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/* vi: set sw=4 ts=4: */
/*
* Fake identd server.
*
* Copyright (C) 2007 Denis Vlasenko
*
* Licensed under GPL version 2, see file LICENSE in this tarball for details.
*/
#include <syslog.h>
#include "busybox.h"
#include "isrv.h"
enum { TIMEOUT = 20 };
/* Why use alarm(TIMEOUT-1)?
* isrv's internal select() will run with timeout=TIMEOUT.
* If nothing happens during TIMEOUT-1 seconds (no accept/read),
* then ALL sessions timed out by now. Instead of closing them one-by-one
* (isrv calls do_timeout for each 'stale' session),
* SIGALRM triggered by alarm(TIMEOUT-1) will kill us, terminating them all.
*/
typedef struct identd_buf_t {
int pos;
int fd_flag;
char buf[64 - 2*sizeof(int)];
} identd_buf_t;
static const char *bogouser = "nobody";
static int new_peer(isrv_state_t *state, int fd)
{
int peer;
identd_buf_t *buf = xzalloc(sizeof(*buf));
alarm(TIMEOUT - 1);
peer = isrv_register_peer(state, buf);
if (peer < 0)
return 0; /* failure */
if (isrv_register_fd(state, peer, fd) < 0)
return peer; /* failure, unregister peer */
buf->fd_flag = fcntl(fd, F_GETFL, 0) | O_NONBLOCK;
isrv_want_rd(state, fd);
return 0;
}
static int do_rd(int fd, void **paramp)
{
identd_buf_t *buf = *paramp;
char *cur, *p;
int sz;
alarm(TIMEOUT - 1);
cur = buf->buf + buf->pos;
fcntl(fd, F_SETFL, buf->fd_flag | O_NONBLOCK);
sz = safe_read(fd, cur, sizeof(buf->buf) - buf->pos);
if (sz < 0) {
if (errno != EAGAIN)
goto term; /* terminate this session if !EAGAIN */
goto ok;
}
buf->pos += sz;
buf->buf[buf->pos] = '\0';
p = strpbrk(cur, "\r\n");
if (p)
*p = '\0';
if (p || !sz || buf->pos == sizeof(buf->buf)) {
/* fd is still in nonblocking mode - we never block here */
fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
goto term;
}
ok:
fcntl(fd, F_SETFL, buf->fd_flag & ~O_NONBLOCK);
return 0;
term:
fcntl(fd, F_SETFL, buf->fd_flag & ~O_NONBLOCK);
free(buf);
return 1;
}
static int do_timeout(void **paramp)
{
return 1; /* terminate session */
}
static void inetd_mode(void)
{
identd_buf_t *buf = xzalloc(sizeof(*buf));
/* We do NOT want nonblocking I/O here! */
buf->fd_flag = fcntl(0, F_GETFL, 0);
while (do_rd(0, (void*)&buf) == 0) /* repeat */;
}
int fakeidentd_main(int argc, char **argv)
{
enum {
OPT_foreground = 0x1,
OPT_inetd = 0x2,
OPT_inetdwait = 0x4,
OPT_nodeamon = 0x7,
OPT_bindaddr = 0x8,
};
const char *bind_address = NULL;
unsigned opt;
int fd;
opt = getopt32(argc, argv, "fiwb:", &bind_address);
if (optind < argc)
bogouser = argv[optind];
/* Daemonize if no -f or -i or -w */
bb_sanitize_stdio(!(opt & OPT_nodeamon));
if (!(opt & OPT_nodeamon)) {
openlog(applet_name, 0, LOG_DAEMON);
logmode = LOGMODE_SYSLOG;
}
if (opt & OPT_inetd) {
inetd_mode();
return 0;
}
/* Ignore closed connections when writing */
signal(SIGPIPE, SIG_IGN);
if (opt & OPT_inetdwait) {
fd = 0;
} else {
fd = create_and_bind_stream_or_die(bind_address,
bb_lookup_port("identd", "tcp", 113));
xlisten(fd, 5);
}
isrv_run(fd, new_peer, do_rd, NULL, do_timeout, TIMEOUT, 1);
return 0;
}
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