padbuf.c (1534B)
1 /* This Source Code Form is subject to the terms of the Mozilla Public 2 * License, v. 2.0. If a copy of the MPL was not distributed with this 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 4 #include "blapit.h" 5 #include "secport.h" 6 #include "secerr.h" 7 8 /* 9 * Prepare a buffer for any padded CBC encryption algorithm, growing to the 10 * appropriate boundary and filling with the appropriate padding. 11 * blockSize must be a power of 2. 12 * 13 * NOTE: If arena is non-NULL, we re-allocate from there, otherwise 14 * we assume (and use) XP memory (re)allocation. 15 */ 16 unsigned char * 17 CBC_PadBuffer(PLArenaPool *arena, unsigned char *inbuf, unsigned int inlen, 18 unsigned int *outlen, int blockSize) 19 { 20 unsigned char *outbuf; 21 unsigned int des_len; 22 unsigned int i; 23 unsigned char des_pad_len; 24 25 /* 26 * We need from 1 to blockSize bytes -- we *always* grow. 27 * The extra bytes contain the value of the length of the padding: 28 * if we have 2 bytes of padding, then the padding is "0x02, 0x02". 29 */ 30 des_len = (inlen + blockSize) & ~(blockSize - 1); 31 32 if (arena != NULL) { 33 outbuf = (unsigned char *)PORT_ArenaGrow(arena, inbuf, inlen, des_len); 34 } else { 35 outbuf = (unsigned char *)PORT_Realloc(inbuf, des_len); 36 } 37 38 if (outbuf == NULL) { 39 PORT_SetError(SEC_ERROR_NO_MEMORY); 40 return NULL; 41 } 42 43 des_pad_len = des_len - inlen; 44 for (i = inlen; i < des_len; i++) 45 outbuf[i] = des_pad_len; 46 47 *outlen = des_len; 48 return outbuf; 49 }