Source Code 1994 March/Source_Code_CD-ROM_Walnut_Creek_March_1994.iso/compsrcs/x/volume19/xroute/part01

Text File | 1993-05-26 | 10.9 KB | 349 lines

Newsgroups: comp.sources.x
From: [e-mail] (Kartik Subbarao)
Subject: v19i089:  xroute - Route X-Protocol through Internet gateways, Part01/01
Message-ID: <[e-mail]>
X-Md4-Signature: 84abc5c42e32c7e4e3c64fd479f9eae4
Sender: [e-mail] (Chris Olson)
Organization: Sterling Software
Date: Fri, 21 May 1993 15:47:43 GMT
Approved: [e-mail]

Submitted-by: [e-mail] (Kartik Subbarao)
Posting-number: Volume 19, Issue 89
Archive-name: xroute/part01
Environment: X11, Inet

xroute routes X packets from one machine to another. It is typically used
to enable programs to run on a gateway which does not route arbitrary packets
between "internal" and "external" hosts. It's a handy program to have around
when dealing with the increasingly common situation of having to run X
programs to and from remote sites across internet gateways. See the man page
for more on how to use xroute.

     -Kartik

#!/bin/sh
# This is a shell archive (produced by shar 3.49)
# To extract the files from this archive, save it to a file, remove
# everything above the "!/bin/sh" line above, and type "sh file_name".
#
# made 05/19/1993 03:13 UTC by subbarao@concorde
# Source directory /u/subbarao/x
#
# existing files will NOT be overwritten unless -c is specified
#
# This shar contains:
# length  mode       name
# ------ ---------- ------------------------------------------
#     18 -rw-r--r-- xroute/Makefile
#    583 -rw-r--r-- xroute/README
#   2816 -rw-r--r-- xroute/xroute.1
#   3794 -rw-r--r-- xroute/xroute.c
#
# ============= xroute/Makefile ==============
if test ! -d 'xroute'; then
    echo 'x - creating directory xroute'
    mkdir 'xroute'
fi
if test -f 'xroute/Makefile' -a X"$1" != X"-c"; then
    echo 'x - skipping xroute/Makefile (File already exists)'
else
echo 'x - extracting xroute/Makefile (Text)'
sed 's/^X//' << 'SHAR_EOF' > 'xroute/Makefile' &&
CFLAGS=-O
xroute:
SHAR_EOF
chmod 0644 xroute/Makefile ||
echo 'restore of xroute/Makefile failed'
Wc_c="`wc -c < 'xroute/Makefile'`"
test 18 -eq "$Wc_c" ||
    echo 'xroute/Makefile: original size 18, current size' "$Wc_c"
fi
# ============= xroute/README ==============
if test -f 'xroute/README' -a X"$1" != X"-c"; then
    echo 'x - skipping xroute/README (File already exists)'
else
echo 'x - extracting xroute/README (Text)'
sed 's/^X//' << 'SHAR_EOF' > 'xroute/README' &&
xroute routes X packets from one machine to another. It is typically used
to enable programs to run on a gateway which does not route arbitrary packets
between "internal" and "external" hosts. It's a handy program to have around
when dealing with the increasingly common situation of having to run X
programs to and from remote sites across internet gateways. See the man page
for more on how to use xroute.
X
xroute compiles and runs fine on various HPs, Suns, SGIs and DECs. If you
have any suggestions, questions, comments, etc, feel free to send me mail -
<[e-mail]>.
SHAR_EOF
chmod 0644 xroute/README ||
echo 'restore of xroute/README failed'
Wc_c="`wc -c < 'xroute/README'`"
test 583 -eq "$Wc_c" ||
    echo 'xroute/README: original size 583, current size' "$Wc_c"
fi
# ============= xroute/xroute.1 ==============
if test -f 'xroute/xroute.1' -a X"$1" != X"-c"; then
    echo 'x - skipping xroute/xroute.1 (File already exists)'
else
echo 'x - extracting xroute/xroute.1 (Text)'
sed 's/^X//' << 'SHAR_EOF' > 'xroute/xroute.1' &&
.TH XROUTE 1 "May 18, 1993"
.SH NAME
xroute \- route X packets through a gateway
.SH SYNOPSIS
.B xroute
[-n numclients] [-d gdisp] host[:display]
.br
.SH DESCRIPTION
XXroute was written to solve the problem of getting an X application to work
