Spew implementation ( https://github.com/varnish/spew ) in golang

spew.go

package main

import (
	"flag"
	"fmt"
	"io"
	"net"
	"os"
	"os/signal"
	"strings"
)

var (
	url             = flag.String("url", "/", "The URL to ask for")
	server          = flag.String("server", "localhost", "Target server to connect to")
	port            = flag.Int("port", 80, "Port number to connect to")
	host_header     = flag.String("host_header", "localhost", "Host header to use")
	conns = flag.Int("conns", 100, "Number of connections to keep open "+
		"concurrently")
	reqs = flag.Int("reqs", 100, "Number of requests to send through "+
		"a connection before reconnecting")
	snd_buff = flag.Int("snd_buff", 1048576000, "Send buffer")
	rcv_buff = flag.Int("rcv_buff", 1048576000, "Receive buffer")

	msg         []byte

	signal_chan = make(chan os.Signal)
)

func createMessage() []byte {
	single_msg := fmt.Sprintf("GET %s HTTP/1.1\r\nHost: %s\r\n\r\n", *url,
		*host_header)
	msg := strings.Repeat(single_msg, *reqs-1)
	msg += fmt.Sprintf("GET %s HTTP/1.1\r\nHost: %s\r\nConnection: close\r\n\r\n",
		*url, *host_header)
	return []byte(msg)
}

func dial(tcp_addr *net.TCPAddr) io.ReadWriteCloser {
	c, err := net.DialTCP(tcp_addr.Network(), nil, tcp_addr)
	if err != nil {
		panic(err)
	}

	c.SetWriteBuffer(*snd_buff)
	c.SetReadBuffer(*rcv_buff)

	return c
}

func write(c io.Writer, msg_len int) {
	bytes_written := 0
	for bytes_written < msg_len {
		n, err := c.Write(msg[bytes_written:])
		if err != nil {
			panic(err)
		}
		bytes_written += n
	}
}

func read(c io.ReadCloser, buf []byte) {
	bytes_read := 0
	for {
		n, err := c.Read(buf)
		if err != nil && err != io.EOF {
			panic(err)
		}
		if n == 0 {
			break
		}
		bytes_read += n
	}
}

func client(tcp_addr *net.TCPAddr) {
	msg_len := len(msg)
	buf := make([]byte, 16384)

	for {
		c := dial(tcp_addr)
		write(c, msg_len)
		read(c, buf)
		c.Close()
	}
}

func main() {
	flag.Parse()

	msg = createMessage()

	addr := fmt.Sprintf("%s:%d", *server, *port)
	tcp_addr, err := net.ResolveTCPAddr("tcp", addr)
	if err != nil {
		panic(err)
	}

	for i := 0; i < *conns; i++ {
		go client(tcp_addr)
	}

	signal.Notify(signal_chan, os.Interrupt)

	<-signal_chan
	fmt.Printf("Exiting on user request\n")
}