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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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* Copyright © 2007-2008 Teddy Hogeborn & Björn Påhlsson
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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 <mandos@fukt.bsnet.se>.
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/* Needed by GPGME, specifically gpgme_data_seek() */
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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 <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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static int dh_bits = 1024;
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static const char *keydir = "/conf/conf.d/mandos";
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static const char *pubkeyfile = "pubkey.txt";
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static const char *seckeyfile = "seckey.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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static ssize_t pgp_packet_decrypt (char *packet, size_t packet_size,
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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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static void debuggnutls(__attribute__((unused)) int level,
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fprintf(stderr, "%s", string);
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static 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", pubkeyfile,
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ret = gnutls_certificate_set_openpgp_key_file
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(es->cred, pubkeyfile, seckeyfile, 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, pubkeyfile, seckeyfile);
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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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static void empty_log(__attribute__((unused)) AvahiLogLevel level,
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__attribute__((unused)) const char *txt){}
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static int start_mandos_communication(const char *ip, uint16_t port,
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AvahiIfIndex 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, port %d\n",
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tcp_sd = socket(PF_INET6, SOCK_STREAM, 0);
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if(if_indextoname((unsigned int)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, port %d\n", ip, port);
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char addrstr[INET6_ADDRSTRLEN] = "";
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if(inet_ntop(to.sin6_family, &(to.sin6_addr), addrstr,
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sizeof(addrstr)) == NULL){
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if(strcmp(addrstr, ip) != 0){
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fprintf(stderr, "Canonical address form: %s\n",
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addrstr, ntohs(to.sin6_port));
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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:
475
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);
532
gnutls_deinit (es.session);
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gnutls_certificate_free_credentials (es.cred);
534
gnutls_global_deinit ();
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static AvahiSimplePoll *simple_poll = NULL;
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static AvahiServer *server = NULL;
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static void resolve_callback(
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AvahiSServiceResolver *r,
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AvahiIfIndex interface,
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AVAHI_GCC_UNUSED AvahiProtocol protocol,
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AvahiResolverEvent event,
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const char *host_name,
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const AvahiAddress *address,
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AVAHI_GCC_UNUSED AvahiStringList *txt,
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AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
554
AVAHI_GCC_UNUSED void* userdata) {
556
assert(r); /* Spurious warning */
558
/* Called whenever a service has been resolved successfully or
563
case AVAHI_RESOLVER_FAILURE:
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fprintf(stderr, "(Resolver) Failed to resolve service '%s' of"
565
" 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];
572
avahi_address_snprint(ip, sizeof(ip), address);
