fix writer race condition

Author: juzeon

main.go

@@ -98,12 +98,14 @@ func main() {
 		slog.Info("Parsed domains", "count", len(domains))
 		ipChan = Iterate(strings.NewReader(strings.Join(domains, "\n")))
 	}
+	outCh := OutWriter(outWriter)
+	defer close(outCh)
 	var wg sync.WaitGroup
 	wg.Add(thread)
 	for i := 0; i < thread; i++ {
 		go func() {
 			for ip := range ipChan {
-				ScanTLS(ip, outWriter)
+				ScanTLS(ip, outCh)
 			}
 			wg.Done()
 		}()

scanner.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"crypto/tls"
-	"io"
 	"log/slog"
 	"net"
 	"strconv"
@@ -17,7 +16,7 @@ var TLSDictionary = map[uint16]string{
 	0x0304: "1.3",
 }
 
-func ScanTLS(ip net.IP, out io.Writer) {
+func ScanTLS(ip net.IP, out chan<- string) {
 	hostPort := net.JoinHostPort(ip.String(), strconv.Itoa(port))
 	conn, err := net.DialTimeout("tcp", hostPort, time.Duration(timeout)*time.Second)
 	if err != nil {
@@ -50,7 +49,7 @@ func ScanTLS(ip net.IP, out io.Writer) {
 		log = slog.Debug
 		feasible = false
 	} else {
-		_, _ = io.WriteString(out, strings.Join([]string{ip.String(), domain, "\"" + issuers + "\""}, ",")+"\n")
+		out <- strings.Join([]string{ip.String(), domain, "\"" + issuers + "\""}, ",") + "\n"
 	}
 	log("Connected to target", "feasible", feasible, "host", ip.String(),
 		"tls", TLSDictionary[state.Version],

utils.go

@@ -92,3 +92,12 @@ func RemoveDuplicateStr(strSlice []string) []string {
 	}
 	return list
 }
+func OutWriter(writer io.Writer) chan<- string {
+	ch := make(chan string)
+	go func() {
+		for s := range ch {
+			_, _ = io.WriteString(writer, s)
+		}
+	}()
+	return ch
+}