1
/* -*- coding: utf-8 -*- */
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* 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
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* <http://avahi.org/browser/examples/core-browse-services.c>. This
8
* 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
15
* 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() */
32
#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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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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/* Used for passing in values through all the callback functions */
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AvahiSimplePoll *simple_poll;
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gnutls_certificate_credentials_t cred;
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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) {
246
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(mandos_context *mc, gnutls_session_t *session,
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gnutls_dh_params_t *dh_params){
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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 (&mc->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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(mc->cred, pubkeyfile, seckeyfile, GNUTLS_OPENPGP_FMT_BASE64);
293
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(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(*dh_params, mc->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(mc->cred, *dh_params);
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// GnuTLS session creation
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if ((ret = gnutls_init(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(*session, mc->priority, &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(*session, GNUTLS_CRD_CERTIFICATE,
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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 (*session,
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gnutls_dh_set_prime_bits (*session, mc->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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char *decrypted_buffer;
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size_t buffer_length = 0;
363
size_t buffer_capacity = 0;
364
ssize_t decrypted_buffer_size;
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char interface[IF_NAMESIZE];
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gnutls_session_t session;
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gnutls_dh_params_t dh_params;
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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] = "";
408
if(inet_ntop(to.sin6_family, &(to.sin6_addr), addrstr,
409
sizeof(addrstr)) == NULL){
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if(strcmp(addrstr, ip) != 0){
413
fprintf(stderr, "Canonical address form: %s\n", addrstr);
418
ret = connect(tcp_sd, (struct sockaddr *) &to, sizeof(to));
424
ret = initgnutls (mc, &session, &dh_params);
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gnutls_transport_set_ptr (session, (gnutls_transport_ptr_t) tcp_sd);
433
fprintf(stderr, "Establishing TLS session with %s\n", ip);
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ret = gnutls_handshake (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
450
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(session, buffer+buffer_length,
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case GNUTLS_E_INTERRUPTED:
474
case GNUTLS_E_REHANDSHAKE:
475
ret = gnutls_handshake (session);
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fprintf(stderr, "\n*** Handshake failed ***\n");
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fprintf(stderr, "Unknown error while reading data from"
485
" encrypted session with mandos server\n");
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gnutls_bye (session, GNUTLS_SHUT_RDWR);
491
buffer_length += (size_t) ret;
495
if (buffer_length > 0){
496
decrypted_buffer_size = pgp_packet_decrypt(buffer,
500
if (decrypted_buffer_size >= 0){
501
while(written < (size_t) decrypted_buffer_size){
502
ret = (int)fwrite (decrypted_buffer + written, 1,
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(size_t)decrypted_buffer_size - written,
505
if(ret == 0 and ferror(stdout)){
507
fprintf(stderr, "Error writing encrypted data: %s\n",
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written += (size_t)ret;
515
free(decrypted_buffer);
524
fprintf(stderr, "Closing TLS session\n");
528
gnutls_bye (session, GNUTLS_SHUT_RDWR);
531
gnutls_deinit (session);
532
gnutls_certificate_free_credentials (mc->cred);
533
gnutls_global_deinit ();
537
static void resolve_callback( AvahiSServiceResolver *r,
538
AvahiIfIndex interface,
539
AVAHI_GCC_UNUSED AvahiProtocol protocol,
540
AvahiResolverEvent event,
544
const char *host_name,
545
const AvahiAddress *address,
547
AVAHI_GCC_UNUSED AvahiStringList *txt,
548
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
550
mandos_context *mc = userdata;
551
assert(r); /* Spurious warning */
553
/* Called whenever a service has been resolved successfully or
558
case AVAHI_RESOLVER_FAILURE:
559
fprintf(stderr, "(Resolver) Failed to resolve service '%s' of"
560
" type '%s' in domain '%s': %s\n", name, type, domain,
561
avahi_strerror(avahi_server_errno(mc->server)));
564
case AVAHI_RESOLVER_FOUND:
566
char ip[AVAHI_ADDRESS_STR_MAX];
567
avahi_address_snprint(ip, sizeof(ip), address);
