/*
This file is part of GNUnet.
Copyright (C) 2011 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see .
SPDX-License-Identifier: AGPL3.0-or-later
*/
/**
* @file src/dns/gnunet-dns-monitor.c
* @brief Tool to monitor DNS queries
* @author Christian Grothoff
*/
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_dns_service.h"
#include "gnunet_dnsparser_lib.h"
/**
* Handle to transport service.
*/
static struct GNUNET_DNS_Handle *handle;
/**
* Option -i.
*/
static int inbound_only;
/**
* Option -o.
*/
static int outbound_only;
/**
* Global return value (0 success).
*/
static int ret;
/**
* Selected level of verbosity.
*/
static unsigned int verbosity;
/**
* Convert numeric DNS record type to a string.
*
* @param type type to convert
* @return type as string, only valid until the next call to this function
*/
static const char *
get_type (uint16_t type)
{
static char buf[6];
switch (type)
{
case GNUNET_DNSPARSER_TYPE_A: return "A";
case GNUNET_DNSPARSER_TYPE_NS: return "NS";
case GNUNET_DNSPARSER_TYPE_CNAME: return "CNAME";
case GNUNET_DNSPARSER_TYPE_SOA: return "SOA";
case GNUNET_DNSPARSER_TYPE_PTR: return "PTR";
case GNUNET_DNSPARSER_TYPE_MX: return "MX";
case GNUNET_DNSPARSER_TYPE_TXT: return "TXT";
case GNUNET_DNSPARSER_TYPE_AAAA: return "AAAA";
case GNUNET_DNSPARSER_TYPE_SRV: return "SRV";
}
GNUNET_snprintf (buf, sizeof(buf), "%u", (unsigned int) type);
return buf;
}
/**
* Convert numeric DNS record class to a string.
*
* @param class class to convert
* @return class as string, only valid until the next call to this function
*/
static const char *
get_class (uint16_t class)
{
static char buf[6];
switch (class)
{
case GNUNET_TUN_DNS_CLASS_INTERNET: return "IN";
case GNUNET_TUN_DNS_CLASS_CHAOS: return "CHAOS";
case GNUNET_TUN_DNS_CLASS_HESIOD: return "HESIOD";
}
GNUNET_snprintf (buf, sizeof(buf), "%u", (unsigned int) class);
return buf;
}
/**
* Output the given DNS query to stdout.
*
* @param query query to display.
*/
static void
display_query (const struct GNUNET_DNSPARSER_Query *query)
{
fprintf (stdout,
"\t\t%s %s: %s\n",
get_class (query->dns_traffic_class),
get_type (query->type),
query->name);
}
/**
* Output the given DNS record to stdout.
*
* @param record record to display.
*/
static void
display_record (const struct GNUNET_DNSPARSER_Record *record)
{
const char *format;
char buf[INET6_ADDRSTRLEN];
char *tmp;
tmp = NULL;
switch (record->type)
{
case GNUNET_DNSPARSER_TYPE_A:
if (record->data.raw.data_len != sizeof(struct in_addr))
format = "";
else
format = inet_ntop (AF_INET, record->data.raw.data, buf, sizeof(buf));
break;
case GNUNET_DNSPARSER_TYPE_AAAA:
if (record->data.raw.data_len != sizeof(struct in6_addr))
format = "";
else
format = inet_ntop (AF_INET6, record->data.raw.data, buf, sizeof(buf));
break;
case GNUNET_DNSPARSER_TYPE_NS:
case GNUNET_DNSPARSER_TYPE_CNAME:
case GNUNET_DNSPARSER_TYPE_PTR:
format = record->data.hostname;
break;
case GNUNET_DNSPARSER_TYPE_SOA:
if (NULL == record->data.soa)
format = "";
else
{
GNUNET_asprintf (&tmp,
"origin: %s, mail: %s, serial = %u, refresh = %u s, retry = %u s, expire = %u s, minimum = %u s",
record->data.soa->mname,
record->data.soa->rname,
(unsigned int) record->data.soa->serial,
(unsigned int) record->data.soa->refresh,
(unsigned int) record->data.soa->retry,
(unsigned int) record->data.soa->expire,
(unsigned int) record->data.soa->minimum_ttl);
format = tmp;
}
break;
case GNUNET_DNSPARSER_TYPE_MX:
if (record->data.mx == NULL)
format = "";
else
{
GNUNET_asprintf (&tmp,
"%u: %s",
record->data.mx->preference,
record->data.mx->mxhost);
format = tmp;
}
break;
case GNUNET_DNSPARSER_TYPE_SRV:
if (NULL == record->data.srv)
format = "";
else
{
GNUNET_asprintf (&tmp,
"priority %u, weight = %s, port = %u, target = %s",
(unsigned int) record->data.srv->priority,
(unsigned int) record->data.srv->weight,
(unsigned int) record->data.srv->port,
record->data.srv->target);
format = tmp;
}
break;
case GNUNET_DNSPARSER_TYPE_TXT:
GNUNET_asprintf (&tmp,
"%.*s",
(unsigned int) record->data.raw.data_len,
record->data.raw.data);
format = tmp;
break;
default:
format = "";
break;
}
fprintf (stdout,
"\t\t%s %s: %s = %s (%u s)\n",
get_class (record->dns_traffic_class),
get_type (record->type),
record->name,
format,
(unsigned int) (GNUNET_TIME_absolute_get_remaining (
record->expiration_time).rel_value_us / 1000LL
/ 1000LL));
GNUNET_free_non_null (tmp);
}
/**
* Signature of a function that is called whenever the DNS service
* encounters a DNS request and needs to do something with it. The
* function has then the chance to generate or modify the response by
* calling one of the three "GNUNET_DNS_request_*" continuations.
