Init

Makefile

@@ -0,0 +1,29 @@
+output/arm64/probe:
+	cd probe \
+	&& GOOS=linux GOARCH=arm64 go build -tags netgo -o ../output/arm64/probe
+
+output/amd64/probe:
+	cd probe \
+	&& GOOS=linux GOARCH=amd64 go build -tags netgo -o ../output/amd64/probe
+
+output/arm64/probe-server:
+	cd probe-server \
+	&& GOOS=linux GOARCH=arm64 go build -tags netgo -o ../output/arm64/probe-server
+
+output/amd64/probe-server:
+	cd probe-server \
+	&& GOOS=linux GOARCH=amd64 go build -tags netgo -o ../output/amd64/probe-server
+
+build-arm64: output/arm64/probe output/arm64/probe-server
+
+build-amd64: output/amd64/probe output/amd64/probe-server
+
+build-all: build-arm64 build-amd64
+
+clean-arm64:
+	rm -f output/arm64/probe*
+
+clean-amd64:
+	rm -f output/amd64/probe*
+
+clean-all: clean-arm64 clean-amd64

go.mod

@@ -0,0 +1,4 @@
+module git.abbiamoundominio.org/blallo/go-prober
+
+go 1.15
+

go.sum

@@ -0,0 +1,12 @@
+github.com/mozilla/mig v0.0.0-20190913234010-9e7e4f525805 h1:aR0FDMk+x7dz50dqbvd5EPobe2cCHvRbUKGD6HhSXhk=
+github.com/mozilla/mig v0.0.0-20190913234010-9e7e4f525805/go.mod h1:2c03209qVdj62h4aUMg8KfnbIGC83caKZB8/4F/7YV4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 h1:hb9wdF1z5waM+dSIICn1l0DkLVDT3hqhhQsDNUmHPRE=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201009025420-dfb3f7c4e634 h1:bNEHhJCnrwMKNMmOx3yAynp5vs5/gRy+XWFtZFu7NBM=
+golang.org/x/sys v0.0.0-20201009025420-dfb3f7c4e634/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

probe-server/main.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"flag"
+	"log"
+	"net"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var PortOutOfRange = errors.New("Port out of allowed range 1-65535")
+var isDebug bool
+
+func init() {
+	isDebug = false
+}
+
+func debug(v ...interface{}) {
+	if isDebug {
+		msg := make([]interface{}, len(v)+1)
+		msg[0] = "[DEBUG]"
+		for i, el := range v {
+			msg[i+1] = el
+		}
+		log.Println(msg...)
+	}
+}
+
+func handleConn(c net.Conn) {
+	defer c.Close()
+	debug("connection established:", c)
+	reader := bufio.NewReader(c)
+
+	for {
+		data, err := reader.ReadString('\n')
+		debug("Data =>", data)
+		if err != nil {
+			log.Fatal(err)
+		}
+		cleanData := strings.TrimSpace(string(data))
+		duration, err := time.ParseDuration(cleanData)
+		if err != nil {
+			log.Fatal(err)
+		}
+		debug("Duration =>", duration)
+		c.Write([]byte("ACK\n"))
+		time.Sleep(duration)
+	}
+
+	log.Println("connection closed:", c)
+}
+
+func parsePort(port int) (string, error) {
+	if port < 1 || port > 65535 {
+		return "", PortOutOfRange
+	}
+	return strconv.Itoa(port), nil
+}
+
+func main() {
+	var address string
+	var port int
+	flag.StringVar(&address, "addr", "", "The target address or ip")
+	flag.IntVar(&port, "port", 0, "The target port")
+	flag.BoolVar(&isDebug, "debug", false, "Enable debug logging")
+	flag.Parse()
+
+	parsedPort, err := parsePort(port)
+	if err != nil {
+		log.Fatal(err)
+	}
+	host := net.JoinHostPort(address, parsedPort)
+	server, err := net.Listen("tcp4", host)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer server.Close()
+
+	for {
+		c, err := server.Accept()
+		if err != nil {
+			log.Fatal(err)
+		}
+		go handleConn(c)
+	}
+}

