changed project structure

cmd/serveg/Config.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"encoding"
+	"errors"
+	"fmt"
+	"io/fs"
+	"net"
+	"os"
+
+	"github.com/BurntSushi/toml"
+)
+
+type Config struct {
+	Port uint16 `toml:"port"`
+	Ip   IP     `toml:"ip"`
+}
+
+func ReadConfig(path string) (*Config, error) {
+	var config = new(Config)
+	tomlMeta, err := toml.DecodeFile(path, config)
+	if err != nil {
+		return nil, err
+	}
+
+	// check if toml contains unknown keys
+	if undecodedKeys := tomlMeta.Undecoded(); len(undecodedKeys) > 0 {
+		return nil, fmt.Errorf("%s: unknown keys: %v", path, undecodedKeys)
+	}
+
+	return config, nil
+}
+
+func DefaultConfig() *Config {
+	return &Config{
+		Port: 8080,
+		Ip:   IP{net.IPv4(127, 0, 0, 1)},
+	}
+}
+
+func ParseOrCreateDefault(path string) (*Config, error) {
+	config, err := ReadConfig(path)
+	if !errors.Is(err, fs.ErrNotExist) {
+		return config, err // either a parsed config, or a real error
+	}
+	config = DefaultConfig()
+	return config, WriteConfig(config, path)
+}
+
+func WriteConfig(config *Config, path string) (err error) {
+	f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o644)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		// Close can report a failed write, so its error matters
+		if closeErr := f.Close(); err == nil {
+			err = closeErr
+		}
+	}()
+	enc := toml.NewEncoder(f)
+	enc.Indent = "    " // 4
+	return enc.Encode(config)
+}
+
+type IP struct {
+	net.IP
+}
+
+var _ encoding.TextUnmarshaler = (*IP)(nil)
+var _ encoding.TextMarshaler = IP{}
+
+func (a *IP) UnmarshalText(text []byte) error {
+	s := string(text)
+	ip := net.ParseIP(s)
+	if ip == nil {
+		return errors.New("can't parse '" + s + "' as IP address")
+	}
+	a.IP = ip
+	return nil
+}

cmd/serveg/main.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"net"
+	"os"
+	"os/signal"
+	"serveg/internal/log"
+	"strconv"
+	"syscall"
+	"time"
+)
+
+func main() {
+	os.Exit(run())
+}
+
+// main with int return value
+func run() int {
+	defer log.Defer()
+	log.StartGoroutine()
+	logger := log.LoggerContext{Name: "main"}
+
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	//defer stop()
+
+	configPath := *flag.String("config", "serveg.toml", "path to config file")
+	flag.Parse()
+
+	conf, err := ParseOrCreateDefault(configPath)
+	if err != nil {
+		logger.Error(err)
+		return 1
+	}
+
+	errCh := make(chan error, 1)
+	go func() { errCh <- server(conf) }()
+	logger.Info("server started")
+
+	select {
+	// server failed to start
+	case err := <-errCh:
+		logger.Error(err)
+		return 1
+	// got SIGINT/SIGTERM
+	case <-ctx.Done():
+		stop() // restore default behaviour: a second Ctrl+C kills immediately
+		logger.Info("shutting down")
+	}
+
+	return 0
+}
+
+func server(conf *Config) error {
+	logger := log.LoggerContext{Name: "server"}
+	addr := net.JoinHostPort(conf.Ip.String(), strconv.Itoa(int(conf.Port)))
+
+	logger.Info("listening at", addr)
+	srv, err := net.Listen("tcp", addr)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = srv.Close() }()
+
+	for i := int64(0); ; i++ {
+		conn, err := srv.Accept()
+		if err != nil {
+			logger.Warn(err)
+			continue
+		}
+		go handleConnection(conn, i)
+	}
+}
+
+func handleConnection(conn net.Conn, n int64) {
+	logger := log.LoggerContext{Name: "conn-" + strconv.FormatInt(n, 10)}
+	defer func() {
+		if r := recover(); r != nil {
+			logger.Error("panic: ", r)
+		}
+		_ = conn.Close()
+	}()
+
+	buf := make([]byte, 4096)
+
+	for {
+		if err := conn.SetDeadline(time.Now().Add(30 * time.Second)); err != nil {
+			logger.Warn(err)
+			break
+		}
+		n, err := conn.Read(buf)
+		if err != nil {
+			logger.Warn(err)
+			break
+		}
+		msgBytes := buf[:n]
+		logger.Info("msg: `", string(msgBytes), "`")
+		if _, err := conn.Write(msgBytes); err != nil {
+			logger.Warn(err)
+			break
+		}
+	}
+}