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/******************************************************************* rebootd.** A daemon which waits on specified UDP port for special string* (password) and reboots the computer.** Run "./rebootd --help" to see options and parameters.** Copyleft 2005 Anatoli Klassen*******************************************************************/#include <stdlib.h>#include <stdio.h>#include <string.h>#include <stdarg.h>#include <ctype.h>#include <errno.h>#include <signal.h>#include <unistd.h>#include <netdb.h>#include <syslog.h>#include <signal.h>#include <fcntl.h>#include <sys/types.h>#include <sys/stat.h>#include <sys/socket.h>#include <sys/wait.h>#include <sys/reboot.h>#include <netinet/in.h>#include <arpa/inet.h>/* name version number */#define APP_NAME "rebootd"#define DEFAULT_PORT 19#define DEFAULT_CFG_FILE "/etc/rebootd.conf"#define CMDSIZE 4096#define BUFSIZE 4096#define MAX_CONFIG_LINE 4096#define PORT_MIN 1#define PORT_MAX 65535/* return values of functions */#define RESULT_OK 0#define RESULT_EXIT 1#define RESULT_ERROR 2#define RESULT_UNEXPECTED 3/* return values for the whole program */#define EXIT_OK 0#define EXIT_USER_ERROR 1#define EXIT_UNEXPECTED 2/* command line and config file parameters */#define PARAM_HELP_1 "-h"#define PARAM_HELP_2 "--help"#define PARAM_VERSION "--version"#define PARAM_INTERFACE "--interface"#define PARAM_PORT "--port"#define PARAM_CONFIG "--config"#define PARAM_PID_FILE "--pid"#define PARAM_DEBUG "--debug"#define CONFIG_INTERFACE "interface"#define CONFIG_PORT "port"#define CONFIG_PASSWORD "password"#define CONFIG_PID_FILE "pid"/* priority of defferent sources of options */#define CFG_PRIO_CMD 1#define CFG_PRIO_CONFIG 2#define CFG_PRIO_DEFAULT 3struct config {char config_file[FILENAME_MAX];char config_file_prio;struct in_addr interface;char interface_prio;ushort port;char port_prio;char password[MAX_CONFIG_LINE];char password_prio;char pid_file[FILENAME_MAX];char pid_file_prio;char debug_mode;};static struct config global_cfg;static int daemonized = 0; /* we are already a daemon */volatile static int reconfig_required = 0; /* we have to stop socket listening and reread config */volatile static int quit_required = 0; /* we have to stop socket listening and exit */static int parse_cmd_line(struct config *cfg, int argc, const char* argv[]);static int parse_config_file(struct config *cfg, const char *config_name);static void check_return(int res);static uint min(uint a, uint b){return (a < b) ? a : b;}static int establish(const struct config *cfg){int s;struct sockaddr_in sa;memset(&sa, 0, sizeof(struct sockaddr_in));sa.sin_family = AF_INET;sa.sin_port = htons(cfg->port);sa.sin_addr.s_addr = (cfg->interface.s_addr ? cfg->interface.s_addr : INADDR_ANY);if((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)return -1;if(bind(s, (struct sockaddr *)&sa, sizeof(struct sockaddr_in)) < 0) {close(s);return -1;}return s;}static void listen_socket(const struct config *cfg, int soc){char buf[BUFSIZE];int br;struct sockaddr_storage ss;socklen_t ss_size;for(;;) {ss_size = sizeof(ss);br = recvfrom(soc, buf, sizeof(buf)-1, 0, (struct sockaddr *)&ss, &ss_size);if(br < 0) {if(errno == EINTR) {if(reconfig_required || quit_required) break;}else {syslog(LOG_INFO, "cannot receive: %s", strerror(errno));}continue;}buf[br] = '\0';sleep(1);syslog(LOG_INFO, "got command");if(0 == strncmp(buf, cfg->password, sizeof(buf))) {if(cfg->debug_mode) {syslog(LOG_INFO, "REBOOT, debug mode");}else {syslog(LOG_EMERG, "REBOOT");sleep(5);if(reboot(RB_AUTOBOOT) < 0) {syslog(LOG_ERR, "cannot reboot, %s", strerror(errno));}}}}}static void print_version(void){printf("%s %s.