Add support for dhcpv6

[Xichen96]

Currently dhcpmon only supports dhcpv4/ipv4

[mssonicbld]

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[Copilot]

Pull Request Overview

This pull request adds comprehensive support for DHCPv6 to dhcpmon, which previously only supported DHCPv4. The changes include adding DHCPv6 packet handling, separate RX/TX sockets for IPv6, DHCPv6 message type definitions, counter management, health checks, and database operations for DHCPv6 counters.

Key changes:

• Introduced DHCPv6 message types and packet handlers for both RX and TX directions
• Added separate socket management for IPv4 and IPv6 DHCP traffic (4 sockets total: rx_sock, tx_sock, rx_sock_v6, tx_sock_v6)
• Implemented DHCPv6-specific validation logic including relay message handling and option parsing

Reviewed Changes

Copilot reviewed 21 out of 22 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/util.h	Added DHCPv6 counter table prefix, helper functions for checksums, address string generation, and debug logging
src/util.cpp	Implemented checksum calculation functions for IP/IPv6 and UDP, JSON generation, and address formatting utilities
src/sock_mgr.h/cpp	New socket manager to handle 4 separate sockets (rx/tx for v4/v6), event management, and counter operations
src/packet_handler.h/cpp	New packet handler module with DHCPv6 message validation logic and packet processing for all 4 socket types
src/main.cpp	Updated command-line parsing and initialization flow to use new socket manager
src/health_check.h/cpp	Extracted health check logic into separate module with DHCPv6 health checks
src/event_mgr.h/cpp	Enhanced event manager with tagging support for event grouping
src/dhcp_mon.h/cpp	Refactored to use socket manager and support DHCPv6 counter updates and health monitoring
src/dhcp_devman.h/cpp	Updated device manager to support IPv6 addresses, vlan/portchannel mapping, and DHCPv6 operations
src/dhcp_device.h/cpp	Added DHCPv6 message types, health check types, and counter operations for IPv6

Comments suppressed due to low confidence (1)

src/dhcp_devman.cpp:1

• The condition logic is incorrect. The intention appears to be ensuring exactly 1 IPv4 address AND exactly 1 IPv6 GUA AND exactly 1 IPv6 LLA. The current condition (num_ipv6_gua != 1 && num_ipv6_lla != 1) will pass if either GUA or LLA equals 1, which is not the intended behavior. It should be (num_ipv6_gua != 1 || num_ipv6_lla != 1) to require both to be exactly 1.

/**

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[Copilot]

Accessing counter->at(i) when counter is not nullptr can throw std::out_of_range exception if the key i doesn't exist in the map. Consider using counter->find(i) or providing a default value using the readonly_access helper function defined in the header.

Suggested change

	std::string value = std::to_string(counter == nullptr ? 0 : counter->at(i));
	uint64_t val = 0;
	if (counter != nullptr) {
	auto it = counter->find(i);
	if (it != counter->end()) {
	val = it->second;
	}
	}
	std::string value = std::to_string(val);

[mssonicbld]

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[mssonicbld]

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[Blueve]

What is the T1+ scenario? The 2nd/3rd hop of DHCP relay?