Re: terminal without telnet

"I also know that telnet and tcp do indeed
behave differently..."

You're talking apples and oranges, which is why it isnt working...

A quick review

A - Application (Layer 7)
P - Presentation (Layer 6)
S - Sesssion (Layer 5)
T - Transport (Layer 4)
N - Network (Layer 3)
D - Data Link (Layer 2)
P - Physical (Layer 1)

Telnet lives at layer 7. TCP lives at Layer 4. You cant connect Layer 7 to
Layer 4. You have to connect Layer 7 to Layer 7.

The application you are trying to write (terminal) is a Layer 7
application, dependent on Layer 4. Just like telnet runs on top of TCP, and
thus you cant have a telnet connection without TCP.

TCP uses the three way handshake (SYN, SYN/ACK, ACK) and once those three
have happened, then a TCP connection is established. But you need something
to send data over that. Having a TCP connection is merely establishing the
highway for the data to transit. You still need something to put data on
the highway.

So, now you have a TCP connection with hercules. Now what? You need a
protocol for your application, and a server and client. You should be able
to conjure that up pretty easily.

Good luck!

Joe

On Fri, Apr 5, 2019 at 10:51 PM kerravon86-/[email protected] [hercules-390] <
[email protected]> wrote:

>
>
> ---In [email protected], <gtaylor@...> wrote :
>
> >> I have tried with "telnet" instead of "tcp" but it still fails to
> connect
> >> to Hercules.
>
> > Can you elaborate?
>
> > Did qemu fail to connect? Did it connect, but the data through the
> > connection didn't do what you wanted?
>
> qemu thinks it has connected, so boots
> my OS. But Hercules fails to say
> "connection received" or whatever.
>
> When I start my application (pdpser)
> I receive an x'ff'.
>
> I also know that telnet and tcp do indeed
> behave differently, since I now have my
> "tnbridge" program working to some
> extent.
>
> > I feel like we're at least talking about a telnet client not connecting
> > to Hercules's telnet server properly. Or at least as desired.
>
> True, that's the situation and it should
> ideally be fixed properly.
>
> > I would be interested in seeing a packet capture of the traffic between
> > Qemu and Hercules.
>
> Ok, I'll try to get that.
>
> > I also find the port 3270 to be interesting. At least I'm used to
> > people using that port for the TN3270 connections. Which I'm guessing
> > Qemu doesn't support.
>
> Right. Normally I do a telnet localhost 3270
> and it works fine with my 1052 terminal
> (modified to be EBCDIC ANSI) or my
> 3215 line mode console.
>
> > You did mention a 1052, which I'm taking to be the ASCII terminal. Is
> > that the device listening on port 3270?
>
> Yes.
>
> > Can we see the germane portion of the Hercules config file?
>
> 0009 1052 noprompt
>
> >> qemu fullscreen is exactly what I'm looking at for when my eyesight
> >> fades and I need bigger letters. It gives me a 25*80 screen. The next
> >> thing I need is for it to be able to drive MVS, which is what I will do
> >> after PDOS/390.
>
> > Please forgive me for asking. But are you using PDOS/390 in Qemu as a
>
> It is PDOS/386 I am running under Qemu.
> PDOS/390 runs under Hercules.
>
> > fancy terminal emulator
>
> It's not fancy, it's very primitive (a 32-bit clone of
> MSDOS), and I will need to add ANSI support to it.
>
> > so that you can have full screen and better font
> > support to more comfortable use MVS running in Hercules?
>
> It is the EBCDIC ANSI terminal I am after, so
> that I can run micro-emacs on MVS. It's easier
> to use PDOS/3x0 as a test bed. Getting
> micro-emacs to run under MVS is pretty
> horrible at the moment. Note that I already
> have things working using "telnet" that
> comes with Cygwin, but just recently I
> realized I could use PDOS/386 to drive
> PDOS/390 or MVS/380.
>
> > I think that's a laudable goal. I suspect there might be simpler ways
> > to achieve that goal. But, I'm happy to help (such as I can) what ever
> > you want to do.
>
> Ok, thanks. I have tried your suggestion of
> bridging the two components, but there is
> a problem somewhere because the
> program terminates early without any
> explanation. If I comment out the reading
> from the client, then I see the complete
