52 lines
1.2 KiB
Go
52 lines
1.2 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package tcpinfo provides platform-agnostic accessors to information about a
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// TCP connection (e.g. RTT, MSS, etc.).
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package tcpinfo
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import (
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"errors"
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"net"
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"time"
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)
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var (
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ErrNotTCP = errors.New("tcpinfo: not a TCP conn")
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ErrUnimplemented = errors.New("tcpinfo: unimplemented")
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)
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// RTT returns the RTT for the given net.Conn.
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//
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// If the net.Conn is not a *net.TCPConn and cannot be unwrapped into one, then
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// ErrNotTCP will be returned. If retrieving the RTT is not supported on the
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// current platform, ErrUnimplemented will be returned.
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func RTT(conn net.Conn) (time.Duration, error) {
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tcpConn, err := unwrap(conn)
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if err != nil {
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return 0, err
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}
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return rttImpl(tcpConn)
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}
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// netConner is implemented by crypto/tls.Conn to unwrap into an underlying
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// net.Conn.
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type netConner interface {
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NetConn() net.Conn
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}
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// unwrap attempts to unwrap a net.Conn into an underlying *net.TCPConn
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func unwrap(nc net.Conn) (*net.TCPConn, error) {
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for {
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switch v := nc.(type) {
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case *net.TCPConn:
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return v, nil
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case netConner:
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nc = v.NetConn()
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default:
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return nil, ErrNotTCP
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}
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}
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}
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