%s.%s\n", APP_NAME, VER_MAJOR, VER_MINOR, VER_REVISION);}static void pring_usage(int argc, const char* argv[]){print_version();printf("\nA daemon which waits on specified UDP port for special");printf(" string (password) and reboots the computer.\n\n");printf("Usage: %s [--debug] [--interface IP] [--port PORT]\n", argv[0]);printf(" [--config CONFIG_FILE] [--pid FILE]\n");printf(" or: %s --version\n", argv[0]);printf(" or: %s --help\n\n", argv[0]);printf("Defaults are port 19, all interfaces, config /etc/rebootd.conf and no PID file.\n");printf("In debug mode do not reboot, just write to log.\n\n");printf("Config file looks like:\n--------------------------\n");printf("interface=192.168.0.1\nport=19\npassword=\"some password\"\n");printf("pid=/var/run/rebootd.pid\n--------------------------\n\n");printf("Then run from any other host:\necho -n \"some password\" | nc -uo host_to_rebot 19\n");}static int print_error(const char *msg, const char *value){if(daemonized) {syslog(LOG_ERR, "%s", msg);if(value) syslog(LOG_ERR, " - %s\n", value);syslog(LOG_ERR, "\n");}else {fprintf(stderr, "%s", msg);if(value) fprintf(stderr, " - %s\n", value);fprintf(stderr, "\n");}return RESULT_ERROR;}static int print_cmd_error(int argc, const char* argv[], const char *msg, const char *value){fprintf(stderr, "%s", msg);if(value) fprintf(stderr, " - %s\n", value);fprintf(stderr, "\n");pring_usage(argc, argv);return RESULT_ERROR;}static int print_config_error(const char *config_name, int line, const char *msg, const char *value){if(daemonized) {syslog(LOG_ERR, "Error in %s, line %d: %s", config_name, line, msg);if(value) syslog(LOG_ERR, " - %s", value);syslog(LOG_ERR, "\n");}else {fprintf(stderr, "Error in %s, line %d: %s", config_name, line, msg);if(value) fprintf(stderr, " - %s", value);fprintf(stderr, "\n");}return RESULT_ERROR;}static int check_abs_path(const char *file_name){if(file_name && file_name[0] != '\0' && file_name[0] != '/') {return print_error("File must have an absolute path", file_name);}return RESULT_OK;}static int read_config(struct config *cfg, int argc, const char* argv[]){int res_cmd_line;int res_config_file;struct config cmd_cfg;struct config file_cfg;memset(cfg, 0, sizeof(struct config));res_cmd_line = parse_cmd_line(&cmd_cfg, argc, argv);if(res_cmd_line != RESULT_OK) return res_cmd_line;if(check_abs_path(cmd_cfg.config_file) != RESULT_OK) return RESULT_ERROR;res_config_file = parse_config_file(&file_cfg,cmd_cfg.config_file[0] != '\0' ? cmd_cfg.config_file : DEFAULT_CFG_FILE);if(res_config_file != RESULT_OK) return res_config_file;if(file_cfg.password[0] == '\0')return print_error("Password is not set", NULL);/* save parsed values to general config */if(cmd_cfg.config_file[0] != '\0') {strncpy(cfg->config_file, cmd_cfg.config_file, sizeof(cfg->config_file));cfg->config_file_prio = CFG_PRIO_CMD;}else {strncpy(cfg->config_file, DEFAULT_CFG_FILE, sizeof(cfg->config_file));cfg->config_file_prio = CFG_PRIO_DEFAULT;}if(cmd_cfg.interface.s_addr) {cfg->interface = cmd_cfg.interface;cfg->interface_prio = CFG_PRIO_CMD;}else if(file_cfg.interface.s_addr) {cfg->interface = file_cfg.interface;cfg->interface_prio = CFG_PRIO_CONFIG;}else {cfg->interface_prio = CFG_PRIO_DEFAULT;}if(cmd_cfg.port) {cfg->port = cmd_cfg.port;cfg->port_prio = CFG_PRIO_CMD;}else if(file_cfg.port) {cfg->port = file_cfg.port;cfg->port_prio = CFG_PRIO_CONFIG;}else {cfg->port = DEFAULT_PORT;cfg->port_prio = CFG_PRIO_DEFAULT;}if(cmd_cfg.pid_file[0] != '\0') {strncpy(cfg->pid_file, cmd_cfg.pid_file, sizeof(cfg->pid_file));cfg->pid_file_prio = CFG_PRIO_CMD;}else if(file_cfg.pid_file[0] != '\0') {strncpy(cfg->pid_file, file_cfg.pid_file, sizeof(cfg->pid_file));cfg->pid_file_prio = CFG_PRIO_CONFIG;}else {cfg->pid_file_prio = CFG_PRIO_DEFAULT;}if(check_abs_path(cfg->config_file) != RESULT_OK) return RESULT_ERROR;strncpy(cfg->password, file_cfg.password, sizeof(cfg->password));cfg->password_prio = CFG_PRIO_CONFIG;cfg->debug_mode = cmd_cfg.debug_mode;return RESULT_OK;}static int reread_config(struct config *cfg, int *reinit_needed){int res_config_file;struct config file_cfg;*reinit_needed = 0;res_config_file = parse_config_file(&file_cfg, cfg->config_file);if(res_config_file != RESULT_OK) return res_config_file;if(file_cfg.password[0] == '\0')return print_error("Password is not set", NULL);/* save parsed values to general config */if(cfg->interface_prio >= CFG_PRIO_CONFIG && cfg->interface.s_addr != file_cfg.interface.s_addr){*reinit_needed = 1;cfg->interface = file_cfg.interface;cfg->interface_prio = CFG_PRIO_CONFIG;}if(cfg->port_prio >= CFG_PRIO_CONFIG && cfg->port != file_cfg.port && file_cfg.port) {*reinit_needed = 1;cfg->port = file_cfg.port;cfg->port_prio = CFG_PRIO_CONFIG;}if(check_abs_path(cfg->config_file) != RESULT_OK) return RESULT_ERROR;strncpy(cfg->password, file_cfg.password, sizeof(cfg->password));cfg->password_prio = CFG_PRIO_CONFIG;return RESULT_OK;}static int parse_interface(const char *s, char **end, struct in_addr *ip){char buf[MAX_CONFIG_LINE];int count;const char *c;c = s;count = 0;while(c[0] != '\0' && !isspace(c[0])) c++, count++;if(count > MAX_CONFIG_LINE) return RESULT_ERROR;strncpy(buf, s, count);buf[count] = '\0';c++;if(end) *end = (char *)c;if(inet_aton(buf, ip) == 1)return RESULT_OK;elsereturn RESULT_ERROR;}static int parse_cmd_line(struct config *cfg, int argc, const char* argv[]){char *end;int i;long port;memset(cfg, 0, sizeof(struct config));for(i = 1; i < argc; i++) {if(0 == strcmp(argv[i], PARAM_INTERFACE)) {if(cfg->interface.s_addr)return print_cmd_error(argc, argv, "Interface is already set", NULL);if(++i < argc) {if(parse_interface(argv[i], (char **)NULL, &cfg->interface) != RESULT_OK)return print_cmd_error(argc, argv,"Cannot parse interface", argv[i]);}else {return print_cmd_error(argc, argv, "Interface expected", NULL);}}else if(0 == strcmp(argv[i], PARAM_PORT)) {if(cfg->port)return print_cmd_error(argc, argv, "Port is already set", NULL);if(++i < argc) {port = strtol(argv[i], &end, 10);if(*end != '\0' || port < PORT_MIN || port > PORT_MAX)return print_cmd_error(argc, argv,"Port number must be integer between 1 and 65535", NULL);cfg->port = (ushort)port;}else {return print_cmd_error(argc, argv, "Port number expected", NULL);}}else