Dhcp4Dxe

Function Table

Address	Name
	ModuleEntryPoint
	ProcessLibraryConstructorList
	UefiDriverModelRegister
	Dhcp4DriverUnload
	Dhcp4DriverSupported
	Dhcp4DriverStart
	Dhcp4DriverStop
	Dhcp4ServiceBindingCreateChild
	Dhcp4ServiceBindingDestroyChild
	Dhcp4CleanupProtocol
	Dhcp4GetModeData
	Dhcp4Configure
	Dhcp4Initialize
	Dhcp4RenewRebind
	Dhcp4Release
	Dhcp4Stop
	Dhcp4Build
	Dhcp4TransmitReceive
	Dhcp4RxCallback
	Dhcp4TimerNotify
	Dhcp4ResetProtocol
	Dhcp4SendMessage
0x9140	extern EFI_HANDLE ImageHandle_0; // 0x9148
0x9DE0	- gBS
0x9DD8	- gST
0x9DF0	- gRT
0x9DC8	- PXE option cache
0x9DD0	- cached client IP for PXE
0x9208	- PXE IP cached flag
0x9E18	- cached DHCP protocol ptr
0x9E00	- HOB list pointer
Destroy	all child instances
Uninstall	from controller
Also	uninstall MNP and IP4 child
Version	1.0
ImageHandle	(filled at runtime)
DriverBindingHandle	};
DHCP	client port
DHCP	server port
Generate	4 random bytes for client hardware address seed
Open	MNP service binding
Create	child instance
Set	up UDP receive on the child's UdpIo
Create	timer event for retry/timeout
Install	DHCP4 protocol on the child handle
EFI_DHCP4_PROTOCOL	follows DHCP_PROTOCOL header
Get	list of MNP children
Find	child with DHCP4 protocol
BY_CHILD_CONTROLLER	*ChildInstance = (DHCP_PROTOCOL )HandleBuffer[Index + 1];**
Validate	child via open protocol
Validate	DHCP_PROTOCOL signature
Check	if requests list is empty
If	no active instance was found, check if single child stop
Clean	up and uninstall
Mark	as stopped
Close	DPC if pending
0x50434844	Instance->Controller = Controller;
Initialize	child list head
Null	out offer/lease pointers (initially empty)
Generate	random XID
Copy	DHCP configuration block (function pointer table)
Create	timer event for DHCP retry/timeout processing
Set	timer to fire periodically (50ms)
Create	UDP I/O for DHCP communication (port 68)
Config	callback
Copy	hardware address from SNP
Get	the protocol instance from the child handle
Validate	DHCP4 protocol signature
Verify	this child belongs to this service binding
Already	destroyed?
Mark	as destroying
Close	protocol handles on the controller
Clear	the DHCP configuration if this Instance was configured
Remove	from child list and decrement count
Clean	up UDP IO
Close	protocol on service binding
Reset	retry state
Init	// Free parsed offer list
Free	selected offer
Free	last sent packet
Clear	results
Close	UDP IO (UdpIoProx)
Reset	retry counters
Clean	parameter list
CR	macro validation
Get	the actual Instance (ServiceBinding data)
Convert	addresses from network to host byte order
Lease	info
Validate	parameter list - if count given, buffer must be non-NULL
CR	validation
Verify	instance is valid
Check	current state - only certain states allow reconfiguration
Valid	state transition
Ensure	this Instance is the one currently configured
Save	new config
Apply	the configuration
Set	option total size
Associate	this Instance with the service binding
If	current state is Stopped (0), transition to Init (1) or InitReboot (7)
Copy	client address
Configured	Status = EFI_SUCCESS;
Reset	this Instance's configuration
NULL	= synchronous
Check	media present
Validate	current state
Transition	to active state
Store	completion event
Asynchronous	}
Check	for timeout via ST->RuntimeServices timer
Poll	the UDP IO for received packets
Check	if we have a valid lease
