/*
 * mod_vd.c for Apache 2.0
 *
 * Copyright 2003 by Anthony Howe.  All rights reserved.
 *
 *
 * Please refer to LICENSE.TXT for the License & Disclaimer. An
 * online copy of the current license for the current version can
 * be found at http://www.snert.com/Software/mod_vd/
 */

#ifndef MAX_LEVELS
#define MAX_LEVELS		10
#endif

/***********************************************************************
 *** No configuration below this point.
 ***********************************************************************/

#define MODULE			"mod_vd"
#define AUTHOR			"achowe@snert.com"
#define VERSION			"2.0"

#include "httpd.h"
#include "http_config.h"

#define CORE_PRIVATE
#include "http_core.h"
#undef CORE_PRIVATE

#include "http_log.h"
#include "http_protocol.h"
#include "http_request.h"

#include "apr.h"
#include "apr_lib.h"
#include "apr_strings.h"

#define APR_WANT_STRFUNC
#include "apr_want.h"

module AP_MODULE_DECLARE_DATA vd_module;

/***********************************************************************
 *** Macros
 ***********************************************************************/

#define UNSET			-1
#define MERGE(p, c)		(c == UNSET ? p : c)
#define MERGE_PTR(p, c)		((void *) c == (void *) 0 ? p : c)

/***********************************************************************
 *** Constants
 ***********************************************************************/


/***********************************************************************
 *** Global variables - should be read-only by child processes.
 ***********************************************************************/

typedef struct conf {
	unsigned int vdChopPrefix;
	unsigned int vdChopSuffix;
	long vdPathPrefixLen;
	char *vdPathPrefix;
	long vdPathSuffixLen;
	char *vdPathSuffix;
	server_rec *server;
	int enable;
} t_conf;

static server_rec *vdMainServer;

/***********************************************************************
 ***  Support routines.
 ***********************************************************************/

static const char *
setUnsignedInt(const char *arg, unsigned int *number)
{
	char *stop;
	long value;

	if (arg == (char *) 0 || *arg == '\0')
		return "Integer unspecified";

	value = strtol(arg, &stop, 10);

	if (*stop != '\0')
		return "Not a decimal integer";

	if (value < 0)
		return "Not a positive integer";

	if (UINT_MAX < value)
		return "Integer too large";

	*number = (unsigned int) value;

	return (const char *) 0;
}

/***********************************************************************
 ***  Phase Handlers
 ***********************************************************************/

static int
vdTranslateName(request_rec *r)
{
	long dots;
	int i, j, n;
	t_conf *conf;
	apr_status_t rc;
	apr_finfo_t finfo;
	char *path, *next;
	const char *dot[MAX_LEVELS+1];

	conf = ap_get_module_config(r->server->module_config, &vd_module);
	if (conf == (t_conf *) 0 || !conf->enable)
		return DECLINED;

	dot[0] = apr_table_get(r->headers_in, "Host");
	if (dot[0] == (char *) 0)
		return DECLINED;

	/* Count dots in the request host name and the string length. */
	for (dots = 1, next = (char *) dot[0]; *next != '\0' && *next != ':'; next++) {
		if (*next == '.') {
			if (MAX_LEVELS <= dots)
				return HTTP_INTERNAL_SERVER_ERROR;
			dot[dots++] = next;
		}
	}

	/* End of host name string. */
	dot[dots] = next;

	/* At this point:
	 *
	 * dot[0] is the start of the host header string.
	 * dot[1] points to the first dot.
	 * ...
	 * dot[dots] points to the terminating \0 or colon.
	 */

	/* You can't handle fewer dots than those that would be removed. */
	if (dots <= conf->vdChopPrefix + conf->vdChopSuffix)
		return DECLINED;

	/* Build filename path string. */
	path = apr_palloc(
		r->pool,
		conf->vdPathPrefixLen
		+ (dot[dots] - dot[0])
		+ conf->vdPathSuffixLen
		+ strlen(r->uri)
		+ 1
	);

