cmd: Fix the computed IPsec max. sequence number

maxSequenceNumber currently iterates over all XFRM states in the ip xfrm
state list output to find the largest sequence number. It however does
so while keeping the parsed sequence numbers as hexadecimal strings.
Hence, a number like "0xc1" is understood as being larger than e.g.
"0x1234".

This commit fixes it by parsing the sequence numbers into int64 before
comparing them.

We also need to adapt the regular expression slightly to avoid
considering the "0x" prefix as part of the number, given
strconv.ParseInt doesn't support it.

Fixes: 2842c49 ("cli: add helper functions for `cilium encrypt`")
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>

cilium/cmd/encrypt_status.go

@@ -8,6 +8,7 @@ import (
 	"os/exec"
 	"reflect"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/prometheus/procfs"
@@ -30,7 +31,7 @@ type void struct{}
 var (
 	voidType    void
 	countErrors int
-	regex       = regexp.MustCompile("oseq[[:blank:]](0[xX][[:xdigit:]]+)?")
+	regex       = regexp.MustCompile("oseq[[:blank:]]0[xX]([[:xdigit:]]+)")
 )
 
 var encryptStatusCmd = &cobra.Command{
@@ -89,13 +90,17 @@ func countUniqueIPsecKeys() int {
 	return len(keys)
 }
 
-func extractMaxSequenceNumber(ipOutput string) string {
-	maxSeqNum := "0"
+func extractMaxSequenceNumber(ipOutput string) int64 {
+	maxSeqNum := int64(0)
 	lines := strings.Split(ipOutput, "\n")
 	for _, line := range lines {
 		matched := regex.FindStringSubmatchIndex(line)
 		if matched != nil {
-			oseq := line[matched[2]:matched[3]]
+			oseq, err := strconv.ParseInt(line[matched[2]:matched[3]], 16, 64)
+			if err != nil {
+				Fatalf("Failed to parse sequence number '%s': %s",
+					line[matched[2]:matched[3]], err)
+			}
 			if oseq > maxSeqNum {
 				maxSeqNum = oseq
 			}
@@ -111,10 +116,10 @@ func maxSequenceNumber() string {
 	}
 	commandOutput := string(out)
 	maxSeqNum := extractMaxSequenceNumber(commandOutput)
-	if maxSeqNum == "0" {
+	if maxSeqNum == 0 {
 		return "N/A"
 	}
-	return fmt.Sprintf("%s/0xffffffff", maxSeqNum)
+	return fmt.Sprintf("0x%x/0xffffffff", maxSeqNum)
 }
 
 func getEncryptionMode() {