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() */
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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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static const char *certdir = "/conf/conf.d/mandos";
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static const char *certfile = "openpgp-client.txt";
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static const char *certkey = "openpgp-client-key.txt";
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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){
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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, 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
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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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/* perror("inet_ntop"); */
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/* fprintf(stderr, "Really connecting to: %s, port %d\n", */
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/* addrstr, ntohs(to.sin6_port)); */
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ret = connect(tcp_sd, (struct sockaddr *) &to, sizeof(to));
424
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:
476
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);
492
buffer_length += (size_t) ret;
496
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){
503
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)){
508
fprintf(stderr, "Error writing encrypted data: %s\n",
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written += (size_t)ret;
516
free(decrypted_buffer);
525
fprintf(stderr, "Closing TLS session\n");
529
gnutls_bye (es.session, GNUTLS_SHUT_RDWR);
532
gnutls_deinit (es.session);
533
gnutls_certificate_free_credentials (es.cred);
534
gnutls_global_deinit ();
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static void resolve_callback( AvahiSServiceResolver *r,
539
AvahiIfIndex interface,
540
AVAHI_GCC_UNUSED AvahiProtocol protocol,
541
AvahiResolverEvent event,
545
const char *host_name,
546
const AvahiAddress *address,
548
AVAHI_GCC_UNUSED AvahiStringList *txt,
549
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
550
AVAHI_GCC_UNUSED void* userdata) {
551
mandos_context *mc = userdata;
552
assert(r); /* Spurious warning */
554
/* Called whenever a service has been resolved successfully or
559
case AVAHI_RESOLVER_FAILURE:
560
fprintf(stderr, "(Resolver) Failed to resolve service '%s' of"
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" type '%s' in domain '%s': %s\n", name, type, domain,
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avahi_strerror(avahi_server_errno(mc->server)));
565
case AVAHI_RESOLVER_FOUND:
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char ip[AVAHI_ADDRESS_STR_MAX];
568
avahi_address_snprint(ip, sizeof(ip), address);
570
fprintf(stderr, "Mandos server \"%s\" found on %s (%s) on"
571
" port %d\n", name, host_name, ip, port);
573
int ret = start_mandos_communication(ip, port, interface, mc);
579
avahi_s_service_resolver_free(r);
582
static void browse_callback( AvahiSServiceBrowser *b,
583
AvahiIfIndex interface,
584
AvahiProtocol protocol,
585
AvahiBrowserEvent event,
589
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
591
mandos_context *mc = userdata;
592
assert(b); /* Spurious warning */
594
/* Called whenever a new services becomes available on the LAN or
595
is removed from the LAN */
599
case AVAHI_BROWSER_FAILURE:
601
fprintf(stderr, "(Browser) %s\n",
602
avahi_strerror(avahi_server_errno(mc->server)));
603
avahi_simple_poll_quit(mc->simple_poll);
606
case AVAHI_BROWSER_NEW:
607
/* We ignore the returned resolver object. In the callback
608
function we free it. If the server is terminated before
609
the callback function is called the server will free
610
the resolver for us. */
612
if (!(avahi_s_service_resolver_new(mc->server, interface, protocol, name,
614
AVAHI_PROTO_INET6, 0,
615
resolve_callback, mc)))
616
