go9p-netfs

A 9P synthetic filesystem that models a subset of Plan 9's /net device interfaces (ip(3), ether(3), bridge(3)) on top of Linux userland networking, served with [go9p](https://github.com/lionkov/go9p).

This was originally an example under p/srv/examples/netfs/ in go9p and is now maintained as a standalone project so it can grow independently of the core 9P library.

See [DESIGN.md](./DESIGN.md) for the full design notes (intent, filesystem shape, semantics, and limitations).

Filesystem shape (current)

/net
  tcp/           working subset: clone-allocated conversations (ctl/data/local/remote/status)
  ndb            small read/write config blob
  log            simple log buffer + controls
  ipifc/         read-only projection of host interfaces
  ipselftab      read-only local address listing
  arp            stub
  iproute        stub
  ether0/        minimal ether(3) surface (mostly stub)
  bridge0/       minimal bridge(3) surface (mostly stub)
  udp/ icmp/ ... protocol dirs (placeholders)

The TCP conversation pattern (/net/tcp/clone + per-id ctl/data) is fully implemented and tested end-to-end against the Go 9P client.

Run

go run ./cmd/go9p-netfs -addr 127.0.0.1:5640

Flags:

• -addr <host:port> — listen address (default :5640)
• -d — print 9P debug messages

From another terminal you can drive it with any go9p client, for example the session helper from your go9p checkout:

go run /Users/erivan01/src/v9fs/go9p/cmd/go9p-session -net tcp -addr 127.0.0.1:5640

Inside the session:

read /net/tcp/clone          # allocates /net/tcp/<id>/
write /net/tcp/<id>/ctl connect example.com!80
write /net/tcp/<id>/data GET / HTTP/1.0\r\nHost: example.com\r\n\r\n
read /net/tcp/<id>/data
write /net/tcp/<id>/ctl close

Mount with the Linux kernel 9p client

sudo mount -t 9p -o trans=tcp,port=5640,version=9p2000.u,uname=$USER 127.0.0.1 /mnt/netfs
ls /mnt/netfs/net

netfs is intentionally light on kernel-write paths — the e2e smoke tests focus on safe reads and clone allocation rather than relying on kernel write compatibility for every synthetic node.

Tests

go test ./...

The userspace tests exercise the TCP conversation flow (clone, connect, data, close, status) end-to-end against an in-process go9p client.

Status

This module currently builds against the rework branch of github.com/ericvh/go9p (pinned via a replace directive in go.mod) until the changes there are merged upstream into github.com/lionkov/go9p.