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//go:build linux || darwin || freebsd
// +build linux darwin freebsd
package utils
import (
"fmt"
"net"
"os"
"strings"
"syscall"
"github.com/valyala/tcplisten"
)
const (
IPV4 string = "tcp4"
IPV6 string = "tcp6"
)
// CreateListener
// - SO_REUSEPORT. This option allows linear scaling server performance
// on multi-CPU servers.
// See https://www.nginx.com/blog/socket-sharding-nginx-release-1-9-1/ for details.
//
// - TCP_DEFER_ACCEPT. This option expects the server reads from the accepted
// connection before writing to them.
//
// - TCP_FASTOPEN. See https://lwn.net/Articles/508865/ for details.
// CreateListener crates socket listener based on DSN definition.
func CreateListener(address string) (net.Listener, error) {
dsn := strings.Split(address, "://")
switch len(dsn) {
case 1:
// assume, that there is no prefix here [127.0.0.1:8000]
return createTCPListener(dsn[0])
case 2:
// we got two part here, first part is the transport, second - address
// [tcp://127.0.0.1:8000] OR [unix:///path/to/unix.socket] OR [error://path]
// where error is wrong transport name
switch dsn[0] {
case "unix":
// check of file exist. If exist, unlink
if fileExists(dsn[1]) {
err := syscall.Unlink(dsn[1])
if err != nil {
return nil, fmt.Errorf("error during the unlink syscall: error %w", err)
}
}
return net.Listen(dsn[0], dsn[1])
case "tcp":
return createTCPListener(dsn[1])
// not an tcp or unix
default:
return nil, fmt.Errorf("invalid Protocol ([tcp://]:6001, unix://file.sock), address: %s", address)
}
// wrong number of split parts
default:
return nil, fmt.Errorf("wrong number of parsed protocol parts, address: %s", address)
}
}
func createTCPListener(addr string) (net.Listener, error) {
cfg := tcplisten.Config{
ReusePort: true,
DeferAccept: true,
FastOpen: true,
}
/*
Options we may have here:
1. [::1]:8080 //ipv6
2. [0:0:..]:8080 //ipv6
3. 127.0.0.1:8080 //ipv4
4. :8080 //ipv4
5. [::]:8080 //ipv6
*/
host, _, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
// consider this is IPv4
if host == "" {
return cfg.NewListener(IPV4, addr)
}
return cfg.NewListener(netw(net.ParseIP(host)), addr)
}
// check if we are listening on the ipv6 or ipv4 address
func netw(addr net.IP) string {
if addr.To4() == nil {
return IPV6
}
return IPV4
}
// fileExists checks if a file exists and is not a directory before we
// try using it to prevent further errors.
func fileExists(filename string) bool {
info, err := os.Stat(filename)
if os.IsNotExist(err) {
return false
}
return !info.IsDir()
}
|
