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#!/usr/bin/env python3
"""gateway.py - host-side "link cable adapter" for gbos networking.
Wraps the emulator, owns its link-port serial (stdio), speaks SLIP, and does
the real network work the Game Boy can't. Modes:
echo - bounce every frame back (loopback test)
http - treat each frame as a URL, HTTP GET it, stream the body back
chat - a simple echo-bot peer (+ a few async messages)
irc - bridge to a real IRC server over TLS; the GB is a chat client and
the gateway does the crypto/TCP/IRC protocol
Reply frames are typed for http (b'D'+chunk .. b'E'); chat/irc frames are the
raw display line.
usage: tools/gateway.py [--mode ...] [--cmd "chat"] [--nick gameboy]
[--channel '#sl0p'] [--keys STR] [--rom PATH]
"""
import os, sys, subprocess, threading, time, argparse, urllib.request
import socket, ssl, re, struct
EMU = os.path.expanduser("~/dev/gbc/build/sl0pboy")
END, ESC, ESC_END, ESC_ESC = 0xC0, 0xDB, 0xDC, 0xDD
CHUNK, LIMIT = 200, 800
def slip_encode(payload):
out = bytearray([END])
for c in payload:
if c == END: out += bytes([ESC, ESC_END])
elif c == ESC: out += bytes([ESC, ESC_ESC])
else: out.append(c)
out.append(END)
return bytes(out)
def http_fetch(payload):
url = bytes(payload).decode("latin1", "replace").strip()
if not url.startswith("http"): url = "http://" + url
sys.stderr.write("\n[gw] GET %s\n" % url)
try:
req = urllib.request.Request(url, headers={"User-Agent": "gbos/0.1"})
with urllib.request.urlopen(req, timeout=8) as r:
body = r.read(LIMIT)
except Exception as e:
body = ("ERR: " + str(e)).encode()
sys.stderr.write("[gw] %d bytes\n" % len(body))
return [b"D" + body[i:i+CHUNK] for i in range(0, len(body), CHUNK)] + [b"E"]
_IRC_FMT = re.compile(r'(\x03\d{0,2}(,\d{1,2})?|[\x00-\x1f])')
def strip_irc(s): return _IRC_FMT.sub('', s)
class IRC:
"""Minimal TLS IRC client. The gateway does all the crypto/protocol."""
def __init__(self, host, port, nick, chan, to_gb):
self.nick, self.chan, self.to_gb, self.buf = nick, chan, to_gb, b""
ctx = ssl.create_default_context()
ctx.check_hostname = False; ctx.verify_mode = ssl.CERT_NONE
self.s = ctx.wrap_socket(socket.create_connection((host, port), timeout=10),
server_hostname=host)
self._send("NICK " + nick)
self._send("USER %s 0 * :gbos on a link cable" % nick)
def _send(self, x): self.s.sendall((x + "\r\n").encode("latin1", "replace"))
def privmsg(self, text): self._send("PRIVMSG %s :%s" % (self.chan, text[:400]))
def loop(self):
while True:
try: d = self.s.recv(4096)
except Exception: return
if not d: return
self.buf += d
while b"\r\n" in self.buf:
line, self.buf = self.buf.split(b"\r\n", 1)
self._handle(line.decode("latin1", "replace"))
def _handle(self, line):
if line.startswith("PING"): self._send("PONG" + line[4:]); return
p = line.split(" ", 3)
if len(p) < 2: return
cmd = p[1]
if cmd == "001":
self._send("JOIN " + self.chan)
self.to_gb("* connected to %s, joining %s" % (p[0].lstrip(":"), self.chan))
elif cmd == "433":
self.nick += "_"; self._send("NICK " + self.nick)
elif cmd == "JOIN" and len(p) >= 3:
who = p[0].lstrip(":").split("!")[0]
if who == self.nick: self.to_gb("* joined %s" % self.chan)
elif cmd == "PRIVMSG" and len(p) >= 4 and p[2].lower() == self.chan.lower():
who = p[0].lstrip(":").split("!")[0]
self.to_gb("%s: %s" % (who, strip_irc(p[3].lstrip(":"))))
def reader(out, inp, on_frame):
buf, in_frame, esc = bytearray(), False, False
while True:
b = out.read(1)
if not b: return
c = b[0]
if c == END:
if in_frame and buf:
for f in on_frame(bytes(buf)):
inp.write(slip_encode(f)); inp.flush()
buf, in_frame, esc = bytearray(), False, False
else:
buf, in_frame, esc = bytearray(), True, False
elif in_frame:
if esc:
c = {ESC_END: END, ESC_ESC: ESC}.get(c, c); esc = False; buf.append(c)
elif c == ESC: esc = True
else: buf.append(c)
else:
sys.stderr.write(chr(c) if 32 <= c < 127 else ("\n" if c == 10 else "."))
