nmblib.c

MC Linux/Unix 终端下文件管理器

    offset = 12;
  }

  /* and any resource records */
  if (nmb->header.ancount && 
      !parse_alloc_res_rec(inbuf,&offset,length,&nmb->answers,
			   nmb->header.ancount))
    return(False);

  if (nmb->header.nscount && 
      !parse_alloc_res_rec(inbuf,&offset,length,&nmb->nsrecs,
			   nmb->header.nscount))
    return(False);
  
  if (nmb->header.arcount && 
      !parse_alloc_res_rec(inbuf,&offset,length,&nmb->additional,
			   nmb->header.arcount))
    return(False);

  return(True);
}

/*******************************************************************
  'Copy constructor' for an nmb packet
  ******************************************************************/
static struct packet_struct *copy_nmb_packet(struct packet_struct *packet)
{  
  struct nmb_packet *nmb;
  struct nmb_packet *copy_nmb;
  struct packet_struct *pkt_copy;

  if(( pkt_copy = (struct packet_struct *)malloc(sizeof(*packet))) == NULL)
  {
    DEBUG(0,("copy_nmb_packet: malloc fail.\n"));
    return NULL;
  }

  /* Structure copy of entire thing. */

  *pkt_copy = *packet;

  /* Ensure this copy is not locked. */
  pkt_copy->locked = False;

  /* Ensure this copy has no resource records. */
  nmb = &packet->packet.nmb;
  copy_nmb = &pkt_copy->packet.nmb;

  copy_nmb->answers = NULL;
  copy_nmb->nsrecs = NULL;
  copy_nmb->additional = NULL;

  /* Now copy any resource records. */

  if (nmb->answers)
  {
    if((copy_nmb->answers = (struct res_rec *)
                  malloc(nmb->header.ancount * sizeof(struct res_rec))) == NULL)
      goto free_and_exit;
    memcpy((char *)copy_nmb->answers, (char *)nmb->answers, 
           nmb->header.ancount * sizeof(struct res_rec));
  }
  if (nmb->nsrecs)
  {
    if((copy_nmb->nsrecs = (struct res_rec *)
                  malloc(nmb->header.nscount * sizeof(struct res_rec))) == NULL)
      goto free_and_exit;
    memcpy((char *)copy_nmb->nsrecs, (char *)nmb->nsrecs, 
           nmb->header.nscount * sizeof(struct res_rec));
  }
  if (nmb->additional)
  {
    if((copy_nmb->additional = (struct res_rec *)
                  malloc(nmb->header.arcount * sizeof(struct res_rec))) == NULL)
      goto free_and_exit;
    memcpy((char *)copy_nmb->additional, (char *)nmb->additional, 
           nmb->header.arcount * sizeof(struct res_rec));
  }

  return pkt_copy;

free_and_exit:

  if(copy_nmb->answers)
    free((char *)copy_nmb->answers);
  if(copy_nmb->nsrecs)
    free((char *)copy_nmb->nsrecs);
  if(copy_nmb->additional)
    free((char *)copy_nmb->additional);
  free((char *)pkt_copy);

  DEBUG(0,("copy_nmb_packet: malloc fail in resource records.\n"));
  return NULL;
}

/*******************************************************************
  'Copy constructor' for a dgram packet
  ******************************************************************/
static struct packet_struct *copy_dgram_packet(struct packet_struct *packet)
{ 
  struct packet_struct *pkt_copy;

  if(( pkt_copy = (struct packet_struct *)malloc(sizeof(*packet))) == NULL)
  {
    DEBUG(0,("copy_dgram_packet: malloc fail.\n"));
    return NULL;
  }

  /* Structure copy of entire thing. */

  *pkt_copy = *packet;

  /* Ensure this copy is not locked. */
  pkt_copy->locked = False;

  /* There are no additional pointers in a dgram packet,
     we are finished. */
  return pkt_copy;
}

