1
/* -*- coding: utf-8 -*- */
3
* Mandos client - get and decrypt data from a Mandos server
5
* This program is partly derived from an example program for an Avahi
6
* service browser, downloaded from
7
* <http://avahi.org/browser/examples/core-browse-services.c>. This
8
* includes the following functions: "resolve_callback",
9
* "browse_callback", and parts of "main".
12
* Copyright © 2007-2008 Teddy Hogeborn & Björn Påhlsson
14
* This program is free software: you can redistribute it and/or
15
* modify it under the terms of the GNU General Public License as
16
* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
19
* This program is distributed in the hope that it will be useful, but
20
* WITHOUT ANY WARRANTY; without even the implied warranty of
21
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22
* General Public License for more details.
24
* You should have received a copy of the GNU General Public License
25
* along with this program. If not, see
26
* <http://www.gnu.org/licenses/>.
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* Contact the authors at <mandos@fukt.bsnet.se>.
31
/* Needed by GPGME, specifically gpgme_data_seek() */
32
#define _LARGEFILE_SOURCE
33
#define _FILE_OFFSET_BITS 64
35
#define _GNU_SOURCE /* TEMP_FAILURE_RETRY() */
41
#include <net/if.h> /* if_nametoindex */
42
#include <sys/ioctl.h> /* ioctl, ifreq, SIOCGIFFLAGS, IFF_UP,
44
#include <net/if.h> /* ioctl, ifreq, SIOCGIFFLAGS, IFF_UP,
47
#include <avahi-core/core.h>
48
#include <avahi-core/lookup.h>
49
#include <avahi-core/log.h>
50
#include <avahi-common/simple-watch.h>
51
#include <avahi-common/malloc.h>
52
#include <avahi-common/error.h>
54
/* Mandos client part */
55
#include <sys/types.h> /* socket(), inet_pton() */
56
#include <sys/socket.h> /* socket(), struct sockaddr_in6,
57
struct in6_addr, inet_pton() */
58
#include <gnutls/gnutls.h> /* All GnuTLS stuff */
59
#include <gnutls/openpgp.h> /* GnuTLS with openpgp stuff */
61
#include <unistd.h> /* close() */
62
#include <netinet/in.h>
63
#include <stdbool.h> /* true */
64
#include <string.h> /* memset */
65
#include <arpa/inet.h> /* inet_pton() */
66
#include <iso646.h> /* not */
67
#include <net/if.h> /* IF_NAMESIZE */
70
#include <errno.h> /* perror() */
76
#define BUFFER_SIZE 256
78
static const char *keydir = "/conf/conf.d/mandos";
79
static const char *pubkeyfile = "pubkey.txt";
80
static const char *seckeyfile = "seckey.txt";
84
const char mandos_protocol_version[] = "1";
86
/* Used for passing in values through all the callback functions */
88
AvahiSimplePoll *simple_poll;
90
gnutls_certificate_credentials_t cred;
92
gnutls_dh_params_t dh_params;
96
size_t adjustbuffer(char **buffer, size_t buffer_length,
97
size_t buffer_capacity){
98
if (buffer_length + BUFFER_SIZE > buffer_capacity){
99
*buffer = realloc(*buffer, buffer_capacity + BUFFER_SIZE);
103
buffer_capacity += BUFFER_SIZE;
105
return buffer_capacity;
109
* Decrypt OpenPGP data using keyrings in HOMEDIR.
