Allow user-specified symmetric crypto algorithms.

[tripe] / ethereal / packet-tripe.c

/* -*-c-*-
 *
 * $Id: packet-tripe.c,v 1.4 2004/04/18 18:08:11 mdw Exp $
 *
 * TrIPE protocol dissector for Ethereal
 *
 * (c) 2003 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Trivial IP Encryption (TrIPE).
 *
 * TrIPE 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.
 * 
 * TrIPE 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 TrIPE; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include "config.h"

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

#include <netinet/in.h>

#include <glib.h>
#include <gmodule.h>
#include <epan/packet.h>
#include <prefs.h>

#ifdef ETHEREAL_BUGGERED
#  define plugin_address_table_t void
#  define plugin_address_table_init(x)
#else
#  include <plugins/plugin_api.h>
#endif

#include "tripe-protocol.h"

/*----- Static variables --------------------------------------------------*/

static int proto_tripe = -1;

static guint hashsz = 20, tagsz = 10, ivsz = 8;

typedef struct hfmp {
  int hf, hf_len, hf_val, tt;
} hfmp;
typedef struct hfge {
  int hf, hf_len, hf_val, hfx_len, hfx_val, hfy_len, hfy_val, tt;
} hfge;

static int hf_tripe_cat = -1;
static int hf_tripe_packet_type = -1;
static int hf_tripe_ct = -1;
static int hf_tripe_ct_seq = -1;
static int hf_tripe_ct_iv = -1;
static int hf_tripe_ct_ct = -1;
static int hf_tripe_ct_tag = -1;
static int hf_tripe_kx_type = -1;
static hfge hf_tripe_kx_mychal = { -1, -1, -1, -1, -1, -1, -1, -1 };
static int hf_tripe_kx_mycookie = -1;
static int hf_tripe_kx_yourcookie = -1;
static hfmp hf_tripe_kx_check = { -1, -1, -1, -1 };
static int hf_tripe_huh = -1;

static int tt_tripe = -1;
static int tt_tripe_ct = -1;

G_MODULE_EXPORT const gchar version[] = VERSION;

/*----- Main code ---------------------------------------------------------*/

static void prefcb(void) { }

static gint gethash(proto_tree *tt, int hf, tvbuff_t *b, gint off)
{
  proto_tree_add_item(tt, hf, b, off, hashsz, FALSE);
  return (off + hashsz); 
}

static gint getmp(proto_tree *tt, const hfmp *hf, tvbuff_t *b, gint off)
{
  guint16 len = tvb_get_ntohs(b, off);
  proto_item *ti = proto_tree_add_item(tt, hf->hf, b, off, len + 2, FALSE);
  tt = proto_item_add_subtree(ti, hf->tt);
  proto_tree_add_item(tt, hf->hf_len, b, off, 2, FALSE);
  proto_tree_add_item(tt, hf->hf_val, b, off + 2, len, FALSE);
  return (off + 2 + len);
}

static gint getge(proto_tree *tt, const hfge *hf, tvbuff_t *b, gint off)
{
  guint16 len = tvb_get_ntohs(b, off), len2;
  guint r;
  proto_item *ti;
  r = tvb_length_remaining(b, off);
  if (r < 4 + len ||
      (len2 = tvb_get_ntohs(b, off + 2 + len), r < 4 + len + len2)) {
    ti = proto_tree_add_item(tt, hf->hf, b, off, len + 2, FALSE);
    tt = proto_item_add_subtree(ti, hf->tt);
    proto_tree_add_item(tt, hf->hf_len, b, off, 2, FALSE);
    proto_tree_add_item(tt, hf->hf_val, b, off + 2, len, FALSE);
    r = off + len + 2;
  } else {
    ti = proto_tree_add_item(tt, hf->hf, b, off, len + len2 + 4, FALSE);
    tt = proto_item_add_subtree(ti, hf->tt);
    proto_tree_add_item(tt, hf->hfx_len, b, off, 2, FALSE);
    proto_tree_add_item(tt, hf->hfx_val, b, off + 2, len, FALSE);
    proto_tree_add_item(tt, hf->hfy_len, b, off + 2 + len, 2, FALSE);
    proto_tree_add_item(tt, hf->hfy_val, b, off + 4 + len, len2, FALSE);
    r = off + len + len2 + 4;
  }    
  return (r);
}

static void dissect_tripe(tvbuff_t *b, packet_info *p, proto_tree *t)
{
  proto_item *ti;
  proto_tree *tt;
  guint8 ty;
  gint off = tvb_raw_offset(b);
  guint32 seq;

