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import fakeidentd module started by Thomas Lundquist

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This commit is contained in:
Mike Frysinger 2005-04-17 07:24:19 +00:00
parent 77dbe738d2
commit fa69f110d9
5 changed files with 459 additions and 0 deletions
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3
include/applets.h
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@ -185,6 +185,9 @@
#ifdef CONFIG_EXPR #ifdef CONFIG_EXPR
APPLET(expr, expr_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER) APPLET(expr, expr_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
#endif #endif
#ifdef CONFIG_FAKEIDENTD
APPLET(fakeidentd, fakeidentd_main, _BB_DIR_USR_SBIN, _BB_SUID_NEVER)
#endif
#ifdef CONFIG_FALSE #ifdef CONFIG_FALSE
APPLET(false, false_main, _BB_DIR_BIN, _BB_SUID_NEVER) APPLET(false, false_main, _BB_DIR_BIN, _BB_SUID_NEVER)
#endif #endif

7
include/usage.h
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@ -575,6 +575,13 @@
"\\( and \\) or null; if \\( and \\) are not used, they return the number \n" \ "\\( and \\) or null; if \\( and \\) are not used, they return the number \n" \
"of characters matched or 0." "of characters matched or 0."
#define fakeidentd_trivial_usage \
"[-b ip] [STRING]"
#define fakeidentd_full_usage \
"Returns a set string to auth requests\n\n"\
"\t-b\tBind to ip address\n"\
"\tSTRING\tThe ident answer string (default is nobody)"
#define false_trivial_usage \ #define false_trivial_usage \
"" ""
#define false_full_usage \ #define false_full_usage \

7
networking/Config.in
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@ -18,6 +18,13 @@ config CONFIG_ARPING
help help
Ping hosts by ARP packets Ping hosts by ARP packets
config CONFIG_FAKEIDENTD
bool "fakeidentd"
default n
help
fakeidentd listens to the ident port and returns a set fake
value whatever it gets.
config CONFIG_FTPGET config CONFIG_FTPGET
bool "ftpget" bool "ftpget"
default n default n

1
networking/Makefile.in
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@ -24,6 +24,7 @@ endif
srcdir=$(top_srcdir)/networking srcdir=$(top_srcdir)/networking
NETWORKING-y:= NETWORKING-y:=
NETWORKING-$(CONFIG_ARPING) += arping.o NETWORKING-$(CONFIG_ARPING) += arping.o
NETWORKING-$(CONFIG_FAKEIDENTD) += fakeidentd.o
NETWORKING-$(CONFIG_FTPGET) += ftpgetput.o NETWORKING-$(CONFIG_FTPGET) += ftpgetput.o
NETWORKING-$(CONFIG_FTPPUT) += ftpgetput.o NETWORKING-$(CONFIG_FTPPUT) += ftpgetput.o
NETWORKING-$(CONFIG_HOSTNAME) += hostname.o NETWORKING-$(CONFIG_HOSTNAME) += hostname.o