110
* Returns -1 on error
112
static ssize_t pgp_packet_decrypt (const char *cryptotext,
115
const char *homedir){
116
gpgme_data_t dh_crypto, dh_plain;
120
size_t plaintext_capacity = 0;
121
ssize_t plaintext_length = 0;
122
gpgme_engine_info_t engine_info;
125
fprintf(stderr, "Trying to decrypt OpenPGP data\n");
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gpgme_check_version(NULL);
130
rc = gpgme_engine_check_version(GPGME_PROTOCOL_OpenPGP);
131
if (rc != GPG_ERR_NO_ERROR){
132
fprintf(stderr, "bad gpgme_engine_check_version: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
137
/* Set GPGME home directory for the OpenPGP engine only */
138
rc = gpgme_get_engine_info (&engine_info);
139
if (rc != GPG_ERR_NO_ERROR){
140
fprintf(stderr, "bad gpgme_get_engine_info: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
144
while(engine_info != NULL){
145
if(engine_info->protocol == GPGME_PROTOCOL_OpenPGP){
146
gpgme_set_engine_info(GPGME_PROTOCOL_OpenPGP,
147
engine_info->file_name, homedir);
150
engine_info = engine_info->next;
152
if(engine_info == NULL){
153
fprintf(stderr, "Could not set GPGME home dir to %s\n", homedir);
157
/* Create new GPGME data buffer from memory cryptotext */
158
rc = gpgme_data_new_from_mem(&dh_crypto, cryptotext, crypto_size,
160
if (rc != GPG_ERR_NO_ERROR){
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fprintf(stderr, "bad gpgme_data_new_from_mem: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
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/* Create new empty GPGME data buffer for the plaintext */
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rc = gpgme_data_new(&dh_plain);
168
if (rc != GPG_ERR_NO_ERROR){
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fprintf(stderr, "bad gpgme_data_new: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
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gpgme_data_release(dh_crypto);
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/* Create new GPGME "context" */
176
rc = gpgme_new(&ctx);
177
if (rc != GPG_ERR_NO_ERROR){
178
fprintf(stderr, "bad gpgme_new: %s: %s\n",
179
gpgme_strsource(rc), gpgme_strerror(rc));
180
plaintext_length = -1;
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/* Decrypt data from the cryptotext data buffer to the plaintext
186
rc = gpgme_op_decrypt(ctx, dh_crypto, dh_plain);
187
if (rc != GPG_ERR_NO_ERROR){
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fprintf(stderr, "bad gpgme_op_decrypt: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
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plaintext_length = -1;
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fprintf(stderr, "Decryption of OpenPGP data succeeded\n");
199
gpgme_decrypt_result_t result;
200
result = gpgme_op_decrypt_result(ctx);
202
fprintf(stderr, "gpgme_op_decrypt_result failed\n");
204
fprintf(stderr, "Unsupported algorithm: %s\n",
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result->unsupported_algorithm);
206
fprintf(stderr, "Wrong key usage: %d\n",
207
result->wrong_key_usage);
208
if(result->file_name != NULL){
209
fprintf(stderr, "File name: %s\n", result->file_name);
211
gpgme_recipient_t recipient;
212
recipient = result->recipients;
214
while(recipient != NULL){
215
fprintf(stderr, "Public key algorithm: %s\n",
216
gpgme_pubkey_algo_name(recipient->pubkey_algo));
217
fprintf(stderr, "Key ID: %s\n", recipient->keyid);
218
fprintf(stderr, "Secret key available: %s\n",
219
recipient->status == GPG_ERR_NO_SECKEY
221
recipient = recipient->next;
227
/* Seek back to the beginning of the GPGME plaintext data buffer */
228
if (gpgme_data_seek(dh_plain, (off_t) 0, SEEK_SET) == -1){
229
perror("pgpme_data_seek");
230
plaintext_length = -1;
236
plaintext_capacity = adjustbuffer(plaintext, (size_t)plaintext_length,
238
if (plaintext_capacity == 0){
239
perror("adjustbuffer");
240
plaintext_length = -1;
244
ret = gpgme_data_read(dh_plain, *plaintext + plaintext_length,
246
/* Print the data, if any */
252
perror("gpgme_data_read");
253
plaintext_length = -1;
256
plaintext_length += ret;
260
fprintf(stderr, "Decrypted password is: ");
261
for(ssize_t i = 0; i < plaintext_length; i++){
262
fprintf(stderr, "%02hhX ", (*plaintext)[i]);
264
fprintf(stderr, "\n");
269
/* Delete the GPGME cryptotext data buffer */
270
gpgme_data_release(dh_crypto);
272
/* Delete the GPGME plaintext data buffer */
273
gpgme_data_release(dh_plain);
274
return plaintext_length;
277
static const char * safer_gnutls_strerror (int value) {
278
const char *ret = gnutls_strerror (value);
284
/* GnuTLS log function callback */
285
static void debuggnutls(__attribute__((unused)) int level,
287
fprintf(stderr, "GnuTLS: %s", string);
290
static int init_gnutls_global(mandos_context *mc){
294
fprintf(stderr, "Initializing GnuTLS\n");
297
if ((ret = gnutls_global_init ())
298
!= GNUTLS_E_SUCCESS) {
299
fprintf (stderr, "GnuTLS global_init: %s\n",
300
safer_gnutls_strerror(ret));
305
/* "Use a log level over 10 to enable all debugging options."
