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/* -*- coding: utf-8 -*- */
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* Mandos client - get and decrypt data from a Mandos server
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* This program is partly derived from an example program for an Avahi
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* service browser, downloaded from
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* <http://avahi.org/browser/examples/core-browse-services.c>. This
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* includes the following functions: "resolve_callback",
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* "browse_callback", and parts of "main".
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* Everything else is Copyright © 2007-2008 Teddy Hogeborn and Björn
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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* Contact the authors at <https://www.fukt.bsnet.se/~belorn/> and
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* <https://www.fukt.bsnet.se/~teddy/>.
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#define _FORTIFY_SOURCE 2
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#define _LARGEFILE_SOURCE
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#define _FILE_OFFSET_BITS 64
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#include <net/if.h> /* if_nametoindex */
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#include <sys/ioctl.h> // ioctl, ifreq, SIOCGIFFLAGS, IFF_UP, SIOCSIFFLAGS
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#include <net/if.h> // ioctl, ifreq, SIOCGIFFLAGS, IFF_UP, SIOCSIFFLAGS
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#include <avahi-core/core.h>
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#include <avahi-core/lookup.h>
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#include <avahi-core/log.h>
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#include <avahi-common/simple-watch.h>
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#include <avahi-common/malloc.h>
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#include <avahi-common/error.h>
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#include <sys/types.h> /* socket(), inet_pton() */
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#include <sys/socket.h> /* socket(), struct sockaddr_in6,
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struct in6_addr, inet_pton() */
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#include <gnutls/gnutls.h> /* All GnuTLS stuff */
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#include <gnutls/openpgp.h> /* GnuTLS with openpgp stuff */
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#include <unistd.h> /* close() */
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#include <netinet/in.h>
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#include <stdbool.h> /* true */
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#include <string.h> /* memset */
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#include <arpa/inet.h> /* inet_pton() */
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#include <iso646.h> /* not */
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#include <errno.h> /* perror() */
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#define BUFFER_SIZE 256
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const char *certdir = "/conf/conf.d/cryptkeyreq/";
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const char *certfile = "openpgp-client.txt";
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const char *certkey = "openpgp-client-key.txt";
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gnutls_session_t session;
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gnutls_certificate_credentials_t cred;
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gnutls_dh_params_t dh_params;
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ssize_t pgp_packet_decrypt (char *packet, size_t packet_size,
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char **new_packet, const char *homedir){
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gpgme_data_t dh_crypto, dh_plain;
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ssize_t new_packet_capacity = 0;
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ssize_t new_packet_length = 0;
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gpgme_engine_info_t engine_info;
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fprintf(stderr, "Trying to decrypt OpenPGP packet\n");
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gpgme_check_version(NULL);
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rc = gpgme_engine_check_version(GPGME_PROTOCOL_OpenPGP);
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if (rc != GPG_ERR_NO_ERROR){
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fprintf(stderr, "bad gpgme_engine_check_version: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
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/* Set GPGME home directory */
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rc = gpgme_get_engine_info (&engine_info);
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if (rc != GPG_ERR_NO_ERROR){
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fprintf(stderr, "bad gpgme_get_engine_info: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
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while(engine_info != NULL){
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if(engine_info->protocol == GPGME_PROTOCOL_OpenPGP){
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gpgme_set_engine_info(GPGME_PROTOCOL_OpenPGP,
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engine_info->file_name, homedir);
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engine_info = engine_info->next;
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if(engine_info == NULL){
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fprintf(stderr, "Could not set home dir to %s\n", homedir);
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/* Create new GPGME data buffer from packet buffer */
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rc = gpgme_data_new_from_mem(&dh_crypto, packet, packet_size, 0);
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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);
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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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/* Create new GPGME "context" */
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rc = gpgme_new(&ctx);
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if (rc != GPG_ERR_NO_ERROR){
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fprintf(stderr, "bad gpgme_new: %s: %s\n",