  /* --- Initialize the summary cells --- */

  if (check_col(p->cinfo, COL_PROTOCOL))
    col_set_str(p->cinfo, COL_PROTOCOL, "TrIPE");
  ty = tvb_get_guint8(b, 0);
  if (check_col(p->cinfo, COL_INFO)) {
    col_clear(p->cinfo, COL_INFO);
    switch (ty & MSG_CATMASK) {
      case MSG_PACKET:
	switch (ty & MSG_TYPEMASK) {
	  case 0:
	    col_set_str(p->cinfo, COL_INFO, "Packet data");
	    break;
	  default:
	    col_add_fstr(p->cinfo, COL_INFO,
			 "Packet data, unknown type code %u",
			 ty & MSG_TYPEMASK);
	    break;
	}
	break;
      case MSG_KEYEXCH:
	switch (ty & MSG_TYPEMASK) {
	  case KX_PRECHAL:
	    col_set_str(p->cinfo, COL_INFO, "Key exchange, prechallenge");
	    break;
	  case KX_COOKIE:
	    col_set_str(p->cinfo, COL_INFO, "Key exchange, cookie");
	    break;
	  case KX_CHAL:
	    col_set_str(p->cinfo, COL_INFO, "Key exchange, challenge");
	    break;
	  case KX_REPLY:
	    col_set_str(p->cinfo, COL_INFO, "Key exchange, reply");
	    break;
	  case KX_SWITCH:
	    col_set_str(p->cinfo, COL_INFO, "Key exchange, switch request");
	    break;
	  case KX_SWITCHOK:
	    col_set_str(p->cinfo, COL_INFO, "Key exchange, switch response");
	    break;
	  default:
	    col_add_fstr(p->cinfo, COL_INFO,
			 "Key exchange, unknown type code %u",
			 ty & MSG_TYPEMASK);
	    break;
	}
	break;
      default:
	col_add_fstr(p->cinfo, COL_INFO,
		     "Unknown category code %u, unknown type code %u",
		     ty & MSG_CATMASK, ty & MSG_TYPEMASK);
	break;
    }
  }

  /* --- Fill in the tree --- */

  if (t) {
    ti = proto_tree_add_item(t, proto_tripe, b, 0, -1, FALSE);
    tt = proto_item_add_subtree(ti, tt_tripe);

    proto_tree_add_item(tt, hf_tripe_cat, b, 0, 1, FALSE);

