adding the scanner-port-format repo to ch2

Author: packetassailant

ch-2/scanner-port-format/portformat.go

@@ -0,0 +1,78 @@
+package portformat
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+)
+
+const (
+	porterrmsg = "Invalid port specification"
+)
+
+func dashSplit(sp string, ports *[]int) error {
+	dp := strings.Split(sp, "-")
+	if len(dp) != 2 {
+		return errors.New(porterrmsg)
+	}
+	start, err := strconv.Atoi(dp[0])
+	if err != nil {
+		return errors.New(porterrmsg)
+	}
+	end, err := strconv.Atoi(dp[1])
+	if err != nil {
+		return errors.New(porterrmsg)
+	}
+	if start > end || start < 1 || end > 65535 {
+		return errors.New(porterrmsg)
+	}
+	for ; start <= end; start++ {
+		*ports = append(*ports, start)
+	}
+	return nil
+}
+
+func convertAndAddPort(p string, ports *[]int) error {
+	i, err := strconv.Atoi(p)
+	if err != nil {
+		return errors.New(porterrmsg)
+	}
+	if i < 1 || i > 65535 {
+		return errors.New(porterrmsg)
+	}
+	*ports = append(*ports, i)
+	return nil
+}
+
+// Parse turns a string of ports separated by '-' or ',' and returns a slice of Ints.
+func Parse(s string) ([]int, error) {
+	ports := []int{}
+	if strings.Contains(s, ",") && strings.Contains(s, "-") {
+		sp := strings.Split(s, ",")
+		for _, p := range sp {
+			if strings.Contains(p, "-") {
+				if err := dashSplit(p, &ports); err != nil {
+					return ports, err
+				}
+			} else {
+				if err := convertAndAddPort(p, &ports); err != nil {
+					return ports, err
+				}
+			}
+		}
+	} else if strings.Contains(s, ",") {
+		sp := strings.Split(s, ",")
+		for _, p := range sp {
+			convertAndAddPort(p, &ports)
+		}
+	} else if strings.Contains(s, "-") {
+		if err := dashSplit(s, &ports); err != nil {
+			return ports, err
+		}
+	} else {
+		if err := convertAndAddPort(s, &ports); err != nil {
+			return ports, err
+		}
+	}
+	return ports, nil
+}