if(0 == strcmp(argv[i], PARAM_CONFIG)) {if(cfg->config_file[0] != '\0')return print_cmd_error(argc, argv, "Config file name is already set", NULL);if(++i < argc) {strncpy(cfg->config_file, argv[i], FILENAME_MAX);if(cfg->config_file[FILENAME_MAX - 1] != '\0')return print_cmd_error(argc, argv,"Config file name is too long", NULL);}else {return print_cmd_error(argc, argv, "Config file name expected", NULL);}}else if(0 == strcmp(argv[i], PARAM_PID_FILE)) {if(cfg->pid_file[0] != '\0')return print_cmd_error(argc, argv, "PID file name is already set", NULL);if(++i < argc) {strncpy(cfg->pid_file, argv[i], FILENAME_MAX);if(cfg->pid_file[FILENAME_MAX - 1] != '\0')return print_cmd_error(argc, argv,"PID file name is too long", NULL);}else {return print_cmd_error(argc, argv, "PID file name expected", NULL);}}else if(0 == strcmp(argv[i], PARAM_DEBUG)) {cfg->debug_mode = 1;}else if(0 == strcmp(argv[i], PARAM_VERSION)) {print_version();return RESULT_EXIT;}else if(0 == strcmp(argv[i], PARAM_HELP_1) || 0 == strcmp(argv[i], PARAM_HELP_2)) {pring_usage(argc, argv);return RESULT_EXIT;}else {return print_cmd_error(argc, argv, "Unknown parameter", argv[i]);}}return RESULT_OK;}static int validate_equal_sign(const char *config_name, const int count, const char *line,uint name_len, char **subline){const char *c;c = line + name_len - 1;if('=' != c[0] && !isspace(c[0]))return print_config_error(config_name, count, "Unknown config parameter", line);while(c[0] != '\0' && isspace(c[0])) c++;if('=' != c[0])return print_config_error(config_name, count, "Equal sign expected", NULL);c++;if(subline) *subline = (char *)c;return RESULT_OK;}static int validate_eol(const char *config_name, const int count, const char *line){while(line[0] != '\0' && isspace(line[0])) line++;if('\0' != line[0] && '#' != line[0])return print_config_error(config_name, count, "End of line expected", NULL);return RESULT_OK;}static int extract_string_value(const char *config_name, const int count, char **subline, int must_quot,char *string, uint len){uint cur_len;int quot;while(*subline[0] != '\0' && isspace(*subline[0])) (*subline)++;if('"' == *subline[0]) {quot = 1;(*subline)++;}else {if(must_quot) {return print_config_error(config_name, count, "Open quot expected", NULL);}else {quot = 0;/* skip spaces if not quoted */while(*subline[0] != '\0' && isspace(*subline[0])) (*subline)++;}}cur_len = 0;while(*subline[0] != '\0'){if(cur_len >= len) return print_config_error(config_name, count, "Value too long", NULL);if(quot && *subline[0] == '"') break;if(!quot && isspace(*subline[0])) break;string[0] = *subline[0];string++;(*subline)++;cur_len++;}string[0] = '\0';if(quot) {if('"' != *subline[0])return print_config_error(config_name, count, "Close quot expected", NULL);(*subline)++;}return RESULT_OK;}static int parse_config_file(struct config *cfg, const char *config_name){FILE *config_file;char buf[MAX_CONFIG_LINE];char *line;char *subline;int count;uint len;long port;int res;memset(cfg, 0, sizeof(struct config));config_file = fopen(config_name, "r");if(!config_file)return print_error("Can not open config file", strerror(errno));count = 0;while(fgets(buf, sizeof(buf), config_file)) {count++;line = buf;/* skip end spaces */len = strlen(line);if(len == MAX_CONFIG_LINE-1)return print_config_error(config_name, count, "Line