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A version of LWIP, provided for backwards compatibility.

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dhcp.c File Reference
Functions

dhcp.c File Reference

Dynamic Host Configuration Protocol client. More...

Go to the source code of this file.

Functions

static void dhcp_handle_ack (struct netif *netif)
 Handle a DHCP ACK packet.
static void dhcp_handle_nak (struct netif *netif)
 Back-off the DHCP client (because of a received NAK response).
static void dhcp_handle_offer (struct netif *netif)
 Remember the configuration offered by a DHCP server.
static err_t dhcp_discover (struct netif *netif)
 Start the DHCP process, discover a DHCP server.
static err_t dhcp_select (struct netif *netif)
 Select a DHCP server offer out of all offers.
static void dhcp_check (struct netif *netif)
 Checks if the offered IP address is already in use.
static void dhcp_bind (struct netif *netif)
 Bind the interface to the offered IP address.
static err_t dhcp_decline (struct netif *netif)
 Decline an offered lease.
static err_t dhcp_rebind (struct netif *netif)
 Rebind with a DHCP server for an existing DHCP lease.
static void dhcp_recv (void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16_t port)
 If an incoming DHCP message is in response to us, then trigger the state machine.
static err_t dhcp_unfold_reply (struct dhcp *dhcp)
 Extract the DHCP message and the DHCP options.
static u8_t * dhcp_get_option_ptr (struct dhcp *dhcp, u8_t option_type)
 Find the offset of a DHCP option inside the DHCP message.
static u8_t dhcp_get_option_byte (u8_t *ptr)
 Return the byte of DHCP option data.
static u16_t dhcp_get_option_short (u8_t *ptr)
 Return the 16-bit value of DHCP option data.
static u32_t dhcp_get_option_long (u8_t *ptr)
 Return the 32-bit value of DHCP option data.
static void dhcp_free_reply (struct dhcp *dhcp)
 Free the incoming DHCP message including contiguous copy of its DHCP options.
static void dhcp_timeout (struct netif *netif)
 A DHCP negotiation transaction, or ARP request, has timed out.
static void dhcp_t1_timeout (struct netif *netif)
 The renewal period has timed out.
static void dhcp_t2_timeout (struct netif *netif)
 The rebind period has timed out.
static err_t dhcp_create_request (struct netif *netif)
 Create a DHCP request, fill in common headers.
static void dhcp_delete_request (struct netif *netif)
 Free previously allocated memory used to send a DHCP request.
static void dhcp_option_trailer (struct dhcp *dhcp)
 Add a DHCP message trailer.
void dhcp_coarse_tmr ()
 The DHCP timer that checks for lease renewal/rebind timeouts.
void dhcp_fine_tmr ()
 DHCP transaction timeout handling.
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.
void dhcp_arp_reply (struct netif *netif, struct ip_addr *addr)
 Match an ARP reply with the offered IP address.
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.
void dhcp_stop (struct netif *netif)
 Remove the DHCP client from the interface.

Detailed Description

Dynamic Host Configuration Protocol client.

Definition in file tag/7/Core/lwIP/core/dhcp.c.

Function Documentation

void dhcp_arp_reply ( struct netif *  netif,
struct ip_addr *  addr 
)

Match an ARP reply with the offered IP address.

if enabled, check whether the offered IP address is not in use, using ARP

Parameters:
netifthe network interface on which the reply was received
addrThe IP address we received a reply from

Definition at line 709 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_bind ( struct netif *  netif ) [static]

Bind the interface to the offered IP address.

Parameters:
netifnetwork interface to bind to the offered address

Definition at line 839 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_check ( struct netif *  netif ) [static]

Checks if the offered IP address is already in use.

It does so by sending an ARP request for the offered address and entering CHECKING state. If no ARP reply is received within a small interval, the address is assumed to be free for use by us.

