util_str.c

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/* 
   Unix SMB/CIFS implementation.
   Samba utility functions
   
   Copyright (C) Andrew Tridgell 1992-2001
   Copyright (C) Simo Sorce      2001-2002
   Copyright (C) Martin Pool     2003
   Copyright (C) James Peach	 2005
   
   This program 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 3 of the License, or
   (at your option) any later version.
   
   This program 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "libcli/raw/smb.h"
#include "system/locale.h"

/**
 * @file
 * @brief String utilities.
 **/


/**
 Trim the specified elements off the front and back of a string.
**/
_PUBLIC_ bool trim_string(char *s, const char *front, const char *back)
{
	bool ret = false;
	size_t front_len;
	size_t back_len;
	size_t len;

	/* Ignore null or empty strings. */
	if (!s || (s[0] == '\0'))
		return false;

	front_len	= front? strlen(front) : 0;
	back_len	= back? strlen(back) : 0;

	len = strlen(s);

	if (front_len) {
		while (len && strncmp(s, front, front_len)==0) {
			/* Must use memmove here as src & dest can
			 * easily overlap. Found by valgrind. JRA. */
			memmove(s, s+front_len, (len-front_len)+1);
			len -= front_len;
			ret=true;
		}
	}
	
	if (back_len) {
		while ((len >= back_len) && strncmp(s+len-back_len,back,back_len)==0) {
			s[len-back_len]='\0';
			len -= back_len;
			ret=true;
		}
	}
	return ret;
}

/**
 Find the number of 'c' chars in a string
**/
_PUBLIC_ _PURE_ size_t count_chars(const char *s, char c)
{
	size_t count = 0;

	while (*s) {
		if (*s == c) count++;
		s ++;
	}

	return count;
}



/**
 Safe string copy into a known length string. maxlength does not
 include the terminating zero.
**/
_PUBLIC_ char *safe_strcpy(char *dest,const char *src, size_t maxlength)
{
	size_t len;

	if (!dest) {
		DEBUG(0,("ERROR: NULL dest in safe_strcpy\n"));
		return NULL;
	}

#ifdef DEVELOPER
	/* We intentionally write out at the extremity of the destination
	 * string.  If the destination is too short (e.g. pstrcpy into mallocd
	 * or fstring) then this should cause an error under a memory
	 * checker. */
	dest[maxlength] = '\0';
	if (PTR_DIFF(&len, dest) > 0) {  /* check if destination is on the stack, ok if so */
		log_suspicious_usage("safe_strcpy", src);
	}
#endif

	if (!src) {
		*dest = 0;
		return dest;
	}  

	len = strlen(src);

	if (len > maxlength) {
		DEBUG(0,("ERROR: string overflow by %u (%u - %u) in safe_strcpy [%.50s]\n",
			 (uint_t)(len-maxlength), (unsigned)len, (unsigned)maxlength, src));
		len = maxlength;
	}
      
	memmove(dest, src, len);
	dest[len] = 0;
	return dest;
}  

/**
 Safe string cat into a string. maxlength does not
 include the terminating zero.
**/
_PUBLIC_ char *safe_strcat(char *dest, const char *src, size_t maxlength)
{
	size_t src_len, dest_len;

	if (!dest) {
		DEBUG(0,("ERROR: NULL dest in safe_strcat\n"));
		return NULL;
	}

	if (!src)
		return dest;
	
#ifdef DEVELOPER
	if (PTR_DIFF(&src_len, dest) > 0) {  /* check if destination is on the stack, ok if so */
		log_suspicious_usage("safe_strcat", src);
	}
#endif
	src_len = strlen(src);
	dest_len = strlen(dest);

	if (src_len + dest_len > maxlength) {
		DEBUG(0,("ERROR: string overflow by %d in safe_strcat [%.50s]\n",
			 (int)(src_len + dest_len - maxlength), src));
		if (maxlength > dest_len) {
			memcpy(&dest[dest_len], src, maxlength - dest_len);
		}
		dest[maxlength] = 0;
		return NULL;
	}
	
	memcpy(&dest[dest_len], src, src_len);
	dest[dest_len + src_len] = 0;
	return dest;
}

/**
 Routine to get hex characters and turn them into a 16 byte array.
 the array can be variable length, and any non-hex-numeric
 characters are skipped.  "0xnn" or "0Xnn" is specially catered
 for.

 valid examples: "0A5D15"; "0x15, 0x49, 0xa2"; "59\ta9\te3\n"


**/
_PUBLIC_ size_t strhex_to_str(char *p, size_t len, const char *strhex)
{
	size_t i;
	size_t num_chars = 0;
	uint8_t   lonybble, hinybble;
	const char     *hexchars = "0123456789ABCDEF";
	char           *p1 = NULL, *p2 = NULL;

	for (i = 0; i < len && strhex[i] != 0; i++) {
		if (strncasecmp(hexchars, "0x", 2) == 0) {
			i++; /* skip two chars */
			continue;
		}

		if (!(p1 = strchr(hexchars, toupper((unsigned char)strhex[i]))))
			break;

		i++; /* next hex digit */

		if (!(p2 = strchr(hexchars, toupper((unsigned char)strhex[i]))))
			break;