is too long", NULL);while(len && isspace(line[len-1])) --len;if(!len) continue;line[len] = '\0';/* skip begin spaces */while(line[0] != '\0' && isspace(line[0])) line++;if('#' == line[0]) { /* skip comment lines */continue;}else if(strncmp(line, CONFIG_INTERFACE, min(sizeof(CONFIG_INTERFACE) - 1, len)) == 0) {if((res = validate_equal_sign(config_name, count, line,sizeof(CONFIG_INTERFACE), &subline)) != RESULT_OK) return res;if(parse_interface(subline, &subline, &cfg->interface) != RESULT_OK)return print_config_error(config_name, count,"Cannot parse interface", NULL);if((res = validate_eol(config_name, count, subline)) != RESULT_OK) return res;}else if(strncmp(line, CONFIG_PORT, min(sizeof(CONFIG_PORT) - 1, len)) == 0) {if((res = validate_equal_sign(config_name, count, line, sizeof(CONFIG_PORT),&subline)) != RESULT_OK) return res;port = strtol(subline, &subline, 10);if(port < PORT_MIN || port > PORT_MAX)return print_config_error(config_name, count,"Port number must be integer between 1 and 65535", NULL);if((res = validate_eol(config_name, count, subline)) != RESULT_OK) return res;cfg->port = (ushort)port;}else if(strncmp(line, CONFIG_PASSWORD, min(sizeof(CONFIG_PASSWORD) - 1, len)) == 0) {if((res = validate_equal_sign(config_name, count, line,sizeof(CONFIG_PASSWORD), &subline)) != RESULT_OK) return res;if((res = extract_string_value(config_name, count, &subline, 1,cfg->password, sizeof(cfg->password))) != RESULT_OK) return res;if((res = validate_eol(config_name, count, subline)) != RESULT_OK) return res;}else if(strncmp(line, CONFIG_PID_FILE, min(sizeof(CONFIG_PID_FILE) - 1, len)) == 0) {if((res = validate_equal_sign(config_name, count, line,sizeof(CONFIG_PID_FILE), &subline)) != RESULT_OK) return res;if((res = extract_string_value(config_name, count, &subline, 0,cfg->pid_file, sizeof(cfg->pid_file))) != RESULT_OK) return res;if((res = validate_eol(config_name, count, subline)) != RESULT_OK) return res;}else {return print_config_error(config_name, count, "Unknown config parameter", line);}}if(ferror(config_file)) {print_error("Config file reading failed", strerror(errno));}if(fclose(config_file) != 0)return print_error("Can not close config file", strerror(errno));return RESULT_OK;}static int save_pid(const char *pid_file, const pid_t pid){int fd;FILE *file;if(!pid_file || pid_file[0] == '\0') return RESULT_OK;unlink(pid_file);fd = open(pid_file, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);if(fd < 0) {syslog(LOG_ERR, "Can open PID file %s for write: %s\n", pid_file, strerror(errno));return RESULT_ERROR;}file = fdopen(fd, "w");if(!file) {syslog(LOG_ERR, "Can open PID file %s for write: %s\n", pid_file, strerror(errno));return RESULT_ERROR;}if(fprintf(file, "%d\n", pid) < 0) {syslog(LOG_ERR, "Can write PID to file %s: %s\n", pid_file, strerror(errno));return RESULT_ERROR;}if(fclose(file) != 0) {syslog(LOG_ERR, "Can not close PID file %s: %s\n", pid_file, strerror(errno));return RESULT_UNEXPECTED;}return RESULT_OK;}static int create_child(int soc){pid_t child;child = fork();if(child == -1) {fprintf(stderr, "Cannot fork: %s\n", strerror(errno));return RESULT_UNEXPECTED; /* an unexpected error */}else if(child > 0) {if(close(soc) != 0) {fprintf(stderr, "Cannot close socket: %s\n", strerror(errno));return RESULT_UNEXPECTED; /* an