308
gnutls_global_set_log_level(11);
309
gnutls_global_set_log_function(debuggnutls);
312
/* OpenPGP credentials */
313
if ((ret = gnutls_certificate_allocate_credentials (&mc->cred))
314
!= GNUTLS_E_SUCCESS) {
315
fprintf (stderr, "GnuTLS memory error: %s\n",
316
safer_gnutls_strerror(ret));
321
fprintf(stderr, "Attempting to use OpenPGP certificate %s"
322
" and keyfile %s as GnuTLS credentials\n", pubkeyfile,
326
ret = gnutls_certificate_set_openpgp_key_file
327
(mc->cred, pubkeyfile, seckeyfile, GNUTLS_OPENPGP_FMT_BASE64);
328
if (ret != GNUTLS_E_SUCCESS) {
330
"Error[%d] while reading the OpenPGP key pair ('%s',"
331
" '%s')\n", ret, pubkeyfile, seckeyfile);
332
fprintf(stdout, "The GnuTLS error is: %s\n",
333
safer_gnutls_strerror(ret));
337
/* GnuTLS server initialization */
338
ret = gnutls_dh_params_init(&mc->dh_params);
339
if (ret != GNUTLS_E_SUCCESS) {
340
fprintf (stderr, "Error in GnuTLS DH parameter initialization:"
341
" %s\n", safer_gnutls_strerror(ret));
344
ret = gnutls_dh_params_generate2(mc->dh_params, mc->dh_bits);
345
if (ret != GNUTLS_E_SUCCESS) {
346
fprintf (stderr, "Error in GnuTLS prime generation: %s\n",
347
safer_gnutls_strerror(ret));
351
gnutls_certificate_set_dh_params(mc->cred, mc->dh_params);
356
static int init_gnutls_session(mandos_context *mc, gnutls_session_t *session){
358
/* GnuTLS session creation */
359
ret = gnutls_init(session, GNUTLS_SERVER);
360
if (ret != GNUTLS_E_SUCCESS){
361
fprintf(stderr, "Error in GnuTLS session initialization: %s\n",
362
safer_gnutls_strerror(ret));
367
ret = gnutls_priority_set_direct(*session, mc->priority, &err);
368
if (ret != GNUTLS_E_SUCCESS) {
369
fprintf(stderr, "Syntax error at: %s\n", err);
370
fprintf(stderr, "GnuTLS error: %s\n",
371
safer_gnutls_strerror(ret));
376
ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,
378
if (ret != GNUTLS_E_SUCCESS) {
379
fprintf(stderr, "Error setting GnuTLS credentials: %s\n",
380
safer_gnutls_strerror(ret));
384
/* ignore client certificate if any. */
385
gnutls_certificate_server_set_request (*session,
388
gnutls_dh_set_prime_bits (*session, mc->dh_bits);
393
/* Avahi log function callback */
394
static void empty_log(__attribute__((unused)) AvahiLogLevel level,
395
__attribute__((unused)) const char *txt){}
397
/* Called when a Mandos server is found */
398
static int start_mandos_communication(const char *ip, uint16_t port,
399
AvahiIfIndex if_index,
402
struct sockaddr_in6 to;
404
char *decrypted_buffer;
405
size_t buffer_length = 0;
406
size_t buffer_capacity = 0;
407
ssize_t decrypted_buffer_size;
410
char interface[IF_NAMESIZE];
411
gnutls_session_t session;
412
gnutls_dh_params_t dh_params;
414
ret = init_gnutls_session (mc, &session);
420
fprintf(stderr, "Setting up a tcp connection to %s, port %d\n",
424
tcp_sd = socket(PF_INET6, SOCK_STREAM, 0);
431
if(if_indextoname((unsigned int)if_index, interface) == NULL){
432
perror("if_indextoname");
435
fprintf(stderr, "Binding to interface %s\n", interface);
438
memset(&to,0,sizeof(to)); /* Spurious warning */
439
to.sin6_family = AF_INET6;
440
/* It would be nice to have a way to detect if we were passed an
441
