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171 lines
4.5 KiB
171 lines
4.5 KiB
.\" |
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.\" Copyright 2020 Danny Sonnenschein <my.card.god@web.de> |
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.\" |
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.\" Permission to use, copy, modify, and distribute this |
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.\" software and its documentation for any purpose and without |
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.\" fee is hereby granted, provided that the above copyright |
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.\" notice appear in all copies and that both that copyright |
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.\" notice and this permission notice appear in supporting |
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.\" documentation, and that the name of M.I.T. not be used in |
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.\" advertising or publicity pertaining to distribution of the |
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.\" software without specific, written prior permission. |
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.\" M.I.T. makes no representations about the suitability of |
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.\" this software for any purpose. It is provided "as is" |
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.\" without express or implied warranty. |
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.\" |
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.TH ARES_PARSE_CAA_REPLY 3 "16 September 2020" |
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.SH NAME |
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ares_parse_caa_reply \- Parse a reply to a DNS query of type CAA |
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.SH SYNOPSIS |
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.nf |
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#include <ares.h> |
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int ares_parse_caa_reply(const unsigned char* \fIabuf\fP, int \fIalen\fP, |
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struct ares_caa_reply **\fIcaa_out\fP); |
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.fi |
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.SH DESCRIPTION |
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The |
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.BR "ares_parse_caa_reply" |
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function parses the response to a query of type CAA into a |
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linked list (one element per sub-string) of |
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.IR "struct ares_caa_reply" |
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The parameters |
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.I abuf |
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and |
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.I alen |
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give the contents of the response. The result is stored in allocated |
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memory and a pointer to it stored into the variable pointed to by |
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.IR caa_out . |
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It is the caller's responsibility to free the resulting |
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.IR caa_out |
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structure when it is no longer needed using the function |
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.B ares_free_data(3) |
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.PP |
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The structure |
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.I ares_caa_reply(3) |
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contains the following fields: |
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.sp |
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.in +4n |
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.nf |
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struct ares_caa_reply { |
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struct ares_caa_reply *next; |
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int critical; |
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unsigned char *property; |
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size_t plength; /* plength excludes null */ |
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unsigned char *value; |
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size_t length; /* length excludes null */ |
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}; |
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.fi |
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.in |
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.PP |
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.SH RETURN VALUES |
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.BR "ares_parse_caa_reply" |
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can return any of the following values: |
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.TP 15 |
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.B ARES_SUCCESS |
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The response was successfully parsed. |
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.TP 15 |
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.B ARES_EBADRESP |
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The response was malformatted. |
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.TP 15 |
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.B ARES_ENODATA |
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The response did not contain an answer to the query. |
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.TP 15 |
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.B ARES_ENOMEM |
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Memory was exhausted. |
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.SH EXAMPLE |
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.nf |
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#include <arpa/inet.h> |
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#include <time.h> |
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#include <sys/time.h> |
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#include <netdb.h> |
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#include <unistd.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include "ares.h" |
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static void dns_callback(void *arg, |
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int status, |
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int timeouts, |
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unsigned char *abuf, |
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int alen) |
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{ |
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struct ares_caa_reply *caa_out; |
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int err; |
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err = ares_parse_caa_reply (abuf, alen, &caa_out); |
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if (err == ARES_SUCCESS) |
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{ |
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struct ares_caa_reply *caa_curr; |
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for (caa_curr=caa_out; caa_curr; caa_curr=caa_curr->next) |
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printf ("%s. CAA %i %s \\"%s\\"\\n", arg, |
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caa_curr->critical, |
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caa_curr->property, |
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caa_curr->value); |
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} |
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else |
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{ |
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printf ("err=%i\\n", err); |
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} |
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ares_free_data (caa_out); |
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} |
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static void main_loop(ares_channel *channel) |
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{ |
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int nfds, count; |
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fd_set readers, writers; |
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struct timeval tv, *tvp; |
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while (1) |
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{ |
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FD_ZERO (&readers); |
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FD_ZERO (&writers); |
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nfds = ares_fds (*channel, &readers, &writers); |
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if (nfds == 0) |
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break; |
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tvp = ares_timeout (*channel, NULL, &tv); |
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count = select (nfds, &readers, &writers, NULL, tvp); |
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ares_process (*channel, &readers, &writers); |
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} |
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} |
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int main(int argc, char **argv) |
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{ |
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const char *sversion; |
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int iversion; |
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int err; |
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sversion = ares_version (&iversion); |
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printf ("c-ares version %s\\n", sversion); |
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char *domain = "wikipedia.org"; |
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if (argc > 1) |
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domain = argv[1]; |
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ares_channel channel; |
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if ((err = ares_init (&channel)) != ARES_SUCCESS) |
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{ |
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printf ("ares_init() failed (%i)\\n", err); |
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exit (EXIT_FAILURE); |
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} |
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ares_query (channel, domain, |
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1, /* ns_c_in */ |
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257, /* T_CAA */ |
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dns_callback, domain); |
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main_loop (&channel); |
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ares_destroy (channel); |
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exit (EXIT_SUCCESS); |
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} |
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.fi |
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.SH AVAILABILITY |
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This function was first introduced in c-ares version 1.17.0. |
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.SH SEE ALSO |
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.BR ares_query (3) |
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.BR ares_free_data (3) |
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.SH AUTHOR |
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Written by Danny Sonnenschein <my.card.god@web.de>, on behalf of platynum, https://platynum.ch
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