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* "browse_callback", and parts of "main".
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* Everything else is
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* Copyright © 2008-2012 Teddy Hogeborn
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* Copyright © 2008-2012 Björn Påhlsson
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* Copyright © 2008-2011 Teddy Hogeborn
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* Copyright © 2008-2011 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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#include <stdio.h> /* fprintf(), stderr, fwrite(),
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stdout, ferror(), remove() */
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#include <stdint.h> /* uint16_t, uint32_t, intptr_t */
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#include <stdint.h> /* uint16_t, uint32_t */
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#include <stddef.h> /* NULL, size_t, ssize_t */
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#include <stdlib.h> /* free(), EXIT_SUCCESS, srand(),
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strtof(), abort() */
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/* This casting via intptr_t is to eliminate warning about casting
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an int to a pointer type. This is exactly how the GnuTLS Guile
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function "set-session-transport-fd!" does it. */
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gnutls_transport_set_ptr(session,
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(gnutls_transport_ptr_t)(intptr_t)tcp_sd);
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/* Spurious warning from -Wint-to-pointer-cast */
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gnutls_transport_set_ptr(session, (gnutls_transport_ptr_t) tcp_sd);
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/* Set effective uid to 0, return errno */
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int raise_privileges(void){
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int old_errno = errno;
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if(seteuid(0) == -1){
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perror_plus("seteuid");
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/* Set effective and real user ID to 0. Return errno. */
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int raise_privileges_permanently(void){
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int old_errno = errno;
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int ret_errno = raise_privileges();
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if(setuid(0) == -1){
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perror_plus("seteuid");
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/* Set effective user ID to unprivileged saved user ID */
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int lower_privileges(void){
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int old_errno = errno;
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if(seteuid(uid) == -1){
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perror_plus("seteuid");
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bool run_network_hooks(const char *mode, const char *interface,
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const float delay){
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struct dirent **direntries;
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int bring_up_interface(const char * const interface, const float delay){
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int old_errno = errno;
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struct ifreq network;
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AvahiIfIndex if_index = (AvahiIfIndex)if_nametoindex(interface);
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fprintf_plus(stderr, "No such interface: \"%s\"\n", interface);
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/* Re-raise priviliges */
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/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
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messages about the network interface to mess up the prompt */
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ret = klogctl(8, NULL, 5);
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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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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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/* Lower privileges */
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strcpy(network.ifr_name, interface);
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ret = ioctl(sd, SIOCGIFFLAGS, &network);
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perror_plus("ioctl SIOCGIFFLAGS");
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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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/* Lower privileges */
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if((network.ifr_flags & IFF_UP) == 0){
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network.ifr_flags |= IFF_UP;
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ret = ioctl(sd, SIOCSIFFLAGS, &network);
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perror_plus("ioctl SIOCSIFFLAGS +IFF_UP");
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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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/* Lower privileges */
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/* 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_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_plus("nanosleep");
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/* Close the socket */
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ret = (int)TEMP_FAILURE_RETRY(close(sd));
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perror_plus("close");
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if(restore_loglevel){
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/* Restores kernel loglevel to default */
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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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/* Lower privileges */
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int main(int argc, char *argv[]){
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AvahiSServiceBrowser *sb = NULL;
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/* If the interface is down, bring it up */
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if((interface[0] != '\0') and (strcmp(interface, "none") != 0)){
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ret = bring_up_interface(interface, delay);
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perror_plus("Failed to bring up interface");
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if(strcmp(interface, "none") != 0){
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if_index = (AvahiIfIndex) if_nametoindex(interface);
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fprintf_plus(stderr, "No such interface: \"%s\"\n", interface);
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exitcode = EX_UNAVAILABLE;
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/* Re-raise priviliges */
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perror_plus("seteuid");
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/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
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messages about the network interface to mess up the prompt */
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ret = klogctl(8, NULL, 5);
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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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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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/* Lower privileges */
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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_plus("ioctl SIOCGIFFLAGS");
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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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exitcode = EX_OSERR;
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/* Lower privileges */
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perror_plus("seteuid");
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if((network.ifr_flags & IFF_UP) == 0){
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network.ifr_flags |= IFF_UP;
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take_down_interface = true;
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ret = ioctl(sd, SIOCSIFFLAGS, &network);
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take_down_interface = false;
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perror_plus("ioctl SIOCSIFFLAGS +IFF_UP");
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exitcode = EX_OSERR;
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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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/* Lower privileges */
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perror_plus("seteuid");
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/* 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_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_plus("nanosleep");
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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));
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perror_plus("close");
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if(restore_loglevel){
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/* Restores kernel loglevel to default */
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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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/* Lower privileges */
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/* Lower privileges */
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perror_plus("seteuid");