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NetBSD/libexec/identd/identd.c

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/* $NetBSD: identd.c,v 1.16 2002/09/23 12:48:02 mycroft Exp $ */
/*
** identd.c A TCP/IP link identification protocol server
**
** This program is in the public domain and may be used freely by anyone
** who wants to.
**
** Last update: 7 Oct 1993
**
** Please send bug fixes/bug reports to: Peter Eriksson <pen@lysator.liu.se>
*/
#if defined(IRIX) || defined(SVR4) || defined(NeXT) || (defined(sco) && sco >= 42) || defined(_AIX4) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(ultrix)
# define SIGRETURN_TYPE void
# define SIGRETURN_TYPE_IS_VOID
#else
# define SIGRETURN_TYPE int
#endif
#ifdef SVR4
# define STRNET
#endif
#ifdef NeXT31
# include <libc.h>
#endif
#ifdef sco
# define USE_SIGALARM
#endif
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <signal.h>
#include <fcntl.h>
#include <poll.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifndef _AUX_SOURCE
# include <sys/file.h>
#endif
#include <sys/time.h>
#include <sys/wait.h>
#include <pwd.h>
#include <grp.h>
#include <netinet/in.h>
#ifndef HPUX7
# include <arpa/inet.h>
#endif
#if defined(MIPS) || defined(BSD43)
extern int errno;
#endif
#if defined(SOLARIS) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__linux__) || defined(_AIX)
# include <unistd.h>
# include <stdlib.h>
# include <string.h>
#endif
#include "identd.h"
#include "error.h"
#include "paths.h"
/* Antique unixes do not have these things defined... */
#ifndef FD_SETSIZE
# define FD_SETSIZE 256
#endif
#ifndef FD_SET
# ifndef NFDBITS
# define NFDBITS (sizeof(int) * NBBY) /* bits per mask */
# endif
# define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#endif
#ifndef FD_ZERO
# define FD_ZERO(p) bzero((char *)(p), sizeof(*(p)))
#endif
char *path_unix = (char *) NULL;
char *path_kmem = (char *) NULL;
int verbose_flag = 0;
int debug_flag = 0;
int syslog_flag = 0;
int multi_flag = 0;
int other_flag = 0;
int unknown_flag = 0;
int noident_flag = 0;
int crypto_flag = 0;
int liar_flag = 0;
int lport = 0;
int fport = 0;
char *charset_name = (char *) NULL;
char *indirect_host = (char *) NULL;
char *indirect_password = (char *) NULL;
char *lie_string = (char *) NULL;
#ifdef ALLOW_FORMAT
int format_flag = 0;
char *format = "%u";
#endif
static int child_pid;
#ifdef LOG_DAEMON
static int syslog_facility = LOG_DAEMON;
#endif
static int comparemem __P((void *, void *, int));
char *clearmem __P((void *, int));
static SIGRETURN_TYPE child_handler __P((int));
int main __P((int, char *[]));
/*
** The structure passing convention for GCC is incompatible with
** Suns own C compiler, so we define our own inet_ntoa() function.
** (This should only affect GCC version 1 I think, a well, this works
** for version 2 also so why bother.. :-)
*/
#if defined(__GNUC__) && defined(__sparc__) && !defined(NeXT)
#ifdef inet_ntoa
#undef inet_ntoa
#endif
char *inet_ntoa(ad)
struct in_addr ad;
{
unsigned long int s_ad;
int a, b, c, d;
static char addr[20];
s_ad = ad.s_addr;
d = s_ad % 256;
s_ad /= 256;
c = s_ad % 256;
s_ad /= 256;
b = s_ad % 256;
a = s_ad / 256;
sprintf(addr, "%d.%d.%d.%d", a, b, c, d);
return addr;
}
#endif
static int comparemem(vp1, vp2, len)
void *vp1;
void *vp2;
int len;
{
unsigned char *p1 = (unsigned char *) vp1;
unsigned char *p2 = (unsigned char *) vp2;
int c;
while (len-- > 0)
if ((c = (int) *p1++ - (int) *p2++) != 0)
return c;
return 0;
