handle errors on regex match operations

cmd/syn-flood/main.go

@@ -13,16 +13,31 @@ import (
 	"strings"
 )
 
+const (
+	IpRegex  = "^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$"
+	DnsRegex = "^(([a-zA-Z]|[a-zA-Z][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z]|[A-Za-z][A-Za-z0-9\\-]*[A-Za-z0-9])$"
+)
+
+var (
+	isIP, isDNS bool
+	err         error
+	sfo         = options.GetSynFloodOptions()
+	host        = sfo.Host
+)
+
 func init() {
 	bannerBytes, _ := ioutil.ReadFile("banner.txt")
 	banner.Init(os.Stdout, true, false, strings.NewReader(string(bannerBytes)))
 }
 
 func main() {
-	sfo := options.GetSynFloodOptions()
-	host := sfo.Host
-	isIP, _ := regexp.MatchString("^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$", host)
-	isDNS, _ := regexp.MatchString("^(([a-zA-Z]|[a-zA-Z][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z]|[A-Za-z][A-Za-z0-9\\-]*[A-Za-z0-9])$", host)
+	if isIP, err = regexp.MatchString(IpRegex, host); err != nil {
+		log.Fatalf("a fatal error occured while matching provided --host with IP regex: %s", err.Error())
+	}
+
+	if isDNS, err = regexp.MatchString(DnsRegex, host); err != nil {
+		log.Fatalf("a fatal error occured while matching provided --host with DNS regex: %s", err.Error())
+	}
 
 	if !isIP && isDNS {
 		log.Printf("%s is a DNS record, making DNS lookup\n", host)
@@ -35,7 +50,7 @@ func main() {
 		host = ipRecords[0].String()
 	}
 
-	if err := raw.StartFlooding(host, sfo.Port, sfo.PayloadLength, sfo.FloodType); err != nil {
+	if err = raw.StartFlooding(host, sfo.Port, sfo.PayloadLength, sfo.FloodType); err != nil {
 		log.Fatalf("an error occured on flooding process: %s", err.Error())
 	}
 }

internal/options/options.go

@@ -31,6 +31,6 @@ type SynFloodOptions struct {
 func (sfo *SynFloodOptions) addFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&sfo.Host, "host", "213.238.175.187", "Provide public ip or DNS of the target")
 	fs.IntVar(&sfo.Port, "port", 443, "Provide reachable port of the target")
-	fs.IntVar(&sfo.PayloadLength, "payloadLength", 1500, "Provide payload length in bytes for each SYN packet")
+	fs.IntVar(&sfo.PayloadLength, "payloadLength", 1400, "Provide payload length in bytes for each SYN packet")
 	fs.StringVar(&sfo.FloodType, "floodType", "syn", "Provide the attack type. Proper values are: syn, ack, synack")
 }