TCP/SLIP implementation for the OS/A65
--------------------------------------
(c) 1997-1998 A. Fachat
0) Warning: This code is experimental and in a late Beta now!
It has bugs, and may damage files on your computer!
The programs are provided "as is", there is no warranty at all,
and the usual disclaimers apply.
I you are a beginner, forget it. This is (still) advanced stuff.
1) Never, never ever run the "fstcp" server on a computer connected
to the Internet!
It has no other security protection than checking the IP address of
an incoming connection request!
Never, never ever run the WWW server on the OS/A computer (C64), if
it is connected to more than your home PC. It reads all files from
the specified (C64 or OS/A) drive!
2) Now that you're warned: What's it for?
The TCP/SLIP implementation can be used for telneting to and
from an OS/A65 computer. Now it's used to transfer files between an
OS/A65 computer and a (Unix) computer. It can also be used as a simple
WWW server now.
I use it on a C64, to transfer files between a PC and a VC1541 disk.
The lowest level you can see is the icmp (internet control message
protocol) level. If you "ping" the OS/A65 computer, it replies.
See "man ping" on a Unix machine. It also replies to "traceroute"
packets appropriately.
Then there are the simple test TCP ports "echo" (7), "discard" (9) and
"chargen" (19). You can telnet to these ports on the OS/A65 computer.
See "man telnet" on how to telnet to a different port.
Another special port is the http port (80). This port is used to
transfer html pages for the World Wide Web (WWW). A special server
is listening on this port and serves requests from a given directory.
The next level is a client-server-application. The server "fstcp"
runs on a connected (unix) system. The client "slipd" runs on the
OS/A65 machine. It tries to connect to a remote server (the fstcp
program on the unix machine) and establishes a TCP connection to the
server. This connection is then used to transfer file data.
The "slipd" internet daemon exports internet capabilities to the
lib6502 library. This is actually the only part that still seems
to be buggy. The www server built into slipd is quite stable, as
is the rest of the OS (has been running for several days without
problems)
The default configuration for slipd (see sysapps/slipd/main.a65)
is to run the builtin WWW server, the telnet server (starts
the apps/inet/tlogin program for login) and the lib6502 stuff.
You have to change login/password/shell in tlogin.a65 to your
preferences.
With the lib6502 inet stuff the apps/inet/telnet program opens
a telnet connection to the host given at the command line
(in doted quad notation).
The procedures described here are for a Linux machine and a C64
with OS/A65 running. For the serial line setup you need root
(superuser) access to the unix machine. It should run without
any changes on any OS/A65 machine with a serial line.
3) IP concepts
a) addresses
In an IP (internet protocol) network, each computer has an IP number.
Normally you have to formally apply at the network information center
for an IP number or net. But there are numbers assigned to be used
in private, non-connected networks.
IP addresses are usually noted in the "doted quad" notation, i.e.
four decimal values from 0-255 each, separated by dots.
The private network I use is are the numbers
192.168.0.*
i.e. the numbers 192.168.0.1 - 192.168.0.254. There are two numbers
missing, they are used as network address (0) and normally as broadcast
address (255).
My unix (i.e. Linux) computer at home has the IP 192.168.0.10. This is
the IP the fstcp server is running on.
My C64 (with the OS/A65 operating system) has the IP 192.168.0.64.
So if the C64 has the slipd program running, I can do a
"ping 192.168.0.64" on my unix machine and get a reply!
b) routing
The internet protocol is a packet oriented network. A packet is
sent from one host to another, which is normally not the final
destination. Each host decides where to send a packet next, to get
the packet to its destination. This process is called routing.
Normally the program "route" is used to tell the computer which packets
to put where.
c) preparing a serial port
If you connect a serial line from the C64 to the unix machine, the
unix machine has to know that it has to send and which IP packets to
send there. There are some ways to achieve this.
The first way is with the command "slattach", which puts the
serial line from "terminal mode" to "SLIP" mode. Then "ifconfig"
configures the "sl0" interface with the IP address. The last command
is "route", which tells the unix OS that is has to send packets to the
C64's IP address to the interface sl0, which goes to the serial line.
The small script "csaip", provided in the oaslip directory, does
everything.
Warning: this script assumes you have network device "sl0" for the
OS/A65 link. If you have a SLIP connection somewhere else already.
this might not be true! The script then mangles your routing tables!
Another way is the program "diplogin" or "sliplogin" which does everything,
see the appropriate man pages.
I have added a program "term9600" which is a little C64 BASIC terminal
program to run the serial line at 9600 - if the kernel ROM allows that.
It can be used to login to the remote host if necessary.
4) TCP concepts
a) addresses
TCP addresses not only contain the IP address of the host, but also
the "port". The Port is like the number of the flat in a house, when the
IP number is the address of this house. Certain port numbers are
registered for a special use. Port 7 (echo) for example will send
all data you send to it back.
