1ARES_PARSE_CAA_REPLY(3) Library Functions Manual ARES_PARSE_CAA_REPLY(3)
2
6 ares_parse_caa_reply - Parse a reply to a DNS query of type CAA
7
9 #include <ares.h>
10 int ares_parse_caa_reply(const unsigned char* abuf, int alen,
12 struct ares_caa_reply **caa_out);
13
15 The ares_parse_caa_reply function parses the response to a query of
16 type CAA into a linked list (one element per sub-string) of struct
17 ares_caa_reply The parameters abuf and alen give the contents of the
18 response. The result is stored in allocated memory and a pointer to it
19 stored into the variable pointed to by caa_out. It is the caller's
20 responsibility to free the resulting caa_out structure when it is no
21 longer needed using the function ares_free_data(3)
22 The structure ares_caa_reply(3) contains the following fields:
24 struct ares_caa_reply {
26 struct ares_caa_reply *next;
27 int critical;
28 unsigned char *property;
29 size_t plength; /* plength excludes null */
30 unsigned char *value;
31 size_t length; /* length excludes null */
32 };
33
35 ares_parse_caa_reply can return any of the following values:
36 ARES_SUCCESS The response was successfully parsed.
38 ARES_EBADRESP The response was malformatted.
40 ARES_ENODATA The response did not contain an answer to the query.
42 ARES_ENOMEM Memory was exhausted.
44
46 #include <arpa/inet.h>
47 #include <time.h>
48 #include <sys/time.h>
49 #include <netdb.h>
50 #include <unistd.h>
52 #include <stdio.h>
53 #include <stdlib.h>
54 #include "ares.h"
56 static void dns_callback(void *arg,
58 int status,
59 int timeouts,
60 unsigned char *abuf,
61 int alen)
62 {
63 struct ares_caa_reply *caa_out;
64 int err;
65 err = ares_parse_caa_reply (abuf, alen, &caa_out);
67 if (err == ARES_SUCCESS)
68 {
69 struct ares_caa_reply *caa_curr;
70 for (caa_curr=caa_out; caa_curr; caa_curr=caa_curr->next)
71 printf ("%s. CAA %i %s \"%s\"\n", arg,
72 caa_curr->critical,
73 caa_curr->property,
74 caa_curr->value);
75 }
76 else
77 {
78 printf ("err=%i\n", err);
79 }
80 ares_free_data (caa_out);
81 }
82 static void main_loop(ares_channel *channel)
84 {
85 int nfds, count;
86 fd_set readers, writers;
87 struct timeval tv, *tvp;
88 while (1)
89 {
90 FD_ZERO (&readers);
91 FD_ZERO (&writers);
92 nfds = ares_fds (*channel, &readers, &writers);
93 if (nfds == 0)
94 break;
95 tvp = ares_timeout (*channel, NULL, &tv);
96 count = select (nfds, &readers, &writers, NULL, tvp);
97 ares_process (*channel, &readers, &writers);
98 }
99 }
100 int main(int argc, char **argv)
102 {
103 const char *sversion;
104 int iversion;
105 int err;
106 sversion = ares_version (&iversion);
108 printf ("c-ares version %s\n", sversion);
109 char *domain = "wikipedia.org";
111 if (argc > 1)
112 domain = argv[1];
113 ares_channel channel;
115 if ((err = ares_init (&channel)) != ARES_SUCCESS)
116 {
117 printf ("ares_init() failed (%i)\n", err);
118 exit (EXIT_FAILURE);
119 }
120 ares_query (channel, domain,
122 1, /* ns_c_in */
123 257, /* T_CAA */
124 dns_callback, domain);
125 main_loop (&channel);
127 ares_destroy (channel);
129 exit (EXIT_SUCCESS);
131 }
132
134 This function was first introduced in c-ares version 1.17.0.
135
137 ares_query(3) ares_free_data(3)
138
140 Written by Danny Sonnenschein <my.card.god@web.de>, on behalf of
141 platynum, https://platynum.ch
142 16 September 2020 ARES_PARSE_CAA_REPLY(3)