1. DNS/dnscache/cache.c

について、ここに記述してください。

/*
100 <= size <= 1000000000.
4 <= hsize <= size/16.
hsize is a power of 2.

hsize <= writer <= oldest <= unused <= size.
If oldest == unused then unused == size.

x is a hash table with the following structure:
x[0...hsize-1]: hsize/4 head links.
x[hsize...writer-1]: consecutive entries, newest entry on the right.
x[writer...oldest-1]: free space for new entries.
x[oldest...unused-1]: consecutive entries, oldest entry on the left.
x[unused...size-1]: unused.

Each hash bucket is a linked list containing the following items:
the head link, the newest entry, the second-newest entry, etc.
Each link is a 4-byte number giving the xor of
the positions of the adjacent items in the list.

Entries are always inserted immediately after the head and removed at the tail.

Each entry contains the following information:
4-byte link; 4-byte keylen; 4-byte datalen; 8-byte expire time; key; data.
*/

char *cache_get(const char *key,unsigned int keylen,unsigned int *datalen,uint32 *ttl)
{
  struct tai expire;
  struct tai now;
  uint32 pos;
  uint32 prevpos;
  uint32 nextpos;
  uint32 u;
  unsigned int loop;
  double d;

  if (!x) return 0;
  if (keylen > MAXKEYLEN) return 0;

  prevpos = hash(key,keylen);
  pos = get4(prevpos);
  loop = 0;

1.1. キャッシュ上の情報のための領域

A : 22+アドレス*4+len(owner)
NS, PTR, CNAME: 22+len(owner)+len(data)
MX: 22+ MX数*2+len(全データ)
その他:  22+ レコード数*2 バイト+(全データ文字列と所有者名の)長さ
存在しないドメイン または サーバフェイル: 22+len(owner)。