IPv4 address here. Now we assume an IPv6 address. */
442
ret = inet_pton(AF_INET6, ip, &to.sin6_addr);
448
fprintf(stderr, "Bad address: %s\n", ip);
451
to.sin6_port = htons(port); /* Spurious warning */
453
to.sin6_scope_id = (uint32_t)if_index;
456
fprintf(stderr, "Connection to: %s, port %d\n", ip, port);
457
char addrstr[INET6_ADDRSTRLEN] = "";
458
if(inet_ntop(to.sin6_family, &(to.sin6_addr), addrstr,
459
sizeof(addrstr)) == NULL){
462
if(strcmp(addrstr, ip) != 0){
463
fprintf(stderr, "Canonical address form: %s\n", addrstr);
468
ret = connect(tcp_sd, (struct sockaddr *) &to, sizeof(to));
474
const char *out = mandos_protocol_version;
477
size_t out_size = strlen(out);
478
ret = TEMP_FAILURE_RETRY(write(tcp_sd, out + written,
479
out_size - written));
485
written += (size_t)ret;
486
if(written < out_size){
489
if (out == mandos_protocol_version){
499
fprintf(stderr, "Establishing TLS session with %s\n", ip);
502
gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) tcp_sd);
504
ret = gnutls_handshake (session);
506
if (ret != GNUTLS_E_SUCCESS){
508
fprintf(stderr, "*** GnuTLS Handshake failed ***\n");
515
/* Read OpenPGP packet that contains the wanted password */
518
fprintf(stderr, "Retrieving pgp encrypted password from %s\n",
523
buffer_capacity = adjustbuffer(&buffer, buffer_length, buffer_capacity);
524
if (buffer_capacity == 0){
525
perror("adjustbuffer");
530
ret = gnutls_record_recv(session, buffer+buffer_length,
537
case GNUTLS_E_INTERRUPTED:
540
case GNUTLS_E_REHANDSHAKE:
541
ret = gnutls_handshake (session);
543
fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");
550
fprintf(stderr, "Unknown error while reading data from"
551
" encrypted session with Mandos server\n");
553
gnutls_bye (session, GNUTLS_SHUT_RDWR);
557
buffer_length += (size_t) ret;
562
fprintf(stderr, "Closing TLS session\n");
565
gnutls_bye (session, GNUTLS_SHUT_RDWR);
567
if (buffer_length > 0){
568
decrypted_buffer_size = pgp_packet_decrypt(buffer,
572
if (decrypted_buffer_size >= 0){
574
while(written < (size_t) decrypted_buffer_size){
575
ret = (int)fwrite (decrypted_buffer + written, 1,
576
(size_t)decrypted_buffer_size - written,
578
if(ret == 0 and ferror(stdout)){
580
fprintf(stderr, "Error writing encrypted data: %s\n",
586
written += (size_t)ret;
588
free(decrypted_buffer);
594
/* Shutdown procedure */
599
gnutls_deinit (session);
600
gnutls_certificate_free_credentials (mc->cred);
601
gnutls_global_deinit ();
605
static void resolve_callback(AvahiSServiceResolver *r,
606
AvahiIfIndex interface,
607
AVAHI_GCC_UNUSED AvahiProtocol protocol,
608
AvahiResolverEvent event,
612
const char *host_name,
613
const AvahiAddress *address,
615
AVAHI_GCC_UNUSED AvahiStringList *txt,
616
AVAHI_GCC_UNUSED AvahiLookupResultFlags
619
mandos_context *mc = userdata;
620
assert(r); /* Spurious warning */
622
/* Called whenever a service has been resolved successfully or
627
case AVAHI_RESOLVER_FAILURE:
628
fprintf(stderr, "(Avahi Resolver) Failed to resolve service '%s'"
629
" of type '%s' in domain '%s': %s\n", name, type, domain,
630
avahi_strerror(avahi_server_errno(mc->server)));
633
case AVAHI_RESOLVER_FOUND:
635
