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tcpmirror.go
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tcpmirror.go
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package main
import (
"flag"
"fmt"
"io"
"net"
"os"
"strings"
)
const (
Version = "1.0.0"
)
var (
listenPtr = flag.String("l", "localhost:8080",
"Listen on `host:port` for incoming traffic to be duplicated")
primaryPtr = flag.String("p", "localhost:9090",
"Relay traffic to primary `host:port` and establish a two way TCP connection")
mirrorPtr = flag.String("m", "localhost:9091",
"Mirror incoming traffic to `host:port[,host:port]...`. Can specify multiple addresses seperated by a comma. Eg. localhost:9091,localhost:9092")
debugPtr = flag.Bool("d", false, "Print debug information on stdout")
)
func main() {
flag.Usage = Usage
flag.Parse()
mirrorAddrs := strings.Split(*mirrorPtr, ",")
fmt.Printf("Listening on %s\n", *listenPtr)
fmt.Printf("Connecting in primary mode to %s\n", *primaryPtr)
fmt.Printf("Duplicating incoming traffic to %s\n", *mirrorPtr)
l, err := net.Listen("tcp", *listenPtr)
if err != nil {
fmt.Fprintf(os.Stderr, "Error listening: ", err.Error())
os.Exit(1)
}
for {
in, _ := l.Accept()
fmt.Printf("Incoming connection from %s\n", in)
p, err := net.Dial("tcp", *primaryPtr)
if err != nil {
fmt.Println("Error connecting to primary: ", err.Error())
os.Exit(1)
}
// create array of writers where writers are
// - all mirrors
// - primary addr
// - stdout (if debug)
ws := make([]io.Writer, len(mirrorAddrs))
for i, mirrorAddr := range mirrorAddrs {
m, err := net.Dial("tcp", mirrorAddr)
if err != nil {
fmt.Println("Error connecting to the mirror address: ", err.Error())
os.Exit(1)
}
ws[i] = m
}
ws = append(ws, p) // add primary
mw := io.MultiWriter(ws...)
go io.Copy(mw, in)
go io.Copy(in, p)
// fmt.Println("After accept")
// fmt.Printf("mw = %v\nin = %v\n", mw, in)
// fmt.Printf("Num goroutines: %d \n", runtime.NumGoroutine())
}
// Close the listener when application closes
}
func Usage() {
fmt.Fprintf(os.Stderr, "tcpmirror version %s\n", Version)
fmt.Fprintf(os.Stderr, "Usage: $ tcpmirror -l <listen_addr> -p <primary_addr> -m <mirror_addrs\n")
fmt.Fprintf(os.Stderr, "Example: $ tcpmirror -l localhost:8080 -p localhost:9090 -m localhost:9091,localhost:9091 \n")
fmt.Fprintf(os.Stderr, "-----------------------\nFlags:\n")
flag.PrintDefaults()
}