Perform IGMPv2 when joining IPv4 multicast groups

Added headers, stats, checksum parsing capabilities from RFC 2236 describing
IGMPv2.

IGMPv2 state machine is implemented for each condition, sending and receiving
IGMP Membership Reports and Leave Group messages with backwards compatibility
with IGMPv1 routers.

Test:
* Implemented igmp header parser and checksum calculator in header/igmp_test.go
* ipv4/igmp_test.go tests incoming and outgoing IGMP messages and pathways.
* Added unit test coverage for IGMPv2 RFC behavior + IGMPv1 backwards
   compatibility in ipv4/igmp_test.go.

Fixes #4682

PiperOrigin-RevId: 343408809

1 files changed, 101 insertions, 0 deletions

diff --git a/pkg/tcpip/header/igmp_test.go b/pkg/tcpip/header/igmp_test.go
new file mode 100644
index 000000000..66e872880
--- /dev/null
+++ b/pkg/tcpip/header/igmp_test.go
@@ -0,0 +1,101 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package header_test
+
+import (
+	"testing"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+)
+
+// TestIGMPHeader tests the functions within header.igmp
+func TestIGMPHeader(t *testing.T) {
+	b := []byte{
+		0x11,       // IGMP Type, Membership Query
+		0xF0,       // Maximum Response Time
+		0xC0, 0xC0, // Checksum
+		0x01, 0x02, 0x03, 0x04, // Group Address
+	}
+
+	igmpHeader := header.IGMP(b)
+
+	if got, want := igmpHeader.Type(), header.IGMPMembershipQuery; got != want {
+		t.Errorf("got igmpHeader.Type() = %x, want = %x", got, want)
+	}
+
+	if got, want := igmpHeader.MaxRespTime(), byte(0xF0); got != want {
+		t.Errorf("got igmpHeader.MaxRespTime() = %x, want = %x", got, want)
+	}
+
+	if got, want := igmpHeader.Checksum(), uint16(0xC0C0); got != want {
+		t.Errorf("got igmpHeader.Checksum() = %x, want = %x", got, want)
+	}
+
+	if got, want := igmpHeader.GroupAddress(), tcpip.Address("\x01\x02\x03\x04"); got != want {
+		t.Errorf("got igmpHeader.GroupAddress() = %s, want = %s", got, want)
+	}
+
+	igmpType := header.IGMPv2MembershipReport
+	igmpHeader.SetType(igmpType)
+	if got := igmpHeader.Type(); got != igmpType {
+		t.Errorf("got igmpHeader.Type() = %x, want = %x", got, igmpType)
+	}
+	if got := header.IGMPType(b[0]); got != igmpType {
+		t.Errorf("got IGMPtype in backing buffer = %x, want %x", got, igmpType)
+	}
+
+	respTime := byte(0x02)
+	igmpHeader.SetMaxRespTime(respTime)
+	if got := igmpHeader.MaxRespTime(); got != respTime {
+		t.Errorf("got igmpHeader.MaxRespTime() = %x, want = %x", got, respTime)
+	}
+
+	checksum := uint16(0x0102)
+	igmpHeader.SetChecksum(checksum)
+	if got := igmpHeader.Checksum(); got != checksum {
+		t.Errorf("got igmpHeader.Checksum() = %x, want = %x", got, checksum)
+	}
+
+	groupAddress := tcpip.Address("\x04\x03\x02\x01")
+	igmpHeader.SetGroupAddress(groupAddress)
+	if got := igmpHeader.GroupAddress(); got != groupAddress {
+		t.Errorf("got igmpHeader.GroupAddress() = %s, want = %s", got, groupAddress)
+	}
+}
+
+// TestIGMPChecksum ensures that the checksum calculator produces the expected
+// checksum.
+func TestIGMPChecksum(t *testing.T) {
+	b := []byte{
+		0x11,       // IGMP Type, Membership Query
+		0xF0,       // Maximum Response Time
+		0xC0, 0xC0, // Checksum
+		0x01, 0x02, 0x03, 0x04, // Group Address
+	}
+
+	igmpHeader := header.IGMP(b)
+
+	// Calculate the initial checksum after setting the checksum temporarily to 0
+	// to avoid checksumming the checksum.
+	initialChecksum := igmpHeader.Checksum()
+	igmpHeader.SetChecksum(0)
+	checksum := ^header.Checksum(b, 0)
+	igmpHeader.SetChecksum(initialChecksum)
+
+	if got := header.IGMPCalculateChecksum(igmpHeader); got != checksum {
+		t.Errorf("got IGMPCalculateChecksum = %x, want %x", got, checksum)
+	}
+}