go-prober/probe/main.go

131 lines
3.0 KiB
Go

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")
}