/* asn1.c
 * Common routines for ASN.1
 * 2007  Anders Broman
 *
 * $Id$
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <glib.h>

#include <string.h>
#include <stdlib.h>
#include <math.h>

#include <epan/packet.h>

#include "asn1.h"

void asn1_ctx_init(asn1_ctx_t *actx, asn1_enc_e encoding, gboolean aligned, packet_info *pinfo) {
  memset(actx, '\0', sizeof(*actx));
  actx->signature = ASN1_CTX_SIGNATURE;
  actx->encoding = encoding;
  actx->aligned = aligned;
  actx->pinfo = pinfo;
}

gboolean asn1_ctx_check_signature(asn1_ctx_t *actx) {
  return actx && (actx->signature == ASN1_CTX_SIGNATURE);
}

void asn1_ctx_clean_external(asn1_ctx_t *actx) {
  memset(&actx->external, '\0', sizeof(actx->external));
  actx->external.hf_index = -1;
  actx->external.encoding = -1;
}

void asn1_ctx_clean_epdv(asn1_ctx_t *actx) {
  memset(&actx->embedded_pdv, '\0', sizeof(actx->embedded_pdv));
  actx->embedded_pdv.hf_index = -1;
  actx->embedded_pdv.identification = -1;
}


/*--- stack/parameters ---*/

void asn1_stack_frame_push(asn1_ctx_t *actx, const gchar *name) {
  asn1_stack_frame_t *frame;

  frame = ep_alloc0(sizeof(asn1_stack_frame_t));
  frame->name = name;
  frame->next = actx->stack;
  actx->stack = frame;
}

void asn1_stack_frame_pop(asn1_ctx_t *actx, const gchar *name) {
  DISSECTOR_ASSERT(actx->stack);
  DISSECTOR_ASSERT(!strcmp(actx->stack->name, name));
  actx->stack = actx->stack->next;
}

void asn1_stack_frame_check(asn1_ctx_t *actx, const gchar *name, const asn1_par_def_t *par_def) {
  const asn1_par_def_t *pd = par_def;
  asn1_par_t *par;

  DISSECTOR_ASSERT(actx->stack);
  DISSECTOR_ASSERT(!strcmp(actx->stack->name, name));

  par = actx->stack->par;
  while (pd->name) {
    DISSECTOR_ASSERT(par);
    DISSECTOR_ASSERT((pd->ptype == ASN1_PAR_IRR) || (par->ptype == pd->ptype));
    par->name = pd->name;
    pd++;
    par = par->next;
  }
  DISSECTOR_ASSERT(!par);
}

static asn1_par_t *get_par_by_name(asn1_ctx_t *actx, const gchar *name) {
  asn1_par_t *par = NULL;

  DISSECTOR_ASSERT(actx->stack);
  par = actx->stack->par;
  while (par) {
    if (!strcmp(par->name, name))
      return par;
    par = par->next;
  }
  return par;
}

static asn1_par_t *push_new_par(asn1_ctx_t *actx) {
  asn1_par_t *par, **pp;

  DISSECTOR_ASSERT(actx->stack);

  par = ep_alloc0(sizeof(asn1_par_t));

  pp = &(actx->stack->par);
  while (*pp)
    pp = &((*pp)->next);
  *pp = par;

  return par;
}

void asn1_param_push_boolean(asn1_ctx_t *actx, gboolean value) {
  asn1_par_t *par;

  par = push_new_par(actx);
  par->ptype = ASN1_PAR_BOOLEAN;
  par->value.v_boolean = value;
}

void asn1_param_push_integer(asn1_ctx_t *actx, gint32 value) {
  asn1_par_t *par;

  par = push_new_par(actx);
  par->ptype = ASN1_PAR_INTEGER;
  par->value.v_integer = value;
}

gboolean asn1_param_get_boolean(asn1_ctx_t *actx, const gchar *name) {
  asn1_par_t *par = NULL;

  par = get_par_by_name(actx, name);
  DISSECTOR_ASSERT(par);
  return par->value.v_boolean;
}

gint32 asn1_param_get_integer(asn1_ctx_t *actx, const gchar *name) {
  asn1_par_t *par = NULL;

  par = get_par_by_name(actx, name);
  DISSECTOR_ASSERT(par);
  return par->value.v_integer;
}


/*--- ROSE ---*/

void rose_ctx_init(rose_ctx_t *rctx) {
  memset(rctx, '\0', sizeof(*rctx));
  rctx->signature = ROSE_CTX_SIGNATURE;
}

gboolean rose_ctx_check_signature(rose_ctx_t *rctx) {
  return rctx && (rctx->signature == ROSE_CTX_SIGNATURE);
}

void rose_ctx_clean_data(rose_ctx_t *rctx) {
  memset(&rctx->d, '\0', sizeof(rctx->d));
  rctx->d.code = -1;
}

asn1_ctx_t *get_asn1_ctx(void *ptr) {
  asn1_ctx_t *actx = (asn1_ctx_t*)ptr;

  if (!asn1_ctx_check_signature(actx)) 
    actx = NULL;

  return actx;
}

rose_ctx_t *get_rose_ctx(void *ptr) {
  rose_ctx_t *rctx = (rose_ctx_t*)ptr;
  asn1_ctx_t *actx = (asn1_ctx_t*)ptr;

  if (!asn1_ctx_check_signature(actx)) 
    actx = NULL;

  if (actx)
    rctx = actx->rose_ctx;

  if (!rose_ctx_check_signature(rctx)) 
    rctx = NULL;

  return rctx;
}

double asn1_get_real(const guint8 *real_ptr, gint real_len) {
  guint8 octet;
  const guint8 *p;
  guint8 *buf;
  double val = 0;

  if (real_len < 1) return val;
  octet = real_ptr[0];
  p = real_ptr + 1;
  real_len -= 1;
  if (octet & 0x80) {  /* binary encoding */
  } else if (octet & 0x40) {  /* SpecialRealValue */
    switch (octet & 0x3F) {
      case 0x00: val = HUGE_VAL; break;
      case 0x01: val = -HUGE_VAL; break;
    }
  } else {  /* decimal encoding */
    buf = ep_strndup(p, real_len);
    val = atof(buf);
  }

  return val;
}