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ru.unix.bsd
- RU.UNIX.BSD ------------------------------------------------------------------
From : Vadim Goncharov 2:5020/400 17 Oct 2005 23:49:28
To : Valentin Davydov
Subject : Re: discard server
--------------------------------------------------------------------------------
Hi Valentin Davydov!
On Mon, 17 Oct 2005 15:53:58 +0000 (UTC); Valentin Davydov wrote about 'discard
server':
VD> Посоветуйте сабж, пожалуйста. Задача - принимать tcp соединения по некоему
VD> порту (например, 9), все приходящие данные дропать, в ответ кроме ackов
VD> ничего не посылать, по стандартному таймауту штатно закрывать соединения.
VD> При этом чтобы жрало как можно меньше ресурсов, в идеале - только таблицы
VD> ядерного tcp/ip стека. Пробовал inetd с его встроенным сервисом, так он
VD> нафоркал несколько сотен потомков и скис. Можно, конечно, thttpd взять,
VD> но нет ли чего попроще, специально для этой цели?
Вот сейчас наваял, жрать должен минимум (естественно, я его проверил
толко на маленьких нагрзках). Таймауты - только SO_KEEPALIVE, нормальные
лень было делать.
>=== begin discard.c ===
/* Simple discard server (c) Vadim Goncharov, 2005.
* Covered by BSD license, no warranty, etc.
*/
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <sys/time.h>
#include <time.h>
#include <sys/stat.h>
#include <strings.h>
#define DISCARDPORTNUM 9
#define BUFSIZE 4096
#define BYTE unsigned char
/* Global vars */
unsigned int listening_port; /* Port on which we listen for connections */
int listening_socket; /* Socket for incoming connections from clients */
BYTE debug; /* 1 for debug mode, else 0 */
int max_sockets; /* max number of clients we can serve */
BYTE quit; /* 1 if time to break endless loop and quit */
fd_set mainset; /* Clients are remebered here */
BYTE buf[BUFSIZE]; /* Dummy input buffer data */
void term_signal(int z)
{
quit = 1;
}
void quit_program(void)
{
int i;
close(listening_socket);
for (i=0; i < max_sockets; i++)
if (FD_ISSET(i, &mainset))
shutdown(i, SHUT_RDWR);
}
void init_sig(void)
{
struct sigaction sv;
memset(&sv, 0, sizeof(struct sigaction));
sv.sa_flags = 0;
sigemptyset(&sv.sa_mask);
#ifdef SA_NOCLDWAIT
sv.sa_flags |= SA_NOCLDWAIT;
#endif
#ifdef SA_NOCLDSTOP
sv.sa_flags |= SA_NOCLDSTOP;
#endif
sv.sa_handler = SIG_IGN;
/* Don't want broken pipes to kill the server. */
sigaction(SIGPIPE, &sv, NULL);
/* ...or any defunct child processes. */
sigaction(SIGCHLD, &sv, NULL);
if (debug == 0) /* For daemon safety SIGHUP shouldn't kill us. */
sigaction(SIGHUP, &sv, NULL);
sv.sa_handler = term_signal;
/* Also, shut down properly. */
sigaction(SIGTERM, &sv, NULL);
sigaction(SIGINT, &sv, NULL);
}
int sock_nonblock(int sock)
{
int flags;
if ((flags = fcntl(sock, F_GETFL, 0)) < 0) {
return -1;
}
/* Non blocking mode */
if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) {
return -1;
}
return 0;
}
int get_listening_socket(int port, int set_to_localhost)
{
int sock;
int yes = 1;
struct sockaddr_in serv_addr;
if(port == 0)
return -1;
memset (&serv_addr, 0, sizeof(struct sockaddr_in));
/* Create socket */
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
return -1;
}
/* Fix the address already in use error */
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &yes,
sizeof(int)) == -1)
{
return -1;
}
memset(&serv_addr, 0, sizeof(struct sockaddr_in));
serv_addr.sin_family = AF_INET;
if (set_to_localhost) {
inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr);
} else {
serv_addr.sin_addr.s_addr = INADDR_ANY;
}
serv_addr.sin_port = htons(port);
/* Bind socket to port */
if (bind(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) == -1) {
return -1;
}
/* Listen on socket */
if (listen(sock, 100) == -1) {
return -1;
}
/* Put socket into non-blocking mode */
if (sock_nonblock(sock) == -1) {
return -1;
}
return(sock);
}
void do_read(int fd)
{
int n, looping;
time_t curtime;
looping = 1;
curtime = time(NULL); /* read from one client for no more than 1 sec */
while ((looping) && (time(NULL) <= curtime)) {