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fprintf(stderr, "Mandos server \"%s\" found on %s (%s) on"
575
" port %d\n", name, host_name, ip, port);
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int ret = start_mandos_communication(ip, port, interface);
583
avahi_s_service_resolver_free(r);
586
static void browse_callback(
587
AvahiSServiceBrowser *b,
588
AvahiIfIndex interface,
589
AvahiProtocol protocol,
590
AvahiBrowserEvent event,
594
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
597
AvahiServer *s = userdata;
598
assert(b); /* Spurious warning */
600
/* Called whenever a new services becomes available on the LAN or
601
is removed from the LAN */
605
case AVAHI_BROWSER_FAILURE:
607
fprintf(stderr, "(Browser) %s\n",
608
avahi_strerror(avahi_server_errno(server)));
609
avahi_simple_poll_quit(simple_poll);
612
case AVAHI_BROWSER_NEW:
613
/* We ignore the returned resolver object. In the callback
614
function we free it. If the server is terminated before
615
the callback function is called the server will free
616
the resolver for us. */
618
if (!(avahi_s_service_resolver_new(s, interface, protocol, name,
620
AVAHI_PROTO_INET6, 0,
621
resolve_callback, s)))
622
fprintf(stderr, "Failed to resolve service '%s': %s\n", name,
623
avahi_strerror(avahi_server_errno(s)));
626
case AVAHI_BROWSER_REMOVE:
629
case AVAHI_BROWSER_ALL_FOR_NOW:
630
case AVAHI_BROWSER_CACHE_EXHAUSTED:
635
/* Combines file name and path and returns the malloced new
636
string. some sane checks could/should be added */
637
static const char *combinepath(const char *first, const char *second){
638
size_t f_len = strlen(first);
639
size_t s_len = strlen(second);
640
char *tmp = malloc(f_len + s_len + 2);
645
memcpy(tmp, first, f_len);
649
memcpy(tmp + f_len + 1, second, s_len);
651
tmp[f_len + 1 + s_len] = '\0';
656
int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char*argv[]) {
657
AvahiServerConfig config;
658
AvahiSServiceBrowser *sb = NULL;
662
int returncode = EXIT_SUCCESS;
663
const char *interface = NULL;
664
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
665
char *connect_to = NULL;
667
debug_int = debug ? 1 : 0;
669
static struct option long_options[] = {
670
{"debug", no_argument, &debug_int, 1},
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{"connect", required_argument, NULL, 'C'},
672
{"interface", required_argument, NULL, 'i'},
673
{"keydir", required_argument, NULL, 'd'},
674
{"seckey", required_argument, NULL, 'c'},
675
{"pubkey", required_argument, NULL, 'k'},
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{"dh-bits", required_argument, NULL, 'D'},
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int option_index = 0;
680
ret = getopt_long (argc, argv, "i:", long_options,
706
dh_bits = atoi(optarg);
714
debug = debug_int ? true : false;
716
pubkeyfile = combinepath(keydir, pubkeyfile);
717
if (pubkeyfile == NULL){
718
perror("combinepath");
722
if(interface != NULL){
723
if_index = (AvahiIfIndex) if_nametoindex(interface);
725
fprintf(stderr, "No such interface: \"%s\"\n", interface);
730
if(connect_to != NULL){
731
/* Connect directly, do not use Zeroconf */
732
/* (Mainly meant for debugging) */
733
char *address = strrchr(connect_to, ':');
735
fprintf(stderr, "No colon in address\n");
739
uint16_t port = (uint16_t) strtol(address+1, NULL, 10);
741
perror("Bad port number");
745
address = connect_to;
746
ret = start_mandos_communication(address, port, if_index);
754
seckeyfile = combinepath(keydir, seckeyfile);
755
if (seckeyfile == NULL){
756
perror("combinepath");
761
avahi_set_log_function(empty_log);
764
/* Initialize the psuedo-RNG */
765
srand((unsigned int) time(NULL));
767
/* Allocate main loop object */
768
if (!(simple_poll = avahi_simple_poll_new())) {
769
fprintf(stderr, "Failed to create simple poll object.\n");
774
/* Do not publish any local records */
775
avahi_server_config_init(&config);
776
config.publish_hinfo = 0;
777
config.publish_addresses = 0;
778
config.publish_workstation = 0;
779
config.publish_domain = 0;
781
/* Allocate a new server */
782
server = avahi_server_new(avahi_simple_poll_get(simple_poll),
783
&config, NULL, NULL, &error);
785
/* Free the configuration data */
786
avahi_server_config_free(&config);
788
/* Check if creating the server object succeeded */
790
fprintf(stderr, "Failed to create server: %s\n",
791
avahi_strerror(error));
792
returncode = EXIT_FAILURE;
796
/* Create the service browser */
797
sb = avahi_s_service_browser_new(server, if_index,
799
"_mandos._tcp", NULL, 0,
800
browse_callback, server);
802
fprintf(stderr, "Failed to create service browser: %s\n",
803
avahi_strerror(avahi_server_errno(server)));
804
returncode = EXIT_FAILURE;
808
/* Run the main loop */
811
fprintf(stderr, "Starting avahi loop search\n");
814
avahi_simple_poll_loop(simple_poll);
819
fprintf(stderr, "%s exiting\n", argv[0]);
824
avahi_s_service_browser_free(sb);
827
avahi_server_free(server);
830
avahi_simple_poll_free(simple_poll);