driver.net.util¶

Network utility functions for address handling, packet context management, and checksum computation.

Overview¶

This unit provides stateless helper routines used across all network protocol layers. It covers copying and comparing MAC and IPv4 addresses, converting address strings to binary, packet context allocation and cleanup, RFC 1071 checksum calculation, and common packet-forwarding helpers.

Dependencies¶

driver.net.types
core.memory

Functions and Procedures¶

Address Copy¶

procedure copyMAC(dst: PMACAddress; src: PMACAddress);
procedure copyIPv4(dst: PIPv4Address; src: PIPv4Address);

Copies a 6-byte MAC or 4-byte IPv4 address from src to dst.

Address Comparison¶

function MACEqual(a, b: TMACAddress): boolean;
function IPEqual(a, b: TIPv4Address): boolean;

Returns true if both addresses are identical byte-for-byte.

Address Parsing¶

function stringToMAC(s: string): TMACAddress;
function stringToIPv4(s: string): TIPv4Address;

Parses a colon-delimited MAC address string (AA:BB:CC:DD:EE:FF) or a dotted-decimal IPv4 string (A.B.C.D) into the corresponding binary record.

Address Formatting¶

procedure writeMACAddress(mac: TMACAddress);
procedure writeMACAddressEx(mac: TMACAddress);
procedure writeIPv4Address(ip: TIPv4Address);
procedure writeIPv4AddressEx(ip: TIPv4Address);

Writes a formatted address string to the system log. The Ex variants omit the trailing newline.

Packet Context Management¶

function newPacketContext: PPacketContext;
procedure freePacketContext(ctx: PPacketContext);

Allocates or frees a TPacketContext on the kernel heap.

Checksum¶

function calculateChecksum(data: pointer; length: uint32): uint16;
function verifyChecksum(data: pointer; length: uint32): boolean;

Computes an RFC 1071 one's complement Internet checksum over length bytes. verifyChecksum returns true if the checksum over the data (including the checksum field) equals zero.

Routing Helpers¶

function sameSubnetIPv4(a, b: TIPv4Address; mask: TIPv4Address): boolean;

Returns true if addresses a and b are on the same subnet given mask.

Context Swap Helpers¶

procedure contextMACSwitch(ctx: PPacketContext);
procedure contextIPv4Switch(ctx: PPacketContext);

Swaps source and destination MAC or IPv4 addresses within the packet context. Used by protocol layers when constructing replies.