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fprintf(stderr, "Mandos server \"%s\" found on %s (%s) on"
570
" port %d\n", name, host_name, ip, port);
572
int ret = start_mandos_communication(ip, port, interface, mc);
578
avahi_s_service_resolver_free(r);
581
static void browse_callback( AvahiSServiceBrowser *b,
582
AvahiIfIndex interface,
583
AvahiProtocol protocol,
584
AvahiBrowserEvent event,
588
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
590
mandos_context *mc = userdata;
591
assert(b); /* Spurious warning */
593
/* Called whenever a new services becomes available on the LAN or
594
is removed from the LAN */
598
case AVAHI_BROWSER_FAILURE:
600
fprintf(stderr, "(Browser) %s\n",
601
avahi_strerror(avahi_server_errno(mc->server)));
602
avahi_simple_poll_quit(mc->simple_poll);
605
case AVAHI_BROWSER_NEW:
606
/* We ignore the returned resolver object. In the callback
607
function we free it. If the server is terminated before
608
the callback function is called the server will free
609
the resolver for us. */
611
if (!(avahi_s_service_resolver_new(mc->server, interface, protocol, name,
613
AVAHI_PROTO_INET6, 0,
614
resolve_callback, mc)))
615
fprintf(stderr, "Failed to resolve service '%s': %s\n", name,
616
avahi_strerror(avahi_server_errno(mc->server)));
619
case AVAHI_BROWSER_REMOVE:
622
case AVAHI_BROWSER_ALL_FOR_NOW:
623
case AVAHI_BROWSER_CACHE_EXHAUSTED:
628
/* Combines file name and path and returns the malloced new
629
string. some sane checks could/should be added */
630
static const char *combinepath(const char *first, const char *second){
631
size_t f_len = strlen(first);
632
size_t s_len = strlen(second);
633
char *tmp = malloc(f_len + s_len + 2);
638
memcpy(tmp, first, f_len); /* Spurious warning */
642
memcpy(tmp + f_len + 1, second, s_len); /* Spurious warning */
644
tmp[f_len + 1 + s_len] = '\0';
649
int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char*argv[]) {
650
AvahiServerConfig config;
651
AvahiSServiceBrowser *sb = NULL;
655
int returncode = EXIT_SUCCESS;
656
const char *interface = "eth0";
657
struct ifreq network;
659
char *connect_to = NULL;
660
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
661
mandos_context mc = { .simple_poll = NULL, .server = NULL,
662
.dh_bits = 1024, .priority = "SECURE256"};
664
debug_int = debug ? 1 : 0;
666
struct option long_options[] = {
667
{"debug", no_argument, &debug_int, 1},
668
{"connect", required_argument, NULL, 'c'},
669
{"interface", required_argument, NULL, 'i'},
670
{"keydir", required_argument, NULL, 'd'},
671
{"seckey", required_argument, NULL, 's'},
672
{"pubkey", required_argument, NULL, 'p'},
673
{"dh-bits", required_argument, NULL, 'D'},
674
{"priority", required_argument, NULL, 'P'},
677
int option_index = 0;
678
ret = getopt_long (argc, argv, "i:", long_options,
705
mc.dh_bits = (unsigned int) strtol(optarg, NULL, 10);
712
mc.priority = optarg;
719
debug = debug_int ? true : false;
721
pubkeyfile = combinepath(keydir, pubkeyfile);
722
if (pubkeyfile == NULL){
723
perror("combinepath");
724
returncode = EXIT_FAILURE;
728
seckeyfile = combinepath(keydir, seckeyfile);
729
if (seckeyfile == NULL){
730
perror("combinepath");
734
if_index = (AvahiIfIndex) if_nametoindex(interface);
736
fprintf(stderr, "No such interface: \"%s\"\n", interface);
740
if(connect_to != NULL){
741
/* Connect directly, do not use Zeroconf */
742
/* (Mainly meant for debugging) */
743
char *address = strrchr(connect_to, ':');
745
fprintf(stderr, "No colon in address\n");
749
uint16_t port = (uint16_t) strtol(address+1, NULL, 10);
751
perror("Bad port number");
755
address = connect_to;
756
ret = start_mandos_communication(address, port, if_index, &mc);
764
sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
767
returncode = EXIT_FAILURE;
770
strcpy(network.ifr_name, interface); /* Spurious warning */
771
ret = ioctl(sd, SIOCGIFFLAGS, &network);
774
perror("ioctl SIOCGIFFLAGS");
775
returncode = EXIT_FAILURE;
778
if((network.ifr_flags & IFF_UP) == 0){
779
network.ifr_flags |= IFF_UP;
780
ret = ioctl(sd, SIOCSIFFLAGS, &network);
782
perror("ioctl SIOCSIFFLAGS");
783
returncode = EXIT_FAILURE;
790
avahi_set_log_function(empty_log);
793
/* Initialize the psuedo-RNG */
794
srand((unsigned int) time(NULL));
796
/* Allocate main loop object */
797
if (!(mc.simple_poll = avahi_simple_poll_new())) {
798
fprintf(stderr, "Failed to create simple poll object.\n");
799
returncode = EXIT_FAILURE;
803
/* Do not publish any local records */
804
avahi_server_config_init(&config);
805
config.publish_hinfo = 0;
806
config.publish_addresses = 0;
807
config.publish_workstation = 0;
808
config.publish_domain = 0;
810
/* Allocate a new server */
811
mc.server=avahi_server_new(avahi_simple_poll_get(mc.simple_poll),
812
&config, NULL, NULL, &error);
814
/* Free the configuration data */
815
avahi_server_config_free(&config);
817
/* Check if creating the server object succeeded */
819
fprintf(stderr, "Failed to create server: %s\n",
820
avahi_strerror(error));
821
returncode = EXIT_FAILURE;
825
/* Create the service browser */
826
sb = avahi_s_service_browser_new(mc.server, if_index,
828
"_mandos._tcp", NULL, 0,
829
browse_callback, &mc);
831
fprintf(stderr, "Failed to create service browser: %s\n",
832
avahi_strerror(avahi_server_errno(mc.server)));
833
returncode = EXIT_FAILURE;
837
/* Run the main loop */
840
fprintf(stderr, "Starting avahi loop search\n");
843
avahi_simple_poll_loop(mc.simple_poll);
848
fprintf(stderr, "%s exiting\n", argv[0]);
853
avahi_s_service_browser_free(sb);
856
avahi_server_free(mc.server);
859
avahi_simple_poll_free(mc.simple_poll);