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gpgme_strsource(rc), gpgme_strerror(rc));
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/* Decrypt data from the FILE pointer to the plaintext data
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rc = gpgme_op_decrypt(ctx, dh_crypto, dh_plain);
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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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fprintf(stderr, "Decryption of OpenPGP packet succeeded\n");
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gpgme_decrypt_result_t result;
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result = gpgme_op_decrypt_result(ctx);
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fprintf(stderr, "gpgme_op_decrypt_result failed\n");
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fprintf(stderr, "Unsupported algorithm: %s\n",
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result->unsupported_algorithm);
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fprintf(stderr, "Wrong key usage: %d\n",
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result->wrong_key_usage);
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if(result->file_name != NULL){
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fprintf(stderr, "File name: %s\n", result->file_name);
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gpgme_recipient_t recipient;
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recipient = result->recipients;
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while(recipient != NULL){
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fprintf(stderr, "Public key algorithm: %s\n",
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gpgme_pubkey_algo_name(recipient->pubkey_algo));
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fprintf(stderr, "Key ID: %s\n", recipient->keyid);
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fprintf(stderr, "Secret key available: %s\n",
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recipient->status == GPG_ERR_NO_SECKEY
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recipient = recipient->next;
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/* Delete the GPGME FILE pointer cryptotext data buffer */
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gpgme_data_release(dh_crypto);
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/* Seek back to the beginning of the GPGME plaintext data buffer */
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if (gpgme_data_seek(dh_plain, (off_t) 0, SEEK_SET) == -1){
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perror("pgpme_data_seek");
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if (new_packet_length + BUFFER_SIZE > new_packet_capacity){
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*new_packet = realloc(*new_packet,
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(unsigned int)new_packet_capacity
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if (*new_packet == NULL){
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new_packet_capacity += BUFFER_SIZE;
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ret = gpgme_data_read(dh_plain, *new_packet + new_packet_length,
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/* Print the data, if any */
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perror("gpgme_data_read");
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new_packet_length += ret;
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/* FIXME: check characters before printing to screen so to not print
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terminal control characters */
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/* fprintf(stderr, "decrypted password is: "); */
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/* fwrite(*new_packet, 1, new_packet_length, stderr); */
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/* fprintf(stderr, "\n"); */
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/* Delete the GPGME plaintext data buffer */
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gpgme_data_release(dh_plain);
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return new_packet_length;
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static const char * safer_gnutls_strerror (int value) {
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const char *ret = gnutls_strerror (value);
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void debuggnutls(__attribute__((unused)) int level,
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fprintf(stderr, "%s", string);
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int initgnutls(encrypted_session *es){
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fprintf(stderr, "Initializing GnuTLS\n");
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if ((ret = gnutls_global_init ())
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!= GNUTLS_E_SUCCESS) {
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fprintf (stderr, "global_init: %s\n", safer_gnutls_strerror(ret));
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gnutls_global_set_log_level(11);
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gnutls_global_set_log_function(debuggnutls);
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/* openpgp credentials */
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if ((ret = gnutls_certificate_allocate_credentials (&es->cred))
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!= GNUTLS_E_SUCCESS) {
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fprintf (stderr, "memory error: %s\n",
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safer_gnutls_strerror(ret));
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fprintf(stderr, "Attempting to use OpenPGP certificate %s"
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" and keyfile %s as GnuTLS credentials\n", certfile,
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ret = gnutls_certificate_set_openpgp_key_file
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(es->cred, certfile, certkey, GNUTLS_OPENPGP_FMT_BASE64);
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if (ret != GNUTLS_E_SUCCESS) {
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(stderr, "Error[%d] while reading the OpenPGP key pair ('%s',"
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ret, certfile, certkey);
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fprintf(stdout, "The Error is: %s\n",
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safer_gnutls_strerror(ret));
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//GnuTLS server initialization
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if ((ret = gnutls_dh_params_init (&es->dh_params))
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!= GNUTLS_E_SUCCESS) {
