socket

README

socket

Go package to parse socket names described in Nginx convention.

Sets the address and port for IP, or the path for a UNIX-domain socket on which the server will accept requests. Both address and port, or only address or only port can be specified. An address may also be a hostname, for example:

socket.Parse("127.0.0.1:8000") // "tcp", "127.0.0.1:8000"
socket.Parse("127.0.0.1") // "tcp", "127.0.0.1:80
socket.Parse("8000") // "tcp", ":8000"
socket.Parse("*:8000") // "tcp", ":8000"
socket.Parse("localhost:8000") // "tcp", "localhost:8000"

IPv6 addresses are specified in square brackets:

socket.Parse("[::]:8000") // "tcp", "[::]:8000"
socket.Parse("[::1]") // "tcp", "[::1]:80"

UNIX-domain sockets are specified with the “unix:” prefix:

socket.Parse("unix:/var/run/nginx.sock") // "unix", "/var/run/nginx.sock"

If only address is given, the port 80 is used.

socket.Parse("localhost") // "tcp", "localhost:80"

Installation and usage

go get github.com/oftn-oswg/socket

package main

import (
	"fmt"
	"io"
	"os"
	"strconv"

	"github.com/oftn-oswg/socket"
)

// This is a simple echo server which creates a socket
// based on the arguments provided to the command. The socket can be
// described with a syntax that nginx, the web server, accepts for its listen directive.
func main() {
	if len(os.Args) < 2 {
		fmt.Fprintf(os.Stderr, "Usage: %s <socket> [<mode>]\n", os.Args[0])
		os.Exit(1)
	}

	mode := os.FileMode(0660)
	if len(os.Args) >= 3 {
		num, err := strconv.ParseInt(os.Args[2], 0, 0)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error parsing file mode: %s\n", err)
			os.Exit(1)
		}
		mode = os.FileMode(num)
	}

	network, address := socket.Parse(os.Args[1])
	listener, err := socket.Listen(network, address, mode)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error creating socket: %s\n", err)
		os.Exit(1)
	}

	for {
		conn, err := listener.Accept()
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			continue
		}

		go func() {
			defer conn.Close()
			_, err := io.Copy(conn, conn)
			if err != nil {
				fmt.Fprintln(os.Stderr, err)
			}
		}()
	}
}

Documentation

Index

• func Listen(network, address string, mode os.FileMode) (net.Listener, error)
• func Parse(value string) (string, string)

Functions

func Listen

func Listen(network, address string, mode os.FileMode) (net.Listener, error)

Listen takes the same arguments as the net.Listen function but includes the mode with which to set the file permissions if creating a Unix socket.

The socket path is appended with ".tmp" before it is created and later renamed.

This function calls syscall.Umask before the socket is created in order to completely restrict the socket before it is restored again with os.Chmod. Therefore, this function is not thread-safe as Umask is non-reentrant.

Additionally, this function will make sure to remove the temporary socket path before creating it.

func Parse

func Parse(value string) (string, string)

Parse produces a struct suitable for net.Dial given a string representing a socket address to bind or connect to