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_SYS_SOCKET_H
20 # include <sys/socket.h>
21 #endif
22 #ifdef HAVE_NETINET_IN_H
23 # include <netinet/in.h>
24 #endif
25 #ifdef HAVE_ARPA_NAMESER_H
26 # include <arpa/nameser.h>
27 #else
28 # include "nameser.h"
29 #endif
30 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
31 # include <arpa/nameser_compat.h>
32 #endif
33
34 #include <stdlib.h>
35 #include "ares.h"
36 #include "ares_dns.h"
37 #include "ares_private.h"
38
39 struct qquery {
40 ares_callback callback;
41 void *arg;
42 };
43
44 static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen);
45
ares__rc4(rc4_key * key,unsigned char * buffer_ptr,int buffer_len)46 void ares__rc4(rc4_key* key, unsigned char *buffer_ptr, int buffer_len)
47 {
48 unsigned char x;
49 unsigned char y;
50 unsigned char* state;
51 unsigned char xorIndex;
52 short counter;
53
54 x = key->x;
55 y = key->y;
56
57 state = &key->state[0];
58 for(counter = 0; counter < buffer_len; counter ++)
59 {
60 x = (unsigned char)((x + 1) % 256);
61 y = (unsigned char)((state[x] + y) % 256);
62 ARES_SWAP_BYTE(&state[x], &state[y]);
63
64 xorIndex = (unsigned char)((state[x] + state[y]) % 256);
65
66 buffer_ptr[counter] = (unsigned char)(buffer_ptr[counter]^state[xorIndex]);
67 }
68 key->x = x;
69 key->y = y;
70 }
71
find_query_by_id(ares_channel channel,unsigned short id)72 static struct query* find_query_by_id(ares_channel channel, unsigned short id)
73 {
74 unsigned short qid;
75 struct list_node* list_head;
76 struct list_node* list_node;
77 DNS_HEADER_SET_QID(((unsigned char*)&qid), id);
78
79 /* Find the query corresponding to this packet. */
80 list_head = &(channel->queries_by_qid[qid % ARES_QID_TABLE_SIZE]);
81 for (list_node = list_head->next; list_node != list_head;
82 list_node = list_node->next)
83 {
84 struct query *q = list_node->data;
85 if (q->qid == qid)
86 return q;
87 }
88 return NULL;
89 }
90
91
92 /* a unique query id is generated using an rc4 key. Since the id may already
93 be used by a running query (as infrequent as it may be), a lookup is
94 performed per id generation. In practice this search should happen only
95 once per newly generated id
96 */
generate_unique_id(ares_channel channel)97 static unsigned short generate_unique_id(ares_channel channel)
98 {
99 unsigned short id;
100
101 do {
102 id = ares__generate_new_id(&channel->id_key);
103 } while (find_query_by_id(channel, id));
104
105 return (unsigned short)id;
106 }
107
ares_query(ares_channel channel,const char * name,int dnsclass,int type,ares_callback callback,void * arg)108 void ares_query(ares_channel channel, const char *name, int dnsclass,
109 int type, ares_callback callback, void *arg)
110 {
111 struct qquery *qquery;
112 unsigned char *qbuf;
113 int qlen, rd, status;
114
115 /* Compose the query. */
116 rd = !(channel->flags & ARES_FLAG_NORECURSE);
117 status = ares_mkquery(name, dnsclass, type, channel->next_id, rd, &qbuf,
118 &qlen);
119 if (status != ARES_SUCCESS)
120 {
121 if (qbuf != NULL) free(qbuf);
122 callback(arg, status, 0, NULL, 0);
123 return;
124 }
125
126 channel->next_id = generate_unique_id(channel);
127
128 /* Allocate and fill in the query structure. */
129 qquery = malloc(sizeof(struct qquery));
130 if (!qquery)
131 {
132 ares_free_string(qbuf);
133 callback(arg, ARES_ENOMEM, 0, NULL, 0);
134 return;
135 }
136 qquery->callback = callback;
137 qquery->arg = arg;
138
139 /* Send it off. qcallback will be called when we get an answer. */
140 ares_send(channel, qbuf, qlen, qcallback, qquery);
141 ares_free_string(qbuf);
142 }
143
qcallback(void * arg,int status,int timeouts,unsigned char * abuf,int alen)144 static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen)
145 {
146 struct qquery *qquery = (struct qquery *) arg;
147 unsigned int ancount;
148 int rcode;
149
150 if (status != ARES_SUCCESS)
151 qquery->callback(qquery->arg, status, timeouts, abuf, alen);
152 else
153 {
154 /* Pull the response code and answer count from the packet. */
155 rcode = DNS_HEADER_RCODE(abuf);
156 ancount = DNS_HEADER_ANCOUNT(abuf);
157
158 /* Convert errors. */
159 switch (rcode)
160 {
161 case NOERROR:
162 status = (ancount > 0) ? ARES_SUCCESS : ARES_ENODATA;
163 break;
164 case FORMERR:
165 status = ARES_EFORMERR;
166 break;
167 case SERVFAIL:
168 status = ARES_ESERVFAIL;
169 break;
170 case NXDOMAIN:
171 status = ARES_ENOTFOUND;
172 break;
173 case NOTIMP:
174 status = ARES_ENOTIMP;
175 break;
176 case REFUSED:
177 status = ARES_EREFUSED;
178 break;
179 }
180 qquery->callback(qquery->arg, status, timeouts, abuf, alen);
181 }
182 free(qquery);
183 }
184