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| author | user <user@clank> | 2026-07-17 19:45:13 +0200 |
|---|---|---|
| committer | user <user@clank> | 2026-07-17 19:45:13 +0200 |
| commit | 4f038ecad87777bc1d74f8f93f267da8cd396446 (patch) | |
| tree | 28332e362bb8c1c75e97483af21c51cc13cffdac /include | |
| parent | docs: investigation notes for the idle link-socket drop (open bug) (diff) | |
| download | gbos-4f038ecad87777bc1d74f8f93f267da8cd396446.tar.gz gbos-4f038ecad87777bc1d74f8f93f267da8cd396446.tar.xz gbos-4f038ecad87777bc1d74f8f93f267da8cd396446.zip | |
net: unbreak ping against hosts that intermittently drop ICMP
Pinging sl0p.foo through gbhub looked hung: DNS resolved, then nothing.
Packet-tracing showed the echo request leaving the hub's TUN and eth0
correctly NATed every time - but 80.78.19.56 blackholes ICMP for all
ids in windows of tens of seconds (provider rate limiting). One lost
reply wedged ping for minutes because net_recv's pump-counted timeout
is effectively unbounded at native emulation speed.
Two fixes:
- NET_RECVNB (op 8): non-blocking recv - one RX pump, $FE if nothing
buffered, same delivery/EOF semantics as NET_RECV otherwise. ping now
waits <=~2s per seq (net_recv_nb + msleep loop), prints 'seq=N
timeout' and moves on, like real ping.
- ICMP echo id was hardcoded $1234 for every GB, every boot, so all
sessions produced byte-identical flows - hostile to NAT conntrack
(keyed on icmp id). wNetEchoId is now our host octet + rDIV timing
noise sampled at DHCP lease, distinct per GB and per boot.
Verified: 8 back-to-back native-speed gbhub runs, zero hangs; a run
that hit a blackhole window printed seq=1 timeout then recovered to
3/4 received. GB<->GB ping and DNS/DHCP unaffected.
Diffstat (limited to 'include')
| -rw-r--r-- | include/gbos.inc | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/gbos.inc b/include/gbos.inc index 937d083..e9f8d7d 100644 --- a/include/gbos.inc +++ b/include/gbos.inc @@ -153,6 +153,9 @@ DEF NET_CLOSE EQU 4 ; NR_SOCK DEF NET_BIND EQU 5 ; NR_SOCK, NR_PORT -> bind local port (UDP) DEF NET_POLL EQU 6 ; pump RX once (answer pings) -> A=0 DEF NET_SETIP EQU 7 ; set our IPv4 address from NR_IP (DHCP) +DEF NET_RECVNB EQU 8 ; like NET_RECV but never blocks: pump once, then + ; A=len if a datagram was buffered, $FE if none yet, + ; 0 on TCP EOF. Lets programs own their timeouts (ping). ; socket types DEF SOCK_ICMP EQU 1 DEF SOCK_UDP EQU 2 |