441
networking/fakeidentd.c Normal file
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@ -0,0 +1,441 @@
/* vi: set sw=4 ts=4: */
/*
* A fake identd server
*
* Adapted to busybox by Thomas Lundquist <thomasez@zelow.no>
* Original Author: Tomi Ollila <too@iki.fi>
* http://www.guru-group.fi/~too/sw/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/syslog.h>
#include <pwd.h>
#include <netdb.h>
#include <sys/syslog.h>
#include <sys/types.h>
#include <sys/time.h>
#include <time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <arpa/inet.h>
#include <sys/uio.h>
#include "busybox.h"
#define IDENT_PORT 113
#define MAXCONNS 20
#define MAXIDLETIME 45
static const char ident_substr[] = " : USERID : UNIX : ";
static const int ident_substr_len = sizeof(ident_substr) - 1;
#define PIDFILE "/var/run/identd.pid"
/*
* We have to track the 'first connection socket' so that we
* don't go around closing file descriptors for non-clients.
*
* descriptor setup normally
* 0 = server socket
* 1 = syslog fd (hopefully -- otherwise this won't work)
* 2 = connection socket after detached from tty. standard error before that
* 3 - 2 + MAXCONNS = rest connection sockets
*
* To try to make sure that syslog fd is what is "requested", the that fd
* is closed before openlog() call. It can only severely fail if fd 0
* is initially closed.
*/
#define FCS 2
/*
* FD of the connection is always the index of the connection structure
* in `conns' array + FCS
*/
struct {
char buf[20];
int len;
time_t lasttime;
} conns[MAXCONNS];
/* When using global variables, bind those at least to a structure. */
struct {
const char *identuser;
fd_set readfds;
int conncnt;
} G;
/*
* Prototypes
*/
static void reply(int s, char *buf);
static void replyError(int s, char *buf);
static const char *nobodystr = "nobody"; /* this needs to be declared like this */
static char *bind_ip_address = "0.0.0.0";
static inline void movefd(int from, int to)
{
if (from != to) {
dup2(from, to);
close(from);
}
}
static void inetbind(void)
{
int s, port;
struct sockaddr_in addr;
int len = sizeof(addr);
int one = 1;
struct servent *se;
if ((se = getservbyname("identd", "tcp")) == NULL)
port = IDENT_PORT;
else
port = se->s_port;
if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
bb_perror_msg_and_die("Cannot create server socket");
setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
memset(&addr, 0, sizeof(addr));
addr.sin_addr.s_addr = inet_addr(bind_ip_address);
addr.sin_family = AF_INET;
addr.sin_port = htons(port);
if (bind(s, (struct sockaddr *)&addr, len) < 0)
bb_perror_msg_and_die("Cannot bind() port %i", IDENT_PORT);
if (listen(s, 5) < 0)
bb_perror_msg_and_die("Cannot listen() on port %i", IDENT_PORT);
movefd(s, 0);
}
static void delpidfile(void)
{
/*
* Usually nobody has no write/delete access to directory /var/run/
* therefore if file cannot be deleted, it is truncated
*/
if (unlink(PIDFILE) < 0)
close(open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0644));
}
static void handlexitsigs(int signum)
{
delpidfile();
exit(0);
}
/* May succeed. If not, won't care. */
static void writepid(uid_t nobody, uid_t nogrp)
{
char buf[24];
int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
if (fd < 0)
return;
snprintf(buf, 23, "%d\n", getpid());
write(fd, buf, strlen(buf));
fchown(fd, nobody, nogrp);
close(fd);
/* should this handle ILL, ... (see signal(7)) */
signal(SIGTERM, handlexitsigs);
signal(SIGINT, handlexitsigs);
signal(SIGQUIT, handlexitsigs);
}
/* return 0 as parent, 1 as child */
static int godaemon(void)
{
uid_t nobody, nogrp;
struct passwd *pw;
switch (fork()) {
case -1:
bb_perror_msg_and_die("Could not fork");
case 0:
pw = getpwnam(nobodystr);
if (pw == NULL)
bb_error_msg_and_die("Cannot find uid/gid of user '%s'", nobodystr);
nobody = pw->pw_uid;
nogrp = pw->pw_gid;
writepid(nobody, nogrp);
close(0);
inetbind();
if (setgid(nogrp)) bb_error_msg_and_die("Could not setgid()");
if (setegid(nogrp)) bb_error_msg_and_die("Could not setegid()");
if (setuid(nobody)) bb_error_msg_and_die("Could not setuid()");
if (seteuid(nobody)) bb_error_msg_and_die("Could not seteuid()");
close(1);
close(2);
signal(SIGHUP, SIG_IGN);
signal(SIGPIPE, SIG_IGN); /* connection closed when writing (raises ???) */
setsid();
openlog(bb_applet_name, 0, LOG_DAEMON);
return 1;
}
return 0;
}
static void deleteConn(int s)
{
int i = s - FCS;
close(s);
G.conncnt--;
/*
