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#include <inttypes.h> /* PRIu16, PRIdMAX, intmax_t,
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#include <assert.h> /* assert() */
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#include <errno.h> /* perror(), errno */
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#include <errno.h> /* perror(), errno,
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program_invocation_short_name */
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#include <time.h> /* nanosleep(), time(), sleep() */
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#include <net/if.h> /* ioctl, ifreq, SIOCGIFFLAGS, IFF_UP,
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SIOCSIFFLAGS, if_indextoname(),
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#include <unistd.h> /* close(), SEEK_SET, off_t, write(),
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getuid(), getgid(), seteuid(),
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setgid(), pause() */
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#include <arpa/inet.h> /* inet_pton(), htons */
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#include <arpa/inet.h> /* inet_pton(), htons, inet_ntop() */
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#include <iso646.h> /* not, or, and */
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#include <argp.h> /* struct argp_option, error_t, struct
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argp_state, struct argp,
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static const char sys_class_net[] = "/sys/class/net";
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char *connect_to = NULL;
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/* Doubly linked list that need to be circularly linked when used */
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typedef struct server{
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AvahiIfIndex if_index;
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struct timespec last_seen;
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/* Used for passing in values through the Avahi callback functions */
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AvahiSimplePoll *simple_poll;
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gnutls_dh_params_t dh_params;
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const char *priority;
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server *current_server;
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} mandos_context;
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/* global context so signal handler can reach it*/
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mandos_context mc = { .simple_poll = NULL, .server = NULL,
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.dh_bits = 1024, .priority = "SECURE256"
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":!CTYPE-X.509:+CTYPE-OPENPGP" };
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":!CTYPE-X.509:+CTYPE-OPENPGP",
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.current_server = NULL };
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sig_atomic_t quit_now = 0;
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int signal_received = 0;
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/* Function to use when printing errors */
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void perror_plus(const char *print_text){
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fprintf(stderr, "Mandos plugin %s: ",
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program_invocation_short_name);
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* Make additional room in "buffer" for at least BUFFER_SIZE more
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* bytes. "buffer_capacity" is how much is currently allocated,
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return buffer_capacity;
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int add_server(const char *ip, uint16_t port,
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AvahiIfIndex if_index,
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server *new_server = malloc(sizeof(server));
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if(new_server == NULL){
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perror_plus("malloc");
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*new_server = (server){ .ip = strdup(ip),
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.if_index = if_index,
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if(new_server->ip == NULL){
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perror_plus("strdup");
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/* unique case of first server */
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if (mc.current_server == NULL){
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new_server->next = new_server;
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new_server->prev = new_server;
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mc.current_server = new_server;
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/* Placing the new server last in the list */
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new_server->next = mc.current_server;
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new_server->prev = mc.current_server->prev;
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new_server->prev->next = new_server;
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mc.current_server->prev = new_server;
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ret = clock_gettime(CLOCK_MONOTONIC, &mc.current_server->last_seen);
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perror_plus("clock_gettime");
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* Initialize GPGME.
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/* OpenPGP credentials */
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gnutls_certificate_allocate_credentials(&mc.cred);
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ret = gnutls_certificate_allocate_credentials(&mc.cred);
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if(ret != GNUTLS_E_SUCCESS){
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fprintf(stderr, "GnuTLS memory error: %s\n", /* Spurious warning
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fprintf(stderr, "GnuTLS memory error: %s\n",
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safer_gnutls_strerror(ret));
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gnutls_global_deinit();
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if(af == AF_INET6 and if_index != AVAHI_IF_UNSPEC){
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char interface[IF_NAMESIZE];
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if(if_indextoname((unsigned int)if_index, interface) == NULL){
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perror("if_indextoname");
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perror_plus("if_indextoname");
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fprintf(stderr, "Connection to: %s%%%s, port %" PRIu16 "\n",
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ip, interface, port);
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int ret = asprintf(&flagname, "%s/%s/flags", sys_class_net,
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if_entry->d_name);
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perror_plus("asprintf");
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int flags_fd = (int)TEMP_FAILURE_RETRY(open(flagname, O_RDONLY));
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if(flags_fd == -1){
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perror_plus("open");
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free(flagname);
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free(flagname);
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typedef short ifreq_flags; /* ifreq.ifr_flags in netdevice(7) */
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/* read line from flags_fd */
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ssize_t to_read = (sizeof(ifreq_flags)*2)+3; /* "0x1003\n" */
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ssize_t to_read = 2+(sizeof(ifreq_flags)*2)+1; /* "0x1003\n" */
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char *flagstring = malloc((size_t)to_read+1); /* +1 for final \0 */
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flagstring[(size_t)to_read] = '\0';
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if(flagstring == NULL){
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perror_plus("malloc");
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close(flags_fd);
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int avahi_loop_with_timeout(AvahiSimplePoll *s, int retry_interval){
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struct timespec now;
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struct timespec waited_time;
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intmax_t block_time;
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if(mc.current_server == NULL){
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"Wait until first server is found. No timeout!\n");
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ret = avahi_simple_poll_iterate(s, -1);
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fprintf(stderr, "Check current_server if we should run it,"
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/* the current time */
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ret = clock_gettime(CLOCK_MONOTONIC, &now);
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perror_plus("clock_gettime");
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/* Calculating in ms how long time between now and server
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who we visted longest time ago. Now - last seen. */
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waited_time.tv_sec = (now.tv_sec
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- mc.current_server->last_seen.tv_sec);
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waited_time.tv_nsec = (now.tv_nsec
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- mc.current_server->last_seen.tv_nsec);
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/* total time is 10s/10,000ms.