		/* get the two nybbles */
		hinybble = PTR_DIFF(p1, hexchars);
		lonybble = PTR_DIFF(p2, hexchars);

		p[num_chars] = (hinybble << 4) | lonybble;
		num_chars++;

		p1 = NULL;
		p2 = NULL;
	}
	return num_chars;
}

/** 
 * Parse a hex string and return a data blob. 
 */
_PUBLIC_ _PURE_ DATA_BLOB strhex_to_data_blob(const char *strhex) 
{
	DATA_BLOB ret_blob = data_blob(NULL, strlen(strhex)/2+1);

	ret_blob.length = strhex_to_str((char *)ret_blob.data, 	
					strlen(strhex), 
					strhex);

	return ret_blob;
}


/**
 * Routine to print a buffer as HEX digits, into an allocated string.
 */
_PUBLIC_ void hex_encode(const unsigned char *buff_in, size_t len, char **out_hex_buffer)
{
	int i;
	char *hex_buffer;

	*out_hex_buffer = malloc_array_p(char, (len*2)+1);
	hex_buffer = *out_hex_buffer;

	for (i = 0; i < len; i++)
		slprintf(&hex_buffer[i*2], 3, "%02X", buff_in[i]);
}

/**
 * talloc version of hex_encode()
 */
_PUBLIC_ char *hex_encode_talloc(TALLOC_CTX *mem_ctx, const unsigned char *buff_in, size_t len)
{
	int i;
	char *hex_buffer;

	hex_buffer = talloc_array(mem_ctx, char, (len*2)+1);

	for (i = 0; i < len; i++)
		slprintf(&hex_buffer[i*2], 3, "%02X", buff_in[i]);

	return hex_buffer;
}

/**
 Substitute a string for a pattern in another string. Make sure there is 
 enough room!

 This routine looks for pattern in s and replaces it with 
 insert. It may do multiple replacements.

 Any of " ; ' $ or ` in the insert string are replaced with _
 if len==0 then the string cannot be extended. This is different from the old
 use of len==0 which was for no length checks to be done.
**/

_PUBLIC_ void string_sub(char *s, const char *pattern, const char *insert, size_t len)
{
	char *p;
	ssize_t ls, lp, li, i;

	if (!insert || !pattern || !*pattern || !s)
		return;

	ls = (ssize_t)strlen(s);
	lp = (ssize_t)strlen(pattern);
	li = (ssize_t)strlen(insert);

	if (len == 0)
		len = ls + 1; /* len is number of *bytes* */

	while (lp <= ls && (p = strstr(s, pattern))) {
		if (ls + (li-lp) >= len) {
			DEBUG(0,("ERROR: string overflow by %d in string_sub(%.50s, %d)\n", 
				 (int)(ls + (li-lp) - len),
				 pattern, (int)len));
			break;
		}
		if (li != lp) {
			memmove(p+li,p+lp,strlen(p+lp)+1);
		}
		for (i=0;i<li;i++) {
			switch (insert[i]) {
			case '`':
			case '"':
			case '\'':
			case ';':
			case '$':
			case '%':
			case '\r':
			case '\n':
				p[i] = '_';
				break;
			default:
				p[i] = insert[i];
			}
		}
		s = p + li;
		ls += (li-lp);
	}
}

/**
 * Talloc'ed version of string_sub
 */
_PUBLIC_ char *string_sub_talloc(TALLOC_CTX *mem_ctx, const char *s, 
				const char *pattern, const char *insert)
{
	const char *p;
	char *ret;
	size_t len, alloc_len;

	if (insert == NULL || pattern == NULL || !*pattern || s == NULL)
		return NULL;

	/* determine length needed */
	len = strlen(s);
	
	for (p = strstr(s, pattern); p != NULL; 
	     p = strstr(p+strlen(pattern), pattern)) {
		len += strlen(insert) - strlen(pattern);
	}

	alloc_len = MAX(len, strlen(s))+1;
	ret = talloc_array(mem_ctx, char, alloc_len);
	if (ret == NULL)
		return NULL;
	strncpy(ret, s, alloc_len);
	string_sub(ret, pattern, insert, alloc_len);

	ret = talloc_realloc(mem_ctx, ret, char, len+1);
	if (ret == NULL)
		return NULL;

	SMB_ASSERT(ret[len] == '\0');

	return ret;
}

/**
 Similar to string_sub() but allows for any character to be substituted. 
 Use with caution!
 if len==0 then the string cannot be extended. This is different from the old
 use of len==0 which was for no length checks to be done.
**/

_PUBLIC_ void all_string_sub(char *s,const char *pattern,const char *insert, size_t len)
{
	char *p;
	ssize_t ls,lp,li;

	if (!insert || !pattern || !s)
		return;

	ls = (ssize_t)strlen(s);
	lp = (ssize_t)strlen(pattern);
	li = (ssize_t)strlen(insert);

	if (!*pattern)
		return;
	
	if (len == 0)
		len = ls + 1; /* len is number of *bytes* */
	
	while (lp <= ls && (p = strstr(s,pattern))) {
		if (ls + (li-lp) >= len) {
			DEBUG(0,("ERROR: string overflow by %d in all_string_sub(%.50s, %d)\n", 
				 (int)(ls + (li-lp) - len),
				 pattern, (int)len));
			break;
		}
		if (li != lp) {
			memmove(p+li,p+lp,strlen(p+lp)+1);
		}
		memcpy(p, insert, li);
		s = p + li;
		ls += (li-lp);
	}
}