Backend: fix IPv6 address parsing erroneous (#28585)

* Backend: Fix parsing of client IP address

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/infra/network/address.go

@@ -0,0 +1,44 @@
+package network
+
+import (
+	"fmt"
+	"net"
+	"regexp"
+)
+
+var reIPv4AndPort = regexp.MustCompile(`^(\d+\.\d+\.\d+\.\d+):\d+$`)
+
+// An IPv6 address/port pair can consist of the IP address enclosed in square brackets followed by a colon and
+// a port, although the colon/port component is actually optional in practice (e.g., we may receive [::1], where
+// we should just strip off the square brackets).
+var reIPv6AndPort = regexp.MustCompile(`^\[(.+)\](:\d+)?$`)
+
+// GetIPFromAddress tries to get an IPv4 or IPv6 address from a host address, potentially including a port.
+func GetIPFromAddress(input string) (net.IP, error) {
+	if a := net.ParseIP(input); len(a) > 0 {
+		return a, nil
+	}
+
+	err := fmt.Errorf("not a valid IP address or IP address/port pair: %q", input)
+
+	// It could potentially be an IP address/port pair
+	var addr string
+	ms := reIPv4AndPort.FindStringSubmatch(input)
+	if len(ms) == 0 {
+		ms := reIPv6AndPort.FindStringSubmatch(input)
+		if len(ms) == 0 {
+			return nil, err
+		}
+
+		addr = ms[1]
+	} else {
+		// Strip off port
+		addr = ms[1]
+	}
+
+	if a := net.ParseIP(addr); len(a) > 0 {
+		return a, nil
+	}
+
+	return nil, err
+}

pkg/infra/network/address_test.go

@@ -0,0 +1,82 @@
+package network
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetIPFromAddress(t *testing.T) {
+	testCases := []struct {
+		desc   string
+		input  string
+		exp    string
+		expErr string
+	}{
+		{
+			desc:  "Valid IPv4",
+			input: "192.168.2.1",
+			exp:   "192.168.2.1",
+		},
+		{
+			desc:  "Valid IPv6",
+			input: "2001:0db8:0000:0000:0000:ff00:0042:8329",
+			exp:   "2001:db8::ff00:42:8329",
+		},
+		{
+			desc:  "Valid IPv6 enclosed in square brackets",
+			input: "[2001:0db8:0000:0000:0000:ff00:0042:8329]",
+			exp:   "2001:db8::ff00:42:8329",
+		},
+		{
+			desc:  "Valid IPv4/port pair",
+			input: "192.168.2.1:5000",
+			exp:   "192.168.2.1",
+		},
+		{
+			desc:  "Valid IPv6/port pair",
+			input: "[2001:0db8:0000:0000:0000:ff00:0042:8329]:5000",
+			exp:   "2001:db8::ff00:42:8329",
+		},
+		{
+			desc:   "Invalid IPv6/port pair",
+			input:  "[2001:0db8:0000:0000:0000:ff00:0042:8329]:5000:2000",
+			expErr: `not a valid IP address or IP address/port pair: "[2001:0db8:0000:0000:0000:ff00:0042:8329]:5000:2000"`,
+		},
+		{
+			desc:   "IPv6 with too many parts",
+			input:  "2001:0db8:0000:0000:0000:ff00:0042:8329:1234",
+			expErr: `not a valid IP address or IP address/port pair: "2001:0db8:0000:0000:0000:ff00:0042:8329:1234"`,
+		},
+		{
+			desc:   "IPv6 with too few parts",
+			input:  "2001:0db8:0000:0000:0000:ff00:0042",
+			expErr: `not a valid IP address or IP address/port pair: "2001:0db8:0000:0000:0000:ff00:0042"`,
+		},
+		{
+			desc:  "Valid shortened IPv6",
+			input: "2001:db8::ff00:42:8329",
+			exp:   "2001:db8::ff00:42:8329",
+		},
+		{
+			desc:  "IPv6 loopback address",
+			input: "::1",
+			exp:   "::1",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			ip, err := GetIPFromAddress(tc.input)
+			if tc.expErr == "" {
+				exp := net.ParseIP(tc.exp)
+				require.NotNil(t, exp)
+				require.NoError(t, err)
+				assert.Equal(t, exp, ip)
+			} else {
+				require.EqualError(t, err, tc.expErr)
+			}
+		})
+	}
+}