From c8c22bfc511ac65036cd8f8462e0a01757eb4372 Mon Sep 17 00:00:00 2001
From: user <user@clank>
Date: Fri, 17 Jul 2026 02:03:05 +0200
Subject: net: real IP stack, milestone A - ICMP echo (you can ping a Game Boy)

Start of an actual TCP/IP stack on gbos (TLS stays in a proxy). netd is a
userland IP responder over SLIP: our address is 10.0.0.2, the SLIP peer
10.0.0.1. It parses IPv4 headers, answers ICMP echo requests, and rebuilds
the packet with correct IP + ICMP checksums (RFC 1071 one's-complement sum,
carry-folded - works fine on the SM83).

c/netd.c + register; tools/gateway.py gains --mode ping: it crafts ICMP echo
requests over SLIP and verifies the replies.

Verified: `netd` answers 4 pings, gateway reports reply from 10.0.0.2 with
cksum=ok for each. Next: UDP, then TCP.
---
 src/programs.asm | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'src')

diff --git a/src/programs.asm b/src/programs.asm
index 180f551..7a01abc 100644
--- a/src/programs.asm
+++ b/src/programs.asm
@@ -118,6 +118,9 @@ ProgWget:
 SECTION "prog_chat",   ROMX[$4000], BANK[27]
 ProgChat:
     INCBIN "c/chat.bin"
+SECTION "prog_netd",   ROMX[$4000], BANK[28]
+ProgNetd:
+    INCBIN "c/netd.bin"
 
 ; -----------------------------------------------------------------------------
 ; PROG_SH (bank 3) - the shell, now written in C (c/sh.c): parses >/</| and
@@ -212,6 +215,8 @@ ProgramTable::
     dw ProgWget
     db LOW(BANK(ProgChat)), HIGH(BANK(ProgChat))
     dw ProgChat
+    db LOW(BANK(ProgNetd)), HIGH(BANK(ProgNetd))
+    dw ProgNetd
 
 ; -----------------------------------------------------------------------------
 ; NameTable (ROM0) - command name -> program id, searched by sys_lookup.
@@ -270,4 +275,6 @@ NameTable::
     db PROG_WGET
     db "chat", 0
     db PROG_CHAT
+    db "netd", 0
+    db PROG_NETD
     db 0
-- 
cgit v1.3.1-sl0p