65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
package tcpreuse
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import (
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"context"
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"net"
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"syscall"
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reuseport "github.com/libp2p/go-reuseport"
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)
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var fallbackDialer net.Dialer
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// reuseErrShouldRetry diagnoses whether to retry after a reuse error.
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// if we failed to bind, we should retry. if bind worked and this is a
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// real dial error (remote end didnt answer) then we should not retry.
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func reuseErrShouldRetry(err error) bool {
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if err == nil {
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return false // hey, it worked! no need to retry.
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}
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// if it's a network timeout error, it's a legitimate failure.
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if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
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return false
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}
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errno, ok := err.(syscall.Errno)
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if !ok { // not an errno? who knows what this is. retry.
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return true
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}
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switch errno {
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case syscall.EADDRINUSE, syscall.EADDRNOTAVAIL:
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return true // failure to bind. retry.
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case syscall.ECONNREFUSED:
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return false // real dial error
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default:
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return true // optimistically default to retry.
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}
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}
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// Dials using reuseport and then redials normally if that fails.
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func reuseDial(ctx context.Context, laddr *net.TCPAddr, network, raddr string) (con net.Conn, err error) {
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if laddr == nil {
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return fallbackDialer.DialContext(ctx, network, raddr)
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}
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d := net.Dialer{
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LocalAddr: laddr,
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Control: reuseport.Control,
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}
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con, err = d.DialContext(ctx, network, raddr)
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if err == nil {
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return con, nil
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}
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if reuseErrShouldRetry(err) && ctx.Err() == nil {
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// We could have an existing socket open or we could have one
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// stuck in TIME-WAIT.
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log.Debugf("failed to reuse port, dialing with a random port: %s", err)
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con, err = fallbackDialer.DialContext(ctx, network, raddr)
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}
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return con, err
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}
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