Adds the client half of TCP -- tcp_connect/tcp_send/tcp_recv/tcp_close --
and wires SOCK_STREAM sockets to it, so the kernel can originate an
outbound stream rather than only answer inbound ones. Inbound segments
are now matched against the connection table before being offered to the
listeners; previously anything not addressed to a listening port was
answered with RST, which would have rejected the SYN-ACK completing our
own handshake.
Transmission is stop-and-wait: one segment outstanding, retransmitted
until acknowledged. Every blocking call is bounded against the timer tick
and halts the CPU between checks, so a silent peer costs a timeout rather
than a hang. Connections linger in TIME_WAIT so a late duplicate cannot
be mistaken for traffic on a new incarnation.
Verifying it against a real peer uncovered two pre-existing bugs that had
made TCP unusable in both directions. Neither was visible from inside the
guest, which is why the servers had looked fine:
1. The TCP and UDP checksums were computed by reading the header a
uint16_t at a time, immediately after the caller stored zero into that
same header's checksum field. Nothing stops the compiler reordering
those word reads around that store, and at -O2 it did: the stale
checksum field was folded into its own result. Every TCP segment the
kernel had ever sent carried a wrong checksum and was silently dropped
by the peer -- no client could complete a handshake with sshd or
httpd, and it is the likely reason DHCP and DNS replies never arrived.
The checksum is now summed a byte at a time through unsigned char
pointers, which may alias any object and so cannot be reordered, and
which also drops the alignment assumption that reading a packed header
as uint16_t made -- a fault rather than a slowdown on ARM. The helper
is shared by IP, TCP and UDP instead of being open-coded four times.
2. net_receive derived the datagram length from the Ethernet frame rather
than from the IP header's total_length, so the padding on any frame
shorter than 60 bytes was delivered as protocol payload. A bare ACK or
FIN appeared to carry six bytes, which pushed the acknowledgement
number out of step with the peer and turned every close into a FIN
retransmission storm answered with RST.
Also adds `tcpconnect` and `httpget` applets, and gives netstat the real
per-connection state and direction from the engine's table.
Verified on x86_64 against a real TCP stack, checked packet by packet in
a capture: `httpget` fetched a 349-byte page from a server on the host --
handshake, 81-byte request, response, orderly four-way close, every
sequence number exact, zero bad checksums, no retransmissions. In the
other direction curl on the host now fetches a live page from the guest's
httpd, which had never worked. Builds clean on x86_64, aarch64 and armv8i.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Fh5z6V7nGPbHvqVG5p4CXX
Turn the networking stubs into a working transport/application stack on top of
the existing L2/L3 (Ethernet/ARP/IPv4/ICMP) core.
UDP (net/ipv4/udp.c)
- Port-demux table with bound receive handlers, pseudo-header checksum,
ephemeral-port allocation, limited-broadcast send (0.0.0.0 -> 255.255.255.255
for DHCP before the interface has an address), and rx/tx/drop counters.
- Wired into the IPv4 receive path (IP_PROTO_UDP dispatch in net/core/net.c).
BSD sockets (net/core/socket.c)
- Real SOCK_DGRAM sockets backed by UDP: bind installs a UDP handler that fills
a per-socket receive ring; send/sendto and recv/recvfrom move datagrams;
ephemeral auto-bind, connect() memorises the peer. Socket table + I/O stats
exposed for introspection.
DNS resolver (net/ipv4/dns.c)
- Builds and parses real A-record queries over UDP/53 (label encoding,
compression-pointer aware answer walk), cache-first with TTL, static-hosts
and dotted-quad fast paths, and a bounded timeout that degrades to fallback
instead of hanging.
DHCP client (net/ipv4/dhcp.c)
- Full DISCOVER/OFFER/REQUEST/ACK handshake over UDP broadcast, option parsing
(mask/router/dns/lease/server-id), applies the lease to the primary
interface, bounded timeouts keep the static config on no response.
Fix (net/ipv4/dns_cache.c): the cache stored IPs as 0xAABBCCDD numeric while the
rest of the stack uses network-byte-order-in-memory (ip_parse/ip_to_str), so a
resolved address came back byte-swapped (nslookup github.com -> 100.121.82.140).
Seeds and dump now use ip_parse/ip_to_str; verified 140.82.121.4.
Userland (lazybox): live ifconfig (real interface + NIC counters, loopback),
netstat with live UDP bindings and transport stats, new `sockstat`, richer
nslookup. Verified in QEMU: boot clean on x86_64/aarch64/armv8i, login as SUB,
ping/nslookup/dhclient/netstat/sockstat all run; DHCP/DNS wire replies are
blocked by the sandbox's slirp but time out cleanly and fall back as designed.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Fh5z6V7nGPbHvqVG5p4CXX
Kernel / memory:
- mm/kmalloc.c: fix "Heap: Out of memory" under the GUI. The desktop allocates
three full-screen 32-bit buffers (~11MB) which overflowed the fixed 16MB pool.
The heap now starts at 32MB and grows on demand from the PMM (16MB regions),
with region-safe coalescing (only merges physically adjacent blocks) so growth
never corrupts across separate PMM allocations. Adds heap_get_grow_count().
Build / run:
- Makefile: merge `run-gui` into `run` so `make run` boots into the graphical
desktop; add `run-headless` (serial-only via QEMU_CMD), bump guest RAM to
256M, update .PHONY and help.
Configure:
- scripts/kconfig/menuconfig.py: gate the curses UI behind isatty() on stdin and
stdout so non-interactive `make configure` stops emitting "nocbreak() returned
ERR" and falls cleanly through to the non-interactive writer.
GUI / userland:
- gui/gui_apps.c: rebuild the System Monitor from hardcoded values into live
telemetry -- real heap used/total/free with a colour-shifting bar, a scrolling
heap-utilisation graph, the grow counter, and real PMM RAM figures.
- lazybox `free`: report how many times the heap has grown.
Auth:
- Default login is now SUB / SUB (Kali-style username==password), seeded first
as the primary uid-0 account and set as the logged-in user; root kept for
compatibility. Hardcoded "root" defaults (whoami, su, passwd, ssh, sshd
session) updated to SUB.
Verified: clean build on x86_64/aarch64/armv8i; GUI boots with 0 OOM/0 panic;
auth engine initialises cleanly; `make configure` fallback is clean.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Fh5z6V7nGPbHvqVG5p4CXX
- Implement flicker-free atomic double-buffered frame rendering and sub-tick input polling in userland/lazybox/snake.c
- Add multi-input support (PS/2 keyboard scancodes and serial ANSI arrow escape sequences)
- Add sound effects (food beep, game over chime) and live speed scaling (+/- keys, P to pause)
- Add POSIX /dev/shm shared memory subsystem in ipc/shm_posix.c and include/ipc/shm_posix.h
- Add DNS resolver cache with TTL tracking in net/ipv4/dns_cache.c and include/net/dns_cache.h
- Add audio tone and jingle synthesizer in sound/beep.c and include/sound/beep.h
- Add %o octal formatting support in lib/vsprintf.c
- Add LazyBox applets: 'shm', 'dnscache', and 'beep'
