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-rw-r--r--src/c-ares/ares_query.c186
1 files changed, 186 insertions, 0 deletions
diff --git a/src/c-ares/ares_query.c b/src/c-ares/ares_query.c
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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
+#ifdef HAVE_ARPA_NAMESER_H
+# include <arpa/nameser.h>
+#else
+# include "nameser.h"
+#endif
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+# include <arpa/nameser_compat.h>
+#endif
+
+#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;
+ short 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);
+}