}
/*
** Return the name of the connecting host, or the IP number as a string.
*/
char *gethost(addr)
struct in_addr *addr;
{
int i;
struct hostent *hp;
hp = gethostbyaddr((char *) addr, sizeof(struct in_addr), AF_INET);
if (hp)
{
char *hname = strdup(hp->h_name);
if (! hname) {
syslog(LOG_ERR, "strdup(%s): %m", hp->h_name);
exit(1);
}
/* Found a IP -> Name match, now try the reverse for security reasons */
hp = gethostbyname(hname);
(void) free(hname);
if (hp)
#ifdef h_addr
for (i = 0; hp->h_addr_list[i]; i++)
if (comparemem(hp->h_addr_list[i],
(unsigned char *) addr,
(int) sizeof(struct in_addr)) == 0)
return (char *) hp->h_name;
#else
if (comparemem(hp->h_addr, addr, sizeof(struct in_addr)) == 0)
return hp->h_name;
#endif
}
return inet_ntoa(*addr);
}
#ifdef USE_SIGALARM
/*
** Exit cleanly after our time's up.
*/
static SIGRETURN_TYPE
alarm_handler(int s)
{
if (syslog_flag)
syslog(LOG_DEBUG, "SIGALRM triggered, exiting");
exit(0);
}
#endif
#if !defined(hpux) && !defined(__hpux) && !defined(SVR4) && \
!defined(_CRAY) && !defined(sco) && !defined(LINUX)
/*
** This is used to clean up zombie child processes
** if the -w or -b options are used.
*/
static SIGRETURN_TYPE
child_handler(dummy)
int dummy;
{
#if defined(NeXT) || (defined(__sgi) && defined(__SVR3))
union wait status;
#else
int status;
#endif
int saved_errno = errno;
while (wait3(&status, WNOHANG, NULL) > 0)
;
errno = saved_errno;
#ifndef SIGRETURN_TYPE_IS_VOID
return 0;
#endif
}
#endif
char *clearmem(vbp, len)
void *vbp;
int len;
{
char *bp = (char *) vbp;
char *cp;
cp = bp;
while (len-- > 0)
*cp++ = 0;
return bp;
}
/*
** Main entry point into this daemon
*/
int main(argc,argv)
int argc;
char *argv[];
{
int i, len;
struct sockaddr_in sin;
struct in_addr laddr, faddr;
int one = 1;
int background_flag = 0;
int timeout = 0;
char *portno = "113";
char *bind_address = (char *) NULL;
int set_uid = 0;
int set_gid = 0;
int inhibit_default_config = 0;
int opt_count = 0; /* Count of option flags */
#ifdef __convex__
argc--; /* get rid of extra argument passed by inetd */
#endif
if (isatty(0))
background_flag = 1;
/*
** Prescan the arguments for "-f<config-file>" switches
*/
inhibit_default_config = 0;
for (i = 1; i < argc && argv[i][0] == '-'; i++)
if (argv[i][1] == 'f')
inhibit_default_config = 1;
/*
** Parse the default config file - if it exists
*/
if (!inhibit_default_config)
parse_config(NULL, 1);
/*
** Parse the command line arguments
*/
for (i = 1; i < argc && argv[i][0] == '-'; i++) {
opt_count++;
switch (argv[i][1])
{
case 'b': /* Start as standalone daemon */
background_flag = 1;
break;
case 'w': /* Start from Inetd, wait mode */
background_flag = 2;
break;
case 'i': /* Start from Inetd, nowait mode */
background_flag = 0;
break;
case 't':
timeout = atoi(argv[i]+2);
break;
case 'p':
portno = argv[i]+2;
break;
case 'a':
bind_address = argv[i]+2;
break;
case 'u':
if (isdigit(argv[i][2]))
set_uid = atoi(argv[i]+2);
else
{
struct passwd *pwd;
pwd = getpwnam(argv[i]+2);
if (!pwd)
ERROR1("no such user (%s) for -u option", argv[i]+2);
else
{
set_uid = pwd->pw_uid;
set_gid = pwd->pw_gid;
}
}
break;
case 'g':
if (isdigit(argv[i][2]))
set_gid = atoi(argv[i]+2);
else
{
struct group *grp;
grp = getgrnam(argv[i]+2);
if (!grp)
ERROR1("no such group (%s) for -g option", argv[i]+2);
else
set_gid = grp->gr_gid;
}
break;
case 'c':
charset_name = argv[i]+2;
break;
case 'r':
indirect_host = argv[i]+2;
break;
case 'l': /* Use the Syslog daemon for logging */
syslog_flag++;
#ifdef LOG_DAEMON
openlog("identd", LOG_PID, syslog_facility);
#else
openlog("identd", LOG_PID);
#endif
break;
case 'o':
other_flag = 1;
break;
case 'e':
unknown_flag = 1;
break;
case 'V': /* Give version of this daemon */
printf("[in.identd, version %s]\r\n", version);
exit(0);
break;
