view libtommath/bn_mp_fwrite.c @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 1051e4eea25a
children
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#include "tommath_private.h"
#ifdef BN_MP_FWRITE_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

#ifndef MP_NO_FILE
mp_err mp_fwrite(const mp_int *a, int radix, FILE *stream)
{
   char *buf;
   mp_err err;
   int len;
   size_t written;

   /* TODO: this function is not in this PR */
   if (MP_HAS(MP_RADIX_SIZE_OVERESTIMATE)) {
      /* if ((err = mp_radix_size_overestimate(&t, base, &len)) != MP_OKAY)      goto LBL_ERR; */
   } else {
      if ((err = mp_radix_size(a, radix, &len)) != MP_OKAY) {
         return err;
      }
   }

   buf = (char *) MP_MALLOC((size_t)len);
   if (buf == NULL) {
      return MP_MEM;
   }

   if ((err = mp_to_radix(a, buf, (size_t)len, &written, radix)) != MP_OKAY) {
      goto LBL_ERR;
   }

   if (fwrite(buf, written, 1uL, stream) != 1uL) {
      err = MP_ERR;
      goto LBL_ERR;
   }
   err = MP_OKAY;


LBL_ERR:
   MP_FREE_BUFFER(buf, (size_t)len);
   return err;
}
#endif

#endif