> bootup of PDOS/390. But obviously I
> then can't enter my own commands.
> Code is below. I'll move on to debugging
> Hercules now to find out why the qemu
> telnet client is not being accepted.
>
> BFN. Paul.
>
> /*********************************************************************/
> /* */
> /* This Program Written by Paul Edwards */
> /* Released to the Public Domain */
> /* */
> /*********************************************************************/
> /*********************************************************************/
> /* */
> /* tnbridge - connect two things requiring telnet */
> /* */
> /*********************************************************************/
>
> #include <stdlib.h>
> #include <stdio.h>
> #include <string.h>
> #include <ctype.h>
>
> #include <unistd.h>
>
> #include <sys/socket.h>
> #include <netdb.h>
>
> static int lsock;
> static int sockfd; /* socket used to communicate with client */
> static int sockh; /* socket used to communicate with host */
> struct hostent *hep;
> struct sockaddr_in sockain;
> struct sockaddr newsocka;
> static int newsocklen;
>
> static unsigned char buf[20000];
> static int cnt;
> static int x;
>
> int main(int argc, char **argv)
> {
> #if 0
> printf("AAA\n");
> printf("%c[2J\n", 0x1b);
> printf("BBB\n");
> printf("CCC\n");
> return (0);
> #endif
> if (argc != 3)
> {
> printf("usage: tnbridge <host port> <client port>\n");
> printf("e.g. tnbridge 3270 32700\n");
> return (EXIT_FAILURE);
> }
>
> sockh = socket(AF_INET, SOCK_STREAM, 0);
> printf("return sockh is %d\n", sockh);
> if (sockh < 0) return (EXIT_FAILURE);
>
> hep = gethostbyname("localhost" /* argv[x] */);
> if (hep == NULL) return (EXIT_FAILURE);
> printf("addr0 is %x\n", hep->h_addr[0]);
>
> memset(&sockain, 0, sizeof sockain);
> sockain.sin_family = AF_INET;
> memcpy(&sockain.sin_addr.s_addr,
> hep->h_addr,
> sizeof sockain.sin_addr.s_addr);
> sockain.sin_port = htons(atoi(argv[1]));
> if (connect(sockh,
> (struct sockaddr *)&sockain,
> sizeof sockain)
> < 0) return (EXIT_FAILURE);
> printf("connected\n");
>
> /* cnt = write(sockh, buf, sizeof buf); */
> /* expecting IAC DO TERMINAL_TYPE */
> cnt = read(sockh, buf, sizeof buf);
> printf("got %d bytes\n", cnt);
> printf("char 0 is %x\n", buf[0]);
> printf("char 1 is %x\n", buf[1]);
> printf("char 2 is %x\n", buf[2]);
> /* printf("%s\n", buf); */
>
> write(sockh, "\xff\xfb\x18", 3); /* IAC WILL TERMINAL_TYPE */
>
> /* expecting IAC SB TERMINAL_TYPE SEND IAC SE */
> cnt = read(sockh, buf, sizeof buf);
> printf("got %d bytes\n", cnt);
> printf("char 0 is %x\n", buf[0]);
> printf("char 1 is %x\n", buf[1]);
> printf("char 2 is %x\n", buf[2]);
> printf("char 3 is %x\n", buf[3]);
> printf("char 4 is %x\n", buf[4]);
> printf("char 5 is %x\n", buf[5]);
>
> write(sockh, "\xff\xfa\x18\x00"
> "ANSI"
> "\xff\xf0", 10);
> /* IAC SB TERMINAL_TYPE IS */
> /* terminal type */
> /* IAC SE */
>
> /* expecting IAC WONT ECHO */
> cnt = read(sockh, buf, sizeof buf);
> printf("got %d bytes\n", cnt);
> printf("char 0 is %x\n", buf[0]);
> printf("char 1 is %x\n", buf[1]);
> printf("char 2 is %x\n", buf[2]);
>
> write(sockh, "\xff\xfe\x01", 3); /* IAC DONT ECHO */
>
> printf("You can connect client now\n");
>
> lsock = socket(AF_INET, SOCK_STREAM, 0);
> printf("return lsock is %d\n", lsock);
> if (lsock < 0) return (EXIT_FAILURE);
>
> memset(&sockain, 0, sizeof sockain);
> sockain.sin_family = AF_INET;
> sockain.sin_addr.s_addr = htonl(INADDR_ANY);
> sockain.sin_port = htons(atoi(argv[2]));
> if (bind(lsock,
> (struct sockaddr *)&sockain,
> sizeof sockain)
> < 0) return (EXIT_FAILURE);
> printf("bound\n");
>
> if (listen(lsock, 64) < 0) return (EXIT_FAILURE);
> printf("heard\n");
>
> sockfd = accept(lsock,
> &newsocka,
> &newsocklen);
> printf("newsock is %d\n", sockfd);
>
> printf("IPL now\n");
>
> /* exit when we don't receive output */
> while (1)
> {
> cnt = read(sockfd, buf, sizeof buf);
> if (cnt > 0)
> {
> printf("got %d bytes from client\n", cnt);
> write(sockh, buf, cnt);
> }
> cnt = read(sockh, buf, sizeof buf);
> if (cnt > 0)
> {
> printf("got %d bytes from host\n", cnt);
> write(sockfd, buf, cnt);
> }
> /* usleep(1000); */
> }
>
> printf("terminating\n");
> close(sockfd);
> close(sockh);
> return (0);
> }
> 
>