/*******************************************************************
  'Copy constructor' for a generic packet
  ******************************************************************/
struct packet_struct *copy_packet(struct packet_struct *packet)
{  
  if(packet->packet_type == NMB_PACKET)
    return copy_nmb_packet(packet);
  else if (packet->packet_type == DGRAM_PACKET)
    return copy_dgram_packet(packet);
  return NULL;
}
 
/*******************************************************************
  free up any resources associated with an nmb packet
  ******************************************************************/
static void free_nmb_packet(struct nmb_packet *nmb)
{  
  if (nmb->answers) free(nmb->answers);
  if (nmb->nsrecs) free(nmb->nsrecs);
  if (nmb->additional) free(nmb->additional);
}

/*******************************************************************
  free up any resources associated with a dgram packet
  ******************************************************************/
static void free_dgram_packet(struct dgram_packet *nmb)
{  
  /* We have nothing to do for a dgram packet. */
}

/*******************************************************************
  free up any resources associated with a packet
  ******************************************************************/
void free_packet(struct packet_struct *packet)
{  
  if (packet->locked) 
    return;
  if (packet->packet_type == NMB_PACKET)
    free_nmb_packet(&packet->packet.nmb);
  else if (packet->packet_type == DGRAM_PACKET)
    free_dgram_packet(&packet->packet.dgram);
  free(packet);
}

/*******************************************************************
  read a packet from a socket and parse it, returning a packet ready
  to be used or put on the queue. This assumes a UDP socket
  ******************************************************************/
struct packet_struct *read_packet(int fd,enum packet_type packet_type)
{
  extern struct in_addr lastip;
  extern int lastport;
  struct packet_struct *packet;
  char buf[MAX_DGRAM_SIZE];
  int length;
  BOOL ok=False;
  
  length = read_udp_socket(fd,buf,sizeof(buf));
  if (length < MIN_DGRAM_SIZE) return(NULL);

  packet = (struct packet_struct *)malloc(sizeof(*packet));
  if (!packet) return(NULL);

  packet->next = NULL;
  packet->prev = NULL;
  packet->ip = lastip;
  packet->port = lastport;
  packet->fd = fd;
  packet->locked = False;
  packet->timestamp = time(NULL);
  packet->packet_type = packet_type;
  switch (packet_type) 
    {
    case NMB_PACKET:
      ok = parse_nmb(buf,length,&packet->packet.nmb);
      break;

    case DGRAM_PACKET:
      ok = parse_dgram(buf,length,&packet->packet.dgram);
      break;
    }
  if (!ok) {
    DEBUG(10,("read_packet: discarding packet id = %d\n", 
                 packet->packet.nmb.header.name_trn_id));
    free_packet(packet);
    return(NULL);
  }

  num_good_receives++;

  DEBUG(5,("Received a packet of len %d from (%s) port %d\n",
	    length, inet_ntoa(packet->ip), packet->port ) );

  return(packet);
}
					 

/*******************************************************************
  send a udp packet on a already open socket
  ******************************************************************/
static BOOL send_udp(int fd,char *buf,int len,struct in_addr ip,int port)
{
  BOOL ret;
  struct sockaddr_in sock_out;

  /* set the address and port */
  memset((char *)&sock_out,'\0',sizeof(sock_out));
  putip((char *)&sock_out.sin_addr,(char *)&ip);
  sock_out.sin_port = htons( port );
  sock_out.sin_family = AF_INET;
  
  DEBUG( 5, ( "Sending a packet of len %d to (%s) on port %d\n",
	      len, inet_ntoa(ip), port ) );
	
  ret = (sendto(fd,buf,len,0,(struct sockaddr *)&sock_out,
		sizeof(sock_out)) >= 0);

  if (!ret)
    DEBUG(0,("Packet send failed to %s(%d) ERRNO=%s\n",
	     inet_ntoa(ip),port,strerror(errno)));

  if (ret)
    num_good_sends++;

  return(ret);
}

/*******************************************************************
  build a dgram packet ready for sending