sys.stderr.flush()
GB_IP, GW_IP = bytes([10,0,0,2]), bytes([10,0,0,1])
def inet_cksum(data):
if len(data) % 2: data += b"\x00"
s = sum(struct.unpack("!%dH" % (len(data)//2), data))
while s >> 16: s = (s & 0xffff) + (s >> 16)
return (~s) & 0xffff
def icmp_echo(seq, payload=b"gbos-ping-0123456789"):
icmp = struct.pack("!BBHHH", 8, 0, 0, 0xBEEF, seq) + payload
icmp = icmp[:2] + struct.pack("!H", inet_cksum(icmp)) + icmp[4:]
ip = struct.pack("!BBHHHBBH", 0x45, 0, 20+len(icmp), seq, 0, 64, 1, 0) + GW_IP + GB_IP
ip = ip[:10] + struct.pack("!H", inet_cksum(ip)) + ip[12:]
return ip + icmp
def udp_packet(sport, dport, payload):
ulen = 8 + len(payload)
udp = struct.pack("!HHHH", sport, dport, ulen, 0) + payload
pseudo = GW_IP + GB_IP + bytes([0, 17]) + struct.pack("!H", ulen)
ck = inet_cksum(pseudo + udp) or 0xffff
udp = udp[:6] + struct.pack("!H", ck) + udp[8:]
ip = struct.pack("!BBHHHBBH", 0x45, 0, 20+ulen, 7, 0, 64, 17, 0) + GW_IP + GB_IP
ip = ip[:10] + struct.pack("!H", inet_cksum(ip)) + ip[12:]
return ip + udp
def main():
ap = argparse.ArgumentParser()
ap.add_argument("--mode", default="echo", choices=["echo", "http", "chat", "irc", "ping", "udp"])
ap.add_argument("--cmd", default="necho")
ap.add_argument("--nick", default="gameboy")
ap.add_argument("--channel", default="#sl0p")
ap.add_argument("--host", default="sl0p.foo")
ap.add_argument("--port", type=int, default=6697)
ap.add_argument("--keys", default=None)
ap.add_argument("--seconds", type=float, default=6.0)
ap.add_argument("--rom", default=os.path.join(os.path.dirname(__file__), "..", "gbos.gb"))
a = ap.parse_args()
cmd = [EMU, "--headless", "--uncapped"]
if a.keys: cmd += ["--keys", a.keys]
cmd.append(a.rom)
p = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE, bufsize=0)
irc_holder = [None]
if a.mode == "irc":
def on_frame(payload):
msg = bytes(payload).decode("latin1", "replace")
if irc_holder[0] is None: return [] # chat not wired to IRC yet
sys.stderr.write("\n[gw] GB -> IRC: %s\n" % msg)
irc_holder[0].privmsg(msg)
return []
elif a.mode == "http":
on_frame = http_fetch
elif a.mode == "chat":
def on_frame(payload):
m = bytes(payload).decode("latin1", "replace")
sys.stderr.write("\n[gw] GB says: %s\n" % m)
return [("<bot> " + m).encode()]
elif a.mode == "udp":
def on_frame(payload):
p = bytes(payload)
if len(p) >= 28 and p[9] == 17:
ihl = (p[0] & 0x0f) * 4
sport, dport, ulen = struct.unpack("!HHH", p[ihl:ihl+6])
data = p[ihl+8:ihl+8+ulen-8]
ck_ok = inet_cksum(GB_IP + GW_IP + bytes([0,17]) + p[ihl+4:ihl+6] + p[ihl:]) == 0
sys.stderr.write("\n[gw] UDP echo %d->%d: %r cksum=%s\n"
% (sport, dport, data, "ok" if ck_ok else "BAD"))
return []
elif a.mode == "ping":
def on_frame(payload):
p = bytes(payload)
if len(p) >= 28 and (p[0] >> 4) == 4 and p[9] == 1:
ihl = (p[0] & 0x0f) * 4
if p[ihl] == 0: # ICMP echo reply
seq = struct.unpack("!H", p[ihl+6:ihl+8])[0]
ok = inet_cksum(p[:ihl]) == 0 and inet_cksum(p[ihl:]) == 0
sys.stderr.write("\n[gw] reply from %d.%d.%d.%d icmp_seq=%d cksum=%s\n"
% (p[12],p[13],p[14],p[15],seq,"ok" if ok else "BAD"))
return []
else:
on_frame = lambda payload: [bytes(payload)]
threading.Thread(target=reader, args=(p.stdout, p.stdin, on_frame), daemon=True).start()
time.sleep(1.0)
p.stdin.write((a.cmd + "\n").encode()); p.stdin.flush()
if a.mode == "irc":
time.sleep(1.5) # let `chat` come up first
def to_gb(text):
try: p.stdin.write(slip_encode(text.encode("latin1", "replace"))); p.stdin.flush()
except Exception: pass
irc_holder[0] = IRC(a.host, a.port, a.nick, a.channel, to_gb)
threading.Thread(target=irc_holder[0].loop, daemon=True).start()
if a.mode == "udp":
time.sleep(1.0)
p.stdin.write(slip_encode(udp_packet(5000, 7, b"hello udp gbos"))); p.stdin.flush()
sys.stderr.write("[gw] sent UDP :5000->:7 'hello udp gbos'\n")
time.sleep(2.0)
if a.mode == "ping":
time.sleep(1.0)
for seq in range(1, 5):
p.stdin.write(slip_encode(icmp_echo(seq))); p.stdin.flush()
sys.stderr.write("[gw] ping 10.0.0.2 icmp_seq=%d\n" % seq)
time.sleep(0.8)
if a.mode == "chat":
time.sleep(1.0)
for m in [b"welcome to sl0pchat", b"<alice> hey gameboy!", b"<bob> nice link cable"]:
p.stdin.write(slip_encode(m)); p.stdin.flush(); time.sleep(0.6)
time.sleep(a.seconds)
try:
p.stdin.write(b"exit\n"); p.stdin.flush()
p.wait(timeout=3)
except Exception:
p.kill()
if __name__ == "__main__":
main()
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