* Most of the time there is 0 connections. Most often that there
* is connections, there is just one connection. When this one connection
* closes, i == G.conncnt = 0 -> no copying.
* When there is more than one connection, the oldest connections closes
* earlier on average. When this happens, the code below starts copying
* the connection structure w/ highest index to the place which which is
* just deleted. This means that the connection structures are no longer
* in chronological order. I'd quess this means that when there is more
* than 1 connection, on average every other connection structure needs
* to be copied over the time all these connections are deleted.
*/
if (i != G.conncnt) {
memcpy(&conns[i], &conns[G.conncnt], sizeof(conns[0]));
movefd(G.conncnt + FCS, s);
}
FD_CLR(G.conncnt + FCS, &G.readfds);
}
static int closeOldest(void)
{
time_t min = conns[0].lasttime;
int idx = 0;
int i;
for (i = 1; i < MAXCONNS; i++)
if (conns[i].lasttime < min)
idx = i;
replyError(idx + FCS, "X-SERVER-TOO-BUSY");
close(idx + FCS);
return idx;
}
static int checkInput(char *buf, int len, int l)
{
int i;
for (i = len; i < len + l; ++i)
if (buf[i] == '\n')
return 1;
return 0;
}
int fakeidentd_main(int argc, char **argv)
{
int flag;
memset(conns, 0, sizeof(conns));
memset(&G, 0, sizeof(G));
FD_ZERO(&G.readfds);
FD_SET(0, &G.readfds);
/* handle -b <ip> parameter */
while ((flag = getopt(argc, argv, "b:")) != EOF) {
switch (flag) {
case 'b':
bind_ip_address = optarg;
break;
default:
bb_show_usage();
}
}
/* handle optional REPLY STRING */
if (optind < argc)
G.identuser = argv[optind];
else
G.identuser = nobodystr;
/* daemonize and have the parent return */
if (godaemon() == 0)
return 0;
while (1) {
fd_set rfds = G.readfds;
struct timeval tv = { 15, 0 };
int i;
int tim = time(NULL);
select(G.conncnt + FCS, &rfds, NULL, NULL, G.conncnt? &tv: NULL);
for (i = G.conncnt - 1; i >= 0; i--) {
int s = i + FCS;
if (FD_ISSET(s, &rfds)) {
char *buf = conns[i].buf;
unsigned int len = conns[i].len;
unsigned int l;
if ((l = read(s, buf + len, sizeof(conns[0].buf) - len)) > 0) {
if (checkInput(buf, len, l)) {
reply(s, buf);
goto deleteconn;
} else if (len + l >= sizeof(conns[0].buf)) {
replyError(s, "X-INVALID-REQUEST");
goto deleteconn;
} else {
conns[i].len += l;
}
} else {
goto deleteconn;
}
conns[i].lasttime = tim;
continue;
deleteconn:
deleteConn(s);
} else {
/* implement as time_after() in linux kernel sources ... */
if (conns[i].lasttime + MAXIDLETIME <= tim) {
replyError(s, "X-TIMEOUT");
deleteConn(s);
}
}
}
if (FD_ISSET(0, &rfds)) {
int s = accept(0, NULL, 0);
if (s < 0) {
if (errno != EINTR) /* EINTR */
syslog(LOG_ERR, "accept: %s", strerror(errno));
} else {
if (G.conncnt == MAXCONNS)
i = closeOldest();
else
i = G.conncnt++;
movefd(s, i + FCS); /* move if not already there */
FD_SET(i + FCS, &G.readfds);
conns[i].len = 0;
conns[i].lasttime = time(NULL);
}
}
} /* end of while(1) */
return 0;
}
static int parseAddrs(char *ptr, char **myaddr, char **heraddr);
static void reply(int s, char *buf)
{
char *myaddr, *heraddr;
myaddr = heraddr = NULL;
if (parseAddrs(buf, &myaddr, &heraddr))
replyError(s, "X-INVALID-REQUEST");
else {
struct iovec iv[6];
iv[0].iov_base = myaddr; iv[0].iov_len = strlen(myaddr);
iv[1].iov_base = ", "; iv[1].iov_len = 2;
iv[2].iov_base = heraddr; iv[2].iov_len = strlen(heraddr);
iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
iv[4].iov_base = (void *)G.identuser; iv[4].iov_len = strlen(G.identuser);
iv[5].iov_base = "\r\n"; iv[5].iov_len = 2;
writev(s, iv, 6);
}
}
static void replyError(int s, char *buf)
{
struct iovec iv[3];
iv[0].iov_base = "0, 0 : ERROR : "; iv[0].iov_len = 15;
iv[1].iov_base = buf; iv[1].iov_len = strlen(buf);
iv[2].iov_base = "\r\n"; iv[2].iov_len = 2;
writev(s, iv, 3);
}
static int chmatch(char c, char *chars)
{
for (; *chars; chars++)
if (c == *chars)
return 1;
return 0;
}
static int skipchars(char **p, char *chars)
{
while (chmatch(**p, chars))
(*p)++;
if (**p == '\r' || **p == '\n')
return 0;
return 1;
}
static int parseAddrs(char *ptr, char **myaddr, char **heraddr)
{
/* parse <port-on-server> , <port-on-client> */
if (!skipchars(&ptr, " \t"))
return -1;
*myaddr = ptr;
if (!skipchars(&ptr, "1234567890"))
return -1;
if (!chmatch(*ptr, " \t,"))
return -1;
*ptr++ = '\0';
if (!skipchars(&ptr, " \t,") )
return -1;
*heraddr = ptr;
skipchars(&ptr, "1234567890");
if (!chmatch(*ptr, " \n\r"))
return -1;
*ptr = '\0';
return 0;
}