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, 57 insertions, 0 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index ad7a5b22f..3c7c5c0a8 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -1434,6 +1434,60 @@ type ICMPStats struct {
 	V6PacketsReceived ICMPv6ReceivedPacketStats
 }
 
+// IGMPPacketStats enumerates counts for all IGMP packet types.
+type IGMPPacketStats struct {
+	// MembershipQuery is the total number of Membership Query messages counted.
+	MembershipQuery *StatCounter
+
+	// V1MembershipReport is the total number of Version 1 Membership Report
+	// messages counted.
+	V1MembershipReport *StatCounter
+
+	// V2MembershipReport is the total number of Version 2 Membership Report
+	// messages counted.
+	V2MembershipReport *StatCounter
+
+	// LeaveGroup is the total number of Leave Group messages counted.
+	LeaveGroup *StatCounter
+}
+
+// IGMPSentPacketStats collects outbound IGMP-specific stats.
+type IGMPSentPacketStats struct {
+	IGMPPacketStats
+
+	// Dropped is the total number of IGMP packets dropped due to link layer
+	// errors.
+	Dropped *StatCounter
+}
+
+// IGMPReceivedPacketStats collects inbound IGMP-specific stats.
+type IGMPReceivedPacketStats struct {
+	IGMPPacketStats
+
+	// Invalid is the total number of IGMP packets received that IGMP could not
+	// parse.
+	Invalid *StatCounter
+
+	// ChecksumErrors is the total number of IGMP packets dropped due to bad
+	// checksums.
+	ChecksumErrors *StatCounter
+
+	// Unrecognized is the total number of unrecognized messages counted, these
+	// are silently ignored for forward-compatibilty.
+	Unrecognized *StatCounter
+}
+
+// IGMPStats colelcts IGMP-specific stats.
+type IGMPStats struct {
+	// IGMPSentPacketStats contains counts of sent packets by IGMP packet type
+	// and a single count of invalid packets received.
+	PacketsSent IGMPSentPacketStats
+
+	// IGMPReceivedPacketStats contains counts of received packets by IGMP packet
+	// type and a single count of invalid packets received.
+	PacketsReceived IGMPReceivedPacketStats
+}
+
 // IPStats collects IP-specific stats (both v4 and v6).
 type IPStats struct {
 	// PacketsReceived is the total number of IP packets received from the
@@ -1639,6 +1693,9 @@ type Stats struct {
 	// ICMP breaks out ICMP-specific stats (both v4 and v6).
 	ICMP ICMPStats
 
+	// IGMP breaks out IGMP-specific stats.
+	IGMP IGMPStats
+
 	// IP breaks out IP-specific stats (both v4 and v6).
 	IP IPStats