gbos.git/tools/tunbridge.py, branch mastergbos - a tiny Unix-flavored OS for the Game Boy Color (kernel, shell, coreutils in C, RAM filesystem)https://git.sl0p.foo/gbos.git/atom/tools/tunbridge.py?h=master2026-07-17T12:11:22Znet: DHCP client - lease the IP at boot instead of hardcoding it2026-07-17T12:11:22Zuseruser@clank2026-07-17T12:11:22Zurn:sha1:a2cb756693229c7880d926d2cdde2f838c697415
The address is no longer baked in. net_init starts at 0.0.0.0; a DHCP client
runs as the first thing on boot (init/shell forks it and waits), and only once
it has a lease (or gives up) does the prompt appear.
Kernel:
- IP is configurable: 0.0.0.0 until leased; NET_SETIP op stores it.
- 16-bit frame length. DHCP/BOOTP packets are ~272 bytes, over the old 255-byte
frame cap, so net_slip_send takes a 16-bit length, net_pump assembles into a
320-byte buffer with a 16-bit wNetRxLen, and udp_send writes a 16-bit IP total.
Payloads stay <=255 (kept small on purpose) so the per-protocol datalen math
is unchanged. wNetTx/wNetRxBuf 256->320, SK_RXBUF 208->288.
Userland:
- c/dhcp.c: DISCOVER->OFFER->REQUEST->ACK over a UDP socket, then net_setip();
times out gracefully (shell still boots) if there's no server. sh.c runs it
before the prompt.
Bridge (self-contained DHCP server, no dnsmasq):
- tunbridge.py + netboot intercept UDP->:67 and answer OFFER/ACK leasing
10.0.0.2 (gateway 10.0.0.1); everything else is bridged/NATed as before.
Regression-tested ICMP/UDP/TCP after the 16-bit change. Verified end to end:
dhcp: discovering
dhcp: leased 10.0.0.2
/# ping 10.0.0.1 -> 4/4 (traffic from the leased address)
net: keep network packets out of the console (fixes shell garbage on netboot)2026-07-17T11:29:42Zuseruser@clank2026-07-17T11:29:42Zurn:sha1:e442252d72f1aab4c332a76983cd3924ce2b492b
The link port is both the console-input fallback and the network. At the shell
prompt the host's multicast (mDNS/LLMNR/IGMP) was fed to the serial and KGetc
read those packet bytes as console input -> garbage in the shell, OSK unusable.
Two-part fix:
- KGetc now skips SLIP frames (0xC0-delimited) on the serial console path, so
inbound packets never surface as console input. Plain injected bytes (the
headless tunbridge command path) still pass through. New wConInSkip flag.
- netboot/tunbridge only forward IP packets destined to 10.0.0.2 (drop the
multicast noise at the bridge).
Verified: GB sits at a clean "/#" prompt while all packets (noise included) are
forwarded; being-pinged (3/3) and wget still work. On the emulator, the OSK is
SELECT=space, START=enter, A=z, B=x, d-pad=WASD/arrows.
net: real routed IP via SLIP<->TUN bridge (you can *ping* a Game Boy)2026-07-17T01:01:58Zuseruser@clank2026-07-17T01:01:58Zurn:sha1:0e5889c7dd431d7cb4cdaacea2702065fd96839f
tunbridge.py opens a TUN device (gbtun0, 10.0.0.1/24), NATs 10.0.0.0/24 out
to the internet, spawns the emulator, and bridges raw IP packets on the TUN
to/from SLIP frames on the link serial. The Game Boy (10.0.0.2) becomes a
genuine routed IP host: the host kernel routes its packets for real, so the
host's own `ping` command reaches it and netd answers.
Verified: `sudo python3 tools/tunbridge.py netd --test`
64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=1.61 ms
4 packets transmitted, 4 received, 0% packet loss
Two hard-won gotchas baked in:
- Under sudo, ~ expands to /root, so resolve EMU/ROM via $SUDO_USER's home.
- Only start feeding host->GB packets AFTER netd is running; raw packet
bytes delivered to gbos's shell (before netd claims the serial) corrupt
the shell and crash the emulator. gb->host draining starts immediately.
Requires /dev/net/tun (on Proxmox LXC: allow cgroup2 device c 10:200 rwm +
bind-mount /dev/net/tun into the container).