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Converting to s from ms by dividing by 1,000,
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and ns to ms by dividing by 1,000,000. */
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block_time = ((retry_interval
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- ((intmax_t)waited_time.tv_sec * 1000))
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- ((intmax_t)waited_time.tv_nsec / 1000000));
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fprintf(stderr, "Blocking for %ld ms\n", block_time);
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if(block_time <= 0){
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ret = start_mandos_communication(mc.current_server->ip,
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mc.current_server->port,
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mc.current_server->if_index,
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mc.current_server->af);
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avahi_simple_poll_quit(mc.simple_poll);
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ret = clock_gettime(CLOCK_MONOTONIC,
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&mc.current_server->last_seen);
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perror_plus("clock_gettime");
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mc.current_server = mc.current_server->next;
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block_time = 0; /* Call avahi to find new Mandos
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servers, but don't block */
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ret = avahi_simple_poll_iterate(s, (int)block_time);
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if (ret > 0 or errno != EINTR) {
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return (ret != 1) ? ret : 0;
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int main(int argc, char *argv[]){
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AvahiSServiceBrowser *sb = NULL;
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bool gnutls_initialized = false;
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bool gpgme_initialized = false;
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float delay = 2.5f;
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double retry_interval = 10; /* 10s between trying a server and
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retrying the same server again */
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struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };
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struct sigaction sigterm_action = { .sa_handler = handle_sigterm };
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.arg = "SECONDS",
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.doc = "Maximum delay to wait for interface startup",
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{ .name = "retry", .key = 132,
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.doc = "Retry interval used when denied by the mandos server",
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* These reproduce what we would get without ARGP_NO_HELP
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if(errno != 0 or tmp == arg or *tmp != '\0'){
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argp_error(state, "Bad delay");
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case 132: /* --retry */
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retry_interval = strtod(arg, &tmp);
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if(errno != 0 or tmp == arg or *tmp != '\0'
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or (retry_interval * 1000) > INT_MAX){
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argp_error(state, "Bad retry interval");
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* These reproduce what we would get without ARGP_NO_HELP
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sigemptyset(&sigterm_action.sa_mask);
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ret = sigaddset(&sigterm_action.sa_mask, SIGINT);
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perror("sigaddset");
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perror_plus("sigaddset");
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exitcode = EX_OSERR;
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ret = sigaddset(&sigterm_action.sa_mask, SIGHUP);
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perror("sigaddset");
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perror_plus("sigaddset");
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exitcode = EX_OSERR;
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ret = sigaddset(&sigterm_action.sa_mask, SIGTERM);
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perror("sigaddset");
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perror_plus("sigaddset");
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exitcode = EX_OSERR;
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ret = sigaction(SIGINT, NULL, &old_sigterm_action);
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perror("sigaction");
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perror_plus("sigaction");
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return EX_OSERR;
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if(old_sigterm_action.sa_handler != SIG_IGN){
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ret = sigaction(SIGINT, &sigterm_action, NULL);
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perror("sigaction");
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perror_plus("sigaction");
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exitcode = EX_OSERR;
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ret = sigaction(SIGHUP, NULL, &old_sigterm_action);
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perror("sigaction");
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perror_plus("sigaction");
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return EX_OSERR;
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if(old_sigterm_action.sa_handler != SIG_IGN){
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ret = sigaction(SIGHUP, &sigterm_action, NULL);
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perror("sigaction");
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perror_plus("sigaction");
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exitcode = EX_OSERR;
