udp.c File Reference

Process an incoming UDP datagram.

Given an incoming UDP datagram (as a chain of pbufs) this function finds a corresponding UDP PCB and hands over the pbuf to the pcbs recv function. If no pcb is found or the datagram is incorrect, the pbuf is freed.

Parameters:

p	pbuf to be demultiplexed to a UDP PCB.
inp	network interface on which the datagram was received.

Send data using UDP.

Parameters:

pcb	UDP PCB used to send the data.
p	chain of pbuf's to be sent.

The datagram will be sent to the current remote_ip & remote_port stored in pcb. If the pcb is not bound to a port, it will automatically be bound to a random port.

Returns:

lwIP error code.

• ERR_OK. Successful. No error occured.
• ERR_MEM. Out of memory.
• ERR_RTE. Could not find route to destination address.
• More errors could be returned by lower protocol layers.

See also:

udp_disconnect() udp_sendto()

Same as udp_send() but with checksum

Send data to a specified address using UDP.

Parameters:

pcb	UDP PCB used to send the data.
p	chain of pbuf's to be sent.
dst_ip	Destination IP address.
dst_port	Destination UDP port.

dst_ip & dst_port are expected to be in the same byte order as in the pcb.

If the PCB already has a remote address association, it will be restored after the data is sent.

Returns:

lwIP error code (

See also:

udp_send for possible error codes)

udp_disconnect() udp_send()

Same as udp_sendto(), but with checksum

Send data to a specified address using UDP. The netif used for sending can be specified.

This function exists mainly for DHCP, to be able to send UDP packets on a netif that is still down.

Parameters:

pcb	UDP PCB used to send the data.
p	chain of pbuf's to be sent.
dst_ip	Destination IP address.
dst_port	Destination UDP port.
netif	the netif used for sending.

dst_ip & dst_port are expected to be in the same byte order as in the pcb.

Returns:

lwIP error code (

See also:

udp_send for possible error codes)

udp_disconnect() udp_send()

Same as udp_sendto_if(), but with checksum

Bind an UDP PCB.

Parameters:

pcb	UDP PCB to be bound with a local address ipaddr and port.
ipaddr	local IP address to bind with. Use IP_ADDR_ANY to bind to all local interfaces.
port	local UDP port to bind with. Use 0 to automatically bind to a random port between UDP_LOCAL_PORT_RANGE_START and UDP_LOCAL_PORT_RANGE_END.

ipaddr & port are expected to be in the same byte order as in the pcb.

Returns:

lwIP error code.

• ERR_OK. Successful. No error occured.
• ERR_USE. The specified ipaddr and port are already bound to by another UDP PCB.

See also:

udp_disconnect()

Connect an UDP PCB.

This will associate the UDP PCB with the remote address.

Parameters:

pcb	UDP PCB to be connected with remote address ipaddr and port.
ipaddr	remote IP address to connect with.
port	remote UDP port to connect with.

Returns:

lwIP error code

ipaddr & port are expected to be in the same byte order as in the pcb.

The udp pcb is bound to a random local port if not already bound.

See also:

udp_disconnect()

TODO: this functionality belongs in upper layers

TODO: this will bind the udp pcb locally, to the interface which is used to route output packets to the remote address. However, we might want to accept incoming packets on any interface!

Disconnect a UDP PCB

Parameters:

pcb	the udp pcb to disconnect.

Set a receive callback for a UDP PCB

This callback will be called when receiving a datagram for the pcb.

Parameters:

pcb	the pcb for wich to set the recv callback
recv	function pointer of the callback function
recv_arg	additional argument to pass to the callback function

Remove an UDP PCB.

Parameters:

pcb	UDP PCB to be removed. The PCB is removed from the list of UDP PCB's and the data structure is freed from memory.

See also:

udp_new()

Create a UDP PCB.

Returns:

The UDP PCB which was created. NULL if the PCB data structure could not be allocated.

See also:

udp_remove()

Print UDP header information for debug purposes.

Parameters:

udphdr

pointer to the udp header in memory.

Definition at line 84 of file udp.c.