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iof-bird-daemon / proto / rip / auth.c @ b21f68b4

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/*
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 *        Rest in pieces - RIP protocol
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 *
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 *        Copyright (c) 1999 Pavel Machek <pavel@ucw.cz>
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 *        Copyright (c) 2004 Ondrej Filip <feela@network.cz>
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 *
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 *        Bug fixes by Eric Leblond <eleblond@init-sys.com>, April 2003
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 * 
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 *        Can be freely distributed and used under the terms of the GNU GPL.
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 */
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#undef LOCAL_DEBUG
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#include "nest/bird.h"
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#include "nest/iface.h"
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#include "nest/protocol.h"
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#include "nest/route.h"
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#include "lib/socket.h"
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#include "lib/resource.h"
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#include "lib/lists.h"
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#include "lib/timer.h"
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#include "lib/md5.h"
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#include "lib/string.h"
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#include "rip.h"
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#define P ((struct rip_proto *) p)
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#define P_CF ((struct rip_proto_config *)p->cf)
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#define PACKETLEN(num) (num * sizeof(struct rip_block) + sizeof(struct rip_packet_heading))
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/*
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 * rip_incoming_authentication - check authentication of incomming packet and return 1 if there's problem.
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 */
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int
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rip_incoming_authentication( struct proto *p, struct rip_block_auth *block, struct rip_packet *packet, int num, ip_addr whotoldme )
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{
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  DBG( "Incoming authentication: " );
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  switch (ntohs(block->authtype)) {        /* Authentication type */
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  case AT_PLAINTEXT: 
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    {
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      struct password_item *passwd = password_find(P_CF->passwords, 1);
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      DBG( "Plaintext passwd" );
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      if (!passwd) {
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        log( L_AUTH "No passwords set and password authentication came" );
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        return 1;
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      }
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      if (strncmp( (char *) (&block->packetlen), passwd->password, 16)) {
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        log( L_AUTH "Passwd authentication failed!" );
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        DBG( "Expected %s, got %.16s\n", passwd->password, &block->packetlen );
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        return 1;
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      }
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    }
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    break;
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  case AT_MD5:
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    DBG( "md5 password" );
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    {
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      struct password_item *pass = NULL, *ptmp;
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      struct rip_md5_tail *tail;
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      struct MD5Context ctxt;
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      char md5sum_packet[16];
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      char md5sum_computed[16];
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      struct neighbor *neigh = neigh_find(p, &whotoldme, 0);
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      list *l = P_CF->passwords;
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      if (ntohs(block->packetlen) != PACKETLEN(num) - sizeof(struct rip_md5_tail) ) {
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        log( L_ERR "Packet length in MD5 does not match computed value" );
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        return 1;
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      }
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      tail = (struct rip_md5_tail *) ((char *) packet + (ntohs(block->packetlen) ));
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      if ((tail->mustbeFFFF != 0xffff) || (tail->mustbe0001 != 0x0100)) {
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        log( L_ERR "MD5 tail signature is not there" );
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        return 1;
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      }
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      WALK_LIST(ptmp, *l)
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      {
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        if (block->keyid != ptmp->id) continue;
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        if ((ptmp->genfrom > now_real) || (ptmp->gento < now_real)) continue;
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        pass = ptmp;
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        break;
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      }
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      if(!pass) return 1;
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      if (!neigh) {
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        log( L_AUTH "Non-neighbour MD5 checksummed packet?" );
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      } else {
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        if (neigh->aux > block->seq) {
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          log( L_AUTH "MD5 protected packet with lower numbers" );
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          return 1;
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        }
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        neigh->aux = block->seq;
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      }
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      memcpy(md5sum_packet, tail->md5, 16);
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      password_cpy(tail->md5, pass->password, 16);
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      MD5Init(&ctxt);
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      MD5Update(&ctxt, (char *) packet, ntohs(block->packetlen) +  sizeof(struct rip_block_auth) );
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      MD5Final(md5sum_computed, &ctxt);
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      if (memcmp(md5sum_packet, md5sum_computed, 16))
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        return 1;
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    }
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  }
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  return 0;
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}
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/*
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 * rip_outgoing_authentication - append authentication information to the packet.
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 * %num: number of rip_blocks already in packets. This function returns size of packet to send.
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 */
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int
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rip_outgoing_authentication( struct proto *p, struct rip_block_auth *block, struct rip_packet *packet, int num )
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{
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  struct password_item *passwd = password_find(P_CF->passwords, 1);
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  if (!P_CF->authtype)
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    return PACKETLEN(num);
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  DBG( "Outgoing authentication: " );
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  if (!passwd) {
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    log( L_ERR "No suitable password found for authentication" );
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    return PACKETLEN(num);
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  }
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  block->authtype = htons(P_CF->authtype);
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  block->mustbeFFFF = 0xffff;
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  switch (P_CF->authtype) {
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  case AT_PLAINTEXT:
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    password_cpy( (char *) (&block->packetlen), passwd->password, 16);
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    return PACKETLEN(num);
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  case AT_MD5:
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    {
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      struct rip_md5_tail *tail;
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      struct MD5Context ctxt;
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      static u32 sequence = 0;
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      if (num > PACKET_MD5_MAX)
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        bug(  "We can not add MD5 authentication to this long packet" );
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      /* need to preset the sequence number to a sane value */
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      if (!sequence)
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        sequence = (u32) time(NULL);
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      block->keyid = passwd->id;
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      block->authlen = sizeof(struct rip_block_auth);
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      block->seq = sequence++;
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      block->zero0 = 0;
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      block->zero1 = 0;
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      block->packetlen = htons(PACKETLEN(num));
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      tail = (struct rip_md5_tail *) ((char *) packet + PACKETLEN(num) );
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      tail->mustbeFFFF = 0xffff;
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      tail->mustbe0001 = 0x0100;
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      password_cpy(tail->md5, passwd->password, 16);
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      MD5Init(&ctxt);
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      MD5Update(&ctxt, (char *) packet, PACKETLEN(num) + sizeof(struct  rip_md5_tail));
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      MD5Final(tail->md5, &ctxt);
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      return PACKETLEN(num) + block->authlen;
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    }
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  default:
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    bug( "Unknown authtype in outgoing authentication?" );
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  }
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}