Actual forwarder program compiles apparently ok.

[userv-utils] / ipif / mech-pkcs5.c

/*
 * PKCS#5 padding
 *
 * arguments: block size to pad to, must be power of 2
 *
 * encoding: append between 1 and n bytes, all of the same value being
 *           the number of bytes appended
 */

#include "forwarder.h"

struct mechdata {
  unsigned mask;
};

static unsigned long setup(struct mechdata **md_r) {
  struct mechdata *md;
  unsigned long blocksize;

  XMALLOC(md);

  blocksize= getarg_ulong();
  md->mask= blocksize - 1;
  arg_assert(!md->mask & blocksize);
  arg_assert(blocksize <= 255);

  *md_r= md;
  return blocksize;
}

static void mes_pkcs5(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  unsigned long blocksize;
  
  blocksize= setup(md_r);
  *maxsuffix_io += blocksize + 1;
}

static void mds_pkcs5(struct mechdata **md_r) {
  setup(md_r);
}

static void menc_pkcs5(struct mechdata *md, struct buffer *buf) {
  unsigned char *pad;
  int padlen;

                                  /* eg with blocksize=4 mask=3 mask+2=5   */
                                  /* msgsize    20    21    22    23   24  */
  padlen= md->mask - buf->size;   /*           -17   -18   -19   -16  -17  */
  padlen &= md->mask;             /*             3     2     1     0    3  */
  padlen++;                       /*             4     3     2     1    4  */

  pad= buf_append(buf,padlen);
  memset(pad,padlen,padlen);
}

static const char *mdec_pkcs5(struct mechdata *md, struct buffer *buf) {
  unsigned char *padp;
  unsigned padlen;
  int i;

  BUF_UNPREPEND(padp,buf,1);
  padlen= *padp;
  if (!padlen || (padlen & ~md->mask)) return "invalid length";

  BUF_UNPREPEND(padp,buf,padlen-1);
  for (i=0; i<padlen-1; i++)
    if (*++padp != padlen) return "corrupted padding";

  return 0;
}

STANDARD_MECHANISMLIST("pkcs5",pkcs5)