From: Bryan C. Mills <bcmills@google.com>
Date: Fri, 26 Jan 2024 17:23:01 +0000 (-0500)
Subject: net: in the fake implementation, allow writes to buffer on closed connections
X-Git-Tag: go1.23rc1~1355
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=47d240ccbb40425b49f14e21145d01dda542a21c;p=gostls13.git

net: in the fake implementation, allow writes to buffer on closed connections

This mimics the apparent behavior of writes on linux/amd64, in which a
write on an already-closed connection silently succeeds — even if the
connection has already been closed by the remote end — provided that
the packet fits in the kernel's send buffer.

I tested this by patching in CL 557437 and running the test on js/wasm
and wasip1/wasm locally.

Fixes #64317.

Change-Id: I43f6a89e5059115cb61e4ffc33a8371057cb67a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/558915
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/net/net_fake.go b/src/net/net_fake.go
index b7ecb39144..2d1e137b6d 100644
--- a/src/net/net_fake.go
+++ b/src/net/net_fake.go
@@ -460,16 +460,6 @@ func (pq *packetQueue) put(q packetQueueState) {
 
 func (pq *packetQueue) closeRead() error {
 	q := pq.get()
-
-	// Discard any unread packets.
-	for q.head != nil {
-		p := q.head
-		q.head = p.next
-		p.clear()
-		packetPool.Put(p)
-	}
-	q.nBytes = 0
-
 	q.readClosed = true
 	pq.put(q)
 	return nil
@@ -557,7 +547,7 @@ func (pq *packetQueue) send(dt *deadlineTimer, b []byte, from sockaddr, block bo
 	}
 	if q.writeClosed {
 		return 0, ErrClosed
-	} else if q.readClosed {
+	} else if q.readClosed && q.nBytes >= q.readBufferBytes {
 		return 0, os.NewSyscallError("send", syscall.ECONNRESET)
 	}
 
@@ -603,11 +593,13 @@ func (pq *packetQueue) recvfrom(dt *deadlineTimer, b []byte, wholePacket bool, c
 	}
 	defer func() { pq.put(q) }()
 
+	if q.readClosed {
+		return 0, nil, ErrClosed
+	}
+
 	p := q.head
 	if p == nil {
 		switch {
-		case q.readClosed:
-			return 0, nil, ErrClosed
 		case q.writeClosed:
 			if q.noLinger {
 				return 0, nil, os.NewSyscallError("recvfrom", syscall.ECONNRESET)