When you open a connection to a port on a remote computer, your own
computer also assigns a local port number to the connection, to have
a full TCP address at the sender side.
b) connections
In contrary to the IP protocol, the TCP is a connection based protocol.
A connection always takes place between two TCP "ports" or
two "pairs of IP and TCP port numbers". This connection is defined
with the properties:
- no data "overtakes" data sent before
- no data is lost
- no data is doubled
(which are all effects that can occur on IP)
With retransmissions, sequence numbers and lots of other things the
TCP ensures that the data is received in order and nothing is missing.
c) establishing a connection
Normally one side creates a "socket" and "binds" it to a specific
local TCP/IP address. It can then either "connect" to a remote
socket, or "listen" for remote connect requests. If the socket
listens on a port, the "accept" call will bind the local and remote
socket to a valid connection.
Normally a server program listens on a socket while the client tries
to connect to it.
d) used ports
I chose to use port "8090" as the port where the fstcp server is
listening at.
The WWW server built into slipd listens at the standard port 80,
and the telnet connection is listening at the standard telnet port (23).
5) Building the programs
a) the "fstcp" server
The fstcp server is a C program, in sysapps/slipd/fstcp.c. Going to the
slipd directory and typing "make fstcp" should work on unix (linux)
machines. In the first lines the port is defined where the server is
listening at.
b) the "slipd" client.
Most other files in the oaslip directory are to build the slip client.
In the first lines of "main.a65" the OS/A65 IP address (MY_IP) is defined.
(note the comma instead of the dots!). But the slipd server listens
for incoming packets and sets its own IP address if necessary.
Also the fstcp server TCP address (IP and port) are defined there.
The WWW server defines its drive and directory it will read the files
from. Do _never_ specify a drive on the fstcp filesystem. The slipd prg
will hang on the first access!
To assemble the files, you have to have my 6502 crossassembler "xa"
in you path, with version above 2.1.4d.
The slipd program is built when running "make" in the sysapps/slipd
subdirectory.
6) running the program
To run the program, do the following steps:
- connect the C64 (either with Daniel Dallmans 9600 baud interface,
or any other RS232 interface supported by OS/A65) and a serial
port of the (Linux-) PC with a Nullmodem cable.
The standard C64 configuration allows an UART16550 at address
$d600. To change that have a look at arch/c64/c64rom.a65, which
holds the configuration for the C64.
- enable SLIP on the serial line by running something similar to
the script oaslip/csaip (does slattach, ifconfig, route).
- If you want fstcp services, start the fstcp server on the unix
host. As arguments it needs the directory (relative from the
starting directory) to export and the IP address to which to export
the directory.
As fstcp might very well be buggy, try to be as cautions as
possible. Never ever run it on a computer connected to the internet.
Never ever run it as root (superuser).
- Transfer the slipd file to a disk accessible to the C64 when running
OS/A65 (using an x1541 cable, for example)
- start OS/A65 on the C64 (see other files, like README.c64)
- You should have a shell prompt (">") with a binking cursor.
Now start the slip.obj program by typing
c:slip.obj a:video4 c: c:tlogin <a:ser1 >a:ser1 &
This starts the slip client from drive c: (usually Commodore serial
IEC device #8, the floppy disk), piping the STDIO
to the C64 serial line ser1 (in standard C64 OS/A65 it's Daniel
Dallmanns 9600 baud interface). STDERR is sent to the 4th virtual
console (first command line parameter). The second parameter
is the drive to use as WWW server file source. The third parameter
is the program to start at a remote login on the telnet port.
The ampersand makes the slip program running in the background.
The slip program receives and sends its SLIP data via STDIO.
STDERR prints (currently a horrible lot of) debugging output.
You can also start the slipd program directly from the C64
ROM, see c64rom.a65
- If enabled, the slip client registers a filesystem with one drive.
On a standard C64 OS/A65 system, it will be drive g:.
If a connection to the server cannot be found, or breaks
later, the fstcp tries to reconnect in periodic intervals.
- You should now be able to ping the C64, and do telnets to the
echo, discard and chargen ports.
- when telneting to the http port (80)
(When the WWW server is enabled in oaslip/main.a65), you can issue
the "GET" command, followed by an URL on the OS/A65 computer.
You then get the specified file.
You can also point your Web browser (netscape) to the C64
with the URL "http://192.168.0.64/index.html". Replace the IP
number with the one you have chosen for your system.
- If fstcp is enabled, it should now also be possible to show the
directory of drive g:, and to read files from or write files to
drive g: This drive will be the contents of the directory given to
the fstcp server, i.e. on your Unix machine!
7) (Known) Bugs
- The WWW server only understands "GET filename" requests. No "http://"
or host prefixes are allowed. At least with Netscape it seems to work.
- The implementation is bloated, and horribly slow.
- Tons of others, I'm sure
- lib6502 binding seems to bug.
