security/nss/lib/softoken/padbuf.c

   1 /* ***** BEGIN LICENSE BLOCK *****
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  10  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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  14  * The Original Code is the Netscape security libraries.
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  16  * The Initial Developer of the Original Code is
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  36 #include "blapit.h"
  37 #include "secport.h"
  38 #include "secerr.h"
  39
  40 /*
  41  * Prepare a buffer for any padded CBC encryption algorithm, growing to the
  42  * appropriate boundary and filling with the appropriate padding.
  43  * blockSize must be a power of 2.
  44  *
  45  * NOTE: If arena is non-NULL, we re-allocate from there, otherwise
  46  * we assume (and use) XP memory (re)allocation.
  47  */
  48 unsigned char *
  49 CBC_PadBuffer(PRArenaPool *arena, unsigned char *inbuf, unsigned int inlen,
  50               unsigned int *outlen, int blockSize)
  51 {
  52     unsigned char *outbuf;
  53     unsigned int   des_len;
  54     unsigned int   i;
  55     unsigned char  des_pad_len;
  56
  57     /*
  58      * We need from 1 to blockSize bytes -- we *always* grow.
  59      * The extra bytes contain the value of the length of the padding:
  60      * if we have 2 bytes of padding, then the padding is "0x02, 0x02".
  61      */
  62     des_len = (inlen + blockSize) & ~(blockSize - 1);
  63
  64     if (arena != NULL) {
  65         outbuf = (unsigned char*)PORT_ArenaGrow (arena, inbuf, inlen, des_len);
  66     } else {
  67         outbuf = (unsigned char*)PORT_Realloc (inbuf, des_len);
  68     }
  69
  70     if (outbuf == NULL) {
  71         PORT_SetError (SEC_ERROR_NO_MEMORY);
  72         return NULL;
  73     }
  74
  75     des_pad_len = des_len - inlen;
  76     for (i = inlen; i < des_len; i++)
  77         outbuf[i] = des_pad_len;
  78
  79     *outlen = des_len;
  80     return outbuf;
  81 }