ceph/src/c-ares/ares_query.c

   1
   2 /* Copyright 1998 by the Massachusetts Institute of Technology.
   3  *
   4  * Permission to use, copy, modify, and distribute this
   5  * software and its documentation for any purpose and without
   6  * fee is hereby granted, provided that the above copyright
   7  * notice appear in all copies and that both that copyright
   8  * notice and this permission notice appear in supporting
   9  * documentation, and that the name of M.I.T. not be used in
  10  * advertising or publicity pertaining to distribution of the
  11  * software without specific, written prior permission.
  12  * M.I.T. makes no representations about the suitability of
  13  * this software for any purpose.  It is provided "as is"
  14  * without express or implied warranty.
  15  */
  16
  17 #include "ares_setup.h"
  18
  19 #ifdef HAVE_NETINET_IN_H
  20 #  include <netinet/in.h>
  21 #endif
  22 #ifdef HAVE_ARPA_NAMESER_H
  23 #  include <arpa/nameser.h>
  24 #else
  25 #  include "nameser.h"
  26 #endif
  27 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
  28 #  include <arpa/nameser_compat.h>
  29 #endif
  30
  31 #include "ares.h"
  32 #include "ares_dns.h"
  33 #include "ares_private.h"
  34
  35 struct qquery {
  36   ares_callback callback;
  37   void *arg;
  38 };
  39
  40 static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen);
  41
  42 static void rc4(rc4_key* key, unsigned char *buffer_ptr, int buffer_len)
  43 {
  44   unsigned char x;
  45   unsigned char y;
  46   unsigned char* state;
  47   unsigned char xorIndex;
  48   short counter;
  49
  50   x = key->x;
  51   y = key->y;
  52
  53   state = &key->state[0];
  54   for(counter = 0; counter < buffer_len; counter ++)
  55   {
  56     x = (unsigned char)((x + 1) % 256);
  57     y = (unsigned char)((state[x] + y) % 256);
  58     ARES_SWAP_BYTE(&state[x], &state[y]);
  59
  60     xorIndex = (unsigned char)((state[x] + state[y]) % 256);
  61
  62     buffer_ptr[counter] = (unsigned char)(buffer_ptr[counter]^state[xorIndex]);
  63   }
  64   key->x = x;
  65   key->y = y;
  66 }
  67
  68 static struct query* find_query_by_id(ares_channel channel, unsigned short id)
  69 {
  70   unsigned short qid;
  71   struct list_node* list_head;
  72   struct list_node* list_node;
  73   DNS_HEADER_SET_QID(((unsigned char*)&qid), id);
  74
  75   /* Find the query corresponding to this packet. */
  76   list_head = &(channel->queries_by_qid[qid % ARES_QID_TABLE_SIZE]);
  77   for (list_node = list_head->next; list_node != list_head;
  78        list_node = list_node->next)
  79     {
  80        struct query *q = list_node->data;
  81        if (q->qid == qid)
  82           return q;
  83     }
  84   return NULL;
  85 }
  86
  87
  88 /* a unique query id is generated using an rc4 key. Since the id may already
  89    be used by a running query (as infrequent as it may be), a lookup is
  90    performed per id generation. In practice this search should happen only
  91    once per newly generated id
  92 */
  93 static unsigned short generate_unique_id(ares_channel channel)
  94 {
  95   unsigned short id;
  96
  97   do {
  98     id = ares__generate_new_id(&channel->id_key);
  99   } while (find_query_by_id(channel, id));
 100
 101   return (unsigned short)id;
 102 }
 103
 104 unsigned short ares__generate_new_id(rc4_key* key)
 105 {
 106   unsigned short r=0;
 107   rc4(key, (unsigned char *)&r, sizeof(r));
 108   return r;
 109 }
 110
 111 void ares_query(ares_channel channel, const char *name, int dnsclass,
 112                 int type, ares_callback callback, void *arg)
 113 {
 114   struct qquery *qquery;
 115   unsigned char *qbuf;
 116   int qlen, rd, status;
 117
 118   /* Compose the query. */
 119   rd = !(channel->flags & ARES_FLAG_NORECURSE);
 120   status = ares_create_query(name, dnsclass, type, channel->next_id, rd, &qbuf,
 121               &qlen, (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : 0);
 122   if (status != ARES_SUCCESS)
 123     {
 124       if (qbuf != NULL) ares_free(qbuf);
 125       callback(arg, status, 0, NULL, 0);
 126       return;
 127     }
 128
 129   channel->next_id = generate_unique_id(channel);
 130
 131   /* Allocate and fill in the query structure. */
 132   qquery = ares_malloc(sizeof(struct qquery));
 133   if (!qquery)
 134     {
 135       ares_free_string(qbuf);
 136       callback(arg, ARES_ENOMEM, 0, NULL, 0);
 137       return;
 138     }
 139   qquery->callback = callback;
 140   qquery->arg = arg;
 141
 142   /* Send it off.  qcallback will be called when we get an answer. */
 143   ares_send(channel, qbuf, qlen, qcallback, qquery);
 144   ares_free_string(qbuf);
 145 }
 146
 147 static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen)
 148 {
 149   struct qquery *qquery = (struct qquery *) arg;
 150   unsigned int ancount;
 151   int rcode;
 152
 153   if (status != ARES_SUCCESS)
 154     qquery->callback(qquery->arg, status, timeouts, abuf, alen);
 155   else
 156     {
 157       /* Pull the response code and answer count from the packet. */
 158       rcode = DNS_HEADER_RCODE(abuf);
 159       ancount = DNS_HEADER_ANCOUNT(abuf);
 160
 161       /* Convert errors. */
 162       switch (rcode)
 163         {
 164         case NOERROR:
 165           status = (ancount > 0) ? ARES_SUCCESS : ARES_ENODATA;
 166           break;
 167         case FORMERR:
 168           status = ARES_EFORMERR;
 169           break;
 170         case SERVFAIL:
 171           status = ARES_ESERVFAIL;
 172           break;
 173         case NXDOMAIN:
 174           status = ARES_ENOTFOUND;
 175           break;
 176         case NOTIMP:
 177           status = ARES_ENOTIMP;
 178           break;
 179         case REFUSED:
 180           status = ARES_EREFUSED;
 181           break;
 182         }
 183       qquery->callback(qquery->arg, status, timeouts, abuf, alen);
 184     }
 185   ares_free(qquery);
 186 }