Hardening URL Construction and IPv6 Support

kubelet-to-gcm/monitor/controller/client.go

@@ -19,6 +19,7 @@ package controller
 import (
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"strings"
@@ -87,7 +88,7 @@ type Client struct {
 // NewClient generates a client to hit the given controller.
 func NewClient(host string, port uint, client *http.Client) (*Client, error) {
 	// Parse our URL upfront, so we can fail fast.
-	urlStr := fmt.Sprintf("http://%s:%d/metrics", host, port)
+	urlStr := fmt.Sprintf("http://%s/metrics", net.JoinHostPort(util.NormalizeHost(host), fmt.Sprint(port)))
 	metricsURL, err := url.Parse(urlStr)
 	if err != nil {
 		return nil, err

kubelet-to-gcm/monitor/controller/client_test.go

@@ -26,6 +26,52 @@ import (
 	"github.com/GoogleCloudPlatform/k8s-stackdriver/kubelet-to-gcm/monitor/util"
 )
 
+func TestNewClient(t *testing.T) {
+	testCases := []struct {
+		name        string
+		host        string
+		port        uint
+		expectedURL string
+	}{
+		{
+			name:        "IPv4",
+			host:        "127.0.0.1",
+			port:        10250,
+			expectedURL: "http://127.0.0.1:10250/metrics",
+		},
+		{
+			name:        "IPv6",
+			host:        "2001:db8::1",
+			port:        10250,
+			expectedURL: "http://[2001:db8::1]:10250/metrics",
+		},
+		{
+			name:        "Bracketed IPv6",
+			host:        "[2001:db8::1]",
+			port:        10250,
+			expectedURL: "http://[2001:db8::1]:10250/metrics",
+		},
+		{
+			name:        "Hostname",
+			host:        "localhost",
+			port:        8080,
+			expectedURL: "http://localhost:8080/metrics",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			c, err := NewClient(tc.host, tc.port, http.DefaultClient)
+			if err != nil {
+				t.Fatalf("NewClient failed: %v", err)
+			}
+			if c.metricsURL.String() != tc.expectedURL {
+				t.Errorf("Expected URL %q, got %q", tc.expectedURL, c.metricsURL.String())
+			}
+		})
+	}
+}
+
 func TestDoRequestAndParse_SizeLimit(t *testing.T) {
 	// Create a mock server that returns a response larger than maxResponseBodySize.
 	largeDataSize := maxResponseBodySize + 1024

kubelet-to-gcm/monitor/kubelet/client.go

@@ -19,6 +19,7 @@ package kubelet
 import (
 	"encoding/json"
 	"fmt"
+	"net"
 	"net/http"
 	"net/url"
 
@@ -46,7 +47,7 @@ func NewClient(host string, port uint, client *http.Client, useAuthPort bool) (*
 	if useAuthPort {
 		protocol = "https"
 	}
-	urlStr := fmt.Sprintf("%s://%s:%d/stats/summary", protocol, host, port)
+	urlStr := fmt.Sprintf("%s://%s/stats/summary", protocol, net.JoinHostPort(util.NormalizeHost(host), fmt.Sprint(port)))
 	summaryURL, err := url.Parse(urlStr)
 	if err != nil {
 		return nil, err

kubelet-to-gcm/monitor/kubelet/client_test.go

@@ -28,6 +28,71 @@ import (
 	stats "k8s.io/kubelet/pkg/apis/stats/v1alpha1"
 )
 
+func TestNewClient(t *testing.T) {
+	testCases := []struct {
+		name        string
+		host        string
+		port        uint
+		useAuthPort bool
+		expectedURL string
+	}{
+		{
+			name:        "IPv4 HTTP",
+			host:        "127.0.0.1",
+			port:        10255,
+			useAuthPort: false,
+			expectedURL: "http://127.0.0.1:10255/stats/summary",
+		},
+		{
+			name:        "IPv4 HTTPS",
+			host:        "127.0.0.1",
+			port:        10250,
+			useAuthPort: true,
+			expectedURL: "https://127.0.0.1:10250/stats/summary",
+		},
+		{
+			name:        "IPv6 HTTP",
+			host:        "2001:db8::1",
+			port:        10255,
+			useAuthPort: false,
+			expectedURL: "http://[2001:db8::1]:10255/stats/summary",
+		},
+		{
+			name:        "IPv6 HTTPS",
+			host:        "2001:db8::1",
+			port:        10250,
+			useAuthPort: true,
+			expectedURL: "https://[2001:db8::1]:10250/stats/summary",
+		},
+		{
+			name:        "Bracketed IPv6 HTTP",
+			host:        "[2001:db8::1]",
+			port:        10255,
+			useAuthPort: false,
+			expectedURL: "http://[2001:db8::1]:10255/stats/summary",
+		},
+		{
+			name:        "Bracketed IPv6 HTTPS",
+			host:        "[2001:db8::1]",
+			port:        10250,
+			useAuthPort: true,
+			expectedURL: "https://[2001:db8::1]:10250/stats/summary",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			c, err := NewClient(tc.host, tc.port, http.DefaultClient, tc.useAuthPort)
+			if err != nil {
+				t.Fatalf("NewClient failed: %v", err)
+			}
+			if c.summaryURL.String() != tc.expectedURL {
+				t.Errorf("Expected URL %q, got %q", tc.expectedURL, c.summaryURL.String())
+			}
+		})
+	}
+}
+
 func TestDoRequestAndUnmarshal_SizeLimit(t *testing.T) {
 	largeDataSize := maxResponseBodySize + 1024
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

kubelet-to-gcm/monitor/util/util.go

@@ -19,6 +19,7 @@ package util
 import (
 	"errors"
 	"io"
+	"strings"
 )
 
 var (
@@ -39,3 +40,14 @@ func ReadWithLimit(r io.Reader, limit int64) ([]byte, error) {
 	}
 	return data, nil
 }
+
+// NormalizeHost handles host strings that may already be bracketed (like IPv6).
+// net.JoinHostPort expects a raw IP or hostname; if it receives a bracketed IPv6,
+// it will double-bracket it.
+func NormalizeHost(host string) string {
+	host = strings.TrimSpace(host)
+	if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") {
+		return host[1 : len(host)-1]
+	}
+	return host
+}

kubelet-to-gcm/monitor/util/util_test.go

@@ -65,3 +65,45 @@ func TestReadWithLimit(t *testing.T) {
 		})
 	}
 }
+
+func TestNormalizeHost(t *testing.T) {
+	testCases := []struct {
+		desc     string
+		input    string
+		expected string
+	}{
+		{
+			desc:     "IPv4",
+			input:    "127.0.0.1",
+			expected: "127.0.0.1",
+		},
+		{
+			desc:     "hostname",
+			input:    "localhost",
+			expected: "localhost",
+		},
+		{
+			desc:     "raw IPv6",
+			input:    "2001:db8::1",
+			expected: "2001:db8::1",
+		},
+		{
+			desc:     "bracketed IPv6",
+			input:    "[2001:db8::1]",
+			expected: "2001:db8::1",
+		},
+		{
+			desc:     "bracketed IPv6 with spaces",
+			input:    " [2001:db8::1] ",
+			expected: "2001:db8::1",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			if got := NormalizeHost(tc.input); got != tc.expected {
+				t.Errorf("NormalizeHost(%q) = %q, want %q", tc.input, got, tc.expected)
+			}
+		})
+	}
+}