	/* Copy initial directory prefix into the path buffer. */
	next = path;
	(void) strcpy(path, conf->vdPathPrefix);
	next += conf->vdPathPrefixLen;

	/* Point the start of the host string at an imaginary leading dot. */
	dot[0]--;

	/* Append levels from right to left to the path. */
	for (i = conf->vdChopPrefix, j = dots - conf->vdChopSuffix; i < j--; ) {
		/* Compute the length of the level name less the dot. */
		n = dot[j+1] - dot[j] - 1;

		/* Append the level to the path plus a slash. */
		strncpy(next, dot[j] + 1, n);
		next += n;
		*next++ = '/';
	}

	/* Append the path suffix less the leading slash. */
	(void) strcpy(next, conf->vdPathSuffix + 1);
	next += conf->vdPathSuffixLen - 1;

	/* Append requested URI. */
	(void) strcpy(next, r->uri);

	ap_log_error(
		APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, vdMainServer,
		"host=[%s] chopLHS=%d chopRHS=%d prefix=[%s] suffix=[%s] path=[%s]",
		dot[0]+1, conf->vdChopPrefix, conf->vdChopSuffix,
		conf->vdPathPrefix, conf->vdPathSuffix, path
	);

	/* Does the path exist? */
        rc = apr_stat(&finfo, path, APR_FINFO_MIN, r->pool);
        if (rc != APR_SUCCESS || finfo.filetype == APR_NOFILE)
        	return DECLINED;

	/* Set the final filename for the request. */
	r->filename = path;
	r->finfo = finfo;

	return OK;
}

/***********************************************************************
 *** Server configuration, merge, and initialisation.
 ***********************************************************************/

static void *
vdCreateSrv(apr_pool_t *p, server_rec *s)
{
	t_conf *conf;

	conf = (t_conf *) apr_palloc(p, sizeof *conf);

	conf->vdChopPrefix = 0;
	conf->vdChopSuffix = 0;

	conf->vdPathPrefix = (char *) 0;
	conf->vdPathPrefixLen = UNSET;

	conf->vdPathSuffix = "";
	conf->vdPathSuffixLen = 0;

	conf->server = s;
	conf->enable = 1;

	return (void *) conf;
}

static void
vdSetDefaultPrefix(apr_pool_t *p, t_conf *conf)
{
	core_server_config *core;

	if (conf != (t_conf *) 0 && conf->vdPathPrefix == (char *) 0) {
		core = ap_get_module_config(conf->server->module_config, &core_module);
		conf->vdPathPrefix = (char *) core->ap_document_root;

		/* Append trailing slash to prefix. */
		if (strrchr(conf->vdPathPrefix, '/')[1] != '\0')
			conf->vdPathPrefix = apr_pstrcat(p, conf->vdPathPrefix, "/", (char *) 0);

		conf->vdPathPrefixLen = strlen(conf->vdPathPrefix);
	}
}

static void *
vdMergeSrv(apr_pool_t *p, void *basev, void *virtv)
{
	vdSetDefaultPrefix(p, (t_conf *) basev);
	vdSetDefaultPrefix(p, (t_conf *) virtv);

	return virtv;
}

static int
vdPostConfig(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s)
{
	t_conf *conf;
	core_server_config *core;

	vdMainServer = s;
        ap_add_version_component(pconf, MODULE "/" VERSION);

	conf = ap_get_module_config(vdMainServer->module_config, &vd_module);
	vdSetDefaultPrefix(pconf, conf);

	return OK;
}

static void
vdHooks(apr_pool_t *p)
{
	ap_hook_post_config(vdPostConfig, NULL, NULL, APR_HOOK_MIDDLE);
	ap_hook_translate_name(vdTranslateName, NULL, NULL, APR_HOOK_MIDDLE);
}

/***********************************************************************
 ***  Configuration Directives
 ***********************************************************************/

