csu3_am335x/EVSE/Modularization/Firewall/yuarel.c

/*
 * yuarel.c
 *
 *  Created on: 2022/12/9
 *      Author: folus
 */
#include "yuarel.h"

/**
 * Parse a non null terminated string into an integer.
 *
 * str: the string containing the number.
 * len: Number of characters to parse.
 */
static inline int natoi(const char *str, size_t len)
{
	int i, r = 0;
	for (i = 0; i < len; i++) {
		r *= 10;
		r += str[i] - '0';
	}

	return r;
}

/**
 * Check if a URL is relative (no scheme and hostname).
 *
 * url: the string containing the URL to check.
 *
 * Returns 1 if relative, otherwise 0.
 */
static inline int is_relative(const char *url)
{
	return (*url == '/') ? 1 : 0;
}

/**
 * Parse the scheme of a URL by inserting a null terminator after the scheme.
 *
 * str: the string containing the URL to parse. Will be modified.
 *
 * Returns a pointer to the hostname on success, otherwise NULL.
 */
static inline char *parse_scheme(char *str)
{
	char *s;

	/* If not found or first in string, return error */
	s = strchr(str, ':');
	if (s == NULL || s == str) {
		return NULL;
	}

	/* If not followed by two slashes, return error */
	if (s[1] == '\0' || s[1] != '/' || s[2] == '\0' || s[2] != '/') {
		return NULL;
	}

	*s = '\0'; // Replace ':' with NULL

	return s + 3;
}

/**
 * Find a character in a string, replace it with '\0' and return the next
 * character in the string.
 *
 * str: the string to search in.
 * find: the character to search for.
 *
 * Returns a pointer to the character after the one to search for. If not
 * found, NULL is returned.
 */
static inline char *find_and_terminate(char *str, char find)
{
	str = strchr(str, find);
	if (NULL == str) {
		return NULL;
	}

	*str = '\0';
	return str + 1;
}

/* Yes, the following functions could be implemented as preprocessor macros
     instead of inline functions, but I think that this approach will be more
     clean in this case. */
static inline char *find_fragment(char *str)
{
	return find_and_terminate(str, '#');
}

static inline char *find_query(char *str)
{
	return find_and_terminate(str, '?');
}

static inline char *find_path(char *str)
{
	return find_and_terminate(str, '/');
}

/**
 * Parse a URL string to a struct.
 *
 * url: pointer to the struct where to store the parsed URL parts.
 * u:   the string containing the URL to be parsed.
 *
 * Returns 0 on success, otherwise -1.
 */
int yuarel_parse(struct yuarel *url, char *u)
{
	if (NULL == url || NULL == u) {
		return -1;
	}

	memset(url, 0, sizeof (struct yuarel));

	/* (Fragment) */
	url->fragment = find_fragment(u);

	/* (Query) */
	url->query = find_query(u);

	/* Relative URL? Parse scheme and hostname */
	if (!is_relative(u)) {
		/* Scheme */
		url->scheme = u;
		u = parse_scheme(u);
		if (u == NULL) {
			return -1;
		}

		/* Host */
		if ('\0' == *u) {
			return -1;
		}
		url->host = u;

		/* (Path) */
		url->path = find_path(u);

		/* (Credentials) */
		u = strchr(url->host, '@');
		if (NULL != u) {
			/* Missing credentials? */
			if (u == url->host) {
				return -1;
			}

			url->username = url->host;
			url->host = u + 1;
			*u = '\0';

			u = strchr(url->username, ':');
			if (NULL == u) {
				return -1;
			}

			url->password = u + 1;
			*u = '\0';
		}

		/* Missing hostname? */
		if ('\0' == *url->host) {
			return -1;
		}

		/* (Port) */
		u = strchr(url->host, ':');
		if (NULL != u && (NULL == url->path || u < url->path)) {
			*(u++) = '\0';
			if ('\0' == *u) {
				return -1;
			}

			if (url->path) {
				url->port = natoi(u, url->path - u - 1);
			} else {
				url->port = atoi(u);
			}
		}

		/* Missing hostname? */
		if ('\0' == *url->host) {
			return -1;
		}
	} else {
		/* (Path) */
		url->path = find_path(u);
	}

	return 0;
}

/**
 * Split a path into several strings.
 *
 * No data is copied, the slashed are used as null terminators and then
 * pointers to each path part will be stored in **parts. Double slashes will be
 * treated as one.
 *
 * path: the path to split.
 * parts: a pointer to an array of (char *) where to store the result.
 * max_parts: max number of parts to parse.
 */
int
yuarel_split_path(char *path, char **parts, int max_parts)
{
	int i = 0;

	if (NULL == path || '\0' == *path) {
		return -1;
	}

	do {
		/* Forward to after slashes */
		while (*path == '/') path++;

		if ('\0' == *path) {
			break;
		}

		parts[i++] = path;

		path = strchr(path, '/');
		if (NULL == path) {
			break;
		}

		*(path++) = '\0';
	} while (i < max_parts);

	return i;
}

int
yuarel_parse_query(char *query, char delimiter, struct yuarel_param *params, int max_params)
{
	int i = 0;

	if (NULL == query || '\0' == *query) {
		return -1;
	}

	params[i++].key = query;
	while (i < max_params && NULL != (query = strchr(query, delimiter))) {
		*query = '\0';
		params[i].key = ++query;
		params[i].val = NULL;

		/* Go back and split previous param */
		if (i > 0) {
			if ((params[i - 1].val = strchr(params[i - 1].key, '=')) != NULL) {
				*(params[i - 1].val)++ = '\0';
			}
		}
		i++;
	}

	/* Go back and split last param */
	if ((params[i - 1].val = strchr(params[i - 1].key, '=')) != NULL) {
		*(params[i - 1].val)++ = '\0';
	}

	return i;
}