case 'v': /* Be verbose */
verbose_flag++;
break;
case 'd': /* Enable debugging */
debug_flag++;
break;
case 'm': /* Enable multiline queries */
multi_flag++;
break;
case 'N': /* Enable users ".noident" files */
noident_flag++;
break;
#ifdef INCLUDE_CRYPT
case 'C': /* Enable encryption. */
{
FILE *keyfile;
if (argv[i][2])
keyfile = fopen(argv[i]+2, "r");
else
keyfile = fopen(PATH_DESKEY, "r");
if (keyfile == NULL)
{
ERROR("cannot open key file for option -C");
}
else
{
char buf[1024];
if (fgets(buf, 1024, keyfile) == NULL)
{
ERROR("cannot read key file for option -C");
}
else
{
init_encryption(buf);
crypto_flag++;
}
fclose(keyfile);
}
}
break;
#endif
#ifdef ALLOW_FORMAT
case 'n': /* Compatibility flag - just send the user number */
format_flag = 1;
format = "%U";
break;
case 'F': /* Output format */
format_flag = 1;
format = argv[i]+2;
break;
#endif
case 'L': /* lie brazenly */
liar_flag = 1;
if (*(argv[i]+2) != '\0')
lie_string = argv[i]+2;
else
#ifdef DEFAULT_LIE_USER
lie_string = DEFAULT_LIE_USER;
#else
ERROR("-L specified with no user name");
#endif
break;
default:
ERROR1("Bad option %s", argv[i]);
break;
}
}
#if defined(_AUX_SOURCE) || defined (SUNOS35)
/* A/UX 2.0* & SunOS 3.5 calls us with an argument XXXXXXXX.YYYY
** where XXXXXXXXX is the hexadecimal version of the callers
** IP number, and YYYY is the port/socket or something.
** It seems to be impossible to pass arguments to a daemon started
** by inetd.
**
** Just in case it is started from something else, then we only
** skip the argument if no option flags have been seen.
*/
if (opt_count == 0)
argc--;
#endif
/*
** Path to kernel namelist file specified on command line
*/
if (i < argc)
path_unix = argv[i++];
/*
** Path to kernel memory device specified on command line
*/
if (i < argc)
path_kmem = argv[i++];
if (i < argc)
ERROR1("Too many arguments: ignored from %s", argv[i]);
/*
** We used to call k_open here. But then the file descriptor
** kd->fd open on /dev/kmem is shared by all child processes.
** From the fork(2) man page:
** o The child process has its own copy of the parent's descriptors. These
** descriptors reference the same underlying objects. For instance, file
** pointers in file objects are shared between the child and the parent
** so that an lseek(2) on a descriptor in the child process can affect a
** subsequent read(2) or write(2) by the parent.
** Thus with concurrent (simultaneous) identd client processes,
** they step on each other's toes when they use kvm_read.
**
** Calling k_open here was a mistake for another reason too: we
** did not yet honor -u and -g options. Presumably we are
** running as root (unless the in.identd file is setuid), and
** then we can open kmem regardless of -u and -g values.
**
**
** Open the kernel memory device and read the nlist table
**
** if (k_open() < 0)
** ERROR("main: k_open");
*/
/*
** Do the special handling needed for the "-b" flag
*/
if (background_flag == 1)
{
struct sockaddr_in addr;
struct servent *sp;
int fd;
if (!debug_flag)
{
if (fork())
exit(0);
close(0);
close(1);
close(2);
if (fork())
exit(0);
}
fd = socket(AF_INET, SOCK_STREAM, 0);
if (fd == -1)
ERROR("main: socket");
if (fd != 0)
dup2(fd, 0);
clearmem((void *) &addr, (int) sizeof(addr));
addr.sin_family = AF_INET;
if (bind_address == (char *) NULL)
addr.sin_addr.s_addr = htonl(INADDR_ANY);
else
{
if (isdigit(bind_address[0]))
addr.sin_addr.s_addr = inet_addr(bind_address);
else
{
struct hostent *hp;
hp = gethostbyname(bind_address);
if (!hp)
ERROR1("no such address (%s) for -a switch", bind_address);
/* This is ugly, should use memcpy() or bcopy() but... */
addr.sin_addr.s_addr = * (unsigned long *) (hp->h_addr);
}
}
if (isdigit(portno[0]))
addr.sin_port = htons(atoi(portno));
else
{
sp = getservbyname(portno, "tcp");
