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/* Copyright 1998 by the Massachusetts Institute of Technology.
*
* Permission to use, copy, modify, and distribute this
* software and its documentation for any purpose and without
* fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting
* documentation, and that the name of M.I.T. not be used in
* advertising or publicity pertaining to distribution of the
* software without specific, written prior permission.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is"
* without express or implied warranty.
*/
#include "ares_setup.h"
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#include "ares_nameser.h"
#include "ares.h"
#include "ares_dns.h"
#include "ares_private.h"
struct qquery {
ares_callback callback;
void *arg;
};
static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen);
static void rc4(rc4_key* key, unsigned char *buffer_ptr, int buffer_len)
{
unsigned char x;
unsigned char y;
unsigned char* state;
unsigned char xorIndex;
int counter;
x = key->x;
y = key->y;
state = &key->state[0];
for(counter = 0; counter < buffer_len; counter ++)
{
x = (unsigned char)((x + 1) % 256);
y = (unsigned char)((state[x] + y) % 256);
ARES_SWAP_BYTE(&state[x], &state[y]);
xorIndex = (unsigned char)((state[x] + state[y]) % 256);
buffer_ptr[counter] = (unsigned char)(buffer_ptr[counter]^state[xorIndex]);
}
key->x = x;
key->y = y;
}
static struct query* find_query_by_id(ares_channel channel, unsigned short id)
{
unsigned short qid;
struct list_node* list_head;
struct list_node* list_node;
DNS_HEADER_SET_QID(((unsigned char*)&qid), id);
/* Find the query corresponding to this packet. */
list_head = &(channel->queries_by_qid[qid % ARES_QID_TABLE_SIZE]);
for (list_node = list_head->next; list_node != list_head;
list_node = list_node->next)
{
struct query *q = list_node->data;
if (q->qid == qid)
return q;
}
return NULL;
}
/* a unique query id is generated using an rc4 key. Since the id may already
be used by a running query (as infrequent as it may be), a lookup is
performed per id generation. In practice this search should happen only
once per newly generated id
*/
static unsigned short generate_unique_id(ares_channel channel)
{
unsigned short id;
do {
id = ares__generate_new_id(&channel->id_key);
} while (find_query_by_id(channel, id));
return (unsigned short)id;
}
unsigned short ares__generate_new_id(rc4_key* key)
{
unsigned short r=0;
rc4(key, (unsigned char *)&r, sizeof(r));
return r;
}
void ares_query(ares_channel channel, const char *name, int dnsclass,
int type, ares_callback callback, void *arg)
{
struct qquery *qquery;
unsigned char *qbuf;
int qlen, rd, status;
/* Compose the query. */
rd = !(channel->flags & ARES_FLAG_NORECURSE);
status = ares_create_query(name, dnsclass, type, channel->next_id, rd, &qbuf,
&qlen, (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : 0);
if (status != ARES_SUCCESS)
{
if (qbuf != NULL) ares_free(qbuf);
callback(arg, status, 0, NULL, 0);
return;
}
channel->next_id = generate_unique_id(channel);
/* Allocate and fill in the query structure. */
qquery = ares_malloc(sizeof(struct qquery));
if (!qquery)
{
ares_free_string(qbuf);
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return;
}
qquery->callback = callback;
qquery->arg = arg;
/* Send it off. qcallback will be called when we get an answer. */
ares_send(channel, qbuf, qlen, qcallback, qquery);
ares_free_string(qbuf);
}
static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen)
{
struct qquery *qquery = (struct qquery *) arg;
unsigned int ancount;
int rcode;
if (status != ARES_SUCCESS)
qquery->callback(qquery->arg, status, timeouts, abuf, alen);
else
{
/* Pull the response code and answer count from the packet. */
rcode = DNS_HEADER_RCODE(abuf);
ancount = DNS_HEADER_ANCOUNT(abuf);
/* Convert errors. */
switch (rcode)
{
case NOERROR:
status = (ancount > 0) ? ARES_SUCCESS : ARES_ENODATA;
break;
case FORMERR:
status = ARES_EFORMERR;
break;
case SERVFAIL:
status = ARES_ESERVFAIL;
break;
case NXDOMAIN:
status = ARES_ENOTFOUND;
break;
case NOTIMP:
status = ARES_ENOTIMP;
break;
case REFUSED:
status = ARES_EREFUSED;
break;
}
qquery->callback(qquery->arg, status, timeouts, abuf, alen);
}
ares_free(qquery);
}
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