*
* When a request is intercepted, this function is called first to
* give the client a chance to do the complete address resolution;
* "rdata" will be NULL for this first call for a DNS request, unless
* some other client has already filled in a response.
*
* If multiple clients exist, all of them are called before the global
* DNS. The global DNS is only called if all of the clients'
* functions call GNUNET_DNS_request_forward. Functions that call
* GNUNET_DNS_request_forward will be called again before a final
* response is returned to the application. If any of the clients'
* functions call GNUNET_DNS_request_drop, the response is dropped.
*
* @param cls closure
* @param rh request handle to user for reply
* @param request_length number of bytes in request
* @param request udp payload of the DNS request
*/
static void
display_request (void *cls,
struct GNUNET_DNS_RequestHandle *rh,
size_t request_length,
const char *request)
{
static const char *return_codes[] = {
"No error", "Format error", "Server failure", "Name error",
"Not implemented", "Refused", "YXDomain", "YXRRset",
"NXRRset", "NOT AUTH", "NOT ZONE", "",
"", "", "", ""
};
static const char *op_codes[] = {
"Query", "Inverse query", "Status", "",
"", "", "", "",
"", "", "", "",
"", "", "", ""
};
struct GNUNET_DNSPARSER_Packet *p;
unsigned int i;
p = GNUNET_DNSPARSER_parse (request, request_length);
if (NULL == p)
{
fprintf (stderr, "Received malformed DNS packet!\n");
// FIXME: drop instead?
GNUNET_DNS_request_forward (rh);
return;
}
fprintf (stdout,
"%s with ID: %5u Flags: %s%s%s%s%s%s, Return Code: %s, Opcode: %s\n",
p->flags.query_or_response ? "Response" : "Query",
p->id,
p->flags.recursion_desired ? "RD " : "",
p->flags.message_truncated ? "MT " : "",
p->flags.authoritative_answer ? "AA " : "",
p->flags.checking_disabled ? "CD " : "",
p->flags.authenticated_data ? "AD " : "",
p->flags.recursion_available ? "RA " : "",
return_codes[p->flags.return_code & 15],
op_codes[p->flags.opcode & 15]);
if (p->num_queries > 0)
fprintf (stdout,
"\tQueries:\n");
for (i = 0; i < p->num_queries; i++)
display_query (&p->queries[i]);
if (p->num_answers > 0)
fprintf (stdout,
"\tAnswers:\n");
for (i = 0; i < p->num_answers; i++)
display_record (&p->answers[i]);
fprintf (stdout, "\n");
GNUNET_DNSPARSER_free_packet (p);
GNUNET_DNS_request_forward (rh);
}
/**
* Shutdown.
*/
static void
do_disconnect (void *cls)
{
if (NULL != handle)
{
GNUNET_DNS_disconnect (handle);
handle = NULL;
}
}
/**
* Main function that will be run by the scheduler.
*
* @param cls closure
* @param args remaining command-line arguments
* @param cfgfile name of the configuration file used (for saving, can be NULL!)
* @param cfg configuration
*/
static void
run (void *cls, char *const *args, const char *cfgfile,
const struct GNUNET_CONFIGURATION_Handle *cfg)
{
enum GNUNET_DNS_Flags flags;
flags = GNUNET_DNS_FLAG_REQUEST_MONITOR | GNUNET_DNS_FLAG_RESPONSE_MONITOR;
if (inbound_only | outbound_only)
flags = 0;
if (inbound_only)
flags |= GNUNET_DNS_FLAG_REQUEST_MONITOR;
if (outbound_only)
flags |= GNUNET_DNS_FLAG_RESPONSE_MONITOR;
handle =
GNUNET_DNS_connect (cfg,
flags,
&display_request,
NULL);
GNUNET_SCHEDULER_add_shutdown (&do_disconnect, NULL);
}
int
main (int argc, char *const *argv)
{
struct GNUNET_GETOPT_CommandLineOption options[] = {
GNUNET_GETOPT_option_flag ('i',
"inbound-only",
gettext_noop ("only monitor DNS queries"),
&inbound_only),
GNUNET_GETOPT_option_flag ('o',
"outbound-only",
gettext_noop ("only monitor DNS queries"),
&outbound_only),
GNUNET_GETOPT_option_verbose (&verbosity),
GNUNET_GETOPT_OPTION_END
};
if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv))
return 2;
ret = (GNUNET_OK ==
GNUNET_PROGRAM_run (argc, argv, "gnunet-dns-monitor",
gettext_noop
("Monitor DNS queries."), options,
&run, NULL)) ? ret : 1;
GNUNET_free_nz ((void *) argv);
return ret;
}
/* end of gnunet-dns-monitor.c */