/*
 * Copyright 2023, Vincent Douillet <vincent@vdouillet.fr>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>

#include <assert.h>
#include <limits.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdlib.h>
#include <kcgi.h>
#include <string.h>

#include "config.h"
#include "str.h"
#include "url.h"

bool
check_request_path(const char *path, const char *suffix)
{
	char 	p [PATH_MAX], resolved[PATH_MAX];
	char   *rp, *data_dir;

	data_dir = config_data_dir();
	if (data_dir == NULL)
		return false;

	/* build absolute path from DATA_DIR */
	if (strlcpy(p, data_dir, sizeof(p)) >= sizeof(p))
		return false;
	if (strlcat(p, "/", sizeof(p)) >= sizeof(p))
		return false;
	if (strlcat(p, path, sizeof(p)) >= sizeof(p))
		return false;
	if (strlen(suffix) > 0) {
		/* add suffix */
		if (strlcat(p, ".", sizeof(p)) >= sizeof(p))
			return false;
		if (strlcat(p, suffix, sizeof(p)) >= sizeof(p))
			return false;
	}
	/* canonicalize the path */
	rp = realpath(p, resolved);
	if (rp == NULL)
		return false;

	/* path must start with DATA_DIR */
	rp[PATH_MAX - 1] = '\0';
	if (strstr(rp, data_dir) != rp)
		return false;

	return true;
}

char   *
url_encode(const char *str)
{
	char   *result;

	if ((result = khttp_urlencode(str)) == NULL)
		return NULL;

	str_replace(result, '+', ' ');
	return result;
}

size_t
url_build(char *dst, size_t dst_sz,...)
{
	va_list path_list;
	char 	p [PATH_MAX];
	char   *encoded, *path, *slash;
	size_t 	c_len, p_len, w_len;

	dst[0] = '\0';
	w_len = 0;
	va_start(path_list, dst_sz);
	while ((path = va_arg(path_list, char *)) != NULL) {
		/* no more space in dst buffer */
		if (w_len >= dst_sz) {
			w_len = 0;
			goto end;
		}

		if (path[0] == '\0')
			continue;

		if (path[0] == '.' && path[1] == '\0')
			continue;

		while (path[0] != '\0') {
			/* no more space in dst buffer */
			if (w_len >= dst_sz) {
				w_len = 0;
				goto end;
			}

			/* skip heading slashes */
			slash = strchr(path, '/');
			if (slash == path) {
				path++;
				continue;
			}

			/* copy string to encode into buffer
			 * if no slash found, copy everything, otherwise stop
			 * before the slash */
			c_len = slash == NULL ? strlen(path) :
			    (size_t) (slash - path);
			if (c_len >= PATH_MAX) {
				w_len = 0;
				goto end;
			}
			p_len = strlcpy(p, path, c_len + 1);
			if (p_len < c_len) {
				w_len = 0;
				goto end;
			}

			/* encode string */
			if ((encoded = url_encode(p)) == NULL) {
				w_len = 0;
				goto end;
			}

			/* append it to the path */
			strlcat(dst, "/", dst_sz);
			w_len = strlcat(dst, encoded, dst_sz);
			free(encoded);
			path += c_len;
		}
	}

end:
	va_end(path_list);
	return w_len;
}