Merge pull request #58731 from yue9944882/feature/beginport-and-offset-expr-port-range

Automatic merge from submit-queue (batch tested with PRs 60457, 60331, 54970, 58731, 60562). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

implement begin-port+offset port range parsing

**What this PR does / why we need it**:

Allocate specific numbers of port from a host by indicating a begin port and its offsets.
This can be used for kube-proxy configuration.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #58730

**Special notes for your reviewer**:

**Release note**:

```release-note
"beginPort+offset" format support for port range which affects kube-proxy only
```

cmd/kube-proxy/app/server.go

@@ -141,7 +141,7 @@ func (o *Options) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&o.config.ResourceContainer, "resource-container", o.config.ResourceContainer, "Absolute name of the resource-only container to create and run the Kube-proxy in (Default: /kube-proxy).")
 	fs.MarkDeprecated("resource-container", "This feature will be removed in a later release.")
 	fs.StringVar(&o.config.ClientConnection.KubeConfigFile, "kubeconfig", o.config.ClientConnection.KubeConfigFile, "Path to kubeconfig file with authorization information (the master location is set by the master flag).")
-	fs.Var(componentconfig.PortRangeVar{Val: &o.config.PortRange}, "proxy-port-range", "Range of host ports (beginPort-endPort, inclusive) that may be consumed in order to proxy service traffic. If unspecified (0-0) then ports will be randomly chosen.")
+	fs.Var(componentconfig.PortRangeVar{Val: &o.config.PortRange}, "proxy-port-range", "Range of host ports (beginPort-endPort, single port or beginPort+offset, inclusive) that may be consumed in order to proxy service traffic. If (unspecified, 0, or 0-0) then ports will be randomly chosen.")
 	fs.StringVar(&o.config.HostnameOverride, "hostname-override", o.config.HostnameOverride, "If non-empty, will use this string as identification instead of the actual hostname.")
 	fs.Var(&o.config.Mode, "proxy-mode", "Which proxy mode to use: 'userspace' (older) or 'iptables' (faster) or 'ipvs' (experimental). If blank, use the best-available proxy (currently iptables).  If the iptables proxy is selected, regardless of how, but the system's kernel or iptables versions are insufficient, this always falls back to the userspace proxy.")
 	fs.Int32Var(o.config.IPTables.MasqueradeBit, "iptables-masquerade-bit", utilpointer.Int32PtrDerefOr(o.config.IPTables.MasqueradeBit, 14), "If using the pure iptables proxy, the bit of the fwmark space to mark packets requiring SNAT with.  Must be within the range [0, 31].")

staging/src/k8s.io/apimachinery/pkg/util/net/port_range.go

@@ -43,14 +43,19 @@ func (pr PortRange) String() string {
 	return fmt.Sprintf("%d-%d", pr.Base, pr.Base+pr.Size-1)
 }
 
-// Set parses a string of the form "min-max", inclusive at both ends, and
+// Set parses a string of the form "value", "min-max", or "min+offset", inclusive at both ends, and
 // sets the PortRange from it.  This is part of the flag.Value and pflag.Value
 // interfaces.
 func (pr *PortRange) Set(value string) error {
-	value = strings.TrimSpace(value)
+	const (
+		SinglePortNotation = 1 << iota
+		HyphenNotation
+		PlusNotation
+	)
 
-	// TODO: Accept "80" syntax
-	// TODO: Accept "80+8" syntax
+	value = strings.TrimSpace(value)
+	hyphenIndex := strings.Index(value, "-")
+	plusIndex := strings.Index(value, "+")
 
 	if value == "" {
 		pr.Base = 0
@@ -58,20 +63,51 @@ func (pr *PortRange) Set(value string) error {
 		return nil
 	}
 
-	hyphenIndex := strings.Index(value, "-")
-	if hyphenIndex == -1 {
-		return fmt.Errorf("expected hyphen in port range")
+	var err error
+	var low, high int
+	var notation int
+
+	if plusIndex == -1 && hyphenIndex == -1 {
+		notation |= SinglePortNotation
+	}
+	if hyphenIndex != -1 {
+		notation |= HyphenNotation
+	}
+	if plusIndex != -1 {
+		notation |= PlusNotation
 	}
 
-	var err error
-	var low int
-	var high int
-	low, err = strconv.Atoi(value[:hyphenIndex])
-	if err == nil {
+	switch notation {
+	case SinglePortNotation:
+		var port int
+		port, err = strconv.Atoi(value)
+		if err != nil {
+			return err
+		}
+		low = port
+		high = port
+	case HyphenNotation:
+		low, err = strconv.Atoi(value[:hyphenIndex])
+		if err != nil {
+			return err
+		}
 		high, err = strconv.Atoi(value[hyphenIndex+1:])
-	}
-	if err != nil {
-		return fmt.Errorf("unable to parse port range: %s: %v", value, err)
+		if err != nil {
+			return err
+		}
+	case PlusNotation:
+		var offset int
+		low, err = strconv.Atoi(value[:plusIndex])
+		if err != nil {
+			return err
+		}
+		offset, err = strconv.Atoi(value[plusIndex+1:])
+		if err != nil {
+			return err
+		}
+		high = low + offset
+	default:
+		return fmt.Errorf("unable to parse port range: %s", value)
 	}
 
 	if low > 65535 || high > 65535 {

staging/src/k8s.io/apimachinery/pkg/util/net/port_range_test.go

@@ -34,13 +34,21 @@ func TestPortRange(t *testing.T) {
 		{" 100-200 ", true, "100-200", 200, 201},
 		{"0-0", true, "0-0", 0, 1},
 		{"", true, "", -1, 0},
-		{"100", false, "", -1, -1},
+		{"100", true, "100-100", 100, 101},
 		{"100 - 200", false, "", -1, -1},
 		{"-100", false, "", -1, -1},
 		{"100-", false, "", -1, -1},
 		{"200-100", false, "", -1, -1},
 		{"60000-70000", false, "", -1, -1},
 		{"70000-80000", false, "", -1, -1},
+		{"70000+80000", false, "", -1, -1},
+		{"1+0", true, "1-1", 1, 2},
+		{"0+0", true, "0-0", 0, 1},
+		{"1+-1", false, "", -1, -1},
+		{"1-+1", false, "", -1, -1},
+		{"100+200", true, "100-300", 300, 301},
+		{"1+65535", false, "", -1, -1},
+		{"0+65535", true, "0-65535", 65535, 65536},
 	}
 
 	for i := range testCases {
@@ -52,7 +60,7 @@ func TestPortRange(t *testing.T) {
 			t.Errorf("expected success, got %q", err)
 			continue
 		} else if err == nil && tc.success == false {
-			t.Errorf("expected failure")
+			t.Errorf("expected failure %#v", testCases[i])
 			continue
 		} else if tc.success {
 			if f.String() != tc.expected {