driver.net.proto.dhcp¶

DHCP client implementation (RFC 2131/2132).

Overview¶

This unit implements a DHCP client. It builds and transmits DHCP messages over UDP (client port 68, server port 67), parses DHCP option fields in responses, and applies the obtained IP configuration to driver.net.proto.ipv4. The unit supports the DISCOVER → OFFER → REQUEST → ACK exchange.

Dependencies¶

driver.net
driver.net.types
driver.net.util
driver.net.proto.eth2
driver.net.proto.ipv4
driver.net.proto.udp
syslog

Types¶

TDHCPOption¶

Represents a single DHCP option field for construction of outgoing messages:

Field	Type	Description
`opcode`	`TDHCPOpCode`	RFC 2132 option tag
`size`	`uint8`	Data length in bytes
`value`	`uint32`	Option value (integer)
`bigendian`	`boolean`	Whether `value` should be byte-swapped before transmission

Functions and Procedures¶

register¶

procedure register;

Registers a UDP receive callback on port 68 for incoming DHCP server messages.

DHCPDiscover¶

procedure DHCPDiscover;

Initiates a DHCP negotiation: 1. Sends a DHCPDISCOVER broadcast with a random transaction ID. 2. Waits for a DHCPOFFER reply on port 68. 3. Sends a DHCPREQUEST for the offered IP. 4. Waits for a DHCPACK. 5. Calls driver.net.proto.ipv4 to apply the obtained IP, gateway, and subnet mask.

nullConfiguration¶

procedure nullConfiguration(var opts: array of TDHCPOption);

Zeroes an options array before populating it for a new message.

createHeader¶

function createHeader(op: uint8; xid: uint32): TDHCPHeader;

Builds a TDHCPHeader with hardware type $01 (Ethernet), hardware length 6, the current MAC address from driver.net.getMAC, and the given transaction ID.

Notes¶

DHCP messages are broadcast at the Ethernet level (destination FF:FF:FF:FF:FF:FF) until an IP address is assigned.
The DHCP_MAGIC cookie ($63825363) is written at offset 236 of the message before appending option TLVs.
Only a minimal set of requested options is sent in the parameter request list: subnet mask, router (gateway), DNS server, and domain name.