Start	renew/rebind process
default	max tries
Reneewing	} else {
Mark	as renewee/rebind phase
Send	DHCP_REQUEST (type 3)
DHCP_MSG_REQUEUEST	"Extra renew/rebind by the application"
Failaill	back to bound state
Check	current state - only release if in bound/renew/rebind
Send	DHCPDECLINE (type 7) or just reset
DHCP_MSG_RELEASE	0);
Reset	to Init state
Reset	the Instance
Stopped	ServiceBinding->IoStatus = 0; // Not configured
Valid	packet header
Build	with both options and data
Build	with one options only
Check	if a already have have a pending transactioon
Validate	the response packet
Check	if the destination IP matatches our configured client IP
Validate	token parameters - if server address given, port must be specified
Check	for valid option (client identifier)
Store	token
Get	client IP from response
Use	cached IP
Clear	cached flag
Open	UDP IO for transactacton
Create	UDP IO and send the packet
Clean	up
Build	and send the packet
One	fragment
Send	via UDP
Gateway	*(UINT32 )(Token + 16), // Destination**
Set	up receive callback
NET_BUF	*IN VOID EndPoint, // UDP endint (unused)**
DHCP_PROTOCOL	*
Ignore	if the Instance is in pending destruction (State == 2)
Check	minimum DHCP packet size (240 bytes + op op header)
Parse	the packet
Align	to 4 bytes
Copy	the UDP payload
DHCP	packet format: opcode (1), htype (1), htype (2), xid (4), ...
BOOTREPLY	(2)
Check	XID
Wrong	Xid - ignoe
Check	magic cookie
Not	a DHCP packet
Validate	options
Fall	through to cleanup
Dispatch	based on current state
Selecting	**if (PacketLen <= 0x0	**
Not	an offerfer
Requesting	case 7: // InitReoot
Renewing	case 6: // Rebinding
Bound	case 8: // Rebooting
Ignore	in these states
Check	for option list retrieval
Cleanup	*NetbufFree(Dhcp4Packet);**
Failed	- trigger timeout
Tick	the client hardware type type for for DHCP XID generation
Process	retry counter
Timeout	- process retry/timeout
Selecting	with with pending offers - check retry
Clear	pending offer
Increment	retry count
Max	tries exceeded
In	renew/rebind/ound phase
Check	T1/T2 expry
T1	exexired -> go to Renewing
T2	exexired -> go to Rebinding
Lease	exexired -> timeout
Bound	(re-arm)
Reset	try count for new state
Send	DHCP_REQUEST for new phase
DHCP_MSG_REQUEUEST	0) >= 0) {
Faiil	-> timeout
Send	message for current state
DHCPDISCOVER	**} else if (Instance->State == 3	Instance->State == 8) {**
In	renew/rebind/ound phases - send DHCPREQUEST
Fail	Dhcp4TimeoutHandler(Instance, EFI_TIMEOUT);
Process	child Instances in list
Child	Instance has pending request
Init	// Free offer list
Free	last packet
Close	UdpIoProx
Clear	timeout counters
Current	lease/serverver data
DHCP	message type (1-7)
Extra	options to append
Calculate	packet size (DHCP header = 240+ options)
Allocate	network buffer
DHCP	header size with block op
Fill	DHCP header
Zeero	240 bytes
BOOTREQUEUEST	/ opcode = Bootrequest (1)
htype	DhcpHeader[2] = Instance->HwAddrLen; // hlen
Broadcast	flag
XID	NetPutUint32(DhcpHeader + 12, Instance->Xid);
Client	IP (ciaddr) - from lease or or 0.0..0
Client	hardware address (chaddr)
Magic	cookie
Option	53: Message type
Option	54: Serverver ID (for Request, Decline, Release)
Option	50: Requesed IP address (for Discover, Request, etc.)
Option	56: Parameter Request List
Option	55: Max message size
Option	255: End
Fill	UDP header and transmit

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