general purpose telnet bouncer.
Mark
mark at coombs.anu.edu.au
Wed Sep 1 20:36:49 PDT 1993
Several people have expressed interest in a utility such as this. It's
existed for several years but Ive recently decided to fix it up into a
releasable condition.
Share and enjoy.
flames to /dev/null
Mark
mark at cairo.anu.edu.au
---------------------- cut here ----------------------------
/* Name: ts2.c */
/* Author: Hal-9000, Richard Stevens, Xanadude, Avalon, Mark */
/* Distribution: Public */
/* Copyright: Held by the respective contributors */
/* Posted to USENET 1st September '93 by Mark mark at cairo.anu.edu.au */
/* This file was telserv.c, part of the Telnet Server package v. 1.0,
written by "Hal-9000". Much of that package was developed by Richard
Stephens and his thanks go to "Xanadude" for providing him with that
section. Performance fix by Darren Reed. */
/* Reworked to add concurrency, password checking and destination selection
on the fly. - Mark 31st Aug 93
Compiled and tested on:
HPUX 9.01 9000/700 series NeXTStep 3.1 NeXT 68040
OSx Pyramid 90x BSD universe SunOS 5.2 sun4c
Ultrix 4.3 DEC RISC
To compile, type "cc -O -s ts2.c -o ts2".
MY_PASSWORD and SERV_TCP_PORT are all that is required to be altered. */
#define MY_PASSWORD "pass"
#define SERV_TCP_PORT 12345 /* port I'll listen for connections on */
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#define QLEN 5
char sbuf[2048], cbuf[2048];
extern int errno;
extern char *sys_errlist[];
void reaper();
int main();
void telcli();
int main(argc, argv)
int argc;
char *argv[];
{
int srv_fd, rem_fd, rem_len, opt = 1;
struct sockaddr_in rem_addr, srv_addr;
bzero((char *) &rem_addr, sizeof(rem_addr));
bzero((char *) &srv_addr, sizeof(srv_addr));
srv_addr.sin_family = AF_INET;
srv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
srv_addr.sin_port = htons(SERV_TCP_PORT);
srv_fd = socket(PF_INET, SOCK_STREAM, 0);
if (bind(srv_fd, (struct sockaddr *) &srv_addr, sizeof(srv_addr)) == -1) {
perror("bind");
exit(-1);
}
listen(srv_fd, QLEN);
close(0); close(1); close(2);
#ifdef TIOCNOTTY
if ((rem_fd = open("/dev/tty", O_RDWR)) >= 0) {
ioctl(rem_fd, TIOCNOTTY, (char *)0);
close(rem_fd);
}
#endif
if (fork()) exit(0);
while (1) {
rem_len = sizeof(rem_addr);
rem_fd=accept(srv_fd, (struct sockaddr *) &rem_addr, &rem_len);
if (rem_fd < 0) {
if (errno == EINTR) continue;
exit(-1);
}
switch(fork()) {
case 0: /* child process */
close(srv_fd); /* close original socket */
telcli(rem_fd); /* process the request */
close(rem_fd);
exit(0);
break;
default:
close(rem_fd); /* parent process */
if (fork()) exit(0); /* let init worry about children */
break;
case -1:
fprintf(stderr, "\n\rfork: %s\n\r", sys_errlist[errno]);
break;
}
}
}
void telcli(source)
int source;
{
int dest;
int found;
struct sockaddr_in sa;
struct hostent *hp;
struct servent *sp;
char gethost[100];
char getport[100];
char string[100];
bzero(gethost, 100);
sprintf(string, "Password: ");
write(source, string, strlen(string));
read(source, gethost, 100);
gethost[(strlen(gethost)-2)] = '\0'; /* kludge alert - kill the \r\n */
if (strcmp(gethost, MY_PASSWORD) != 0) {
sprintf(string, "Wrong password, got %s.\n", gethost);
write(source, string, strlen(string));
close(source);
exit(0);
}
do {
found = 0;
bzero(gethost,100);
sprintf(string, "Host: ");
write(source, string, strlen(string));