Parameters:
netifthe netif under DHCP control

Definition at line 188 of file tag/7/Core/lwIP/core/dhcp.c.

void dhcp_coarse_tmr ( void   )

The DHCP timer that checks for lease renewal/rebind timeouts.

to be called every minute

Definition at line 312 of file tag/7/Core/lwIP/core/dhcp.c.

static err_t dhcp_create_request ( struct netif *  netif ) [static]

Create a DHCP request, fill in common headers.

Parameters:
netifthe netif under DHCP control

default global transaction identifier starting value (easy to match with a packet analyser). We simply increment for each new request. Predefine DHCP_GLOBAL_XID to a better value or a function call to generate one at runtime, any supporting function prototypes can be defined in DHCP_GLOBAL_XID_HEADER

Definition at line 1362 of file tag/7/Core/lwIP/core/dhcp.c.

static err_t dhcp_decline ( struct netif *  netif ) [static]

Decline an offered lease.

Tell the DHCP server we do not accept the offered address. One reason to decline the lease is when we find out the address is already in use by another host (through ARP).

Parameters:
netifthe netif under DHCP control

Definition at line 736 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_delete_request ( struct netif *  netif ) [static]

Free previously allocated memory used to send a DHCP request.

Parameters:
netifthe netif under DHCP control

Definition at line 1437 of file tag/7/Core/lwIP/core/dhcp.c.

static err_t dhcp_discover ( struct netif *  netif ) [static]

Start the DHCP process, discover a DHCP server.

Parameters:
netifthe netif under DHCP control

Definition at line 780 of file tag/7/Core/lwIP/core/dhcp.c.

void dhcp_fine_tmr ( void   )

DHCP transaction timeout handling.

to be called every half second

A DHCP server is expected to respond within a short period of time. This timer checks whether an outstanding DHCP request is timed out.

Definition at line 345 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_free_reply ( struct dhcp *  dhcp ) [static]

Free the incoming DHCP message including contiguous copy of its DHCP options.

Definition at line 1244 of file tag/7/Core/lwIP/core/dhcp.c.

static u8_t dhcp_get_option_byte ( u8_t *  ptr ) [static]

Return the byte of DHCP option data.

Parameters:
clientDHCP client.
ptrpointer obtained by dhcp_get_option_ptr().
Returns:
byte value at the given address.

Definition at line 1563 of file tag/7/Core/lwIP/core/dhcp.c.

static u32_t dhcp_get_option_long ( u8_t *  ptr ) [static]

Return the 32-bit value of DHCP option data.

Parameters:
clientDHCP client.
ptrpointer obtained by dhcp_get_option_ptr().
Returns:
byte value at the given address.

Definition at line 1597 of file tag/7/Core/lwIP/core/dhcp.c.

static u8_t * dhcp_get_option_ptr ( struct dhcp *  dhcp,
u8_t  option_type 
) [static]

Find the offset of a DHCP option inside the DHCP message.

Parameters:
dhcpDHCP client
option_type
Returns:
a byte offset into the UDP message where the option was found, or zero if the given option was not found.

Definition at line 1485 of file tag/7/Core/lwIP/core/dhcp.c.

static u16_t dhcp_get_option_short ( u8_t *  ptr ) [static]

Return the 16-bit value of DHCP option data.

Parameters:
clientDHCP client.
ptrpointer obtained by dhcp_get_option_ptr().
Returns:
byte value at the given address.

Definition at line 1579 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_handle_ack ( struct netif *  netif ) [static]

Handle a DHCP ACK packet.

Parameters:
netifthe netif under DHCP control

Patch #1308 TODO: we must check if the file field is not overloaded by DHCP options!

Definition at line 468 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_handle_nak ( struct netif *  netif ) [static]

Back-off the DHCP client (because of a received NAK response).

Back-off the DHCP client because of a received NAK. Receiving a NAK means the client asked for something non-sensible, for example when it tries to renew a lease obtained on another network.

