrays(p, add->xmethods, base->xmethods);
    return new;
}

static const char *add_action(cmd_parms *cmd, action_dir_config *m, char *type,
			      char *script)
{
    ap_table_setn(m->action_types, type, script);
    return NULL;
}

static const char *set_script(cmd_parms *cmd, action_dir_config *m,
                              char *method, char *script)
{
    int methnum;

    methnum = ap_method_number_of(method);
    if (methnum == M_TRACE) {
	return "TRACE not allowed for Script";
    }
    else if (methnum != M_INVALID) {
        m->scripted[methnum] = script;
    }
    else {
	/*
	 * We used to return "Unknown method type for Script"
	 * but now we actually handle unknown methods.
	 */
	xmethod_t *xm;
	xmethod_t *list;
	int i;

	/*
	 * Scan through the list; if the method already has a script
	 * defined, overwrite it.  Otherwise, add it.
	 */
	list = (xmethod_t *) m->xmethods->elts;
	for (i = 0; i < m->xmethods->nelts; ++i) {
	    xm = &list[i];
	    if (strcmp(method, xm->method) == 0) {
		xm->script = script;
		break;
	    }
	}
	if (i <= m->xmethods->nelts) {
	    xm = ap_push_array(m->xmethods);
	    xm->method = method;
	    xm->script = script;
	}
    }
    return NULL;
}

static const command_rec action_cmds[] =
{
    {"Action", add_action, NULL, OR_FILEINFO, TAKE2,
     "a media type followed by a script name"},
    {"Script", set_script, NULL, ACCESS_CONF | RSRC_CONF, TAKE2,
     "a method followed by a script name"},
    {NULL}
};

static int action_handler(request_rec *r)
{
    action_dir_config *conf = (action_dir_config *)
        ap_get_module_config(r->per_dir_config, &action_module);
    const char *t, *action = r->handler ? r->handler : 
	ap_field_noparam(r->pool, r->content_type);
    const char *script;
    int i;

    /* Set allowed stuff */
    for (i = 0; i < METHODS; ++i) {
	if (conf->scripted[i]) {
	    r->allowed |= (1 << i);
	}
    }

    /* First, check for the method-handling scripts */
    if (r->method_number == M_GET) {
        if (r->args) {
            script = conf->scripted[M_GET];
	}
        else {
            script = NULL;
	}
    }
    else {
	if (r->method_number != M_INVALID) {
	    script = conf->scripted[r->method_number];
	}
	else {
	    int j;
	    xmethod_t *xm;
	    xmethod_t *list;

	    script = NULL;
	    list = (xmethod_t *) conf->xmethods->elts;
	    for (j = 0; j < conf->xmethods->nelts; ++j) {
		xm = &list[j];
		if (strcmp(r->method, xm->method) == 0) {
		    script = xm->script;
		    break;
		}
	    }
	}
    }

    /* Check for looping, which can happen if the CGI script isn't */
    if (script && r->prev && r->prev->prev) {
	return DECLINED;
    }

    /* Second, check for actions (which override the method scripts) */
    if ((t = ap_table_get(conf->action_types,
			  action ? action : ap_default_type(r)))) {
	script = t;
    }

    if (script == NULL) {
	return DECLINED;
    }

    ap_internal_redirect_handler(ap_pstrcat(r->pool, script,
					    ap_escape_uri(r->pool,
							  r->uri),
					    r->args ? "?" : NULL,
					    r->args, NULL), r);
    return OK;
}

static const handler_rec action_handlers[] =
{
    {"*/*", action_handler},
    {NULL}
};

module action_module =
{
    STANDARD_MODULE_STUFF,
    NULL,			/* initializer */
    create_action_dir_config,	/* dir config creater */
    merge_action_dir_configs,	/* dir merger --- default is to override */
    NULL,			/* server config */
    NULL,			/* merge server config */
    action_cmds,		/* command table */
    action_handlers,		/* handlers */
    NULL,			/* filename translation */
    NULL,			/* check_user_id */
    NULL,			/* check auth */
    NULL,			/* check access */
    NULL,			/* type_checker */
    NULL,			/* fixups */
    NULL,			/* logger */
    NULL,			/* header parser */
    NULL,			/* child_init */
    NULL,			/* child_exit */
    NULL			/* post read-request */
};