1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
/* 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_NETDB_H
# include <netdb.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
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include "ares.h"
#include "ares_dns.h"
#include "ares_nowarn.h"
#include "ares_private.h"
int ares_parse_ptr_reply(const unsigned char *abuf, int alen, const void *addr,
int addrlen, int family, struct hostent **host)
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len;
long len;
const unsigned char *aptr;
char *ptrname, *hostname, *rr_name, *rr_data;
struct hostent *hostent;
int aliascnt = 0;
int alias_alloc = 8;
char ** aliases;
/* Set *host to NULL for all failure cases. */
*host = NULL;
/* Give up if abuf doesn't have room for a header. */
if (alen < HFIXEDSZ)
return ARES_EBADRESP;
/* Fetch the question and answer count from the header. */
qdcount = DNS_HEADER_QDCOUNT(abuf);
ancount = DNS_HEADER_ANCOUNT(abuf);
if (qdcount != 1)
return ARES_EBADRESP;
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares__expand_name_for_response(aptr, abuf, alen, &ptrname, &len);
if (status != ARES_SUCCESS)
return status;
if (aptr + len + QFIXEDSZ > abuf + alen)
{
free(ptrname);
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Examine each answer resource record (RR) in turn. */
hostname = NULL;
aliases = malloc(alias_alloc * sizeof(char *));
if (!aliases)
{
free(ptrname);
return ARES_ENOMEM;
}
for (i = 0; i < (int)ancount; i++)
{
/* Decode the RR up to the data field. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
if (status != ARES_SUCCESS)
break;
aptr += len;
if (aptr + RRFIXEDSZ > abuf + alen)
{
free(rr_name);
status = ARES_EBADRESP;
break;
}
rr_type = DNS_RR_TYPE(aptr);
rr_class = DNS_RR_CLASS(aptr);
rr_len = DNS_RR_LEN(aptr);
aptr += RRFIXEDSZ;
if (rr_class == C_IN && rr_type == T_PTR
&& strcasecmp(rr_name, ptrname) == 0)
{
/* Decode the RR data and set hostname to it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len);
if (status != ARES_SUCCESS)
{
free(rr_name);
break;
}
if (hostname)
free(hostname);
hostname = rr_data;
aliases[aliascnt] = malloc((strlen(rr_data)+1) * sizeof(char));
if (!aliases[aliascnt])
{
free(rr_name);
status = ARES_ENOMEM;
break;
}
strncpy(aliases[aliascnt], rr_data, strlen(rr_data)+1);
aliascnt++;
if (aliascnt >= alias_alloc) {
char **ptr;
alias_alloc *= 2;
ptr = realloc(aliases, alias_alloc * sizeof(char *));
if(!ptr) {
free(rr_name);
status = ARES_ENOMEM;
break;
}
aliases = ptr;
}
}
if (rr_class == C_IN && rr_type == T_CNAME)
{
/* Decode the RR data and replace ptrname with it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len);
if (status != ARES_SUCCESS)
{
free(rr_name);
break;
}
free(ptrname);
ptrname = rr_data;
}
free(rr_name);
aptr += rr_len;
if (aptr > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
}
if (status == ARES_SUCCESS && !hostname)
status = ARES_ENODATA;
if (status == ARES_SUCCESS)
{
/* We got our answer. Allocate memory to build the host entry. */
hostent = malloc(sizeof(struct hostent));
if (hostent)
{
hostent->h_addr_list = malloc(2 * sizeof(char *));
if (hostent->h_addr_list)
{
hostent->h_addr_list[0] = malloc(addrlen);
if (hostent->h_addr_list[0])
{
hostent->h_aliases = malloc((aliascnt+1) * sizeof (char *));
if (hostent->h_aliases)
{
/* Fill in the hostent and return successfully. */
hostent->h_name = hostname;
for (i=0 ; i<aliascnt ; i++)
hostent->h_aliases[i] = aliases[i];
hostent->h_aliases[aliascnt] = NULL;
hostent->h_addrtype = aresx_sitoss(family);
hostent->h_length = aresx_sitoss(addrlen);
memcpy(hostent->h_addr_list[0], addr, addrlen);
hostent->h_addr_list[1] = NULL;
*host = hostent;
free(aliases);
free(ptrname);
return ARES_SUCCESS;
}
free(hostent->h_addr_list[0]);
}
free(hostent->h_addr_list);
}
free(hostent);
}
status = ARES_ENOMEM;
}
for (i=0 ; i<aliascnt ; i++)
if (aliases[i])
free(aliases[i]);
free(aliases);
if (hostname)
free(hostname);
free(ptrname);
return status;
}
|