char ip[AVAHI_ADDRESS_STR_MAX];
636
avahi_address_snprint(ip, sizeof(ip), address);
638
fprintf(stderr, "Mandos server \"%s\" found on %s (%s, %d) on"
639
" port %d\n", name, host_name, ip, interface, port);
641
int ret = start_mandos_communication(ip, port, interface, mc);
647
avahi_s_service_resolver_free(r);
650
static void browse_callback( AvahiSServiceBrowser *b,
651
AvahiIfIndex interface,
652
AvahiProtocol protocol,
653
AvahiBrowserEvent event,
657
AVAHI_GCC_UNUSED AvahiLookupResultFlags
660
mandos_context *mc = userdata;
661
assert(b); /* Spurious warning */
663
/* Called whenever a new services becomes available on the LAN or
664
is removed from the LAN */
668
case AVAHI_BROWSER_FAILURE:
670
fprintf(stderr, "(Avahi browser) %s\n",
671
avahi_strerror(avahi_server_errno(mc->server)));
672
avahi_simple_poll_quit(mc->simple_poll);
675
case AVAHI_BROWSER_NEW:
676
/* We ignore the returned Avahi resolver object. In the callback
677
function we free it. If the Avahi server is terminated before
678
the callback function is called the Avahi server will free the
681
if (!(avahi_s_service_resolver_new(mc->server, interface,
682
protocol, name, type, domain,
683
AVAHI_PROTO_INET6, 0,
684
resolve_callback, mc)))
685
fprintf(stderr, "Avahi: Failed to resolve service '%s': %s\n",
686
name, avahi_strerror(avahi_server_errno(mc->server)));
689
case AVAHI_BROWSER_REMOVE:
692
case AVAHI_BROWSER_ALL_FOR_NOW:
693
case AVAHI_BROWSER_CACHE_EXHAUSTED:
695
fprintf(stderr, "No Mandos server found, still searching...\n");
701
/* Combines file name and path and returns the malloced new
702
string. some sane checks could/should be added */
703
static const char *combinepath(const char *first, const char *second){
704
size_t f_len = strlen(first);
705
size_t s_len = strlen(second);
706
char *tmp = malloc(f_len + s_len + 2);
711
memcpy(tmp, first, f_len); /* Spurious warning */
715
memcpy(tmp + f_len + 1, second, s_len); /* Spurious warning */
717
tmp[f_len + 1 + s_len] = '\0';
722
int main(int argc, char *argv[]){
723
AvahiSServiceBrowser *sb = NULL;
726
int exitcode = EXIT_SUCCESS;
727
const char *interface = "eth0";
728
struct ifreq network;
732
char *connect_to = NULL;
733
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
734
mandos_context mc = { .simple_poll = NULL, .server = NULL,
735
.dh_bits = 1024, .priority = "SECURE256"};
738
/* Temporary int to get the address of for getopt_long */
739
int debug_int = debug ? 1 : 0;
741
struct option long_options[] = {
742
{"debug", no_argument, &debug_int, 1},
743
{"connect", required_argument, NULL, 'c'},
744
{"interface", required_argument, NULL, 'i'},
745
{"keydir", required_argument, NULL, 'd'},
746
{"seckey", required_argument, NULL, 's'},
747
{"pubkey", required_argument, NULL, 'p'},
748
{"dh-bits", required_argument, NULL, 'D'},
749
{"priority", required_argument, NULL, 'P'},
752
int option_index = 0;
753
ret = getopt_long (argc, argv, "i:", long_options,
780
mc.dh_bits = (unsigned int) strtol(optarg, NULL, 10);
787
mc.priority = optarg;
791
/* getopt_long() has already printed a message about the
792
unrcognized option, so just exit. */
796
