cephFS: fix fetchIP to support more formats

internal/csi-addons/networkfence/fencing.go

@@ -22,6 +22,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -210,11 +211,24 @@ func (ac *activeClient) fetchIP() (string, error) {
 	// example: "inst": "client.4305 172.21.9.34:0/422650892",
 	// then returning value will be 172.21.9.34
 	clientInfo := ac.Inst
-	parts := strings.Fields(clientInfo)
-	if len(parts) >= 2 {
-		lastColonIndex := strings.LastIndex(parts[1], ":")
-		firstPart := parts[1][:lastColonIndex]
-		ip := net.ParseIP(firstPart)
+
+	// Attempt to extract the IP address using a regular expression
+	// the regular expression aims to match either a complete IPv6
+	// address or a complete IPv4 address follows by any prefix (v1 or v2)
+	// if exists
+	// (?:v[0-9]+:): this allows for an optional prefix starting with "v"
+	// followed by one or more digits and a colon.
+	// The ? outside the group makes the entire prefix section optional.
+	// (?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}: this allows to check for
+	// standard IPv6 address.
+	// |: Alternation operator to allow matching either the IPv6 pattern
+	// with a prefix or the IPv4 pattern.
+	// '(?:\d+\.){3}\d+: This part matches a standard IPv4 address.
+	re := regexp.MustCompile(`(?:v[0-9]+:)?([0-9a-fA-F]{1,4}(:[0-9a-fA-F]{1,4}){7}|(?:\d+\.){3}\d+)`)
+	ipMatches := re.FindStringSubmatch(clientInfo)
+
+	if len(ipMatches) > 0 {
+		ip := net.ParseIP(ipMatches[1])
 		if ip != nil {
 			return ip.String(), nil
 		}

internal/csi-addons/networkfence/fencing_test.go

@@ -73,6 +73,11 @@ func TestFetchIP(t *testing.T) {
 			expectedIP:  "2001:db8:85a3::8a2e:370:7334",
 			expectedErr: false,
 		},
+		{
+			clientInfo:  "client.24152 v1:100.64.0.7:0/3658550259",
+			expectedIP:  "100.64.0.7",
+			expectedErr: false,
+		},
 		{
 			clientInfo:  "",
 			expectedIP:  "",