  XXXX This currently doesn't handle packets too big for one
  datagram. It should split them and use the packet_offset, more and
  first flags to handle the fragmentation. Yuck.
  ******************************************************************/
static int build_dgram(char *buf,struct packet_struct *p)
{
  struct dgram_packet *dgram = &p->packet.dgram;
  unsigned char *ubuf = (unsigned char *)buf;
  int offset=0;

  /* put in the header */
  ubuf[0] = dgram->header.msg_type;
  ubuf[1] = (((int)dgram->header.flags.node_type)<<2);
  if (dgram->header.flags.more) ubuf[1] |= 1;
  if (dgram->header.flags.first) ubuf[1] |= 2;
  RSSVAL(ubuf,2,dgram->header.dgm_id);
  putip(ubuf+4,(char *)&dgram->header.source_ip);
  RSSVAL(ubuf,8,dgram->header.source_port);
  RSSVAL(ubuf,12,dgram->header.packet_offset);

  offset = 14;

  if (dgram->header.msg_type == 0x10 ||
      dgram->header.msg_type == 0x11 ||
      dgram->header.msg_type == 0x12) {      
    offset += put_nmb_name((char *)ubuf,offset,&dgram->source_name);
    offset += put_nmb_name((char *)ubuf,offset,&dgram->dest_name);
  }

  memcpy(ubuf+offset,dgram->data,dgram->datasize);
  offset += dgram->datasize;

  /* automatically set the dgm_length */
  dgram->header.dgm_length = offset;
  RSSVAL(ubuf,10,dgram->header.dgm_length); 

  return(offset);
}

/*******************************************************************
  build a nmb name
 *******************************************************************/
void make_nmb_name( struct nmb_name *n, const char *name, int type )
{
	extern pstring global_scope;
	memset( (char *)n, '\0', sizeof(struct nmb_name) );
	StrnCpy( n->name, name, 15 );
	strupper( n->name );
	n->name_type = (unsigned int)type & 0xFF;
	StrnCpy( n->scope, global_scope, 63 );
	strupper( n->scope );
}

/*******************************************************************
  Compare two nmb names
  ******************************************************************/

BOOL nmb_name_equal(struct nmb_name *n1, struct nmb_name *n2)
{
  return ((n1->name_type == n2->name_type) &&
         strequal(n1->name ,n2->name ) &&
         strequal(n1->scope,n2->scope));
}

/*******************************************************************
  build a nmb packet ready for sending

  XXXX this currently relies on not being passed something that expands
  to a packet too big for the buffer. Eventually this should be
  changed to set the trunc bit so the receiver can request the rest
  via tcp (when that becomes supported)
  ******************************************************************/
static int build_nmb(char *buf,struct packet_struct *p)
{
  struct nmb_packet *nmb = &p->packet.nmb;
  unsigned char *ubuf = (unsigned char *)buf;
  int offset=0;

  /* put in the header */
  RSSVAL(ubuf,offset,nmb->header.name_trn_id);
  ubuf[offset+2] = (nmb->header.opcode & 0xF) << 3;
  if (nmb->header.response) ubuf[offset+2] |= (1<<7);
  if (nmb->header.nm_flags.authoritative && 
      nmb->header.response) ubuf[offset+2] |= 0x4;
  if (nmb->header.nm_flags.trunc) ubuf[offset+2] |= 0x2;
  if (nmb->header.nm_flags.recursion_desired) ubuf[offset+2] |= 0x1;
  if (nmb->header.nm_flags.recursion_available &&
      nmb->header.response) ubuf[offset+3] |= 0x80;
  if (nmb->header.nm_flags.bcast) ubuf[offset+3] |= 0x10;
  ubuf[offset+3] |= (nmb->header.rcode & 0xF);

