Simple Toy DHCP Client

Simple client that prints out a list of interfaces to use, once one is selected it proceeds to broadcast a discover message and waits for a reply from a local dhcp server. Handles the offer and makes a request, looking for a final ack before exiting.

Wireshark pcap is included.

Example output from program

=== Ack -> Client ===
Message type: 2
Hardware Type: 1
Hardware Length: 6
XID: [23 23 43 23]
Client IP: [0 0 0 0]
Your IP: [192 168 0 5]
Server IP: [0 0 0 0]
Gateway IP: [0 0 0 0]
Client Hardware Address: [212 59 4 32 53 210 0 0 0 0 0 0 0 0 0 0]
Options: Option Name: Message Type
Code: 53
Len: 1
Data: [5]
Option Name: Server ID
Code: 54
Len: 4
Data: [192 168 0 1]
Option Name: Lease Time
Code: 51
Len: 4
Data: [0 1 81 128]
Option Name: Subnet Mask
Code: 1
Len: 4
Data: [255 255 255 0]
Option Name: Router
Code: 3
Len: 4
Data: [192 168 0 1]
Option Name: DNS Server(s)
Code: 6
Len: 4
Data: [192 168 0 1]
Option Name: END
Code: 255
Len: 0
Data: []

Example output from Wireshark

Dynamic Host Configuration Protocol (ACK)

    Message type: Boot Reply (2)

    Hardware type: Ethernet (0x01)

    Hardware address length: 6

    Hops: 0

    Transaction ID: 0x17172b17

    Seconds elapsed: 0

    Bootp flags: 0x0000 (Unicast)

    Client IP address: 0.0.0.0 (0.0.0.0)

    Your (client) IP address: 192.168.0.5 (192.168.0.5)

    Next server IP address: 0.0.0.0 (0.0.0.0)

    Relay agent IP address: 0.0.0.0 (0.0.0.0)

    Client MAC address: Babylon.local (d4:3b:04:20:35:d2)

    Client hardware address padding: 00000000000000000000

    Server host name not given

    Boot file name not given

    Magic cookie: DHCP

    Option: (53) DHCP Message Type (ACK)

        Length: 1

        DHCP: ACK (5)

    Option: (54) DHCP Server Identifier (192.168.0.1)

        Length: 4

        DHCP Server Identifier: 192.168.0.1 (192.168.0.1)

    Option: (51) IP Address Lease Time

        Length: 4

        IP Address Lease Time: (86400s) 1 day

    Option: (1) Subnet Mask (255.255.255.0)

        Length: 4

        Subnet Mask: 255.255.255.0

    Option: (3) Router

        Length: 4

        Router: 192.168.0.1 (192.168.0.1)

    Option: (6) Domain Name Server

        Length: 4

        Domain Name Server: 192.168.0.1 (192.168.0.1)

    Option: (255) End

        Option End: 255

Things Left TODO

- Add more code documentation
- Add some basic test cases

Notice

Purely a fun project and not meant to be a serious attempt at implementing a DHCP client.