    off = 1;
    switch (ty & MSG_CATMASK) {
      case MSG_PACKET:
	proto_tree_add_item(tt, hf_tripe_packet_type, b, 0, 1, FALSE);
	switch (ty & MSG_TYPEMASK) {
	  case 0:
	    goto ct;
	  default:
	    goto huh;
	}
	break;
      case MSG_KEYEXCH:
	proto_tree_add_item(tt, hf_tripe_kx_type, b, 0, 1, FALSE);
	switch (ty & MSG_TYPEMASK) {
	  case KX_PRECHAL:
	    off = getge(tt, &hf_tripe_kx_mychal, b, off);
	    goto tail;
	  case KX_COOKIE:
	    off = getge(tt, &hf_tripe_kx_mychal, b, off);
	    off = gethash(tt, hf_tripe_kx_yourcookie, b, off);
	    goto tail;
	  case KX_CHAL:
	    off = getge(tt, &hf_tripe_kx_mychal, b, off);
	    off = gethash(tt, hf_tripe_kx_yourcookie, b, off);
	    off = getmp(tt, &hf_tripe_kx_check, b, off);
	    goto tail;
	  case KX_REPLY:
	    off = gethash(tt, hf_tripe_kx_mycookie, b, off);
	    off = gethash(tt, hf_tripe_kx_yourcookie, b, off);
	    off = getmp(tt, &hf_tripe_kx_check, b, off);
	    goto ct;
	  case KX_SWITCH:
	    off = gethash(tt, hf_tripe_kx_mycookie, b, off);
	    off = gethash(tt, hf_tripe_kx_yourcookie, b, off);
	    goto ct;
	  case KX_SWITCHOK:
	    goto ct;
	  default:
	    goto huh;
	}
	break;
      default:
	goto huh;
    }
  tail:
    if (tvb_offset_exists(b, off))
      goto huh;
    goto done;
  huh:
    proto_tree_add_item(tt, hf_tripe_huh, b, off, -1, FALSE);
    goto done;
  ct:
    ti = proto_tree_add_item(tt, hf_tripe_ct, b, off, -1, FALSE);
    seq = tvb_get_ntohl(b, off + tagsz);
    proto_item_set_text(ti, "Encrypted ciphertext (sequence number %lu)",
			(unsigned long)seq);
    tt = proto_item_add_subtree(ti, tt_tripe_ct);
    if (tagsz) {
      proto_tree_add_item(tt, hf_tripe_ct_tag, b, off, tagsz, FALSE);
      off += tagsz;
    }
    proto_tree_add_item(tt, hf_tripe_ct_seq, b, off, 4, FALSE);
    off += 4;
    if (ivsz) {
      proto_tree_add_item(tt, hf_tripe_ct_iv, b, off, ivsz, FALSE);
      off += ivsz;
    }
    proto_tree_add_item(ti, hf_tripe_ct_ct, b, off, -1, FALSE);
    goto done;
  done:;
  }  
}

void proto_register_tripe(void)
{
  module_t *mod;

  static value_string vs_kxtype[] = {
    { KX_PRECHAL,	"KX_PRECHAL (prechallenge)" },
    { KX_COOKIE,	"KX_COOKIE (cookie)" },
    { KX_CHAL,		"KX_CHAL (challenge)" },
    { KX_REPLY,		"KX_REPLY (reply)" },
    { KX_SWITCH,	"KX_SWITCH (switch request)" },
    { KX_SWITCHOK,	"KX_SWITCHOK (switch response)" },
    { 0,		0 }
  };