/* Set the global debug flag from the temporary int */
797
debug = debug_int ? true : false;
800
pubkeyfile = combinepath(keydir, pubkeyfile);
801
if (pubkeyfile == NULL){
802
perror("combinepath");
803
exitcode = EXIT_FAILURE;
807
seckeyfile = combinepath(keydir, seckeyfile);
808
if (seckeyfile == NULL){
809
perror("combinepath");
813
ret = init_gnutls_global(&mc);
815
fprintf(stderr, "init_gnutls_global\n");
832
if_index = (AvahiIfIndex) if_nametoindex(interface);
834
fprintf(stderr, "No such interface: \"%s\"\n", interface);
838
if(connect_to != NULL){
839
/* Connect directly, do not use Zeroconf */
840
/* (Mainly meant for debugging) */
841
char *address = strrchr(connect_to, ':');
843
fprintf(stderr, "No colon in address\n");
844
exitcode = EXIT_FAILURE;
848
uint16_t port = (uint16_t) strtol(address+1, NULL, 10);
850
perror("Bad port number");
851
exitcode = EXIT_FAILURE;
855
address = connect_to;
856
ret = start_mandos_communication(address, port, if_index, &mc);
858
exitcode = EXIT_FAILURE;
860
exitcode = EXIT_SUCCESS;
865
/* If the interface is down, bring it up */
867
sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
870
exitcode = EXIT_FAILURE;
873
strcpy(network.ifr_name, interface); /* Spurious warning */
874
ret = ioctl(sd, SIOCGIFFLAGS, &network);
876
perror("ioctl SIOCGIFFLAGS");
877
exitcode = EXIT_FAILURE;
880
if((network.ifr_flags & IFF_UP) == 0){
881
network.ifr_flags |= IFF_UP;
882
ret = ioctl(sd, SIOCSIFFLAGS, &network);
884
perror("ioctl SIOCSIFFLAGS");
885
exitcode = EXIT_FAILURE;
893
avahi_set_log_function(empty_log);
896
/* Initialize the pseudo-RNG for Avahi */
897
srand((unsigned int) time(NULL));
899
/* Allocate main Avahi loop object */
900
mc.simple_poll = avahi_simple_poll_new();
901
if (mc.simple_poll == NULL) {
902
fprintf(stderr, "Avahi: Failed to create simple poll"
904
exitcode = EXIT_FAILURE;
909
AvahiServerConfig config;
910
/* Do not publish any local Zeroconf records */
911
avahi_server_config_init(&config);
912
config.publish_hinfo = 0;
913
config.publish_addresses = 0;
914
config.publish_workstation = 0;
915
config.publish_domain = 0;
917
/* Allocate a new server */
918
mc.server = avahi_server_new(avahi_simple_poll_get
919
(mc.simple_poll), &config, NULL,
922
/* Free the Avahi configuration data */
923
avahi_server_config_free(&config);
926
/* Check if creating the Avahi server object succeeded */
927
if (mc.server == NULL) {
928
fprintf(stderr, "Failed to create Avahi server: %s\n",
929
avahi_strerror(error));
930
exitcode = EXIT_FAILURE;
934
/* Create the Avahi service browser */
935
sb = avahi_s_service_browser_new(mc.server, if_index,
937
"_mandos._tcp", NULL, 0,
938
browse_callback, &mc);
940
fprintf(stderr, "Failed to create service browser: %s\n",
941
avahi_strerror(avahi_server_errno(mc.server)));
942
exitcode = EXIT_FAILURE;
946
/* Run the main loop */
949
fprintf(stderr, "Starting Avahi loop search\n");
952
avahi_simple_poll_loop(mc.simple_poll);
957
fprintf(stderr, "%s exiting\n", argv[0]);
962
avahi_s_service_browser_free(sb);
964
if (mc.server != NULL)
965
avahi_server_free(mc.server);
967
if (mc.simple_poll != NULL)
968
avahi_simple_poll_free(mc.simple_poll);