/* function central read */
n = read(fd, buf, BUFSIZE);
if (n > 0) {
continue;
}
if (n == -1) { /* an error has occured */
if (errno == EINTR) {
if (time(NULL) > curtime) {
looping = 0;
}
continue;
}
looping = 0;
if (errno != EAGAIN) {
if (debug)
printf("Error - In do_read()/read() for fd=%d: %s\n", fd, strerror(errno));
}
}
if (n == 0) { /* connection closed */
if (debug)
printf("Client with fd=%d closed connection\n", fd);
looping = 0;
/* close client and forget about it */
FD_CLR(fd, &mainset);
shutdown(fd, SHUT_RDWR);
}
}
}
void get_socket_action(void)
{
struct sockaddr_in client;
int clilen;
int yes = 1;
fd_set fds;
struct timeval tv;
int i, nfds, maxfd;
time_t curtime;
tv.tv_sec = 1;
tv.tv_usec = 0;
FD_ZERO(&fds);
maxfd = listening_socket;
/* Add our listening tcp socket to the set... */
if (listening_socket != -1)
FD_SET(listening_socket, &fds);
/* ... and the established client connections */
for (i=0; i < max_sockets; i++)
if (FD_ISSET(i, &mainset)) { /* check in loop for setting maxfd */
FD_SET(i, &fds);
if (i > maxfd)
maxfd = i;
}
/* The very central select, where the program should spend most of its time
*/
nfds = select(maxfd+1, &fds, NULL, NULL, &tv);
if (nfds <= 0) {
if ((nfds < 0) && (errno != EINTR)) {
if (debug) {
printf("Error - In get_socket_action()/select(read): %s\n",
strerror(errno));
}
}
return;
}
/* Check if it's a new connection */
if (FD_ISSET(listening_socket, &fds) && (nfds > 0)) {
nfds--;
curtime = time(NULL);
clilen = sizeof(client);
do {
i = accept(listening_socket, (struct sockaddr *)&client, &clilen);
if (i > 0)
break;
else
if ((errno == EAGAIN) || (errno == ECONNABORTED))
goto check_input;
} while ((time(NULL) > curtime) && (errno == EINTR));
if (i < 0) {
if (debug) {
printf("accept() error: %s\n", strerror(errno));
}
goto check_input;
}
/* Put socket into non-blocking mode */
if (sock_nonblock(i) == -1) {
/* can't make socket nonblocking */
close(i);
goto check_input;
}
/* Avoid dead peers */
if (setsockopt(i, SOL_SOCKET, SO_KEEPALIVE, &yes, sizeof(int)) == -1) {
close(i);
goto check_input;
}
/* new user accepted */
FD_SET(i, &mainset);
if (debug)
printf("New client connected, fd=%d\n", i);
}
check_input:
/* Do input from all clients */
i = 0;
while ((i < max_sockets) && (nfds > 0)) {
if (FD_ISSET(i, &fds)) {
nfds--;
do_read(i);
}
i++;
}
}
int main(int argc, char *argv[])
{
int fd;
int erret;
int x;
int pid;
/* init vars */
listening_port = DISCARDPORTNUM;
max_sockets = getdtablesize();
if(max_sockets > FD_SETSIZE)
max_sockets = FD_SETSIZE;
listening_socket = -1;
debug = 0;
quit = 0;
FD_ZERO(&mainset);
/* prepare server */
if ((listening_socket = get_listening_socket(listening_port, 0)) == -1)
{
printf("Bind failed.\nRemember, to use a listening port below 1024, you need
to be root.\nAlso, make sure that you don't have another instance of the
program\nalready running.\n");
return 1;
}
if ((argc > 1) && ((strcmp(argv[1], "-d")) == 0))
debug = 1;
init_sig();
if (debug == 0)
{
/* Make program a daemon */
pid = fork();
if (pid < 0)
{
perror("fork");
exit(EXIT_FAILURE);
}
if (pid > 0)
exit(EXIT_SUCCESS);
if (setsid() < 0)
{
perror("setsid");
exit(EXIT_FAILURE);
}
pid = fork();
if (pid > 0) /* ensure we can't regain control tty */
exit(EXIT_SUCCESS);
else if (pid < 0)
exit(EXIT_FAILURE);;
chdir("/");
umask(0);
for (x = 0; x <= 2; x++)
{
if (close(x) != 0)
{
printf("Error - When closing fd=%d while daemonizing, exiting\n",
x);
exit(EXIT_FAILURE);
}
}
fd = open("/dev/null", O_RDWR);
if (fd >= 0)
{
erret = dup2(fd, 1);
erret = dup2(fd, 2);
}
}
if (debug) {
printf("Discrad server is up and running in debug mode\n");
}
/* Main server I/O loop. */
while (quit == 0)
{
get_socket_action();
}
quit_program();
return 0;
}
>=== end discard.c ===
--
WBR, Vadim Goncharov. ICQ#166852181 mailto:vadim_nuclight@mail.ru
[Moderator of RU.ANTI-ECOLOGY][FreeBSD][http://antigreen.org][LJ:/nuclight]
--- slrn/0.9.8.1 on FreeBSD 4.11/i386
* Origin: Nuclear Lightning @ Tomsk, TPU AVTF Hostel (2:5020/400@fidonet)
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