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src/ltc/misc/ssh/ssh_decode_sequence_multi.c  view on Meta::CPAN

/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
#include "tomcrypt_private.h"

/**
   @file ssh_decode_sequence_multi.c
   SSH data type representation as per RFC4251, Russ Williams
*/

#ifdef LTC_SSH

/**
  Decode a SSH sequence using a VA list
  @param in     The input buffer
  @param inlen  [in/out] The length of the input buffer and on output the amount of decoded data
  @remark <...> is of the form <type, data*> (int, <unsigned char*,ulong32*,ulong64*>) except for string&name-list <type, data, size*> (int, void*, unsigned long*)
  @return CRYPT_OK on success
*/
int ssh_decode_sequence_multi(const unsigned char *in, unsigned long *inlen, ...)
{
   int           err;
   va_list       args;
   ssh_data_type type;
   void          *vdata;
   unsigned char *cdata;
   char          *sdata;
   ulong32       *u32data;
   ulong64       *u64data;
   unsigned long *bufsize;
   ulong32       size;
   unsigned long remaining;

   LTC_ARGCHK(in    != NULL);
   LTC_ARGCHK(inlen != NULL);

   remaining = *inlen;
   /* Decode values from buffer */
   va_start(args, inlen);
   while ((type = (ssh_data_type)va_arg(args, int)) != LTC_SSHDATA_EOL) {
      /* Size of length field */
      if (type == LTC_SSHDATA_STRING ||
          type == LTC_SSHDATA_NAMELIST ||
          type == LTC_SSHDATA_MPINT)
      {
         /* Check we'll not read too far */
         if (remaining < 4) {
            err = CRYPT_BUFFER_OVERFLOW;
            goto error;
         }
      }

      /* Calculate (or read) length of data */
      size = 0xFFFFFFFFU;
      switch (type) {
         case LTC_SSHDATA_BYTE:
         case LTC_SSHDATA_BOOLEAN:
            size = 1;
            break;
         case LTC_SSHDATA_UINT32:
            size = 4;
            break;
         case LTC_SSHDATA_UINT64:
            size = 8;
            break;
         case LTC_SSHDATA_STRING:
         case LTC_SSHDATA_NAMELIST:
         case LTC_SSHDATA_MPINT:
            LOAD32H(size, in);
            in += 4;
            remaining -= 4;
            break;

         case LTC_SSHDATA_EOL:
            /* Should never get here */
            err = CRYPT_INVALID_ARG;