read(source, gethost, 100);
gethost[(strlen(gethost)-2)] = '\0';
hp = gethostbyname(gethost);
if (hp) {
found++;
#if !defined(h_addr) /* In 4.3, this is a #define */
#if defined(hpux) || defined(NeXT) || defined(ultrix) || defined(POSIX)
memcpy((caddr_t)&sa.sin_addr, hp->h_addr_list[0], hp->h_length);
#else
bcopy(hp->h_addr_list[0], &sa.sin_addr, hp->h_length);
#endif
#else /* defined(h_addr) */
#if defined(hpux) || defined(NeXT) || defined(ultrix) || defined(POSIX)
memcpy((caddr_t)&sa.sin_addr, hp->h_addr, hp->h_length);
#else
bcopy(hp->h_addr, &sa.sin_addr, hp->h_length);
#endif
#endif /* defined(h_addr) */
sprintf(string, "Found address for %s\n", hp->h_name);
write(source, string, strlen(string));
} else {
if (inet_addr(gethost) == -1) {
found = 0;
sprintf(string, "Didnt find address for %s\n", gethost);
write(source, string, strlen(string));
} else {
found++;
sa.sin_addr.s_addr = inet_addr(gethost);
}
}
} while (!found);
sa.sin_family = AF_INET;
sprintf(string, "Port: ");
write(source, string, strlen(string));
read(source, getport, 100);
gethost[(strlen(getport)-2)] = '\0';
sa.sin_port = htons((unsigned) atoi(getport));
if (sa.sin_port == 0) {
sp = getservbyname(getport, "tcp");
if (sp)
sa.sin_port = sp->s_port;
else {
sprintf(string, "%s: bad port number\n", getport);
write(source, string, strlen(string));
return;
}
}
sprintf(string, "Trying %s...\n", (char *) inet_ntoa(sa.sin_addr));
write(source, string, strlen(string));
if ((dest = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("telcli: socket");
exit(1);
}
connect(dest, (struct sockaddr *) &sa, sizeof(sa));
sprintf(string, "Connected to %s port %d...\n", inet_ntoa(sa.sin_addr),
ntohs(sa.sin_port));
write(source, string, strlen(string));
#ifdef FNDELAY
fcntl(source,F_SETFL,fcntl(source,F_GETFL,0)|FNDELAY);
fcntl(dest,F_SETFL,fcntl(dest,F_GETFL,0)|FNDELAY);
#else
fcntl(source,F_SETFL,O_NDELAY);
fcntl(dest,F_SETFL,O_NDELAY);
#endif
communicate(dest,source);
close(dest);
exit(0);
}
communicate(sfd,cfd) {
char *chead, *ctail, *shead, *stail;
int num, nfd, spos, cpos;
extern int errno;
fd_set rd, wr;
chead = ctail = cbuf;
cpos = 0;
shead = stail = sbuf;
spos = 0;
while (1) {
FD_ZERO(&rd);
FD_ZERO(&wr);
if (spos < sizeof(sbuf)-1) FD_SET(sfd, &rd);
if (ctail > chead) FD_SET(sfd, &wr);
if (cpos < sizeof(cbuf)-1) FD_SET(cfd, &rd);
if (stail > shead) FD_SET(cfd, &wr);
nfd = select(256, &rd, &wr, 0, 0);
if (nfd <= 0) continue;
if (FD_ISSET(sfd, &rd)) {
num=read(sfd,stail,sizeof(sbuf)-spos);
if ((num==-1) && (errno != EWOULDBLOCK)) return;
if (num==0) return;
if (num>0) {
spos += num;
stail += num;
if (!--nfd) continue;
}
}
if (FD_ISSET(cfd, &rd)) {
num=read(cfd,ctail,sizeof(cbuf)-cpos);
if ((num==-1) && (errno != EWOULDBLOCK)) return;
if (num==0) return;
if (num>0) {
cpos += num;
ctail += num;
if (!--nfd) continue;
}
}
if (FD_ISSET(sfd, &wr)) {
num=write(sfd,chead,ctail-chead);
if ((num==-1) && (errno != EWOULDBLOCK)) return;
if (num>0) {
chead += num;
if (chead == ctail) {
chead = ctail = cbuf;
cpos = 0;
}
if (!--nfd) continue;
}
}
if (FD_ISSET(cfd, &wr)) {
num=write(cfd,shead,stail-shead);
if ((num==-1) && (errno != EWOULDBLOCK)) return;
if (num>0) {
shead += num;
if (shead == stail) {
shead = stail = sbuf;
spos = 0;
}
if (!--nfd) continue;
}
}
}
}
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