Implement connection retry by downscaling ssl options

cmd/main.go

@@ -3,8 +3,10 @@ package main
 import (
 	"bufio"
 	"crypto/x509"
+	"errors"
 	"flag"
 	"fmt"
+	"log"
 	"os"
 	"strconv"
 	"strings"
@@ -48,7 +50,7 @@ func formatSize(size int64) string {
 	return FloatToString(float64(size)) + "B"
 }
 
-func searchCommand(args []string) {
+func execSearch(args []string) {
 	searchCmd := flag.NewFlagSet("search", flag.ExitOnError)
 	sortByFilename := searchCmd.Bool("s", false, "sort results by filename")
 
@@ -76,7 +78,7 @@ func searchCommand(args []string) {
 	printer.Print()
 }
 
-func transferLoop(transfer *xdcc.XdccTransfer) {
+func transferLoop(transfer xdcc.Transfer) {
 	bar := pb.NewProgressBar()
 
 	evts := transfer.PollEvents()
@@ -104,7 +106,7 @@ func suggestUnknownAuthoritySwitch(err error) {
 	}
 }
 
-func doTransfer(transfer *xdcc.XdccTransfer) {
+func doTransfer(transfer xdcc.Transfer) {
 	err := transfer.Start()
 	if err != nil {
 		fmt.Println(err)
@@ -116,7 +118,15 @@ func doTransfer(transfer *xdcc.XdccTransfer) {
 }
 
 func parseFlags(flagSet *flag.FlagSet, args []string) []string {
-	findFirstFlag := func(args []string) int {
+	flagIdx := findFirstFlag(args)
+	if flagIdx < 0 {
+		return args
+	}
+	flagSet.Parse(args[flagIdx:])
+	return args[:flagIdx]
+}
+
+func findFirstFlag(args []string) int {
 	for i, arg := range args {
 		if strings.HasPrefix(arg, "-") || strings.HasPrefix(arg, "--") {
 			return i
@@ -124,13 +134,6 @@ func parseFlags(flagSet *flag.FlagSet, args []string) []string {
 	}
 	return -1
 }
-	flagIdx := findFirstFlag(args)
-	if flagIdx >= 0 {
-		flagSet.Parse(args[flagIdx:])
-		return args[:flagIdx]
-	}
-	return args
-}
 
 func loadUrlListFile(filePath string) []string {
 	file, err := os.Open(filePath)
@@ -156,17 +159,17 @@ func loadUrlListFile(filePath string) []string {
 }
 
 func printGetUsageAndExit(flagSet *flag.FlagSet) {
-	fmt.Printf("usage: get url1 url2 ... [-o path] [-i file] [--allow-unknown-authority]\n\nFlag set:\n")
+	fmt.Printf("usage: get url1 url2 ... [-o path] [-i file] [--ssl-only]\n\nFlag set:\n")
 	flagSet.PrintDefaults()
 	os.Exit(0)
 }
 
-func getCommand(args []string) {
+func execGet(args []string) {
 	getCmd := flag.NewFlagSet("get", flag.ExitOnError)
 	path := getCmd.String("o", ".", "output folder of dowloaded file")
 	inputFile := getCmd.String("i", "", "input file containing a list of urls")
-	skipCertificateCheck := getCmd.Bool("allow-unknown-authority", false, "skip x509 certificate check during tls connection")
-	noSSL := getCmd.Bool("no-ssl", false, "disable SSL.")
+
+	sslOnly := getCmd.Bool("ssl-only", false, "force the client to use TSL connection")
 
 	urlList := parseFlags(getCmd, args)
 
@@ -180,41 +183,45 @@ func getCommand(args []string) {
 
 	wg := sync.WaitGroup{}
 	for _, urlStr := range urlList {
-		if strings.HasPrefix(urlStr, "irc://") {
 		url, err := xdcc.ParseURL(urlStr)
+		if errors.Is(err, xdcc.ErrInvalidURL) {
+			log.Printf("no valid irc url: %s\n", urlStr)
+			continue
+		}
 
 		if err != nil {
-				fmt.Println(err.Error())
+			log.Println(err.Error())
 			os.Exit(1)
 		}
 
+		transfer := xdcc.NewTransfer(xdcc.Config{
+			File:    *url,
+			OutPath: *path,
+			SSLOnly: *sslOnly,
+		})
+
 		wg.Add(1)
-			transfer := xdcc.NewTransfer(*url, *path, !*noSSL, *skipCertificateCheck)
-			go func(transfer *xdcc.XdccTransfer) {
+		go func(transfer xdcc.Transfer) {
 			doTransfer(transfer)
 			wg.Done()
 		}(transfer)
-		} else {
-			fmt.Printf("no valid irc url %s\n", urlStr)
-		}
 	}
 	wg.Wait()
 }
 
 func main() {
-
 	if len(os.Args) < 2 {
-		fmt.Println("one of the following subcommands is expected: [search, get]")
+		log.Println("one of the following subcommands is expected: [search, get]")
 		os.Exit(1)
 	}
 
 	switch os.Args[1] {
 	case "search":
-		searchCommand(os.Args[2:])
+		execSearch(os.Args[2:])
 	case "get":
-		getCommand(os.Args[2:])
+		execGet(os.Args[2:])
 	default:
-		fmt.Println("no such command: ", os.Args[1])
+		log.Println("no such command: ", os.Args[1])
 		os.Exit(1)
 	}
 }

xdcc/url.go

@@ -29,15 +29,17 @@ func parseSlot(slotStr string) (int, error) {
 	return strconv.Atoi(slotStr)
 }
 
