DHCPv4

Functions
void	dhcp_set_struct (struct netif *netif, struct dhcp *dhcp)
void	dhcp_cleanup (struct netif *netif)
err_t	dhcp_start (struct netif *netif)
void	dhcp_inform (struct netif *netif)
err_t	dhcp_renew (struct netif *netif)
err_t	dhcp_release (struct netif *netif)
void	dhcp_stop (struct netif *netif)

Detailed Description

DHCP (IPv4) related functions This is a DHCP client for the lwIP TCP/IP stack. It aims to conform with RFC 2131 and RFC 2132.

Options: DHCP_COARSE_TIMER_SECS (recommended 60 which is a minute) DHCP_FINE_TIMER_MSECS (recommended 500 which equals TCP coarse timer)

dhcp_start() starts a DHCP client instance which configures the interface by obtaining an IP address lease and maintaining it.

Use dhcp_release() to end the lease and use dhcp_stop() to remove the DHCP client.

See also

DHCPv4

Function Documentation

dhcp_cleanup()

void dhcp_cleanup

(

struct netif *

netif

)

Removes a struct dhcp from a netif.

ATTENTION: Only use this when not using dhcp_set_struct() to allocate the struct dhcp since the memory is passed back to the heap.

Parameters

netif

the netif from which to remove the struct dhcp

dhcp_inform()

void dhcp_inform

(

struct netif *

netif

)

Inform a DHCP server of our manual configuration.

This informs DHCP servers of our fixed IP address configuration by sending an INFORM message. It does not involve DHCP address configuration, it is just here to be nice to the network.

Parameters

netif

The lwIP network interface

dhcp_release()

err_t dhcp_release

(

struct netif *

netif

)

Release a DHCP lease (usually called before dhcp_stop).

Parameters

netif

network interface which must release its lease

dhcp_renew()

err_t dhcp_renew

(

struct netif *

netif

)

Renew an existing DHCP lease at the involved DHCP server.

Parameters

netif

network interface which must renew its lease

dhcp_set_struct()

void dhcp_set_struct	(	struct netif *	netif,
		struct dhcp *	dhcp
	)

Set a statically allocated struct dhcp to work with. Using this prevents dhcp_start to allocate it using mem_malloc.

Parameters

netif	the netif for which to set the struct dhcp
dhcp	(uninitialised) dhcp struct allocated by the application

dhcp_start()

err_t dhcp_start

(

struct netif *

netif

)

Start DHCP negotiation for a network interface.

If no DHCP client instance was attached to this interface, a new client is created first. If a DHCP client instance was already present, it restarts negotiation.

Parameters

netif

The lwIP network interface

Returns

lwIP error code

• ERR_OK - No error
• ERR_MEM - Out of memory

dhcp_stop()

void dhcp_stop

(

struct netif *

netif

)

Remove the DHCP client from the interface.

Parameters

netif

The network interface to stop DHCP on