fprintf(stderr, "Failed to resolve service '%s': %s\n", name,
617
avahi_strerror(avahi_server_errno(s)));
620
case AVAHI_BROWSER_REMOVE:
623
case AVAHI_BROWSER_ALL_FOR_NOW:
624
case AVAHI_BROWSER_CACHE_EXHAUSTED:
629
/* Combines file name and path and returns the malloced new
630
string. some sane checks could/should be added */
631
static const char *combinepath(const char *first, const char *second){
632
size_t f_len = strlen(first);
633
size_t s_len = strlen(second);
634
char *tmp = malloc(f_len + s_len + 2);
639
memcpy(tmp, first, f_len);
643
memcpy(tmp + f_len + 1, second, s_len);
645
tmp[f_len + 1 + s_len] = '\0';
650
int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char*argv[]) {
651
AvahiServerConfig config;
652
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 = 2048, .priority = "SECURE256"};
665
static struct option long_options[] = {
666
{"debug", no_argument, (int *)&debug, 1},
667
{"connect", required_argument, 0, 'C'},
668
{"interface", required_argument, 0, 'i'},
669
{"certdir", required_argument, 0, 'd'},
670
{"certkey", required_argument, 0, 'c'},
671
{"certfile", required_argument, 0, 'k'},
672
{"dh_bits", required_argument, 0, 'D'},
673
{"priority", required_argument, 0, 'p'},
676
int option_index = 0;
677
ret = getopt_long (argc, argv, "i:", long_options,
706
tmp = strtol(optarg, NULL, 10);
707
if (errno == ERANGE){
715
mc.priority = optarg;
722
certfile = combinepath(certdir, certfile);
723
if (certfile == NULL){
724
perror("combinepath");
725
returncode = EXIT_FAILURE;
729
certkey = combinepath(certdir, certkey);
730
if (certkey == NULL){
731
perror("combinepath");
732
returncode = EXIT_FAILURE;
736
if_index = (AvahiIfIndex) if_nametoindex(interface);
738
fprintf(stderr, "No such interface: \"%s\"\n", interface);
742
if(connect_to != NULL){
743
/* Connect directly, do not use Zeroconf */
744
/* (Mainly meant for debugging) */
745
char *address = strrchr(connect_to, ':');
747
fprintf(stderr, "No colon in address\n");
751
uint16_t port = (uint16_t) strtol(address+1, NULL, 10);
753
perror("Bad port number");
757
address = connect_to;
758
ret = start_mandos_communication(address, port, if_index);
766
sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
769
returncode = EXIT_FAILURE;
772
strcpy(network.ifr_name, interface);
773
ret = ioctl(sd, SIOCGIFFLAGS, &network);
776
perror("ioctl SIOCGIFFLAGS");
777
returncode = EXIT_FAILURE;
780
if((network.ifr_flags & IFF_UP) == 0){
781
network.ifr_flags |= IFF_UP;
782
ret = ioctl(sd, SIOCSIFFLAGS, &network);
784
perror("ioctl SIOCSIFFLAGS");
785
returncode = EXIT_FAILURE;
792
avahi_set_log_function(empty_log);
795
/* Initialize the psuedo-RNG */
796
srand((unsigned int) time(NULL));
798
/* Allocate main loop object */
799
if (!(mc.simple_poll = avahi_simple_poll_new())) {
800
fprintf(stderr, "Failed to create simple poll object.\n");
801
returncode = EXIT_FAILURE;
805
/* Do not publish any local records */
806
avahi_server_config_init(&config);
807
config.publish_hinfo = 0;
808
config.publish_addresses = 0;
809
config.publish_workstation = 0;
810
config.publish_domain = 0;
812
/* Allocate a new server */
813
mc.server = avahi_server_new(avahi_simple_poll_get(simple_poll),
814
&config, NULL, NULL, &error);
816
/* Free the configuration data */
817
avahi_server_config_free(&config);
819
/* Check if creating the server object succeeded */
821
fprintf(stderr, "Failed to create server: %s\n",
822
avahi_strerror(error));
823
returncode = EXIT_FAILURE;
827
/* Create the service browser */
828
sb = avahi_s_service_browser_new(mc.server, if_index,
830
"_mandos._tcp", NULL, 0,
831
browse_callback, &mc);
833
fprintf(stderr, "Failed to create service browser: %s\n",
834
avahi_strerror(avahi_server_errno(mc.server)));
835
returncode = EXIT_FAILURE;
839
/* Run the main loop */
842
fprintf(stderr, "Starting avahi loop search\n");
845
avahi_simple_poll_loop(simple_poll);
850
fprintf(stderr, "%s exiting\n", argv[0]);
855
avahi_s_service_browser_free(sb);
858
avahi_server_free(mc.server);
861
avahi_simple_poll_free(simple_poll);