  RSSVAL(ubuf,offset+4,nmb->header.qdcount);
  RSSVAL(ubuf,offset+6,nmb->header.ancount);
  RSSVAL(ubuf,offset+8,nmb->header.nscount);
  RSSVAL(ubuf,offset+10,nmb->header.arcount);
  
  offset += 12;
  if (nmb->header.qdcount) {
    /* XXXX this doesn't handle a qdcount of > 1 */
    offset += put_nmb_name((char *)ubuf,offset,&nmb->question.question_name);
    RSSVAL(ubuf,offset,nmb->question.question_type);
    RSSVAL(ubuf,offset+2,nmb->question.question_class);
    offset += 4;
  }

  if (nmb->header.ancount)
    offset += put_res_rec((char *)ubuf,offset,nmb->answers,
			  nmb->header.ancount);

  if (nmb->header.nscount)
    offset += put_res_rec((char *)ubuf,offset,nmb->nsrecs,
			  nmb->header.nscount);

  /*
   * The spec says we must put compressed name pointers
   * in the following outgoing packets :
   * NAME_REGISTRATION_REQUEST, NAME_REFRESH_REQUEST,
   * NAME_RELEASE_REQUEST.
   */

  if((nmb->header.response == False) &&
     ((nmb->header.opcode == NMB_NAME_REG_OPCODE) ||
      (nmb->header.opcode == NMB_NAME_RELEASE_OPCODE) ||
      (nmb->header.opcode == NMB_NAME_REFRESH_OPCODE_8) ||
      (nmb->header.opcode == NMB_NAME_REFRESH_OPCODE_9) ||
      (nmb->header.opcode == NMB_NAME_MULTIHOMED_REG_OPCODE)) &&
     (nmb->header.arcount == 1)) {

    offset += put_compressed_name_ptr(ubuf,offset,nmb->additional,12);

  } else if (nmb->header.arcount) {
    offset += put_res_rec((char *)ubuf,offset,nmb->additional,
			  nmb->header.arcount);  
  }
  return(offset);
}


/*******************************************************************
  send a packet_struct
  ******************************************************************/
BOOL send_packet(struct packet_struct *p)
{
  char buf[1024];
  int len=0;

  memset(buf,'\0',sizeof(buf));

  switch (p->packet_type) 
    {
    case NMB_PACKET:
      len = build_nmb(buf,p);
      debug_nmb_packet(p);
      break;

    case DGRAM_PACKET:
      len = build_dgram(buf,p);
      break;
    }

  if (!len) return(False);

  return(send_udp(p->fd,buf,len,p->ip,p->port));
}

/****************************************************************************
  receive a packet with timeout on a open UDP filedescriptor
  The timeout is in milliseconds
  ***************************************************************************/
struct packet_struct *receive_packet(int fd,enum packet_type type,int t)
{
  fd_set fds;
  struct timeval timeout;

  FD_ZERO(&fds);
  FD_SET(fd,&fds);
  timeout.tv_sec = t/1000;
  timeout.tv_usec = 1000*(t%1000);

  sys_select(fd+1,&fds,&timeout);

  if (FD_ISSET(fd,&fds)) 
    return(read_packet(fd,type));

  return(NULL);
}


/****************************************************************************
return the number of bits that match between two 4 character buffers
  ***************************************************************************/
static int matching_bits(uchar *p1, uchar *p2)
{
	int i, j, ret = 0;
	for (i=0; i<4; i++) {
		if (p1[i] != p2[i]) break;
		ret += 8;
	}

	if (i==4) return ret;

	for (j=0; j<8; j++) {
		if ((p1[i] & (1<<(7-j))) != (p2[i] & (1<<(7-j)))) break;
		ret++;
	}	
	
	return ret;
}


static uchar sort_ip[4];

/****************************************************************************
compare two query reply records
  ***************************************************************************/
static int name_query_comp(uchar *p1, uchar *p2)
{
	return matching_bits(p2+2, sort_ip) - matching_bits(p1+2, sort_ip);
}

/****************************************************************************
sort a set of 6 byte name query response records so that the IPs that
have the most leading bits in common with the specified address come first
  ***************************************************************************/
void sort_query_replies(char *data, int n, struct in_addr ip)
{
	if (n <= 1) return;

	putip(sort_ip, (char *)&ip);

	qsort(data, n, 6, QSORT_CAST name_query_comp);
}