/*
 * Copyright (C) 2007 voice-system.ro
 *
 * This file is part of opensips, a free SIP server.
 *
 * opensips is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * opensips is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 *

 */
/*!
 * \file
 * \brief Generic string handling functions
 */

#include "parser/parse_uri.h"

#include "ut.h"
#include "strcommon.h"

/*! \brief
 * add backslashes to special characters
 */
int escape_common(char *dst, const char *src, int src_len)
{
	int i, j;

	if(dst==0 || src==0 || src_len<=0)
		return 0;
	j = 0;
	for(i=0; i<src_len; i++)
	{
		switch(src[i])
		{
			case '\'':
				dst[j++] = '\\';
				dst[j++] = src[i];
				break;
			case '"':
				dst[j++] = '\\';
				dst[j++] = src[i];
				break;
			case '\\':
				dst[j++] = '\\';
				dst[j++] = src[i];
				break;
			case '\0':
				dst[j++] = '\\';
				dst[j++] = '0';
				break;
			default:
				dst[j++] = src[i];
		}
	}
	return j;
}

/*! \brief
 * remove backslashes to special characters
 */
int unescape_common(char *dst, const char *src, int src_len)
{
	int i, j;

	if(dst==0 || src==0 || src_len<=0)
		return 0;
	j = 0;
	i = 0;
	while(i<src_len)
	{
		if(src[i]=='\\' && i+1<src_len)
		{
			switch(src[i+1])
			{
				case '\'':
					dst[j++] = '\'';
					i++;
					break;
				case '"':
					dst[j++] = '"';
					i++;
					break;
				case '\\':
					dst[j++] = '\\';
					i++;
					break;
				case '0':
					dst[j++] = '\0';
					i++;
					break;
				default:
					dst[j++] = src[i];
			}
		} else {
			dst[j++] = src[i];
		}
		i++;
	}
	return j;
}

/*! \brief
 * replace &#xx; with ascii character
 */
int unescape_xml(char *dst, const char *src, int src_len)
{
	int i, j;

	if(dst==0 || src==0 || src_len<=0)
		return 0;
	j = 0;
	i = 0;
	while(i<src_len)
	{
		if(src[i]=='&' && i+4<src_len && src[i+1]=='#' && src[i+4]==';' &&
			src[i+2]>='0' && src[i+2]<='9' && src[i+3]>='0' && src[i+3]<='9') {
			dst[j++] = (src[i+2]-'0')*10 + src[i+3] - '0';
			i += 5;
		} else {
			dst[j++] = src[i++];
		}
	}
	return j;
}

/*! \brief Compute MD5 checksum */
void compute_md5(char *dst, const char *src, int src_len)
{
	MD5_CTX context;
	char digest[16];
	MD5Init (&context);
  	MD5Update (&context, src, src_len);
	MD5Final (digest, &context);
	string2hex(digest, 16, dst);
}

/*! \brief Unscape all printable ASCII characters */
int _unescape_user(const str_const *sin, str *sout)
{
	char *at, c;
	const char *p;

	if(sin==NULL || sout==NULL || sout->s==NULL
			|| sin->len<0 || sout->len < sin->len+1) {
		return -1;
	}

	at = sout->s;
	if (sin->s==NULL || sin->len==0)
		goto done;

	p  = sin->s;

	while(p < sin->s+sin->len)
	{
		if (*p == '%')
		{
			p++;
			switch (*p)
			{
				case '0':
				case '1':
				case '2':
				case '3':
				case '4':
				case '5':
				case '6':
				case '7':
				case '8':
				case '9':
					c = (*p - '0') << 4;
				break;
				case 'a':
				case 'b':
				case 'c':
				case 'd':
				case 'e':
				case 'f':
					c = (*p - 'a' + 10) << 4;
				break;
				case 'A':
				case 'B':
				case 'C':
				case 'D':
				case 'E':
				case 'F':
					c = (*p - 'A' + 10) << 4;
				break;
				default:
					LM_ERR("invalid hex digit <%u>\n", (unsigned int)*p);
					return -1;
			}
			p++;
			switch (*p)
			{
				case '0':
				case '1':
				case '2':
				case '3':
				case '4':
				case '5':
				case '6':
				case '7':
				case '8':
				case '9':
					c =  c + (*p - '0');
				break;
				case 'a':
				case 'b':
				case 'c':
				case 'd':
				case 'e':
				case 'f':
					c = c + (*p - 'a' + 10);
				break;
				case 'A':
				case 'B':
				case 'C':
				case 'D':
				case 'E':
				case 'F':
					c = c + (*p - 'A' + 10);
				break;
				default:
					LM_ERR("invalid hex digit <%u>\n", (unsigned int)*p);
					return -1;
			}
			if ((c < 32) || (c > 126))
			{
				LM_ERR("invalid escaped character <%u>\n", (unsigned int)c);
				return -1;
			}
			*at++ = c;
		} else {
			*at++ = *p;
		}
		p++;
	}