probe/main.go

@@ -0,0 +1,130 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"os"
+	"strconv"
+	"time"
+)
+
+var PortNotInRange = errors.New("the port number is not in the 0-65535 range")
+var ServiceNotFound = errors.New("the service is not known")
+var isDebug bool
+
+func init() {
+	isDebug = false
+}
+
+func debug(v ...interface{}) {
+	if isDebug {
+		msg := make([]interface{}, len(v)+1)
+		msg[0] = "[DEBUG]"
+		for i, el := range v {
+			msg[i+1] = el
+		}
+		log.Println(msg...)
+	}
+}
+
+func connect(addr, port string) net.Conn {
+	target := net.JoinHostPort(addr, port)
+	conn, err := net.Dial("tcp", target)
+	if err != nil {
+		log.Fatal(err)
+	}
+	zero := time.Time{}
+	if err = conn.SetDeadline(zero); err != nil {
+		log.Fatal(err)
+	}
+	return conn
+}
+
+func validatePort(port int) error {
+	if port < 1 || port > 65535 {
+		return PortNotInRange
+	}
+	return nil
+}
+
+func getPort(srv string, port int) (string, error) {
+	if port != 0 {
+		return strconv.Itoa(port), nil
+	}
+	return srv, nil
+}
+
+func initLogger(logFile string) (*os.File, error) {
+	f, err := os.OpenFile(logFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	if err != nil {
+		return nil, err
+	}
+	wrt := io.MultiWriter(os.Stdout, f)
+	log.SetOutput(wrt)
+	return f, nil
+}
+
+// TODO: planned function that should do some ping measurement and return
+// the highest value found.
+func findLatency(address string) (time.Duration, error) {
+	return time.Second, nil
+}
+
+func main() {
+	var address, srv, logFile string
+	var port int
+	var interval, latency, zero time.Duration
+	flag.StringVar(&address, "addr", "", "The target address or ip")
+	flag.IntVar(&port, "port", 0, "The target port")
+	flag.StringVar(&srv, "srv", "", "The target service (will be translated to default port, if -port not provided)")
+	flag.StringVar(&logFile, "log-file", "", "The file path to log to")
+	flag.DurationVar(&interval, "interval", time.Second, "Internal refresh duration (defaults to 1s)")
+	flag.DurationVar(&latency, "latency", zero, "Internal refresh duration (defaults to 1s)")
+	flag.BoolVar(&isDebug, "debug", false, "Enable debug logging")
+	flag.Parse()
+	if port != 0 {
+		validatePort(port)
+	}
+	if logFile == "" {
+		log.Println("Logging only to stdout")
+	} else if f, err := initLogger(logFile); err != nil {
+		log.Fatalf("error opening file: %v", err)
+		f.Close()
+	} else {
+		defer f.Close()
+	}
+	parsedPort, err := getPort(srv, port)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if latency == zero {
+		latency, err = findLatency(address)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+	log.Printf("Logging every %v\n", interval)
+	log.Printf("Latency is %v\n", latency)
+	conn := connect(address, parsedPort)
+	intervalStr := fmt.Sprintf("%v\n", interval)
+	for conn != nil {
+		conn.Write([]byte(intervalStr))
+		conn.SetReadDeadline(time.Now().Add(latency))
+		if data, err := bufio.NewReader(conn).ReadString('\n'); err != nil {
+			log.Print(err)
+			conn.Close()
+			conn = nil
+		} else {
+			debug("Data =>", data)
+			conn.SetReadDeadline(time.Now().Add(interval + latency))
+		}
+		time.Sleep(interval)
+	}
+
+	log.Println("Connection closed")
+}

units/probe-server.service

@@ -0,0 +1,7 @@
+[Unit]
+Description=Probe server to allow testing of long-lived connections
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/probe-server -port ${PROBE_PORT}
+Restart=always

units/probe.service

@@ -0,0 +1,8 @@
+[Unit]
+Description=Probe network for disconnections on long-lived connections
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/probe -addr ${PROBE_HOST} -port ${PROBE_PORT} -log-file /var/log/probe/probe.log
+Restart=always
+RestartSec=60