dhcpz

A DHCP protocol library for Zig.

Installation

zig fetch --save git+https://github.com/cloudboss/dhcpz

Then in your build.zig:

const dhcpz = b.dependency("dhcpz", .{
    .target = target,
});
exe.root_module.addImport("dhcpz", dhcpz.module("dhcpz"));

Example

const std = @import("std");
const v4 = @import("dhcpz").v4;

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    // Create DHCPDISCOVER
    const mac = [6]u8{ 0x02, 0x00, 0x00, 0x00, 0x00, 0x01 };
    var discover = try v4.createDiscover(allocator, 0x12345678, mac);
    defer discover.deinit();

    // Encode to bytes
    var buf: [1500]u8 = undefined;
    const len = try discover.encode(&buf);

    // Send buf[0..len] over UDP to port 67...

    // Decode response
    var response = try v4.Message.decode(allocator, received_data);
    defer response.deinit();

    // Check message type
    if (response.options.getMessageType()) |msg_type| {
        if (msg_type == .offer) {
            // Handle DHCPOFFER
            const offered_ip = response.yiaddr;
            const subnet = response.options.get(.subnet_mask);
            const gateway = response.options.get(.router);
            // ...
        }
    }
}

API

All DHCPv4 types are under dhcpz.v4.

Types

• v4.Message - DHCP message with header fields and options
• v4.Option - Tagged union of all supported option types
• v4.MessageType - DISCOVER, OFFER, REQUEST, ACK, NAK, etc.
• v4.OptionCode - Option type codes
• v4.Ipv4Addr - [4]u8 alias for IPv4 addresses

Functions

• v4.createDiscover(allocator, xid, mac) - Create DHCPDISCOVER message
• v4.createRequest(allocator, xid, mac, requested_ip, server_id) - Create DHCPREQUEST message

Message Methods

• Message.init(allocator) - Create empty message
• Message.deinit() - Free all allocated memory
• Message.encode(buf) - Encode to bytes, returns length
• Message.decode(allocator, data) - Decode from bytes
• Message.setXid(xid) - Set transaction ID
• Message.setChaddr(mac) - Set client hardware address
• Message.setBroadcast(bool) - Set broadcast flag

Options Methods

• Options.append(option) - Add an option (takes ownership of slice data)
• Options.get(tag) - Get option by tag, returns payload or null
• Options.getMessageType() - Convenience for getting message type

Building

zig build test

License

MIT