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DHCP API

DHCP (Dynamic Host Configuration Protocol) client and server interfaces, covering both IPv4 (dhcpc_* / dhcpd_*) and IPv6 (dhcp6c_*) address allocation protocols.

Header files: #include <netutils/dhcpc.h>, #include <netutils/dhcp6c.h>, #include <netutils/dhcpd.h>

openvela Implementation Notes

• IPv4 client: The dhcpc_* series encapsulates the complete DHCP client state machine (DISCOVER/OFFER/REQUEST/ACK)
• IPv6 client: The dhcp6c_* series implements the DHCPv6 client protocol
• Server: The dhcpd_* series provides simple DHCP server capabilities for IP allocation in hotspot/AP mode
• Asynchronous calls: The *_request_async interfaces provide callback-based invocation to avoid blocking the current thread
• Configuration dependency: Requires enabling CONFIG_NETUTILS_DHCPC / CONFIG_NETUTILS_DHCP6C / CONFIG_NETUTILS_DHCPD

DHCP Client

Header file: #include <netutils/dhcpc.h>

dhcpc_open

void *dhcpc_open(const char *interface, const void *mac_addr, int mac_len);

Creates a DHCP client session.

Parameters:

• interface Network interface name (e.g., "eth0").
• mac_addr MAC address.
• mac_len MAC address length.

Returns:

Returns a session handle on success, or NULL on failure.

dhcpc_request

int dhcpc_request(void *handle, struct dhcpc_state *presult);

Performs DHCP negotiation to obtain an IP address (blocking call).

Parameters:

• handle Session handle returned by dhcpc_open().
• presult Stores the obtained network configuration (IP, subnet mask, gateway, DNS, lease time).

Returns:

Returns 0 on success, or -1 on failure.

dhcpc_request_async

int dhcpc_request_async(void *handle, dhcpc_callback_t callback);

Asynchronously performs DHCP negotiation, running in a background thread and returning results via callback.

Parameters:

• handle Session handle.
• callback Result callback function.

Returns:

Returns 0 on successful start, or -1 on failure.

dhcpc_cancel

void dhcpc_cancel(void *handle);

Cancels an ongoing DHCP negotiation.

dhcpc_close

void dhcpc_close(void *handle);

Closes the DHCP client session and releases all resources. Internally calls dhcpc_cancel() first.

DHCPv6 Client

Header file: #include <netutils/dhcp6c.h>

dhcp6c_open

void *dhcp6c_open(const char *interface);

Creates a DHCPv6 client session.

Parameters:

• interface Network interface name.

Returns:

Returns a session handle on success, or NULL on failure.

dhcp6c_request

int dhcp6c_request(void *handle, struct dhcp6c_state *presult);

Performs DHCPv6 negotiation to obtain an address (blocking call).

dhcp6c_request_async

int dhcp6c_request_async(void *handle, dhcp6c_callback_t callback);

Asynchronously performs DHCPv6 negotiation.

dhcp6c_cancel

void dhcp6c_cancel(void *handle);

Cancels an ongoing DHCPv6 negotiation.

dhcp6c_close

void dhcp6c_close(void *handle);

Closes the DHCPv6 client session.

DHCP Server

Header file: #include <netutils/dhcpd.h>

dhcpd_run

int dhcpd_run(const char *interface);

Runs the DHCP server on the current thread (blocking, returns only on error).

dhcpd_start

int dhcpd_start(const char *interface);

Starts the DHCP server daemon as a background task.

Returns:

Returns 0 on success, or a negative error code on failure.

dhcpd_stop

int dhcpd_stop(void);

Stops the running DHCP server daemon.

dhcpd_set_startip

int dhcpd_set_startip(in_addr_t startip);

Configures the starting IP address of the DHCP server address pool.

Parameters:

• startip Starting IP address (network byte order).

Returns:

Always returns 0.

dhcpd_set_routerip

int dhcpd_set_routerip(in_addr_t routerip);

Configures the default gateway address distributed by the DHCP server to clients.

Parameters:

• routerip Default gateway IP (network byte order).

Returns:

Always returns 0.

dhcpd_set_netmask

int dhcpd_set_netmask(in_addr_t netmask);

Configures the subnet mask distributed by the DHCP server to clients.

Parameters:

• netmask Subnet mask (network byte order).

Returns:

Always returns 0.

dhcpd_set_dnsip

int dhcpd_set_dnsip(in_addr_t dnsip);

Configures the DNS server address distributed by the DHCP server to clients.

Parameters:

• dnsip DNS server IP (network byte order).

Returns:

Always returns 0.