Stream: git-wasmtime

Topic: wasmtime / PR #13934 wasi-sockets: Unify the p2 & p3 impl...

Wasmtime GitHub notifications bot (Jul 22 2026 at 14:38):

badeend opened PR #13934 from badeend:addr-checks to bytecodealliance:main:

Currently, the shared socket code (crates/wasi/src/sockets/*) is modeled after the
p2 interface, with p3 bindings papering over the differences. Some
functionality is duplicated between the p2/* and p3/* implementations. This has
already caused bugs in the past.

Since the p3 interface is strictly a superset of p2, I think it makes more sense to invert that relationship. This PR updates the shared code to become the canonical (p3-shaped)
implementation with the p3's bindings now a thin wrapper around it. All
p2-only behavior & state is moved into the p2 bindings layer. Think of: artificial restrictions like disallowing implicit
binds, and the start/finish async bookkeeping.

Other notable changes:

• Each socket now stores its own copy of the WasiCtx's
  socket_addr_check at creation time, allowing all permission checks to live in
  the shared socket code instead of being split across p2/p3. The p2
  Network resource is now just an unforgeable capability token (its
  permission-checking responsibilities are gone).

• Removed the Bound state; whether a socket is bound is now determined
  lazily via getsockname/local_addr instead of tracked explicitly.
  This simplifies the implementation of UdpSocket::send, allowing it to return a future that can run to completion independently, without needing to rendezvous back with the socket to update its state.

• Updated SocketAddrUse:
  - added TcpListen, TcpAccept, UdpReceive checks.
  - replaced UdpConnect with calls to UdpSend and UdpReceive. On UDP sockets, "connecting" is just a local operation that sets the default remote address for future sends and receives. It does not actually do any I/O on its own.
  - Note to reviewer: this is a breaking change.

• Tcp&UdpSocket::connect now also issue a permission
  check for the implicit bind that the OS performs when connecting an
  unbound socket, matching the check already done for explicit binds. Following through the changes of https://github.com/bytecodealliance/wasmtime/pull/13677

• Removed the StdView type introduced in https://github.com/bytecodealliance/wasmtime/pull/13872 infavour of direct usage of BorrowedFd

Added test coverage for previously-untested behavior:

• test_udp_disconnect_local_address (p2 & p3): disconnecting a UDP
  socket should keep it bound. Exercises the removal of the explicit Bound
  state in favor of lazily-derived bound status.

• test_udp_send_receive_multiple (p2): a single send/receive call
  can carry multiple datagrams at once (bulk send/receive over a
  connected stream()).

• test_udp_receive_after_connect (p2): datagrams from different peers
  queued before a socket is connected are correctly filtered so that
  stream(Some(addr)) only returns datagrams from the provided address.

---

All-in-all, the goal of this PR is to consolidate the socket code (even further) into a single place and make it less error-prone to maintain. I realize there's quite a bit of unannounced code movement here, so let me know what you think.

Wasmtime GitHub notifications bot (Jul 22 2026 at 14:38):

badeend requested pchickey for a review on PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 14:38):

badeend requested wasmtime-wasi-reviewers for a review on PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 14:38):

badeend requested wasmtime-core-reviewers for a review on PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:05):

github-actions[bot] added the label wasi on PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:46):

alexcrichton unassigned pchickey from PR #13934 wasi-sockets: Unify the p2 & p3 implementations.

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:46):

alexcrichton requested alexcrichton for a review on PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:55):

:thumbs_up: alexcrichton submitted PR review:

Thanks so much for this! This all sounds great to me and I think the refactoring's a good idea. Do you think long-term it would be possible to fold the utils.rs module into the tcp/udp modules directly? That seems a vestige of a time where it was a home of common functionality between p2/p3, but nowadays that should just be {Tcp,Udp}Socket. (Fine to happen in a follow-up PR of course)

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:55):

:speech_balloon: alexcrichton created PR review comment:

For this the handling of finish is a bit subtle, but the basic idea is that this continues to do everything below and then instead of returning Pending at the last second it returns Cancelled instead. That gives sort of a "final chance" to get everything completed

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:55):

:speech_balloon: alexcrichton created PR review comment:

Similar comment to below on finish here

Wasmtime GitHub notifications bot (Jul 22 2026 at 17:55):

:speech_balloon: alexcrichton created PR review comment:

Similar comment to below on finish here

Wasmtime GitHub notifications bot (Jul 22 2026 at 20:26):

badeend updated PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 20:34):

:memo: badeend submitted PR review.

Wasmtime GitHub notifications bot (Jul 22 2026 at 20:34):

:speech_balloon: badeend created PR review comment:

My reasoning was that; if the guest cancels the read/write, there's no point in us to querying the OS again for something the guest isn't interested in anymore. Which is why I had the early return.

But I'm fine with giving it one last poll. See latest commit.

Wasmtime GitHub notifications bot (Jul 22 2026 at 20:44):

badeend commented on PR #13934:

Do you think long-term it would be possible to fold the utils.rs module into the tcp/udp modules directly?

For the things that are explicitly marked as tcp_* & udp_*; Yes, that should be possible.

There are also a bunch of functions that are shared between tcp & udp, like:

• is_valid_address_family
• normalize_get_buffer_size
• get_ip_ttl
• unspecified_addr
• ..

For those , I think the best we can do is move them into mod.rs.

Wasmtime GitHub notifications bot (Jul 22 2026 at 21:20):

:memo: alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Jul 22 2026 at 21:21):

:speech_balloon: alexcrichton created PR review comment:

Yeah the intent of the guest is a bit ambiguous because it could mean "I still want to try to finish, but clear out otherwise" vs "I'm totally uninterested in the result just clean up" which is conflated right now

Wasmtime GitHub notifications bot (Jul 22 2026 at 21:21):

alexcrichton commented on PR #13934:

Makes sense yeah, not something worth proactively doing necessarily, just curious!

Wasmtime GitHub notifications bot (Jul 22 2026 at 21:21):

alexcrichton added PR #13934 wasi-sockets: Unify the p2 & p3 implementations to the merge queue.

Wasmtime GitHub notifications bot (Jul 22 2026 at 21:53):

:check: alexcrichton merged PR #13934.

Wasmtime GitHub notifications bot (Jul 22 2026 at 21:53):

alexcrichton removed PR #13934 wasi-sockets: Unify the p2 & p3 implementations from the merge queue.

Last updated: Jul 29 2026 at 05:03 UTC