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DHCPv4
Functions

DHCPv4
[IPv4]

DHCP (IPv4) related functions This is a DHCP client for the lwIP TCP/IP stack. More...

Functions

void dhcp_set_struct (struct netif *netif, struct dhcp *dhcp)
 Set a statically allocated struct dhcp to work with.
void dhcp_cleanup (struct netif *netif)
 Removes a struct dhcp from a netif.
err_t dhcp_start (struct netif *netif)
 Start DHCP negotiation for a network interface.
void dhcp_inform (struct netif *netif)
 Inform a DHCP server of our manual configuration.
err_t dhcp_renew (struct netif *netif)
 Renew an existing DHCP lease at the involved DHCP server.
err_t dhcp_release (struct netif *netif)
 Release a DHCP lease (usually called before dhcp_stop).
void dhcp_stop (struct netif *netif)
 Remove the DHCP client from the interface.

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

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:
netifthe netif from which to remove the struct dhcp

Definition at line 697 of file lwip_dhcp.c.

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:
netifThe lwIP network interface

Definition at line 802 of file lwip_dhcp.c.

err_t dhcp_release ( struct netif *  netif )

Release a DHCP lease (usually called before dhcp_stop).

Parameters:
netifnetwork interface which must release its lease

Definition at line 1280 of file lwip_dhcp.c.

err_t dhcp_renew ( struct netif *  netif )

Renew an existing DHCP lease at the involved DHCP server.

Parameters:
netifnetwork interface which must renew its lease

Definition at line 1127 of file lwip_dhcp.c.

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

Definition at line 676 of file lwip_dhcp.c.

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:
netifThe lwIP network interface
Returns:
lwIP error code
  • ERR_OK - No error
  • ERR_MEM - Out of memory

Definition at line 721 of file lwip_dhcp.c.

void dhcp_stop ( struct netif *  netif )

Remove the DHCP client from the interface.

Parameters:
netifThe network interface to stop DHCP on

Definition at line 1343 of file lwip_dhcp.c.

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