We clear any existing set IP address and restart DHCP negotiation afresh (as per RFC2131 3.2.3).

Parameters:
netifthe netif under DHCP control

Definition at line 161 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_handle_offer ( struct netif *  netif ) [static]

Remember the configuration offered by a DHCP server.

Parameters:
netifthe netif under DHCP control

Definition at line 214 of file tag/7/Core/lwIP/core/dhcp.c.

void dhcp_inform ( struct netif *  netif )

Inform a DHCP server of our manual configuration.

inform server of our manual IP address

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 650 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_option_trailer ( struct dhcp *  dhcp ) [static]

Add a DHCP message trailer.

Adds the END option to the DHCP message, and if necessary, up to three padding bytes.

Parameters:
dhcpDHCP state structure

Definition at line 1461 of file tag/7/Core/lwIP/core/dhcp.c.

static err_t dhcp_rebind ( struct netif *  netif ) [static]

Rebind with a DHCP server for an existing DHCP lease.

Parameters:
netifnetwork interface which must rebind with a DHCP server

Definition at line 987 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_recv ( void *  arg,
struct udp_pcb *  pcb,
struct pbuf *  p,
struct ip_addr *  addr,
u16_t  port 
) [static]

If an incoming DHCP message is in response to us, then trigger the state machine.

Definition at line 1262 of file tag/7/Core/lwIP/core/dhcp.c.

err_t dhcp_release ( struct netif *  netif )

Release a DHCP lease.

release the DHCP lease, usually called before dhcp_stop()

Parameters:
netifnetwork interface which must release its lease

Definition at line 1051 of file tag/7/Core/lwIP/core/dhcp.c.

err_t dhcp_renew ( struct netif *  netif )

Renew an existing DHCP lease at the involved DHCP server.

enforce early lease renewal (not needed normally)

Parameters:
netifnetwork interface which must renew its lease

Definition at line 920 of file tag/7/Core/lwIP/core/dhcp.c.

static err_t dhcp_select ( struct netif *  netif ) [static]

Select a DHCP server offer out of all offers.

Simply select the first offer received.

Parameters:
netifthe netif under DHCP control
Returns:
lwIP specific error (see error.h)

Definition at line 241 of file tag/7/Core/lwIP/core/dhcp.c.

err_t dhcp_start ( struct netif *  netif )

Start DHCP negotiation for a network interface.

start DHCP configuration

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 572 of file tag/7/Core/lwIP/core/dhcp.c.

void dhcp_stop ( struct netif *  netif )

Remove the DHCP client from the interface.

stop DHCP configuration

Parameters:
netifThe network interface to stop DHCP on

Definition at line 1105 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_t1_timeout ( struct netif *  netif ) [static]

The renewal period has timed out.

Parameters:
netifthe netif under DHCP control

Definition at line 433 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_t2_timeout ( struct netif *  netif ) [static]

The rebind period has timed out.

Parameters:
netifthe netif under DHCP control

Definition at line 451 of file tag/7/Core/lwIP/core/dhcp.c.

static void dhcp_timeout ( struct netif *  netif ) [static]

A DHCP negotiation transaction, or ARP request, has timed out.

The timer that was started with the DHCP or ARP request has timed out, indicating no response was received in time.

Parameters:
netifthe netif under DHCP control

Definition at line 378 of file tag/7/Core/lwIP/core/dhcp.c.

static err_t dhcp_unfold_reply ( struct dhcp *  dhcp ) [static]

Extract the DHCP message and the DHCP options.

Extract the DHCP message and the DHCP options, each into a contiguous piece of memory. As a DHCP message is variable sized by its options, and also allows overriding some fields for options, the easy approach is to first unfold the options into a conitguous piece of memory, and use that further on.

copy the DHCP message without options

copy the DHCP options

Definition at line 1198 of file tag/7/Core/lwIP/core/dhcp.c.

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