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fprintf (stderr, "Error in dh parameter initialization: %s\n",
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safer_gnutls_strerror(ret));
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if ((ret = gnutls_dh_params_generate2 (es->dh_params, DH_BITS))
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!= GNUTLS_E_SUCCESS) {
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fprintf (stderr, "Error in prime generation: %s\n",
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safer_gnutls_strerror(ret));
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gnutls_certificate_set_dh_params (es->cred, es->dh_params);
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// GnuTLS session creation
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if ((ret = gnutls_init (&es->session, GNUTLS_SERVER))
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!= GNUTLS_E_SUCCESS){
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fprintf(stderr, "Error in GnuTLS session initialization: %s\n",
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safer_gnutls_strerror(ret));
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if ((ret = gnutls_priority_set_direct (es->session, "NORMAL", &err))
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!= GNUTLS_E_SUCCESS) {
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fprintf(stderr, "Syntax error at: %s\n", err);
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fprintf(stderr, "GnuTLS error: %s\n",
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safer_gnutls_strerror(ret));
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if ((ret = gnutls_credentials_set
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(es->session, GNUTLS_CRD_CERTIFICATE, es->cred))
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!= GNUTLS_E_SUCCESS) {
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fprintf(stderr, "Error setting a credentials set: %s\n",
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safer_gnutls_strerror(ret));
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/* ignore client certificate if any. */
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gnutls_certificate_server_set_request (es->session,
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gnutls_dh_set_prime_bits (es->session, DH_BITS);
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void empty_log(__attribute__((unused)) AvahiLogLevel level,
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__attribute__((unused)) const char *txt){}
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int start_mandos_communication(const char *ip, uint16_t port,
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unsigned int if_index){
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struct sockaddr_in6 to;
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encrypted_session es;
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char *decrypted_buffer;
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size_t buffer_length = 0;
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size_t buffer_capacity = 0;
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ssize_t decrypted_buffer_size;
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char interface[IF_NAMESIZE];
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fprintf(stderr, "Setting up a tcp connection to %s\n", ip);
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tcp_sd = socket(PF_INET6, SOCK_STREAM, 0);
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if(if_indextoname(if_index, interface) == NULL){
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perror("if_indextoname");
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fprintf(stderr, "Binding to interface %s\n", interface);
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memset(&to,0,sizeof(to)); /* Spurious warning */
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to.sin6_family = AF_INET6;
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ret = inet_pton(AF_INET6, ip, &to.sin6_addr);
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fprintf(stderr, "Bad address: %s\n", ip);
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to.sin6_port = htons(port); /* Spurious warning */
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to.sin6_scope_id = (uint32_t)if_index;
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fprintf(stderr, "Connection to: %s\n", ip);
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ret = connect(tcp_sd, (struct sockaddr *) &to, sizeof(to));
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ret = initgnutls (&es);
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gnutls_transport_set_ptr (es.session,
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(gnutls_transport_ptr_t) tcp_sd);
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fprintf(stderr, "Establishing TLS session with %s\n", ip);
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ret = gnutls_handshake (es.session);
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if (ret != GNUTLS_E_SUCCESS){
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fprintf(stderr, "\n*** Handshake failed ***\n");
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//Retrieve OpenPGP packet that contains the wanted password
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fprintf(stderr, "Retrieving pgp encrypted password from %s\n",
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if (buffer_length + BUFFER_SIZE > buffer_capacity){
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buffer = realloc(buffer, buffer_capacity + BUFFER_SIZE);
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buffer_capacity += BUFFER_SIZE;
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ret = gnutls_record_recv
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(es.session, buffer+buffer_length, BUFFER_SIZE);
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case GNUTLS_E_INTERRUPTED:
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case GNUTLS_E_REHANDSHAKE:
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ret = gnutls_handshake (es.session);
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fprintf(stderr, "\n*** Handshake failed ***\n");
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fprintf(stderr, "Unknown error while reading data from"
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" encrypted session with mandos server\n");
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gnutls_bye (es.session, GNUTLS_SHUT_RDWR);
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buffer_length += (size_t) ret;
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if (buffer_length > 0){
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decrypted_buffer_size = pgp_packet_decrypt(buffer,
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if (decrypted_buffer_size >= 0){
