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//go:build unix
/*
* Copyright 2023 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package internal
import (
"net"
"syscall"
"time"
"golang.org/x/sys/unix"
)
// NetDialerWithTCPKeepalive returns a net.Dialer that enables TCP keepalives on
// the underlying connection with OS default values for keepalive parameters.
//
// TODO: Once https://github.com/golang/go/issues/62254 lands, and the
// appropriate Go version becomes less than our least supported Go version, we
// should look into using the new API to make things more straightforward.
func NetDialerWithTCPKeepalive() *net.Dialer {
return &net.Dialer{
// Setting a negative value here prevents the Go stdlib from overriding
// the values of TCP keepalive time and interval. It also prevents the
// Go stdlib from enabling TCP keepalives by default.
KeepAlive: time.Duration(-1),
// This method is called after the underlying network socket is created,
// but before dialing the socket (or calling its connect() method). The
// combination of unconditionally enabling TCP keepalives here, and
// disabling the overriding of TCP keepalive parameters by setting the
// KeepAlive field to a negative value above, results in OS defaults for
// the TCP keealive interval and time parameters.
Control: func(_, _ string, c syscall.RawConn) error {
return c.Control(func(fd uintptr) {
unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1)
})
},
}
}
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