The visible goal was a Web app: type a URL, see the page, fetched over the
TCP stack SUB-OS built. Getting there surfaced -- and forced fixes to --
two deeper problems.
Async HTTP client (net/http_client.c)
tcp_connect/recv all block, so fetching from the GUI would freeze the
compositor. Fetches now run on one long-lived kernel worker thread that
services a single-slot mailbox; the requester posts a job and polls its
state. Ownership follows the state, and the two hand-off points (worker
completion, requester release) run under interrupts-off, so a window can
close mid-fetch with neither leak nor use-after-free. do_fetch returns
its terminal state rather than publishing it, closing a window where the
requester could free the job before finalize read it.
Cooperative scheduling for the idle thread (the core fix)
The login prompt, the shell and the GUI compositor all run on the pid-0
idle thread, which the scheduler by design never preempts (sched_tick
skips pid 0) and never requeues on a yield (weave_on clear). So it could
neither be preempted to let the worker run, nor cleanly yield -- the
worker was simply starved, and an early attempt to yield from it froze
the shell outright. The idle thread now joins the weave rotation once
hardware interrupts are live, and the network wait loops (tcp, dns, ping,
the worker's idle) yield through a new net_wait() instead of halting the
CPU. The compositor spends its frame-budget slack yielding too. Result:
a background fetch progresses while the desktop holds 54 FPS.
Web app (gui/gui_app_web.c)
A text browser: URL bar, Go, and a Raw/Reader toggle. Raw shows the
response verbatim; Reader strips markup (dropping <script>/<style>
bodies), decodes the common entities, and word-wraps the body. The line
index is cached against content/view/width so scrolling and idle
repaints are free. It only ever polls the worker, so it never stalls.
TCP throughput (the limit flagged last time)
The 32-slot table with a 2 s TIME_WAIT linger capped sustained serving
at ~16 req/s. The table is now 64 slots, a connection this end closed
after serving a request lingers 250 ms rather than 2 s, and expired
TIME_WAIT entries are reaped from the count path so a quiet table still
drains. netstat/netmon gained served-since-boot and peak-slots counters.
Also: a `webget` CLI (the async client from a shell), listen/accept
introspection already present, and a globe icon for the app.
Verified on x86_64: `webget` fetched an 812-byte page (HTTP 200, 10 ms) on
the worker thread; the GUI Web app rendered the same page in Reader mode
while the desktop held 54 FPS; an 80-request burst through the 64-slot
table returned 80/80 (was 39/40 before) and netstat reported "80 served,
peak 33 of 64 slots" -- a peak that would have overflowed the old table.
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
