Fix envoy canBind (#6238)

* Fix envoy cli canBind function

The string form of an Addr was including the CIDR causing the str equals to not match.

* Remove debug prints

command/connect/envoy/envoy.go

@@ -165,7 +165,8 @@ func parseAddress(addrStr string) (string, int, error) {
 	return addr, port, nil
 }
 
-func canBind(addr string) bool {
+// canBindInternal is here mainly so we can unit test this with a constant net.Addr list
+func canBindInternal(addr string, ifAddrs []net.Addr) bool {
 	if addr == "" {
 		return false
 	}
@@ -175,21 +176,34 @@ func canBind(addr string) bool {
 		return false
 	}
 
-	ifAddrs, err := net.InterfaceAddrs()
-
-	if err != nil {
-		return false
-	}
+	ipStr := ip.String()
 
 	for _, addr := range ifAddrs {
-		if addr.String() == ip.String() {
-			return true
+		switch v := addr.(type) {
+		case *net.IPNet:
+			if v.IP.String() == ipStr {
+				return true
+			}
+		default:
+			if addr.String() == ipStr {
+				return true
+			}
 		}
 	}
 
 	return false
 }
 
+func canBind(addr string) bool {
+	ifAddrs, err := net.InterfaceAddrs()
+
+	if err != nil {
+		return false
+	}
+
+	return canBindInternal(addr, ifAddrs)
+}
+
 func (c *cmd) Run(args []string) int {
 	if err := c.flags.Parse(args); err != nil {
 		return 1

command/connect/envoy/envoy_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"flag"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -20,7 +21,7 @@ import (
 
 var update = flag.Bool("update", false, "update golden files")
 
-func TestCatalogCommand_noTabs(t *testing.T) {
+func TestEnvoyCommand_noTabs(t *testing.T) {
 	t.Parallel()
 	if strings.ContainsRune(New(nil).Help(), '\t') {
 		t.Fatal("help has tabs")
@@ -527,3 +528,99 @@ func testMockAgentProxyConfig(cfg map[string]interface{}) http.HandlerFunc {
 		w.Write(cfgJSON)
 	})
 }
+
+func TestEnvoyCommand_canBindInternal(t *testing.T) {
+	t.Parallel()
+	type testCheck struct {
+		expected bool
+		addr     string
+	}
+
+	type testCase struct {
+		ifAddrs []net.Addr
+		checks  map[string]testCheck
+	}
+
+	parseIPNets := func(t *testing.T, in ...string) []net.Addr {
+		var out []net.Addr
+		for _, addr := range in {
+			ip := net.ParseIP(addr)
+			require.NotNil(t, ip)
+			out = append(out, &net.IPNet{IP: ip})
+		}
+		return out
+	}
+
+	parseIPs := func(t *testing.T, in ...string) []net.Addr {
+		var out []net.Addr
+		for _, addr := range in {
+			ip := net.ParseIP(addr)
+			require.NotNil(t, ip)
+			out = append(out, &net.IPAddr{IP: ip})
+		}
+		return out
+	}
+
+	cases := map[string]testCase{
+		"IPNet": {
+			parseIPNets(t, "10.3.0.2", "198.18.0.1", "2001:db8:a0b:12f0::1"),
+			map[string]testCheck{
+				"ipv4": {
+					true,
+					"10.3.0.2",
+				},
+				"secondary ipv4": {
+					true,
+					"198.18.0.1",
+				},
+				"ipv6": {
+					true,
+					"2001:db8:a0b:12f0::1",
+				},
+				"ipv4 not found": {
+					false,
+					"1.2.3.4",
+				},
+				"ipv6 not found": {
+					false,
+					"::ffff:192.168.0.1",
+				},
+			},
+		},
+		"IPAddr": {
+			parseIPs(t, "10.3.0.2", "198.18.0.1", "2001:db8:a0b:12f0::1"),
+			map[string]testCheck{
+				"ipv4": {
+					true,
+					"10.3.0.2",
+				},
+				"secondary ipv4": {
+					true,
+					"198.18.0.1",
+				},
+				"ipv6": {
+					true,
+					"2001:db8:a0b:12f0::1",
+				},
+				"ipv4 not found": {
+					false,
+					"1.2.3.4",
+				},
+				"ipv6 not found": {
+					false,
+					"::ffff:192.168.0.1",
+				},
+			},
+		},
+	}
+
+	for name, tcase := range cases {
+		t.Run(name, func(t *testing.T) {
+			for checkName, check := range tcase.checks {
+				t.Run(checkName, func(t *testing.T) {
+					require.Equal(t, check.expected, canBindInternal(check.addr, tcase.ifAddrs))
+				})
+			}
+		})
+	}
+}