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// Copyright (C) 2019-2024 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package util
import (
"errors"
"net"
"syscall"
)
// TCPInfo provides socket-level TCP information.
type TCPInfo struct {
RTT uint32 `json:",omitempty"` // smoothed RTT
RTTVar uint32 `json:",omitempty"` // RTT variance
RTTMin uint32 `json:",omitempty"` // smallest observed RTT on the connection
SndMSS, RcvMSS uint32 `json:",omitempty"` // send and receive maximum segment size
SndCwnd uint32 `json:",omitempty"` // sender congestion window
SndWnd uint32 `json:",omitempty"` // send window advertised to receiver
RcvWnd uint32 `json:",omitempty"` // receive window advertised to sender
// tcpi_delivery_rate: The most recent goodput, as measured by
// tcp_rate_gen(). If the socket is limited by the sending
// application (e.g., no data to send), it reports the highest
// measurement instead of the most recent. The unit is bytes per
// second (like other rate fields in tcp_info).
Rate uint64 `json:",omitempty"`
// tcpi_delivery_rate_app_limited: A boolean indicating if the goodput
// was measured when the socket's throughput was limited by the
// sending application.
AppLimited bool `json:",omitempty"`
}
var (
// ErrNotSyscallConn is reported when GetConnTCPInfo is passed a connection that doesn't satisfy the syscall.Conn interface.
ErrNotSyscallConn = errors.New("conn doesn't satisfy syscall.Conn")
// ErrTCPInfoUnsupported is reported if TCP information is not available for this platform.
ErrTCPInfoUnsupported = errors.New("GetConnRTT not supported on this platform")
// ErrNoTCPInfo is reported if getsockopt returned no TCP info for some reason.
ErrNoTCPInfo = errors.New("getsockopt returned no TCP info")
)
// GetConnTCPInfo returns statistics for a TCP connection collected by the
// underlying network implementation, using a system call on Linux and Mac
// and returning an error for unsupported platforms.
func GetConnTCPInfo(conn net.Conn) (*TCPInfo, error) {
if conn == nil {
return nil, ErrNotSyscallConn
}
sysconn, ok := conn.(syscall.Conn)
if sysconn == nil || !ok {
return nil, ErrNotSyscallConn
}
raw, err := sysconn.SyscallConn()
if err != nil {
return nil, err
}
return getConnTCPInfo(raw)
}
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