over a gateway that will not route packets directly between "internal" and
"external" hosts.
X
The X server listens on port 6000 + \fId\fP for requests made to display
\fId\fP. For example, "xterm -display zoof:2" sends packets to port 6002 on
zoof, data destined for zoof:3 goes to port 6003, etc. By acting as a
pipe between an X port on the gateway machine and an X port on the local
machine, xroute provides a way for internal hosts to X off of external
hosts, and vice versa.
X
.SH EXAMPLE
Let's say that I wanted to run xrn from a foo.bar.edu, a host on the outside,
pass it through the gateway, and display it on concorde, my machine.
X
First, I would pick an arbitrary display number to set my remote DISPLAY
variable:
X
foo.bar.edu% setenv DISPLAY gateway.biz.com:2
X
Then, I would xhost (or add the corresponding line to .Xauthority) BOTH the
gateway and the external machine. (This is necessary due to where the X
packets look like they're coming from).
X
concorde% xhost gateway.biz.com foo.bar.edu
X
If I couldn't resolve foo.bar.edu by name locally, I'd have to use nslookup
on the gateway, snarf the IP address, and xhost the IP address.
X
We now set up the route between concorde and foo.bar.edu:
X
gateway% xroute -d 2 concorde:0
X
With the route in place, I can now run xrn:
X
foo.bar.edu% xrn
X
And automagically, it pops up on concorde:0. (Alternatively, I could have
not specified the -d argument, and would set my DISPLAY on foo.bar.edu
according to the number that xroute printed)
X
Note that the reverse is just as easily possible. If I want to display an X
application from concorde to foo.bar.edu, I would set up the proper xhosting
on foo.bar.edu, and would run
X
xroute -d 2 foo.bar.edu:0
X
on the gateway.
X
.SH OPTIONS
.TP
.B\-d
specifies the port number (6000 + gdisp) on the gateway to act as the proxy "X
server". When omitted, xroute picks the lowest port available >= 6000, and
prints the corresponding display number.
.TP
.B\-n
specifies the number of X clients you wish to route through the gateway to
your system. It defaults to 1. The main program exits after \fInumclients\fP
clients have established connections.
.TP
If no display is specified in the local hostname, it defaults to 0.
X
.SH AUTHOR
Kartik Subbarao <[e-mail]>
X
.SH COMMENTS
Routing X packets the standard way outperforms \fBxroute\fP. Nevertheless,
this program is very useful when, due to security concerns or other factors,
arbitrary packets cannot be routed between internal and external machines.
X
Enhancements, questions, comments, etc. are welcome.
SHAR_EOF
chmod 0644 xroute/xroute.1 ||
echo 'restore of xroute/xroute.1 failed'
Wc_c="`wc -c < 'xroute/xroute.1'`"
test 2816 -eq "$Wc_c" ||
    echo 'xroute/xroute.1: original size 2816, current size' "$Wc_c"
fi
# ============= xroute/xroute.c ==============
if test -f 'xroute/xroute.c' -a X"$1" != X"-c"; then
    echo 'x - skipping xroute/xroute.c (File already exists)'
else
echo 'x - extracting xroute/xroute.c (Text)'
sed 's/^X//' << 'SHAR_EOF' > 'xroute/xroute.c' &&
/* xroute.c, by Kartik Subbarao <[e-mail]> */
X
# include <stdio.h>
# include <sys/types.h>
# include <sys/time.h>
# include <netdb.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <sys/socket.h>
# include <string.h>
# include <sys/wait.h>
#ifdef sgi
# define _BSD_SIGNALS
#endif
# include <signal.h>
# include <errno.h>
X
# define XPORT 6000
X
char buf[8192];
X
usage()
{
X    fprintf(stderr,"usage: xroute [-n numclients] [-d gdisp] host[:display]\n");
X    exit(1);
}
X
#ifdef hpux
waiter() {int st;while (wait3(&st, WNOHANG, NULL) > 0);signal(SIGCHLD, waiter);}
#else
waiter() { union wait st; while (wait3(&st, WNOHANG, NULL) > 0); }
#endif
X
main(argc, argv)
int argc; char *argv[];
{
X    int o; extern char *optarg; extern int optind; char *lhost, *p;
