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/* vi: set sw=4 ts=4: */
/*
* Fake identd server.
*
* Copyright (C) 2007 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config FAKEIDENTD
//config: bool "fakeidentd (8.7 kb)"
//config: default y
//config: select FEATURE_SYSLOG
//config: help
//config: fakeidentd listens on the ident port and returns a predefined
//config: fake value on any query.
//applet:IF_FAKEIDENTD(APPLET(fakeidentd, BB_DIR_USR_SBIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_FAKEIDENTD) += isrv_identd.o isrv.o
//usage:#define fakeidentd_trivial_usage
//usage: "[-fiw] [-b ADDR] [STRING]"
//usage:#define fakeidentd_full_usage "\n\n"
//usage: "Provide fake ident (auth) service\n"
//usage: "\n -f Run in foreground"
//usage: "\n -i Inetd mode"
//usage: "\n -w Inetd 'wait' mode"
//usage: "\n -b ADDR Bind to specified address"
//usage: "\n STRING Ident answer string (default: nobody)"
#include "libbb.h"
#include "common_bufsiz.h"
#include <syslog.h>
#include "isrv.h"
enum { TIMEOUT = 20 };
typedef struct identd_buf_t {
int pos;
char buf[64 - sizeof(int)];
} identd_buf_t;
#define bogouser bb_common_bufsiz1
static int new_peer(isrv_state_t *state, int fd)
{
int peer;
identd_buf_t *buf = xzalloc(sizeof(*buf));
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 */
ndelay_on(fd);
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;
cur = buf->buf + buf->pos;
sz = safe_read(fd, cur, sizeof(buf->buf) - 1 - buf->pos);
if (sz < 0) {
if (errno != EAGAIN)
goto term;
return 0; /* "session is ok" */
}
buf->pos += sz;
buf->buf[buf->pos] = '\0';
p = strpbrk(cur, "\r\n");
if (p)
*p = '\0';
if (!p && sz)
return 0; /* "session is ok" */
/* Terminate session. If we are in server mode, then
* fd is still in nonblocking mode - we never block here */
if (fd == 0)
fd++; /* inetd mode? then write to fd 1 */
fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
/*
* Why bother if we are going to close fd now anyway?
* if (server)
* ndelay_off(fd);
*/
term:
free(buf);
return 1; /* "terminate" */
}
static int do_timeout(void **paramp UNUSED_PARAM)
{
return 1; /* terminate session */
}
static void inetd_mode(void)
{
identd_buf_t *buf = xzalloc(sizeof(*buf));
/* buf->pos = 0; - xzalloc did it */
do
alarm(TIMEOUT);
/* Note: we do NOT want nonblocking I/O here! */
while (do_rd(0, (void*)&buf) == 0);
}
int fakeidentd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int fakeidentd_main(int argc UNUSED_PARAM, char **argv)
{
enum {
OPT_foreground = 0x1,
OPT_inetd = 0x2,
OPT_inetdwait = 0x4,
OPT_fiw = 0x7,
OPT_bindaddr = 0x8,
};
const char *bind_address = NULL;
unsigned opt;
int fd;
setup_common_bufsiz();
opt = getopt32(argv, "fiwb:", &bind_address);
strcpy(bogouser, "nobody");
if (argv[optind])
strncpy(bogouser, argv[optind], COMMON_BUFSIZE - 1);
/* Daemonize if no -f and no -i and no -w */
if (!(opt & OPT_fiw))
bb_daemonize_or_rexec(0, argv);
/* Where to log in inetd modes? "Classic" inetd
* probably has its stderr /dev/null'ed (we need log to syslog?),
* but daemontools-like utilities usually expect that children
* log to stderr. I like daemontools more. Go their way.
* (Or maybe we need yet another option "log to syslog") */
if (!(opt & OPT_fiw) /* || (opt & OPT_syslog) */) {
openlog(applet_name, LOG_PID, LOG_DAEMON);
logmode = LOGMODE_SYSLOG;
}
if (opt & OPT_inetd) {
inetd_mode();
return 0;
}
/* Ignore closed connections when writing */
signal(SIGPIPE, SIG_IGN);
fd = 0;
if (!(opt & OPT_inetdwait)) {
fd = create_and_bind_stream_or_die(bind_address,
bb_lookup_std_port("identd", "tcp", 113));
xlisten(fd, 5);
}
isrv_run(fd, new_peer, do_rd, /*do_wr:*/ NULL, do_timeout,
TIMEOUT, (opt & OPT_inetdwait) ? TIMEOUT : 0);
return 0;
}
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