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/******************************************************************
*
* Daemon which waiting on specified TCP port for special string
* and reboot the computer.
*
* Command line: rebootdaemon [--port PORT] [--config CONFIG_FILE]
* Defaults are port 19 and config /etc/rebootdaemon.conf.
*
* Config file looks like:
* --------------------------
* port=19
* password="some password"
* --------------------------
*
* Usage example (from any other host):
* echo -n "some password" | nc host_to_rebot 19
*
* Copyleft 2005 Anatoli Klassen
*
******************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <netdb.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/reboot.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define PORT 19
#define CFG_FILE "/etc/rebootdaemon.conf"
#define CMDSIZE 4096
#define BUFSIZE 4096
#define MAX_CONFIG_LINE 4096
#define PORT_MIN 1
#define PORT_MAX 65535
#define PARAM_PORT_1 "-p"
#define PARAM_PORT_2 "--port"
#define PARAM_CONFIG_1 "-c"
#define PARAM_CONFIG_2 "--config"
#define CONFIG_PORT "port"
#define CONFIG_PASSWORD "password"
struct config {
int port;
char password[MAX_CONFIG_LINE];
};
static struct config cfg;
static int parse_cmd_line(int argc, char* argv[], long *port, char *config_name);
static int parse_config_file(char *config_name, long *port, char *password);
static int min(int a, int b)
{
return (a < b) ? a : b;
}
static int establish(unsigned short portnum)
{
int s;
struct sockaddr_in sa;
memset(&sa, 0, sizeof(struct sockaddr_in));
sa.sin_family = AF_INET;
sa.sin_port = htons(portnum);
sa.sin_addr.s_addr = INADDR_ANY;
if((s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
return -1;
if(bind(s, (struct sockaddr *)&sa, sizeof(struct sockaddr_in)) < 0) {
close(s);
return -1;
}
listen(s, 1);
return s;
}
static int print_cmd_error(char *msg, char *value)
{
fprintf(stderr, "%s", msg);
if(value) fprintf(stderr, " - %s\n", value);
fprintf(stderr, "\n");
return 0;
}
static int print_config_error(char *config_name, int line, char *msg, char *value)
{
fprintf(stderr, "Error in %s, line %d: %s", config_name, line, msg);
if(value) fprintf(stderr, " - %s", value);
fprintf(stderr, "\n");
return 0;
}
static int read_config(int argc, char* argv[])
{
long cmd_port;
long file_port;
char cmd_config[MAX_CONFIG_LINE];
if(!parse_cmd_line(argc, argv, &cmd_port, cmd_config)) return 0;
if(!parse_config_file(cmd_config[0] != '\0' ? cmd_config : CFG_FILE, &file_port, cfg.password)) return 0;
if(cfg.password[0] == '\0') {
fprintf(stderr, "Password is not set\n");
return 0;
}
if(cmd_port > 0)
cfg.port = (int)cmd_port;
else if(file_port > 0)
cfg.port = (int)file_port;
else
cfg.port = PORT;
return 1;
}
static int parse_cmd_line(int argc, char* argv[], long *port, char *config_name)
{
char *end;
int i;
*port = 0;
config_name[0] = '\0';
for(i = 1; i < argc; i++) {
if(0 == strcmp(argv[i], PARAM_PORT_1) || 0 == strcmp(argv[i], PARAM_PORT_2)) {
if(*port > 0)
return print_cmd_error("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("Port number must be integer between 1 and 65535", NULL);
}
else {
return print_cmd_error("Port number expected", NULL);
}
}
else if(0 == strcmp(argv[i], PARAM_CONFIG_1) || 0 == strcmp(argv[i], PARAM_CONFIG_2)) {
if(config_name[0] != '\0')
return print_cmd_error("Config file is already set", NULL);
if(++i < argc) {
strncpy(config_name, argv[i], MAX_CONFIG_LINE);