/*
 * VdPathPrefix document-root-prefix
 * Context: global, <VirtualHost>
 */
static const char *
VdPathPrefix(cmd_parms *cmd, void *dconf, const char *path)
{
	t_conf *conf;
	apr_status_t rc;
	apr_finfo_t finfo;

	conf = ap_get_module_config(cmd->server->module_config, &vd_module);

	/* Append trailing slash to prefix. */
	if (strrchr(path, '/')[1] != '\0')
		path = apr_pstrcat(cmd->temp_pool, path, "/", (char *) 0);

        conf->vdPathPrefix = ap_server_root_relative(cmd->pool, path);
        conf->vdPathPrefixLen = strlen(conf->vdPathPrefix);

        rc = apr_stat(&finfo, conf->vdPathPrefix, APR_FINFO_MIN, cmd->temp_pool);
        if (rc != APR_SUCCESS || finfo.filetype != APR_DIR)
        	return "VdPathPrefix does not refer to directory.";

	return (const char *) 0;
}

/*
 * VdPathSuffix document-root-suffix
 * Context: global, <VirtualHost>
 */
static const char *
VdPathSuffix(cmd_parms *cmd, void *dconf, const char *path)
{
	t_conf *conf;

	conf = ap_get_module_config(cmd->server->module_config, &vd_module);

	/* Prepend slash to path suffix. */
	if (path[0] != '/')
		path = apr_pstrcat(cmd->temp_pool, "/", path, (char *) 0);

        conf->vdPathSuffix = apr_pstrdup(cmd->pool, path);
        conf->vdPathSuffixLen = strlen(conf->vdPathSuffix);

	return (const char *) 0;
}

/*
 * VdChopSuffix number
 * Context: global, <VirtualHost>
 */
static const char *
VdChopPrefix(cmd_parms *cmd, void *dconf, const char *number)
{
	t_conf *conf;

	conf = ap_get_module_config(cmd->server->module_config, &vd_module);

	return setUnsignedInt(number, &conf->vdChopPrefix);
}

/*
 * VdChopSuffix number
 * Context: global, <VirtualHost>
 */
static const char *
VdChopSuffix(cmd_parms *cmd, void *dconf, const char *number)
{
	t_conf *conf;

	conf = ap_get_module_config(cmd->server->module_config, &vd_module);

	return setUnsignedInt(number, &conf->vdChopSuffix);
}

/*
 * VdEnable boolean
 *
 * context: global, <VirtualHost>
 */
static const char *
VdEnable(cmd_parms *cmd, void *dconf, int flag)
{
	t_conf *conf;

	conf = ap_get_module_config(cmd->server->module_config, &vd_module);
	conf->enable = flag;

	return (const char *) 0;
}

static command_rec vdCommands[] = {
	AP_INIT_FLAG(
		"VdEnable", VdEnable, NULL, RSRC_CONF,
		"Turn the module on or off."
	),

	AP_INIT_TAKE1(
		"VdPathPrefix", VdPathPrefix, NULL, RSRC_CONF,
		"Virtual domain directory root prefix."
	),

	AP_INIT_TAKE1(
		"VdPathSuffix", VdPathSuffix, NULL, RSRC_CONF,
		"Virtual domain directory root suffix."
	),

	AP_INIT_TAKE1(
		"VdChopPrefix", VdChopPrefix, NULL, RSRC_CONF,
		"Number of domain levels to remove from the left hand side."
	),

	AP_INIT_TAKE1(
		"VdChopSuffix", VdChopSuffix, NULL, RSRC_CONF,
		"Number of domain levels to remove from the right hand side."
	),

	{ NULL }
};

/***********************************************************************
 ***  Module Definition Block
 ***********************************************************************/

/* Dispatch list for API hooks */
module AP_MODULE_DECLARE_DATA vd_module = {
	STANDARD20_MODULE_STUFF,
	NULL,			/* create per-dir    config structures */
	NULL,			/* merge  per-dir    config structures */
	vdCreateSrv,		/* create per-server config structures */
	vdMergeSrv,		/* merge  per-server config structures */
	vdCommands,		/* apr_table_t of config file commands */
	vdHooks			/* register hooks */
};