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ret = sigaction(SIGTERM, NULL, &old_sigterm_action);
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perror("sigaction");
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perror_plus("sigaction");
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return EX_OSERR;
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if(old_sigterm_action.sa_handler != SIG_IGN){
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ret = sigaction(SIGTERM, &sigterm_action, NULL);
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perror("sigaction");
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perror_plus("sigaction");
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exitcode = EX_OSERR;
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bool restore_loglevel = true;
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restore_loglevel = false;
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perror_plus("klogctl");
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#endif /* __linux__ */
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sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
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perror_plus("socket");
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exitcode = EX_OSERR;
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#ifdef __linux__
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if(restore_loglevel){
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ret = klogctl(7, NULL, 0);
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perror_plus("klogctl");
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#endif /* __linux__ */
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ret = seteuid(uid);
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perror_plus("seteuid");
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strcpy(network.ifr_name, interface);
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ret = ioctl(sd, SIOCGIFFLAGS, &network);
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perror("ioctl SIOCGIFFLAGS");
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perror_plus("ioctl SIOCGIFFLAGS");
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#ifdef __linux__
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if(restore_loglevel){
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ret = klogctl(7, NULL, 0);
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perror_plus("klogctl");
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#endif /* __linux__ */
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ret = ioctl(sd, SIOCSIFFLAGS, &network);
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take_down_interface = false;
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perror("ioctl SIOCSIFFLAGS +IFF_UP");
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perror_plus("ioctl SIOCSIFFLAGS +IFF_UP");
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exitcode = EX_OSERR;
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#ifdef __linux__
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if(restore_loglevel){
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ret = klogctl(7, NULL, 0);
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perror_plus("klogctl");
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#endif /* __linux__ */
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ret = seteuid(uid);
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perror_plus("seteuid");
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/* sleep checking until interface is running */
1659
/* Sleep checking until interface is running.
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Check every 0.25s, up to total time of delay */
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for(int i=0; i < delay * 4; i++){
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ret = ioctl(sd, SIOCGIFFLAGS, &network);
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perror("ioctl SIOCGIFFLAGS");
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perror_plus("ioctl SIOCGIFFLAGS");
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} else if(network.ifr_flags & IFF_RUNNING){
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struct timespec sleeptime = { .tv_nsec = 250000000 };
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ret = nanosleep(&sleeptime, NULL);
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if(ret == -1 and errno != EINTR){
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perror("nanosleep");
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perror_plus("nanosleep");
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1674
if(not take_down_interface){
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/* We won't need the socket anymore */
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ret = (int)TEMP_FAILURE_RETRY(close(sd));
1678
perror_plus("close");
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#ifdef __linux__
1712
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fprintf(stderr, "Starting Avahi loop search\n");
1715
avahi_simple_poll_loop(mc.simple_poll);
1859
ret = avahi_loop_with_timeout(mc.simple_poll,
1860
(int)(retry_interval * 1000));
1862
fprintf(stderr, "avahi_loop_with_timeout exited %s\n",
1863
(ret == 0) ? "successfully" : "with error");
1739
1888
if(gpgme_initialized){
1740
1889
gpgme_release(mc.ctx);
1892
/* Cleans up the circular linked list of Mandos servers the client
1894
if(mc.current_server != NULL){
1895
mc.current_server->prev->next = NULL;
1896
while(mc.current_server != NULL){
1897
server *next = mc.current_server->next;
1898
free(mc.current_server);
1899
mc.current_server = next;
1743
1903
/* Take down the network interface */
1744
1904
if(take_down_interface){
1747
1907
ret = seteuid(0);
1909
perror_plus("seteuid");
1751
1911
if(geteuid() == 0){
1752
1912
ret = ioctl(sd, SIOCGIFFLAGS, &network);
1754
perror("ioctl SIOCGIFFLAGS");
1914
perror_plus("ioctl SIOCGIFFLAGS");
1755
1915
} else if(network.ifr_flags & IFF_UP) {
1756
1916
network.ifr_flags &= ~(short)IFF_UP; /* clear flag */
1757
1917
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1759
perror("ioctl SIOCSIFFLAGS -IFF_UP");
1919
perror_plus("ioctl SIOCSIFFLAGS -IFF_UP");
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1922
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1924
perror_plus("close");
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1926
/* Lower privileges permanently */
1768
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ret = setuid(uid);
1930
perror_plus("setuid");