  static hf_register_info hfs[] = {
    &hf_tripe_cat, {
      "Message category", "tripe.cat",
      FT_UINT8, BASE_HEX, 0, MSG_CATMASK
    },
    &hf_tripe_packet_type, {
      "Packet message type", "tripe.packet.type",
      FT_UINT8, BASE_HEX, 0, MSG_TYPEMASK,
      "This is the TrIPE packet type subcode."
    },
    &hf_tripe_ct, {
      "Encrypted ciphertext", "tripe.ct",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is an encrypted message."
    },
    &hf_tripe_ct_seq, {
      "Ciphertext sequence number", "tripe.ct.seq",
      FT_UINT32, BASE_DEC, 0, 0,
      "This is the unique sequence number for the ciphertext."
    },
    &hf_tripe_ct_iv, {
      "Ciphertext initialization vector", "tripe.ct.iv",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the initialization vector used for the actual encryption."
    },
    &hf_tripe_ct_ct, {
      "Actual encrypted data", "tripe.ct.ct",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the encrypted message.  Reading it ought to be hard."
    },
    &hf_tripe_ct_tag, {
      "Message authentication code", "tripe.ct.tag",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the message authentication code tag for the ciphertext."
    },
    &hf_tripe_kx_type, {
      "Key-exchange message type", "tripe.kx.type",
      FT_UINT8, BASE_HEX, vs_kxtype, MSG_TYPEMASK,
      "This is the TrIPE key-exchange type subcode."
    },
    &hf_tripe_kx_mychal.hf, {
      "Sender's challenge data", "tripe.kx.mychal",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the sender's challenge."
    },
    &hf_tripe_kx_mychal.hf_len, {
      "Challenge length", "tripe.kx.mychal.len",
      FT_UINT16, BASE_DEC, 0, 0,
      "This is the length of the sender's challenge."
    },
    &hf_tripe_kx_mychal.hf_val, {
      "Challenge", "tripe.kx.mychal.val",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the value of the sender's challenge."
    },
    &hf_tripe_kx_mychal.hfx_len, {
      "Challenge x length", "tripe.kx.mychal.x.len",
      FT_UINT16, BASE_DEC, 0, 0,
      "This is the length of the sender's challenge x-coordinate."
    },
    &hf_tripe_kx_mychal.hfy_val, {
      "Challenge x value", "tripe.kx.mychal.x.val",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the value of the sender's challenge x-coordinate."
    },
    &hf_tripe_kx_mychal.hfy_len, {
      "Challenge y length", "tripe.kx.mychal.y.len",
      FT_UINT16, BASE_DEC, 0, 0,
      "This is the length of the sender's challenge x-coordinate."
    },
    &hf_tripe_kx_mychal.hfx_val, {
      "Challenge y value", "tripe.kx.mychal.y.val",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the value of the sender's challenge x-coordinate."
    },
    &hf_tripe_kx_mycookie, {
      "Sender's hashed cookie", "tripe.kx.mycookie",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the hash of the sender's challenge."
    },
    &hf_tripe_kx_yourcookie, {
      "Recipient's hashed cookie", "tripe.kx.yourcookie",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the hash of the recipient's challenge."
    },
    &hf_tripe_kx_check.hf, {
      "Challenge check-value", "tripe.kx.check",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is an encrypted check-value which proves that the sender "
      "knows the answer to the challenge, and that it is therefore honest."
    },
    &hf_tripe_kx_check.hf_len, {
      "Check-value length", "tripe.kx.check.len",
      FT_UINT16, BASE_DEC, 0, 0,
      "This is the length of the encrypted check-value."
    },
    &hf_tripe_kx_check.hf_val, {
      "Check-value data", "tripe.kx.check.val",
      FT_BYTES, BASE_NONE, 0, 0,
      "This is the actual encrypted check-value."
    },
    &hf_tripe_huh, {
      "Unknown data", "tripe.huh",
      FT_BYTES, BASE_NONE, 0, 0,
      "I don't know what's meant to appear here."
    },
  };

  static gint *tts[] = {
    &tt_tripe,
    &tt_tripe_ct,
    &hf_tripe_kx_mychal.tt,
    &hf_tripe_kx_check.tt,
  };

  proto_tripe = proto_register_protocol("TrIPE", "TrIPE", "tripe");
  proto_register_field_array(proto_tripe, hfs, array_length(hfs));
  proto_register_subtree_array(tts, array_length(tts));

  mod = prefs_register_protocol(proto_tripe, prefcb);
  prefs_register_uint_preference(mod, "hashsz", "Hash length",
				 "hash function output length (in octets)",
				 10, &hashsz);
  prefs_register_uint_preference(mod, "tagsz", "MAC tag length",
				 "MAC tag length (in octets)", 10, &tagsz);
  prefs_register_uint_preference(mod, "ivsz", "IV length",
				 "block cipher initialization vector length"
				 " (in octets)",
				 10, &ivsz);
}

void proto_reg_handoff_tripe(void)
{
  dissector_handle_t dh;

  dh = create_dissector_handle(dissect_tripe, proto_tripe);
  dissector_add("udp.port", 22003, dh);
}

G_MODULE_EXPORT void plugin_reg_handoff(void)
{
  proto_reg_handoff_tripe();
}

G_MODULE_EXPORT void plugin_init(plugin_address_table_t *pat)
{
  plugin_address_table_init(pat);
  if (proto_tripe == -1)
    proto_register_tripe();
}

/*----- That's all, folks -------------------------------------------------*/