url.c

/*******************************************************************
 *  url编码和解码，解决url中包含中文的问题.
 *  参考博客:http://blog.csdn.net/langeldep/article/details/6264058
 *  本人做了少量的修改.
 *******************************************************************/

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>

#include "url.h"

static unsigned char hexchars[] = "0123456789ABCDEF";

static
int htoi(char *s) {
	int value;
	int c;

	c = ((unsigned char *)s)[0];
	if (isupper(c))
		c = tolower(c);
	value = (c >= '0' && c <= '9' ? c - '0' : c - 'a' + 10) * 16;

	c = ((unsigned char *)s)[1];
	if (isupper(c))
		c = tolower(c);
	value += c >= '0' && c <= '9' ? c - '0' : c - 'a' + 10;

	return (value);
}


char *url_encode(char const *s, int len, int *new_length) {
	register unsigned char c;
	unsigned char *to, *start;
	unsigned char const *from, *end;

	from = (unsigned char *)s;
	end = (unsigned char *)s + len;
	start = to = (unsigned char *)calloc(1, 3 * len + 1);

	while (from < end) 	{
		c = *from++;

		if (c == ' ') {
			*to++ = '+';
		}
		else if ((c < '0' && c != '-' && c != '.') ||
			(c < 'A' && c > '9') ||
			(c > 'Z' && c < 'a' && c != '_') ||
			(c > 'z')) {
			to[0] = '%';
			to[1] = hexchars[c >> 4];
			to[2] = hexchars[c & 15];
			to += 3;
		}
		else {
			*to++ = c;
		}
	}
	*to = 0;
	if (new_length) {
		*new_length = to - start;
	}
	return (char *)start;
}


int url_decode(char *str, int len) {
	char *dest = str;
	char *data = str;

	while (len--) {
		if (*data == '+') {
			*dest = ' ';
		}
		else if (*data == '%' && len >= 2 && isxdigit((int)*(data + 1)) && isxdigit((int)*(data + 2))) {
			*dest = (char)htoi(data + 1);
			data += 2;
			len -= 2;
		}
		else {
			*dest = *data;
		}
		data++;
		dest++;
	}
	*dest = '\0';
	return dest - str;
}