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/*
* This file is part of Go Responsiveness.
*
* Go Responsiveness is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software Foundation,
* either version 2 of the License, or (at your option) any later version.
* Go Responsiveness 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with Go Responsiveness. If not, see <https://www.gnu.org/licenses/>.
*/
package probe
import (
"context"
"fmt"
"io"
"net/http"
"net/http/httptrace"
"os"
"time"
"github.com/network-quality/goresponsiveness/constants"
"github.com/network-quality/goresponsiveness/debug"
"github.com/network-quality/goresponsiveness/extendedstats"
"github.com/network-quality/goresponsiveness/utilities"
)
type ProbeType int64
type ProbeConfiguration struct {
ConnectToAddr string
URL string
Host string
CongestionControl *string
InsecureSkipVerify bool
}
type ProbeDataPoint struct {
Time time.Time `Description:"Time of the generation of the data point." Formatter:"Format" FormatterArgument:"01-02-2006-15-04-05.000"`
RoundTripCount uint64 `Description:"The number of round trips measured by this data point."`
Duration time.Duration `Description:"The duration for this measurement." Formatter:"Seconds"`
TCPRtt time.Duration `Description:"The underlying connection's RTT at probe time." Formatter:"Seconds"`
TCPCwnd uint32 `Description:"The underlying connection's congestion window at probe time."`
Type ProbeType `Description:"The type of the probe." Formatter:"Value"`
CongestionControl string `Description:"The congestion control algorithm used."`
}
const (
SelfUp ProbeType = iota
SelfDown
Foreign
)
type ProbeRoundTripCountType uint16
const (
DefaultDownRoundTripCount ProbeRoundTripCountType = 1
SelfUpRoundTripCount ProbeRoundTripCountType = 1
SelfDownRoundTripCount ProbeRoundTripCountType = 1
ForeignRoundTripCount ProbeRoundTripCountType = 3
)
func (pt ProbeType) Value() string {
if pt == SelfUp {
return "SelfUp"
} else if pt == SelfDown {
return "SelfDown"
}
return "Foreign"
}
func (pt ProbeType) IsSelf() bool {
return pt == SelfUp || pt == SelfDown
}
func Probe(
managingCtx context.Context,
client *http.Client,
probeUrl string,
probeHost string, // optional: for use with a test_endpoint
probeType ProbeType,
probeId uint,
congestionControl *string,
captureExtendedStats bool,
debugging *debug.DebugWithPrefix,
) (*ProbeDataPoint, error) {
if client == nil {
return nil, fmt.Errorf("cannot start a probe with a nil client")
}
probeTracer := NewProbeTracer(client, probeType, probeId, congestionControl, debugging)
time_before_probe := time.Now()
probe_req, err := http.NewRequestWithContext(
httptrace.WithClientTrace(managingCtx, probeTracer.trace),
"GET",
probeUrl,
nil,
)
if err != nil {
return nil, err
}
// Used to disable compression
probe_req.Header.Set("Accept-Encoding", "identity")
probe_req.Header.Set("User-Agent", utilities.UserAgent())
probe_resp, err := client.Do(probe_req)
if err != nil {
if debug.IsDebug(debugging.Level) {
fmt.Printf(
"(%s) (%s Probe %v) An error occurred during http.Do: %v\n",
debugging.Prefix,
probeType.Value(),
probeId,
err,
)
}
return nil, err
}
// Header.Get returns "" when not set
if probe_resp.Header.Get("Content-Encoding") != "" {
return nil, fmt.Errorf("Content-Encoding header was set (compression not allowed)")
}
// TODO: Make this interruptable somehow by using _ctx_.
_, err = io.ReadAll(probe_resp.Body)
if err != nil {
if debug.IsDebug(debugging.Level) {
fmt.Printf(
"(%s) (%s Probe %v) An error occurred during io.ReadAll: %v\n",
debugging.Prefix,
probeType.Value(),
probeId,
err,
)
}
return nil, err
}
time_after_probe := time.Now()
// Depending on whether we think that Close() requires another RTT (via TCP), we
// may need to move this before/after capturing the after time.
probe_resp.Body.Close()
sanity := time_after_probe.Sub(time_before_probe)
// When the probe is run on a load-generating connection (a self probe) there should
// only be a single round trip that is measured. We will take the accumulation of all these
// values just to be sure, though. Because of how this traced connection was launched, most
// of the values will be 0 (or very small where the time that go takes for delivering callbacks
// and doing context switches pokes through). When it is !isSelfProbe then the values will
// be significant and we want to add them regardless!
totalDelay := probeTracer.GetTLSAndHttpHeaderDelta() + probeTracer.GetHttpDownloadDelta(
time_after_probe,
) + probeTracer.GetTCPDelta()
// We must have reused the connection if we are a self probe!
if probeType.IsSelf() && !probeTracer.stats.ConnectionReused {
fmt.Fprintf(os.Stderr,
"(%s) (%s Probe %v) Probe should have reused a connection, but it didn't!\n",
debugging.Prefix,
probeType.Value(),
probeId,
)
panic(!probeTracer.stats.ConnectionReused)
}
if debug.IsDebug(debugging.Level) {
fmt.Printf(
"(%s) (%s Probe %v) sanity vs total: %v vs %v\n",
debugging.Prefix,
probeType.Value(),
probeId,
sanity,
totalDelay,
)
}
roundTripCount := DefaultDownRoundTripCount
if probeType == Foreign {
roundTripCount = ForeignRoundTripCount
}
// Careful!!! It's possible that this channel has been closed because the Prober that
// started it has been stopped. Writing to a closed channel will cause a panic. It might not
// matter because a panic just stops the go thread containing the paniced code and we are in
// a go thread that executes only this function.
defer func() {
isThreadPanicing := recover()
if isThreadPanicing != nil && debug.IsDebug(debugging.Level) {
fmt.Printf(
"(%s) (%s Probe %v) Probe attempted to write to the result channel after its invoker ended (official reason: %v).\n",
debugging.Prefix,
probeType.Value(),
probeId,
isThreadPanicing,
)
}
}()
tcpRtt := time.Duration(0 * time.Second)
tcpCwnd := uint32(0)
// TODO: Only get the extended stats for a connection if the user has requested them overall.
if captureExtendedStats && extendedstats.ExtendedStatsAvailable() {
tcpInfo, err := extendedstats.GetTCPInfo(probeTracer.stats.ConnInfo.Conn)
if err == nil {
tcpRtt = time.Duration(tcpInfo.Rtt) * time.Microsecond
tcpCwnd = tcpInfo.Snd_cwnd
} else {
fmt.Printf("Warning: Could not fetch the extended stats for a probe: %v\n", err)
}
}
return &ProbeDataPoint{
Time: time_before_probe,
RoundTripCount: uint64(roundTripCount),
Duration: totalDelay,
TCPRtt: tcpRtt,
TCPCwnd: tcpCwnd,
Type: probeType,
CongestionControl: *utilities.Conditional(congestionControl == nil,
&constants.DefaultL4SCongestionControlAlgorithm, congestionControl),
}, nil
}
|
