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1 
2 /* Copyright 1998 by the Massachusetts Institute of Technology.
3  * Copyright (C) 2012 Marko Kreen <markokr@gmail.com>
4  *
5  * Permission to use, copy, modify, and distribute this
6  * software and its documentation for any purpose and without
7  * fee is hereby granted, provided that the above copyright
8  * notice appear in all copies and that both that copyright
9  * notice and this permission notice appear in supporting
10  * documentation, and that the name of M.I.T. not be used in
11  * advertising or publicity pertaining to distribution of the
12  * software without specific, written prior permission.
13  * M.I.T. makes no representations about the suitability of
14  * this software for any purpose.  It is provided "as is"
15  * without express or implied warranty.
16  */
17 
18 #include "ares_setup.h"
19 
20 #ifdef HAVE_NETINET_IN_H
21 #  include <netinet/in.h>
22 #endif
23 #ifdef HAVE_NETDB_H
24 #  include <netdb.h>
25 #endif
26 #ifdef HAVE_ARPA_INET_H
27 #  include <arpa/inet.h>
28 #endif
29 #ifdef HAVE_ARPA_NAMESER_H
30 #  include <arpa/nameser.h>
31 #else
32 #  include "nameser.h"
33 #endif
34 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
35 #  include <arpa/nameser_compat.h>
36 #endif
37 
38 #include "ares.h"
39 #include "ares_dns.h"
40 #include "ares_data.h"
41 #include "ares_private.h"
42 
43 int
ares_parse_soa_reply(const unsigned char * abuf,int alen,struct ares_soa_reply ** soa_out)44 ares_parse_soa_reply(const unsigned char *abuf, int alen,
45 		     struct ares_soa_reply **soa_out)
46 {
47   const unsigned char *aptr;
48   long len;
49   char *qname = NULL, *rr_name = NULL;
50   struct ares_soa_reply *soa = NULL;
51   int qdcount, ancount;
52   int status;
53 
54   if (alen < HFIXEDSZ)
55     return ARES_EBADRESP;
56 
57   /* parse message header */
58   qdcount = DNS_HEADER_QDCOUNT(abuf);
59   ancount = DNS_HEADER_ANCOUNT(abuf);
60   if (qdcount != 1 || ancount != 1)
61     return ARES_EBADRESP;
62   aptr = abuf + HFIXEDSZ;
63 
64   /* query name */
65   status = ares__expand_name_for_response(aptr, abuf, alen, &qname, &len);
66   if (status != ARES_SUCCESS)
67     goto failed_stat;
68   aptr += len;
69 
70   /* skip qtype & qclass */
71   if (aptr + QFIXEDSZ > abuf + alen)
72     goto failed;
73   aptr += QFIXEDSZ;
74 
75   /* rr_name */
76   status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
77   if (status != ARES_SUCCESS)
78     goto failed_stat;
79   aptr += len;
80 
81   /* skip rr_type, rr_class, rr_ttl, rr_rdlen */
82   if (aptr + RRFIXEDSZ > abuf + alen)
83     goto failed;
84   aptr += RRFIXEDSZ;
85 
86   /* allocate result struct */
87   soa = ares_malloc_data(ARES_DATATYPE_SOA_REPLY);
88   if (!soa)
89     {
90       status = ARES_ENOMEM;
91       goto failed_stat;
92     }
93 
94   /* nsname */
95   status = ares__expand_name_for_response(aptr, abuf, alen, &soa->nsname, &len);
96   if (status != ARES_SUCCESS)
97     goto failed_stat;
98   aptr += len;
99 
100   /* hostmaster */
101   status = ares__expand_name_for_response(aptr, abuf, alen, &soa->hostmaster, &len);
102   if (status != ARES_SUCCESS)
103     goto failed_stat;
104   aptr += len;
105 
106   /* integer fields */
107   if (aptr + 5 * 4 > abuf + alen)
108     goto failed;
109   soa->serial = DNS__32BIT(aptr + 0 * 4);
110   soa->refresh = DNS__32BIT(aptr + 1 * 4);
111   soa->retry = DNS__32BIT(aptr + 2 * 4);
112   soa->expire = DNS__32BIT(aptr + 3 * 4);
113   soa->minttl = DNS__32BIT(aptr + 4 * 4);
114 
115   ares_free(qname);
116   ares_free(rr_name);
117 
118   *soa_out = soa;
119 
120   return ARES_SUCCESS;
121 
122 failed:
123   status = ARES_EBADRESP;
124 
125 failed_stat:
126   ares_free_data(soa);
127   if (qname)
128     ares_free(qname);
129   if (rr_name)
130     ares_free(rr_name);
131   return status;
132 }
133 
134