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/*
* server/main.c
*/
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <syslog.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "dnbd2.h"
#include "tree.h"
#include "file.h"
#include "config.h"
#include "query.h"
char *cfile = NULL; /* path to config file */
void *tree = NULL; /* tree containing datasets */
int server_fd; /* file descriptor for UPD communication */
struct sockaddr_in server_addr;
/*
* Flags and signal handlers.
*/
int sig_exit, sig_config;
void exit_handler(int sig);
void config_handler(int sig);
/*
* Function to configure server. We call it with LOAD on
* initialization and with RELOAD when SIGHUP is caught.
*/
enum config_action { LOAD, RELOAD };
int configure(enum config_action action);
void print_usage(void);
int daemon_init(void);
int main(int argc, char **argv)
{
int ret;
ssize_t n;
socklen_t len;
dnbd2_data_reply_t reply;
dnbd2_data_request_t request;
struct sockaddr_in client_addr;
struct sigaction exit_act, config_act;
if (argc != 2) {
print_usage();
return -1;
}
cfile = argv[1];
openlog(argv[0], LOG_PID, LOG_LOCAL2);
syslog(LOG_NOTICE, "Starting DNBD2 Server.");
/* Load datasets and bind to socket. */
if (configure(LOAD) == -1)
goto out_no_start;
/* Daemonize. */
ret = daemon_init();
if (ret == -1) {
syslog(LOG_ERR, "Could not fork and background.");
goto out_no_start;
}
/* Setup signal handlers. */
sigaction(SIGTERM, NULL, &exit_act);
exit_act.sa_flags &= ~SA_RESTART;
exit_act.sa_handler = exit_handler;
sigaction(SIGHUP, NULL, &config_act);
config_act.sa_flags &= ~SA_RESTART;
config_act.sa_handler = config_handler;
sigaction(SIGTERM, &exit_act, NULL);
sigaction(SIGINT, &exit_act, NULL);
sigaction(SIGHUP, &config_act, NULL);
while (1) {
if (sig_exit) {
syslog(LOG_NOTICE, "Stopping Server.");
exit(0);
}
if (sig_config) {
syslog(LOG_NOTICE, "Reloading configuration.");
if (configure(RELOAD) == -1)
syslog(LOG_ERR, "Not using new configuration.");
sig_config = 0;
}
/* Receive request. */
len = sizeof(client_addr);
n = recvfrom(server_fd, &request, sizeof(request), 0,
&client_addr, &len);
if (n == -1 || n != sizeof(request))
continue;
/* Process request. */
ret = handle_query(&request, &reply, &tree);
if (ret == -1)
continue;
/* Send reply. */
sendto(server_fd, &reply, sizeof(reply), 0, &client_addr, len);
}
return 0;
out_no_start:
syslog(LOG_ERR, "Server not started.");
fprintf(stderr, "Server not started - "
"consult your syslog for errors.\n");
return -1;
}
void config_handler(int sig)
{
sig_config = 1;
}
void exit_handler(int sig)
{
sig_exit = 1;
}
int cmp_addr(struct sockaddr_in addr1, struct sockaddr_in addr2)
{
int diff = memcmp(&addr1.sin_addr.s_addr,
&addr2.sin_addr.s_addr,
sizeof(in_addr_t));
if (diff)
return diff;
return memcmp(&addr1.sin_port,
&addr2.sin_port,
sizeof(in_port_t));
}
int configure(enum config_action action)
{
void *tmp_tree = NULL;
int datasets, ret, tmp_fd = server_fd;
struct sockaddr_in tmp_addr;
datasets = parse_config_file(cfile, &tmp_addr, &tmp_tree);
if (datasets <= 0)
return -1;
/* Create a socket and bind to it. */
if (action == LOAD || cmp_addr(tmp_addr, server_addr)) {
tmp_fd = socket(PF_INET, SOCK_DGRAM, 0);
if (tmp_fd == -1) {
syslog(LOG_ERR, "Could not create socket.");
return -1;
}
ret = bind(tmp_fd, (struct sockaddr *) &tmp_addr,
sizeof(tmp_addr));
if (ret == -1) {
close(tmp_fd);
syslog(LOG_ERR, "Could not assign name to socket.");
return -1;
}
}
/* Make new socket available and close the old one if necesary. */
if (action == RELOAD && cmp_addr(tmp_addr, server_addr)) {
if (close(server_fd) == -1 ) {
syslog(LOG_ERR, "Could not close socket.");
}
}
server_fd = tmp_fd;
server_addr = tmp_addr;
tree_destroy(tree);
tree = tmp_tree;
return 0;
}
void print_usage(void)
{
printf("usage: dnbd2-dserver config-file\n");
}
int daemon_init(void)
{
pid_t pid = fork();
if (pid == -1)
return pid;
if (pid != 0) {
/* We are the parent. */
exit(0);
}
/* We are the child. */
setsid();
chdir("/");
umask(0);
return 0;
}
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