+var ErrInvalidURL = errors.New("invalid IRC url")
+
 // url has the following format: irc://network/channel/bot/slot
 func ParseURL(url string) (*IRCFile, error) {
 	if !strings.HasPrefix(url, "irc://") {
-		return nil, errors.New("not an IRC url")
+		return nil, ErrInvalidURL
 	}
 
 	fields := strings.Split(strings.TrimPrefix(url, "irc://"), "/")
 	if len(fields) != ircFileURLFields {
-		return nil, errors.New("invalid IRC url")
+		return nil, ErrInvalidURL
 	}
 
 	slot, err := parseSlot(fields[3])

xdcc/xdcc.go

@@ -127,6 +127,37 @@ type TransferAbortedEvent struct {
 
 const maxConnAttempts = 5
 
+type Transfer interface {
+	Start() error
+	PollEvents() chan TransferEvent
+}
+
+type retryTransfer struct {
+	*XdccTransfer
+	conf Config
+}
+
+func (t *retryTransfer) Start() error {
+	t1 := newXdccTransfer(t.conf, true, false)
+	if err := t1.conn.Connect(); err == nil {
+		t.XdccTransfer = t1
+		return nil
+	}
+
+	t2 := newXdccTransfer(t.conf, true, true)
+	if err := t1.conn.Connect(); err == nil {
+		t.XdccTransfer = t2
+		return nil
+	}
+
+	t.XdccTransfer = newXdccTransfer(t.conf, false, false)
+	return t.XdccTransfer.conn.Connect()
+}
+
+func (t *retryTransfer) PollEvents() chan TransferEvent {
+	return t.XdccTransfer.PollEvents()
+}
+
 type XdccTransfer struct {
 	filePath     string
 	url          IRCFile
@@ -136,14 +167,32 @@ type XdccTransfer struct {
 	events       chan TransferEvent
 }
 
-func NewTransfer(url IRCFile, filePath string, enableSSL bool, skipCertificateCheck bool) *XdccTransfer {
+type Config struct {
+	File    IRCFile
+	OutPath string
+	SSLOnly bool
+}
+
+func NewTransfer(c Config) Transfer {
+	if c.SSLOnly {
+		return newXdccTransfer(c, true, false)
+	}
+
+	return &retryTransfer{
+		conf: c,
+	}
+}
+
+func newXdccTransfer(c Config, enableSSL bool, skipCertificateCheck bool) *XdccTransfer {
 	rand.Seed(time.Now().UTC().UnixNano())
 	nick := IRCClientUserName + strconv.Itoa(int(rand.Uint32()))
 
+	file := c.File
+
 	config := irc.NewConfig(nick)
 	config.SSL = enableSSL
-	config.SSLConfig = &tls.Config{ServerName: url.Network, InsecureSkipVerify: skipCertificateCheck}
-	config.Server = url.Network
+	config.SSLConfig = &tls.Config{ServerName: file.Network, InsecureSkipVerify: skipCertificateCheck}
+	config.Server = file.Network
 	config.NewNick = func(nick string) string {
 		return nick + "" + strconv.Itoa(int(rand.Uint32()))
 	}
@@ -152,13 +201,13 @@ func NewTransfer(url IRCFile, filePath string, enableSSL bool, skipCertificateCh
 
 	t := &XdccTransfer{
 		conn:         conn,
-		url:          url,
-		filePath:     filePath,
+		url:          file,
+		filePath:     c.OutPath,
 		started:      false,
 		connAttempts: 0,
 		events:       make(chan TransferEvent, defaultEventChanSize),
 	}
-	t.setupHandlers(url.Channel, url.UserName, url.Slot)
+	t.setupHandlers(file.Channel, file.UserName, file.Slot)
 	return t
 }
 
@@ -211,7 +260,7 @@ func (transfer *XdccTransfer) setupHandlers(channel string, userName string, slo
 			}
 
 			if (err != nil || transfer.connAttempts >= maxConnAttempts) && !transfer.started {
-				transfer.notifyEvent(&TransferAbortedEvent{Error: "disconnected from server"})
+				transfer.notifyEvent(&TransferAbortedEvent{Error: err.Error()})
 			}
 
 			transfer.connAttempts++