quickjs-tart

quickjs-based runtime for wallet-core logic
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ares_parse_caa_reply.3 (3871B)

      1 .\"
      2 .\" Copyright 2020 Danny Sonnenschein <my.card.god@web.de>
      3 .\" SPDX-License-Identifier: MIT
      4 .\"
      5 .TH ARES_PARSE_CAA_REPLY 3 "16 September 2020"
      6 .SH NAME
      7 ares_parse_caa_reply \- Parse a reply to a DNS query of type CAA
      8 .SH SYNOPSIS
      9 .nf
     10 #include <ares.h>
     11 
     12 int ares_parse_caa_reply(const unsigned char* \fIabuf\fP, int \fIalen\fP,
     13                          struct ares_caa_reply **\fIcaa_out\fP);
     14 .fi
     15 .SH DESCRIPTION
     16 The
     17 .BR "ares_parse_caa_reply" 
     18 function parses the response to a query of type CAA into a
     19 linked list (one element per sub-string) of
     20 .IR "struct ares_caa_reply"
     21 The parameters
     22 .I abuf
     23 and
     24 .I alen
     25 give the contents of the response.  The result is stored in allocated
     26 memory and a pointer to it stored into the variable pointed to by
     27 .IR caa_out .
     28 It is the caller's responsibility to free the resulting
     29 .IR caa_out
     30 structure when it is no longer needed using the function
     31 .B ares_free_data(3)
     32 .PP
     33 The structure 
     34 .I ares_caa_reply(3)
     35 contains the following fields:
     36 .sp
     37 .in +4n
     38 .nf
     39 struct ares_caa_reply {
     40   struct ares_caa_reply *next;
     41   int                    critical;
     42   unsigned char         *property;
     43   size_t                 plength; /* plength excludes null */
     44   unsigned char         *value;
     45   size_t                 length;  /* length excludes null */
     46 };
     47 .fi
     48 .in
     49 .PP
     50 .SH RETURN VALUES
     51 .BR "ares_parse_caa_reply"
     52 can return any of the following values:
     53 .TP 15
     54 .B ARES_SUCCESS
     55 The response was successfully parsed.
     56 .TP 15
     57 .B ARES_EBADRESP
     58 The response was malformatted.
     59 .TP 15
     60 .B ARES_ENODATA
     61 The response did not contain an answer to the query.
     62 .TP 15
     63 .B ARES_ENOMEM
     64 Memory was exhausted.
     65 .SH EXAMPLE
     66 .nf
     67 #include <arpa/inet.h>
     68 #include <time.h>
     69 #include <sys/time.h>
     70 #include <netdb.h>
     71 
     72 #include <unistd.h>
     73 #include <stdio.h>
     74 #include <stdlib.h>
     75 
     76 #include "ares.h"
     77 
     78 static void dns_callback(void *arg,
     79                          int status,
     80                          int timeouts,
     81                          unsigned char *abuf,
     82                          int alen)
     83   {
     84     struct ares_caa_reply *caa_out;
     85     int err;
     86 
     87     err = ares_parse_caa_reply (abuf, alen, &caa_out);
     88     if (err == ARES_SUCCESS)
     89       {
     90         struct ares_caa_reply *caa_curr;
     91         for (caa_curr=caa_out; caa_curr; caa_curr=caa_curr->next)
     92           printf ("%s. CAA %i %s \\"%s\\"\\n", arg,
     93                                             caa_curr->critical,
     94                                             caa_curr->property,
     95                                             caa_curr->value);
     96       }
     97     else
     98       {
     99         printf ("err=%i\\n", err);
    100       }
    101     ares_free_data (caa_out);
    102   }
    103 
    104 static void main_loop(ares_channel_t **channel)
    105   {
    106     int nfds, count;
    107     fd_set readers, writers;
    108     struct timeval tv, *tvp;
    109     while (1)
    110       {
    111         FD_ZERO (&readers);
    112         FD_ZERO (&writers);
    113         nfds = ares_fds (*channel, &readers, &writers);
    114         if (nfds == 0)
    115           break;
    116         tvp = ares_timeout (*channel, NULL, &tv);
    117         count = select (nfds, &readers, &writers, NULL, tvp);
    118         ares_process (*channel, &readers, &writers);
    119       }
    120   }
    121 
    122 int main(int argc, char **argv)
    123   {
    124     const char *sversion;
    125     int iversion;
    126     int err;
    127 
    128     sversion = ares_version (&iversion);
    129     printf ("c-ares version %s\\n", sversion);
    130 
    131     char *domain = "wikipedia.org";
    132     if (argc > 1)
    133       domain = argv[1];
    134 
    135     ares_channel_t *channel;
    136     if ((err = ares_init (&channel)) != ARES_SUCCESS)
    137       {
    138         printf ("ares_init() failed (%i)\\n", err);
    139         exit (EXIT_FAILURE);
    140       }
    141 
    142     ares_query (channel, domain,
    143                 1,   /* ns_c_in */
    144                 257, /* T_CAA */
    145                 dns_callback, domain);
    146 
    147     main_loop (&channel);
    148 
    149     ares_destroy (channel);
    150 
    151     exit (EXIT_SUCCESS);
    152   }
    153 .fi
    154 .SH AVAILABILITY
    155 This function was first introduced in c-ares version 1.17.0.
    156 .SH SEE ALSO
    157 .BR ares_query (3)
    158 .BR ares_free_data (3)