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while(written < (size_t)decrypted_buffer_size){
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ret = (int)fwrite (decrypted_buffer + written, 1,
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(size_t)decrypted_buffer_size - written,
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if(ret == 0 and ferror(stdout)){
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fprintf(stderr, "Error writing encrypted data: %s\n",
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written += (size_t)ret;
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free(decrypted_buffer);
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fprintf(stderr, "Closing TLS session\n");
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gnutls_bye (es.session, GNUTLS_SHUT_RDWR);
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gnutls_deinit (es.session);
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gnutls_certificate_free_credentials (es.cred);
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gnutls_global_deinit ();
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static AvahiSimplePoll *simple_poll = NULL;
529
static AvahiServer *server = NULL;
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static void resolve_callback(
532
AvahiSServiceResolver *r,
533
AvahiIfIndex interface,
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AVAHI_GCC_UNUSED AvahiProtocol protocol,
535
AvahiResolverEvent event,
539
const char *host_name,
540
const AvahiAddress *address,
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AVAHI_GCC_UNUSED AvahiStringList *txt,
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AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
544
AVAHI_GCC_UNUSED void* userdata) {
546
assert(r); /* Spurious warning */
548
/* Called whenever a service has been resolved successfully or
553
case AVAHI_RESOLVER_FAILURE:
554
fprintf(stderr, "(Resolver) Failed to resolve service '%s' of"
555
" type '%s' in domain '%s': %s\n", name, type, domain,
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avahi_strerror(avahi_server_errno(server)));
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case AVAHI_RESOLVER_FOUND:
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char ip[AVAHI_ADDRESS_STR_MAX];
562
avahi_address_snprint(ip, sizeof(ip), address);
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fprintf(stderr, "Mandos server \"%s\" found on %s (%s) on"
565
" port %d\n", name, host_name, ip, port);
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int ret = start_mandos_communication(ip, port,
568
(unsigned int) interface);
574
avahi_s_service_resolver_free(r);
577
static void browse_callback(
578
AvahiSServiceBrowser *b,
579
AvahiIfIndex interface,
580
AvahiProtocol protocol,
581
AvahiBrowserEvent event,
585
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
588
AvahiServer *s = userdata;
589
assert(b); /* Spurious warning */
591
/* Called whenever a new services becomes available on the LAN or
592
is removed from the LAN */
596
case AVAHI_BROWSER_FAILURE:
598
fprintf(stderr, "(Browser) %s\n",
599
avahi_strerror(avahi_server_errno(server)));
600
avahi_simple_poll_quit(simple_poll);
603
case AVAHI_BROWSER_NEW:
604
/* We ignore the returned resolver object. In the callback
605
function we free it. If the server is terminated before
606
the callback function is called the server will free
607
the resolver for us. */
609
if (!(avahi_s_service_resolver_new(s, interface, protocol, name,
611
AVAHI_PROTO_INET6, 0,
612
resolve_callback, s)))
613
fprintf(stderr, "Failed to resolve service '%s': %s\n", name,
614
avahi_strerror(avahi_server_errno(s)));
617
case AVAHI_BROWSER_REMOVE:
620
case AVAHI_BROWSER_ALL_FOR_NOW:
621
case AVAHI_BROWSER_CACHE_EXHAUSTED:
626
/* combinds file name and path and returns the malloced new string. som sane checks could/should be added */
627
const char *combinepath(const char *first, const char *second){
629
tmp = malloc(strlen(first) + strlen(second) + 2);
635
if (first[0] != '\0' and first[strlen(first) - 1] != '/'){
643
int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char*argv[]) {
644
AvahiServerConfig config;
645
AvahiSServiceBrowser *sb = NULL;
648
int returncode = EXIT_SUCCESS;
649
const char *interface = "eth0";
650
struct ifreq network;
654
static struct option long_options[] = {
655
{"debug", no_argument, (int *)&debug, 1},
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{"interface", required_argument, 0, 'i'},
657
{"certdir", required_argument, 0, 'd'},
658
{"certkey", required_argument, 0, 'c'},
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{"certfile", required_argument, 0, 'k'},
662
int option_index = 0;
663
ret = getopt_long (argc, argv, "i:", long_options,
690
certfile = combinepath(certdir, certfile);
691
if (certfile == NULL){
692
returncode = EXIT_FAILURE;
696
certkey = combinepath(certdir, certkey);
697
if (certkey == NULL){
698
returncode = EXIT_FAILURE;
702
sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
705
returncode = EXIT_FAILURE;
708
strcpy(network.ifr_name, interface);
709
ret = ioctl(sd, SIOCGIFFLAGS, &network);
712
perror("ioctl SIOCGIFFLAGS");
713
returncode = EXIT_FAILURE;
716
if((network.ifr_flags & IFF_UP) == 0){
717
network.ifr_flags |= IFF_UP;
718
ret = ioctl(sd, SIOCSIFFLAGS, &network);
720
perror("ioctl SIOCSIFFLAGS");
721
returncode = EXIT_FAILURE;
728
avahi_set_log_function(empty_log);
731
/* Initialize the psuedo-RNG */
732
srand((unsigned int) time(NULL));
734
/* Allocate main loop object */
735
if (!(simple_poll = avahi_simple_poll_new())) {
736
fprintf(stderr, "Failed to create simple poll object.\n");
737
returncode = EXIT_FAILURE;
741
/* Do not publish any local records */
742
avahi_server_config_init(&config);
743
config.publish_hinfo = 0;
744
config.publish_addresses = 0;
745
config.publish_workstation = 0;
746
config.publish_domain = 0;
748
/* Allocate a new server */
749
server = avahi_server_new(avahi_simple_poll_get(simple_poll),
750
&config, NULL, NULL, &error);
752
/* Free the configuration data */
753
avahi_server_config_free(&config);
755
/* Check if creating the server object succeeded */
757
fprintf(stderr, "Failed to create server: %s\n",
758
avahi_strerror(error));
759
returncode = EXIT_FAILURE;
763
/* Create the service browser */
764
sb = avahi_s_service_browser_new(server,
766
if_nametoindex(interface),
768
"_mandos._tcp", NULL, 0,
769
browse_callback, server);
771
fprintf(stderr, "Failed to create service browser: %s\n",
772
avahi_strerror(avahi_server_errno(server)));
773
returncode = EXIT_FAILURE;
777
/* Run the main loop */
780
fprintf(stderr, "Starting avahi loop search\n");
783
avahi_simple_poll_loop(simple_poll);
788
fprintf(stderr, "%s exiting\n", argv[0]);
793
avahi_s_service_browser_free(sb);
796
avahi_server_free(server);
799
avahi_simple_poll_free(simple_poll);