net: check for MPTCP in DialTCP and ListenTCP
Setting GODEBUG=multipathtcp= [1] has no effects on apps using
ListenTCP or DialTCP directly.
According to the documentation, these functions are supposed to act like
Listen and Dial respectively:
ListenTCP acts like Listen for TCP networks.
DialTCP acts like Dial for TCP networks.
So when reading this, I think we should expect GODEBUG=multipathtcp= to
act on these functions as well.
Also, since #69016, MPTCP is used by default (if supported) with TCP
listeners. Similarly, when ListenTCP is used directly, MPTCP is
unexpectedly not used. It is strange to have a different behaviour.
So now, ListenTCP and DialTCP also check for MPTCP. Those are the exact
same checks that are done in dial.go, see Listen and dialSingle.
[1] https://pkg.go.dev/net#Dialer.SetMultipathTCP
Fixes #70500
Change-Id: I646431a74571668e505493fa8c1b2206bf30ed09
GitHub-Last-Rev:
69a31a1b033497fa219309410f16c4524aa6bba9
GitHub-Pull-Request: golang/go#70501
Reviewed-on: https://go-review.googlesource.com/c/go/+/630715
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>