pimd/pim_util.c

   1 /*
   2   PIM for Quagga
   3   Copyright (C) 2008  Everton da Silva Marques
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2 of the License, or
   8   (at your option) any later version.
   9
  10   This program is distributed in the hope that it will be useful, but
  11   WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13   General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License
  16   along with this program; see the file COPYING; if not, write to the
  17   Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  18   MA 02110-1301 USA
  19 */
  20
  21 #include <zebra.h>
  22
  23 #include "log.h"
  24
  25 #include "pim_util.h"
  26
  27 /*
  28   RFC 3376: 4.1.7. QQIC (Querier's Query Interval Code)
  29
  30   If QQIC < 128,  QQI = QQIC
  31   If QQIC >= 128, QQI = (mant | 0x10) << (exp + 3)
  32
  33   0 1 2 3 4 5 6 7
  34   +-+-+-+-+-+-+-+-+
  35   |1| exp | mant  |
  36   +-+-+-+-+-+-+-+-+
  37
  38   Since exp=0..7 then (exp+3)=3..10, then QQI has
  39   one of the following bit patterns:
  40
  41   exp=0: QQI = 0000.0000.1MMM.M000
  42   exp=1: QQI = 0000.0001.MMMM.0000
  43   ...
  44   exp=6: QQI = 001M.MMM0.0000.0000
  45   exp=7: QQI = 01MM.MM00.0000.0000
  46   --------- ---------
  47   0x4  0x0  0x0  0x0
  48 */
  49 uint8_t igmp_msg_encode16to8(uint16_t value)
  50 {
  51   uint8_t code;
  52
  53   if (value < 128) {
  54     code = value;
  55   }
  56   else {
  57     uint16_t mask = 0x4000;
  58     uint8_t  exp;
  59     uint16_t mant;
  60     for (exp = 7; exp > 0; --exp) {
  61       if (mask & value)
  62         break;
  63       mask >>= 1;
  64     }
  65     mant = 0x000F & (value >> (exp + 3));
  66     code = ((uint8_t) 1 << 7) | ((uint8_t) exp << 4) | (uint8_t) mant;
  67   }
  68
  69   return code;
  70 }
  71
  72 /*
  73   RFC 3376: 4.1.7. QQIC (Querier's Query Interval Code)
  74
  75   If QQIC < 128,  QQI = QQIC
  76   If QQIC >= 128, QQI = (mant | 0x10) << (exp + 3)
  77
  78   0 1 2 3 4 5 6 7
  79   +-+-+-+-+-+-+-+-+
  80   |1| exp | mant  |
  81   +-+-+-+-+-+-+-+-+
  82 */
  83 uint16_t igmp_msg_decode8to16(uint8_t code)
  84 {
  85   uint16_t value;
  86
  87   if (code < 128) {
  88     value = code;
  89   }
  90   else {
  91     uint16_t mant = (code & 0x0F);
  92     uint8_t  exp  = (code & 0x70) >> 4;
  93     value = (mant | 0x10) << (exp + 3);
  94   }
  95
  96   return value;
  97 }
  98
  99 void pim_pkt_dump(const char *label, const uint8_t *buf, int size)
 100 {
 101   zlog_debug("%s: pkt dump size=%d",
 102              label,
 103              size);
 104   zlog_hexdump(buf, size);
 105 }