if (sp == (struct servent *) NULL)
ERROR1("main: getservbyname: %s", portno);
addr.sin_port = sp->s_port;
}
#ifdef SO_REUSEADDR
setsockopt(0, SOL_SOCKET, SO_REUSEADDR, (void *) &one, sizeof(one));
#endif
if (bind(0, (struct sockaddr *) &addr, sizeof(addr)) < 0)
ERROR("main: bind");
}
if (background_flag)
{
if (listen(0, 3) < 0)
ERROR("main: listen");
}
if (set_gid)
{
if (setgid(set_gid) == -1)
ERROR("main: setgid");
/* Call me paranoid... PSz */
if (getgid() != set_gid)
ERROR2("main: setgid failed: wanted %d, got GID %d", set_gid, getgid());
if (getegid() != set_gid)
ERROR2("main: setgid failed: wanted %d, got EGID %d", set_gid, getegid());
}
if (set_uid)
{
if (setuid(set_uid) == -1)
ERROR("main: setuid");
/* Call me paranoid... PSz */
if (getuid() != set_uid)
ERROR2("main: setuid failed: wanted %d, got UID %d", set_uid, getuid());
if (geteuid() != set_uid)
ERROR2("main: setuid failed: wanted %d, got EUID %d", set_uid, geteuid());
}
/*
** Do some special handling if the "-b" or "-w" flags are used
*/
if (background_flag)
{
int nfds, fd;
struct pollfd set[1];
struct sockaddr sad;
int sadlen;
/*
** Set up the SIGCHLD signal child termination handler so
** that we can avoid zombie processes hanging around and
** handle childs terminating before being able to complete the
** handshake.
*/
#if (defined(SVR4) || defined(hpux) || defined(__hpux) || defined(IRIX) || \
defined(_CRAY) || defined(_AUX_SOURCE) || defined(sco) || \
defined(LINUX))
signal(SIGCHLD, SIG_IGN);
#else
signal(SIGCHLD, child_handler);
#endif
set[0].fd = 0;
set[0].events = POLLIN;
/*
** Loop and dispatch client handling processes
*/
do
{
#ifdef USE_SIGALARM
/*
** Terminate if we've been idle for 'timeout' seconds
*/
if (background_flag == 2 && timeout)
{
signal(SIGALRM, alarm_handler);
alarm(timeout);
}
#endif
/*
** Wait for a connection request to occur.
** Ignore EINTR (Interrupted System Call).
*/
do
{
#ifndef USE_SIGALARM
if (timeout)
nfds = poll(set, 1, timeout * 1000);
else
#endif
nfds = poll(set, 1, INFTIM);
} while (nfds < 0 && errno == EINTR);
/*
** An error occurred in select? Just die
*/
if (nfds < 0)
ERROR("main: poll");
/*
** Timeout limit reached. Exit nicely
*/
if (nfds == 0)
exit(0);
#ifdef USE_SIGALARM
/*
** Disable the alarm timeout
*/
alarm(0);
#endif
/*
** Accept the new client
*/
sadlen = sizeof(sad);
errno = 0;
fd = accept(0, &sad, &sadlen);
if (fd == -1)
ERROR1("main: accept. errno = %d", errno);
/*
** And fork, then close the fd if we are the parent.
*/
child_pid = fork();
} while (child_pid && (close(fd), 1));
/*
** We are now in child, the parent has returned to "do" above.
*/
if (dup2(fd, 0) == -1)
ERROR("main: dup2: failed fd 0");
if (dup2(fd, 1) == -1)
ERROR("main: dup2: failed fd 1");
if (dup2(fd, 2) == -1)
ERROR("main: dup2: failed fd 2");
}
/*
** Get foreign internet address
*/
len = sizeof(sin);
if (getpeername(0, (struct sockaddr *) &sin, &len) == -1)
{
/*
** A user has tried to start us from the command line or
** the network link died, in which case this message won't
** reach to other end anyway, so lets give the poor user some
** errors.
*/
perror("in.identd: getpeername()");
exit(1);
}
faddr = sin.sin_addr;
#ifdef STRONG_LOG
if (syslog_flag)
syslog(LOG_INFO, "Connection from %s", gethost(&faddr));
#endif
/*
** Get local internet address
*/
len = sizeof(sin);
#ifdef ATTSVR4
if (t_getsockname(0, (struct sockaddr *) &sin, &len) == -1)
#else
if (getsockname(0, (struct sockaddr *) &sin, &len) == -1)
#endif
{
/*
** We can just die here, because if this fails then the
** network has died and we haven't got anyone to return
** errors to.
*/
exit(1);
}
laddr = sin.sin_addr;
/*
** Get the local/foreign port pair from the luser
*/
parse(stdin, &laddr, &faddr);
exit(0);
}
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