unexpected error */}return RESULT_EXIT; /* we are the parent */}else {return RESULT_OK; /* we are the child */}}static int close_descr(int d){if(close(d) != 0) {syslog(LOG_ERR, "Cannot close descriptor %d: %s\n", d, strerror(errno));return RESULT_UNEXPECTED;}return RESULT_OK;}static void delete_pid_file(void){if(global_cfg.pid_file && global_cfg.pid_file[0] != '\0') {if(unlink(global_cfg.pid_file) != 0) {syslog(LOG_ERR, "Cannot delete PID file %s: %s\n",global_cfg.pid_file, strerror(errno));}}}static void reconfig_signal(void){syslog(LOG_INFO, "reconfig");reconfig_required = 1;}static void quit_signal(void){syslog(LOG_WARNING, "quit");quit_required = 1;}static void signal_handler(int sig){int saved_errno = errno;switch(sig) {case SIGHUP:reconfig_signal();break;case SIGINT:case SIGTERM:case SIGQUIT:quit_signal();break;}errno = saved_errno;}static int init_signal_handler(int sig){struct sigaction sa;sa.sa_flags = 0;sa.sa_handler = signal_handler;sigemptyset(&sa.sa_mask);if(sigaction(sig, &sa, (struct sigaction *)NULL) != 0) {syslog(LOG_ERR, "Cannot register handler for signal %d: %s\n", sig, strerror(errno));return RESULT_UNEXPECTED;}return RESULT_OK;}static int init_signals(void){if(init_signal_handler(SIGHUP) != RESULT_OK) return RESULT_UNEXPECTED;if(init_signal_handler(SIGINT) != RESULT_OK) return RESULT_UNEXPECTED;if(init_signal_handler(SIGTERM) != RESULT_OK) return RESULT_UNEXPECTED;if(init_signal_handler(SIGQUIT) != RESULT_OK) return RESULT_UNEXPECTED;return RESULT_OK;}static void check_return(int res){if(daemonized && res != RESULT_OK) {delete_pid_file();syslog(LOG_WARNING, "quit");}switch(res) {case RESULT_EXIT: exit(EXIT_OK); return; /* no error but exit */case RESULT_ERROR: exit(EXIT_USER_ERROR); return; /* user error */case RESULT_UNEXPECTED: exit(EXIT_UNEXPECTED); return; /* unexpected error */}}int main(int argc, const char* argv[]){int soc;int reinit_needed;/* get config */check_return(read_config(&global_cfg, argc, argv));/* try to listen the port */if((soc = establish(&global_cfg)) < 0) {fprintf(stderr, "Cannot listen to port %i\n", global_cfg.port);return EXIT_USER_ERROR;}/* fork and release the console */check_return(create_child(soc));/* continue as first child */if(setsid() == -1) {fprintf(stderr, "Cannot create session: %s\n", strerror(errno));return EXIT_UNEXPECTED;}/* fork the second time */check_return(create_child(soc));/* continue as final child */if(init_signals() != RESULT_OK) return EXIT_UNEXPECTED;if(chdir("/") < 0) {fprintf(stderr, "Cannot chdir to /: %s\n", strerror(errno));return EXIT_UNEXPECTED;}umask(0);check_return(save_pid(global_cfg.pid_file, getpid()));daemonized = 1;/* from now do not use console for error output */if(close_descr(0) != RESULT_OK) return EXIT_UNEXPECTED;if(close_descr(1) != RESULT_OK) return EXIT_UNEXPECTED;if(close_descr(2) != RESULT_OK) return EXIT_UNEXPECTED;for(;;) {syslog(LOG_INFO, "listen on %d", global_cfg.port);listen_socket(&global_cfg, soc);if(quit_required) {break;}else if(reconfig_required) {reconfig_required = 0;check_return(reread_config(&global_cfg, &reinit_needed));if(reinit_needed) {close(soc);if((soc = establish(&global_cfg)) < 0) {syslog(LOG_ERR, "Cannot listen to port %i\n", global_cfg.port);check_return(RESULT_ERROR);}}}}delete_pid_file();return EXIT_OK;}