if(config_name[MAX_CONFIG_LINE - 1] != '\0')
return print_cmd_error("Config file name is too long", NULL);
}
else {
return print_cmd_error("Config file expected", NULL);
}
}
else {
return print_cmd_error("Unknown parameter", argv[i]);
}
}
return 1;
}
static int parse_config_file(char *config_name, long *port, char *password)
{
FILE *config_file;
char buf[MAX_CONFIG_LINE];
char *line;
char *subline;
char *cur;
int count;
config_file = fopen(config_name, "r");
if(!config_file) {
fprintf(stderr, "Can not open config file %s: %s\n", config_name, strerror(errno));
return 0;
}
count = 0;
while(fgets(buf, sizeof(buf), config_file)) {
count++;
line = buf;
/* skip end spaces */
int len = strlen(line);
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_PORT, min(sizeof(CONFIG_PORT) - 1, len)) == 0) {
subline = line + sizeof(CONFIG_PORT) - 1;
while(subline[0] != '\0' && isspace(subline[0])) subline++;
if('=' != subline[0])
return print_config_error(config_name, count, "Equal sign expected", NULL);
subline++;
*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);
while(subline[0] != '\0' && isspace(subline[0])) subline++;
if('\0' != subline[0] && '#' != subline[0])
return print_config_error(config_name, count, "End of line expected", NULL);
}
else if(strncmp(line, CONFIG_PASSWORD, min(sizeof(CONFIG_PASSWORD) - 1, len)) == 0) {
subline = line + sizeof(CONFIG_PASSWORD) - 1;
while(subline[0] != '\0' && isspace(subline[0])) subline++;
if('=' != subline[0])
return print_config_error(config_name, count, "Equal sign expected", NULL);
subline++;
while(subline[0] != '\0' && isspace(subline[0])) subline++;
if('"' != subline[0])
return print_config_error(config_name, count, "Open quot expected", NULL);
subline++;
cur = password;
while(subline[0] != '\0' && subline[0] != '"') {
cur[0] = subline[0];
cur++;
subline++;
}
cur[0] = '\0';
if('"' != subline[0])
return print_config_error(config_name, count, "Close quot expected", NULL);
subline++;
while(subline[0] != '\0' && isspace(subline[0])) subline++;
if('\0' != subline[0] && '#' != subline[0])
return print_config_error(config_name, count, "End of line expected", NULL);
}
else {
return print_config_error(config_name, count, "Unknown config parameter", line);
}
}
if(fclose(config_file) != 0) {
fprintf(stderr, "Can not close config file %s: %s\n", config_name, strerror(errno));
return 0;
}
return 1;
}
int main(int argc, char* argv[])
{
int s, t;
char cmd[CMDSIZE];
char buf[BUFSIZE];
char* msg;
int br;
struct sockaddr_in sa;
socklen_t sa_len;
if(!read_config(argc, argv)) return 1;
if((s = establish(cfg.port)) < 0) {
fprintf(stderr, "Cannot listen to port %i\n", cfg.port);
return 1;
}
for(;;) {
sa_len = sizeof(sa);
if((t = accept(s, (struct sockaddr *)&sa, &sa_len)) < 0) {
if(errno == EINTR) /* EINTR might happen on accept(), */
continue; /* try again */
msg = strerror(errno);
syslog(LOG_ERR, "cannot get connection, %s", msg);
continue;
}
msg = inet_ntoa(sa.sin_addr);
syslog(LOG_INFO, "connect from %s", msg);
cmd[0] = '\0';
while((br = recv(t, buf, BUFSIZE, 0)) > 0) {
strncat(cmd, buf, min(br, sizeof(cmd) - strlen(cmd) - 1));
}
sleep(1);
close(t);
syslog(LOG_INFO, "got command [%s]", cmd);
if(0 == strncmp(cmd, cfg.password, sizeof(cmd))) {
syslog(LOG_EMERG, "REBOOT");
sleep(5);
if(reboot(RB_AUTOBOOT) < 0) {
msg = strerror(errno);
syslog(LOG_ERR, "cannot reboot, %s", msg);
}
}
}
return 0;
}