tinc/src/protocol_key.c

/*
    protocol_key.c -- handle the meta-protocol, key exchange
    Copyright (C) 1999-2002 Ivo Timmermans <itimmermans@bigfoot.com>,
                  2000-2002 Guus Sliepen <guus@sliepen.warande.net>

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

    $Id: protocol_key.c,v 1.1.4.6 2002/03/22 13:31:18 guus Exp $
*/

#include "config.h"

#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <stdio.h>
#include <stdarg.h>
#include <errno.h>

#include <utils.h>
#include <xalloc.h>
#include <avl_tree.h>

#include "conf.h"
#include "net.h"
#include "netutl.h"
#include "protocol.h"
#include "meta.h"
#include "connection.h"
#include "node.h"
#include "edge.h"

#include "system.h"

int mykeyused = 0;

int send_key_changed(connection_t *c, node_t *n)
{
  connection_t *other;
  avl_node_t *node;
cp
  /* Only send this message if some other daemon requested our key previously.
     This reduces unnecessary key_changed broadcasts.
  */

  if(n == myself && !mykeyused)
    return 0;

  for(node = connection_tree->head; node; node = node->next)
    {
      other = (connection_t *)node->data;
      if(other->status.active && other != c)
        send_request(other, "%d %lx %s", KEY_CHANGED, random(), n->name);
    }
cp
  return 0;
}

int key_changed_h(connection_t *c)
{
  char name[MAX_STRING_SIZE];
  avl_node_t *node;
  connection_t *other;
  node_t *n;
cp
  if(sscanf(c->buffer, "%*d %*x "MAX_STRING, name) != 1)
    {
      syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "KEY_CHANGED",
             c->name, c->hostname);
      return -1;
    }

  if(seen_request(c->buffer))
    return 0;

  n = lookup_node(name);

  if(!n)
    {
      syslog(LOG_ERR, _("Got %s from %s (%s) origin %s which does not exist"), "KEY_CHANGED",
             c->name, c->hostname, name);
      return -1;
    }

  n->status.validkey = 0;
  n->status.waitingforkey = 0;
  n->sent_seqno = 0;

  /* Tell the others */

  for(node = connection_tree->head; node; node = node->next)
    {
      other = (connection_t *)node->data;
      if(other->status.active && other != c)
        send_request(other, "%s", c->buffer);
    }
cp
  return 0;
}

int send_req_key(connection_t *c, node_t *from, node_t *to)
{
cp
  return send_request(c, "%d %s %s", REQ_KEY,
                      from->name, to->name);
}

int req_key_h(connection_t *c)
{
  char from_name[MAX_STRING_SIZE];
  char to_name[MAX_STRING_SIZE];
  node_t *from, *to;
cp
  if(sscanf(c->buffer, "%*d "MAX_STRING" "MAX_STRING, from_name, to_name) != 2)
    {
       syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "REQ_KEY",
              c->name, c->hostname);
       return -1;
    }

  from = lookup_node(from_name);

  if(!from)
    {
      syslog(LOG_ERR, _("Got %s from %s (%s) origin %s which does not exist in our connection list"), "REQ_KEY",
             c->name, c->hostname, from_name);
      return -1;
    }

  to = lookup_node(to_name);
  
  if(!to)
    {
      syslog(LOG_ERR, _("Got %s from %s (%s) destination %s which does not exist in our connection list"), "REQ_KEY",
             c->name, c->hostname, to_name);
      return -1;
    }

  /* Check if this key request is for us */

  if(to == myself)	/* Yes, send our own key back */
    {
      mykeyused = 1;
      from->received_seqno = 0;
      send_ans_key(c, myself, from);
    }
  else
    {
/* Proxy keys
      if(to->status.validkey)
        {
          send_ans_key(c, to, from);
        }
      else
*/
        send_req_key(to->nexthop->connection, from, to);
    }

cp
  return 0;
}

int send_ans_key(connection_t *c, node_t *from, node_t *to)
{
  char key[MAX_STRING_SIZE];
cp
  bin2hex(from->key, key, from->keylength);
  key[from->keylength * 2] = '\0';
cp
  return send_request(c, "%d %s %s %s %d %d %d %d", ANS_KEY,
                      from->name, to->name, key, from->cipher?from->cipher->nid:0, from->digest?from->digest->type:0, from->maclength, from->compression);
}

int ans_key_h(connection_t *c)
{
  char from_name[MAX_STRING_SIZE];
  char to_name[MAX_STRING_SIZE];
  char key[MAX_STRING_SIZE];
  int cipher, digest, maclength, compression;
  node_t *from, *to;
cp
  if(sscanf(c->buffer, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d", from_name, to_name, key, &cipher, &digest, &maclength, &compression) != 7)
    {
       syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "ANS_KEY",
              c->name, c->hostname);
       return -1;
    }

  from = lookup_node(from_name);

  if(!from)
    {
      syslog(LOG_ERR, _("Got %s from %s (%s) origin %s which does not exist in our connection list"), "ANS_KEY",
             c->name, c->hostname, from_name);
      return -1;
    }

  to = lookup_node(to_name);

  if(!to)
    {
      syslog(LOG_ERR, _("Got %s from %s (%s) destination %s which does not exist in our connection list"), "ANS_KEY",
             c->name, c->hostname, to_name);
      return -1;
    }

  /* Forward it if necessary */

  if(to != myself)
    {
      return send_request(to->nexthop->connection, "%s", c->buffer);
    }

  /* Update our copy of the origin's packet key */

  if(from->key)
    free(from->key);

  from->key = xstrdup(key);
  from->keylength = strlen(key) / 2;
  hex2bin(from->key, from->key, from->keylength);
  from->key[from->keylength] = '\0';

  from->status.validkey = 1;
  from->status.waitingforkey = 0;
  
  /* Check and lookup cipher and digest algorithms */

  if(cipher)
    {
      from->cipher = EVP_get_cipherbynid(cipher);
      if(!from->cipher)
	{
	  syslog(LOG_ERR, _("Node %s (%s) uses unknown cipher!"), from->name, from->hostname);
	  return -1;
	}
      if(from->keylength != from->cipher->key_len + from->cipher->iv_len)
	{
	  syslog(LOG_ERR, _("Node %s (%s) uses wrong keylength!"), from->name, from->hostname);
	  return -1;
        }
    }
  else
    {
      from->cipher = NULL;
    }

  from->maclength = maclength;

  if(digest)
    {
      from->digest = EVP_get_digestbynid(digest);
      if(!from->digest)
	{
	  syslog(LOG_ERR, _("Node %s (%s) uses unknown digest!"), from->name, from->hostname);
	  return -1;
	}
      if(from->maclength > from->digest->md_size || from->maclength < 0)
	{
	  syslog(LOG_ERR, _("Node %s (%s) uses bogus MAC length!"), from->name, from->hostname);
	  return -1;
	}
    }
  else
    {
      from->digest = NULL;
    }

  from->compression = compression;
  
  flush_queue(from);
cp
  return 0;
}