done:
	*at = 0;
	sout->len = at - sout->s;

	LM_DBG("unescaped string is <%s>\n", sout->s);
	return 0;
}

/*! \brief
 * Escape all printable characters that are not valid in user
 * part of request uri
 * no_need_to_escape = unreserved | user-unreserved
 * unreserved = aplhanum | mark
 * mark = - | _ | . | ! | ~ | * | ' | ( | )
 * user-unreserved = & | = | + | $ | , | ; | ? | /
 */
int _escape_user(const str_const *sin, str *sout)
{

	char *at;
	const char *p;
	unsigned char x;

	if(sin==NULL || sout==NULL || sin->s==NULL || sout->s==NULL
			|| sin->len<0 || sout->len < 3*sin->len+1)
		return -1;

	at = sout->s;
	p  = sin->s;
	while (p < sin->s+sin->len)
	{
	 	if (*p < 32 || *p > 126)
		{
			LM_ERR("invalid escaped character <%u>\n", (unsigned int)*p);
			return -1;
		}

		if (is_username_char(*p)) {
			*at = *p;
		} else {
			*at++ = '%';
			x = (*p) >> 4;
			if (x < 10)
			{
				*at++ = x + '0';
			} else {
				*at++ = x - 10 + 'a';
			}
			x = (*p) & 0x0f;
			if (x < 10) {
				*at = x + '0';
			} else {
				*at = x - 10 + 'a';
			}
		}

		at++;
		p++;
	}
	*at = 0;
	sout->len = at - sout->s;
	LM_DBG("escaped string is <%s>\n", sout->s);
	return 0;
}


int _unescape_param(const str_const *sin, str *sout)
{
	return unescape_user(sin, sout);
}


/*! \brief
 * Escape all printable characters that are not valid in
 * a param part of request uri:
 * no_need_to_escape = unreserved | param-unreserved
 * unreserved = aplhanum | mark
 * mark = - | _ | . | ! | ~ | * | ' | ( | )
 * param-unreserved = [ | ] | / | : | & | + | $
 */
int _escape_param(const str_const *sin, str *sout)
{
	char *at;
	const char *p;
	unsigned char x;

	if (sin==NULL || sout==NULL || sin->s==NULL || sout->s==NULL ||
		sin->len<0 || sout->len < 3*sin->len+1)
		return -1;

	at = sout->s;
	p  = sin->s;
	while (p < sin->s+sin->len) {
		if (*p < 32 || *p > 126) {
			LM_ERR("invalid escaped character <%u>\n", (unsigned int)*p);
			return -1;
		}
		if (isalnum((int)*p)) {
			*at = *p;
		} else {
			switch (*p) {
				/* unreserved chars */
				case '-':
				case '_':
				case '.':
				case '!':
				case '~':
				case '*':
				case '\'':
				case '(':
				case ')':
				/* param unreserved chars */
				case '[':
				case ']':
				case '/':
				case ':':
				case '&':
				case '+':
				case '$':
					*at = *p;
					break;
				default:
					*at++ = '%';
					x = (*p) >> 4;
					if (x < 10)
					{
						*at++ = x + '0';
					} else {
						*at++ = x - 10 + 'a';
					}
					x = (*p) & 0x0f;
					if (x < 10) {
						*at = x + '0';
					} else {
						*at = x - 10 + 'a';
					}
			}
		}
		at++;
		p++;
	}
	*at = 0;
	sout->len = at - sout->s;
	LM_DBG("escaped string is <%s>\n", sout->s);

	return 0;
}