Before this patch, on a system that only supports IPv6, we would
get EAFNOSUPPORT and decide that MPTCP might be available later.
The effect is that every socket tries to get MPTCP. If the system
does not support MPTCP, every socket call turns into two system calls.
Also avoid the uname if MPTCP is not supported.
For #56539
Change-Id: I628b44eda83b455f5493a9dd59076f1acea2f65b
Reviewed-on: https://go-review.googlesource.com/c/go/+/616335
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
This new TCPConn method returns whether the connection is using MPTCP or
if a fallback to TCP has been done, e.g. because the other peer doesn't
support MPTCP.
When working on the new E2E test linked to MPTCP (#56539), it looks like
the user might need to know such info to be able to do some special
actions (report, stop, etc.). This also improves the test to make sure
MPTCP has been used as expected.
Regarding the implementation, from kernel version 5.16, it is possible
to use:
getsockopt(..., SOL_MPTCP, MPTCP_INFO, ...)
and check if EOPNOTSUPP (IPv4) or ENOPROTOOPT (IPv6) is returned. If it
is, it means a fallback to TCP has been done. See this link for more
details:
https://github.com/multipath-tcp/mptcp_net-next/issues/294
Before v5.16, there is no other simple way, from the userspace, to check
if the created socket did a fallback to TCP. Netlink requests could be
done to try to find more details about a specific socket but that seems
quite a heavy machinery. Instead, only the protocol is checked on older
kernels.
The E2E test has been modified to check that the MPTCP connection didn't
do any fallback to TCP, explicitely validating the two methods
(SO_PROTOCOL and MPTCP_INFO) if it is supported by the host.
This work has been co-developed by Gregory Detal
<gregory.detal@tessares.net> and Benjamin Hesmans
<benjamin.hesmans@tessares.net>.
Fixes#59166
Change-Id: I5a313207146f71c66c349aa8588a2525179dd8b8
Reviewed-on: https://go-review.googlesource.com/c/go/+/471140
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Specific MPTCP errors could happen but only one is detectable: if
ENOPROTOOPT errno is returned, it likely means MPTCP has been disable
via this sysctl knob: net.mptcp.enabled.
But because MPTCP could be blocked by the administrator using different
techniques (SELinux, etc.) making the socket creation returning other
errors, it looks better to always retry to create a "plain" TCP socket
when any errors are returned.
This work has been co-developed by Gregory Detal
<gregory.detal@tessares.net>.
Updates #56539
Change-Id: I94fb8448dae351e1d3135b4f182570979c6b36d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/471138
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Similar to dialMPTCP, this listenMPTCP function is called when the user
has requested MPTCP via SetMultipathTCP in the ListenConfig.
This function falls back to listenTCP on operating systems that do not
support MPTCP or if MPTCP is not supported.
On ListenConfig side, MultipathTCP function can be used to know if the
package will try to use MPTCP or not when Listen is called.
Note that this new listenMPTCP function returns a TCPListener object and
not a new MPTCP dedicated one. The reasons are similar as the ones
explained in the parent commit introducing dialTCP: if MPTCP is used by
default later, Listen will return a different object that could break
existing applications expecting TCPListener.
This work has been co-developped by Gregory Detal
<gregory.detal@tessares.net>.
Updates #56539
Change-Id: I010f1d87f921bbac9e157cef2212c51917852353
Reviewed-on: https://go-review.googlesource.com/c/go/+/471137
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This function is called when the user has requested MPTCP via
SetMultipathTCP in the Dialer.
This new function falls back to dialTCP on operating systems that do not
support MPTCP or if MPTCP is not supported.
On Dialer side, MultipathTCP function can be used to know if the package
will try to use MPTCP or not when Dial is called.
Note that this new dialMPTCP function returns a TCPConn object, like
dialTCP. A new MPTCPConn object using the following composition could
have been returned:
type MPTCPConn struct {
*TCPConn
}
But the drawback is that if MPTCP is used by default one day (see #56539
issue on GitHub), Dial will return a different object: this new
MPTCPConn type instead of the previously expected TCPConn. This can
cause issues for apps checking the returned object.
This work has been co-developped by Gregory Detal
<gregory.detal@tessares.net>.
Updates #56539
Change-Id: I0f9b5b81f630b39142bdd553d4f1b4c775f1dff0
Reviewed-on: https://go-review.googlesource.com/c/go/+/471136
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
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This currently defines an internal function supportsMultipathTCP which
reports whether MPTCP[1] is supported on the current platform.
Only Linux is supported here.
The check on Linux is performed once by attemting to create an MPTCP
socket and look at the returned error:
- If the protocol is not supported, EINVAL (kernel < 5.6) or
EPROTONOSUPPORT (kernel >= 5.6) is returned and there is no point to
try again.
- Other errors can be returned:
- ENOPROTOOPT: the sysctl knob net.mptcp.enabled is set to 0
- Unpredictable ones: if MPTCP is blocked using SELinux, eBPF, etc.
These other errors are due to modifications that can be reverted during
the session: MPTCP can be available again later. In this case, it is
fine to always try to create an MPTCP socket and fallback to TCP in case
of error.
This work has been co-developped by Gregory Detal
<gregory.detal@tessares.net>.
[1] https://www.rfc-editor.org/rfc/rfc8684.html
Updates #56539
Change-Id: Ic84fe85aad887a2be4556a898e649bf6b6f12f03
Reviewed-on: https://go-review.googlesource.com/c/go/+/471135
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Ian Lance Taylor
Oleksandr Redko
Matthieu Baerts