X    int ldisp, gdisp = -1; /* display numbers */
X    int ls, gs, rs; /* sockets -- local, gateway, remote */
X    struct sockaddr_in rad; int radlen = sizeof rad;
X    int numcli = 1, pid;
X
X    while ((o = getopt(argc, argv, "n:d:")) != -1)
X        switch (o) {
X        case 'n': if (optarg) numcli = atoi(optarg); break;
X        case 'd': if (optarg) gdisp = atoi(optarg); break;
X        default: usage();
X        }
X
X    if (!argv[optind]) usage();
X    ldisp = (p = strchr(argv[optind], ':')) && p[1] ? atoi(p+1) : 0;
X    if (p) *p = '\0'; lhost = argv[optind];
X
X    gs = tcpssocket(gdisp);
X    signal(SIGCHLD, waiter);
X    signal(SIGHUP, SIG_IGN);
X
X    if (fork()) exit(0); /* background ourself */
X
X    for (; numcli; numcli--) {
X        while ((rs = accept(gs, &rad, &radlen)) == -1 && errno == EINTR);
X        if (rs == -1) exit(1);
X        switch (fork()) {
X        case -1: exit(1);
X        case 0: ls = tcpcsocket(lhost, XPORT + ldisp); route(ls, rs); break;
X        default: close(rs);
X        }
X    }
X    exit(0);
}
X
route(ls, rs)
int ls, rs;
{
X    fd_set rdset, trdset, wrset, twrset;
X    int maxfds, n, tmp; char *b;
X
X    maxfds = (ls > rs ? ls : rs) + 1;
X    FD_ZERO(&rdset); FD_ZERO(&trdset); FD_ZERO(&wrset); FD_ZERO(&twrset);
X    FD_SET(ls, &rdset); FD_SET(ls, &wrset);
X    FD_SET(rs, &rdset); FD_SET(rs, &wrset);
X    trdset = rdset; twrset = wrset;
X
X    for (;; rdset = trdset, wrset = twrset) {
X        if (select(maxfds, &rdset, &wrset, NULL, NULL) == -1) exit(1);
X
X        if (FD_ISSET(ls, &rdset) && FD_ISSET(rs, &wrset)) {
X            if ((n = read(ls, buf, sizeof buf)) <= 0) exit(n);
X            for (b = buf; n; n -= tmp, b += tmp)
X                if ((tmp = write(rs, b, n)) <= 0) exit(tmp);
X        }
X        if (FD_ISSET(rs, &rdset) && FD_ISSET(ls, &wrset)) {
X            if ((n = read(rs, buf, sizeof buf)) <= 0) exit(n);
X            for (b = buf; n; n -= tmp, b += tmp)
X                if ((tmp = write(ls, b, n)) <= 0) exit(tmp);
X        }
X    }
}
X
tcpssocket(gdisp)
int gdisp;
{
X    int i, s; struct sockaddr_in sa;
X
X    if ((s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
X        perror("socket"), exit(1);
X
X       sa.sin_family = AF_INET; sa.sin_addr.s_addr = htonl(INADDR_ANY);
X
X    if (gdisp == -1) /* If it wasn't specified */
X        for (i = XPORT; ; i++) { /* find the first available port > XPORT */
X            sa.sin_port = htons(i);
X            if (bind(s, &sa, sizeof(sa)) == 0) {
X                printf("%d\n", i-XPORT); break;
X            }
X        }
X    else {
X        sa.sin_port = htons(XPORT+gdisp);
X        if (bind(s, &sa, sizeof(sa)) == -1) perror("bind"), exit(1);
X    }
X
X    if (listen(s, 5) == -1) perror("listen"), exit(1);
X
X    return s;
}
X
tcpcsocket(host, port)
char *host; int port;
{
X    int s, e;
X    struct sockaddr_in sa;
X    struct hostent *hent;
X    extern char *sys_errlist[];
X
X    if ((s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) exit(1);
X
X    if (! (hent = gethostbyname(host))) {
X        e = errno;
X        if ((sa.sin_addr.s_addr = inet_addr(host)) == -1)
X            fprintf(stderr, "%s: %s\n", host, sys_errlist[e]), exit(1);
X    }
X       else bcopy(hent->h_addr, (char *) &sa.sin_addr, hent->h_length);
X
X    sa.sin_family = AF_INET; sa.sin_port = htons(port);
X
X    if (connect(s, &sa, sizeof(sa)) == -1)
X        fprintf(stderr, "%s: connect: %s\n", host, sys_errlist[errno]), exit(1);
X
X    return s;
}
SHAR_EOF
chmod 0644 xroute/xroute.c ||
echo 'restore of xroute/xroute.c failed'
Wc_c="`wc -c < 'xroute/xroute.c'`"
test 3794 -eq "$Wc_c" ||
    echo 'xroute/xroute.c: original size 3794, current size' "$Wc_c"
fi
exit 0

exit 0 # Just in case...
--
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