lwIP 2.1.3 Lightweight IP stack

Functions
UDP
APIs » "raw" APIs

## Functions
err_t | udp_send (struct udp_pcb *pcb, struct pbuf *p)
err_t | udp_sendto (struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip, u16_t dst_port)
err_t | udp_sendto_if (struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif)
err_t | udp_sendto_if_src (struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif, const ip_addr_t *src_ip)
err_t | udp_bind (struct udp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port)
void | udp_bind_netif (struct udp_pcb *pcb, const struct netif *netif)
err_t | udp_connect (struct udp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port)
void | udp_disconnect (struct udp_pcb *pcb)
void | udp_recv (struct udp_pcb *pcb, udp_recv_fn recv, void *recv_arg)
void | udp_remove (struct udp_pcb *pcb)
struct udp_pcb * | udp_new (void)
struct udp_pcb * | udp_new_ip_type (u8_t type)

## Detailed Description

User Datagram Protocol module

See also
  APIs

## Function Documentation

## ◆ udp_bind()

err_t udp_bind | ( | struct udp_pcb * | pcb,
|  | const ip_addr_t * | ipaddr,
|  | u16_t | port
| ) |  |

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_ANY_TYPE 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 occurred.
  - ERR_USE. The specified ipaddr and port are already bound to by another UDP PCB.

See also
  udp_disconnect()

## ◆ udp_bind_netif()

void udp_bind_netif | ( | struct udp_pcb * | pcb,
|  | const struct netif * | netif
| ) |  |

Bind an UDP PCB to a specific netif. After calling this function, all packets received via this PCB are guaranteed to have come in via the specified netif, and all outgoing packets will go out via the specified netif.

Parameters

  pcb | UDP PCB to be bound.
  netif | netif to bind udp pcb to. Can be NULL.

See also
  udp_disconnect()

## ◆ udp_connect()

err_t udp_connect | ( | struct udp_pcb * | pcb,
|  | const ip_addr_t * | ipaddr,
|  | u16_t | port
| ) |  |

Sets the remote end of the pcb. This function does not generate any network traffic, but only sets the remote address of the pcb.

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()

## ◆ udp_disconnect()

void udp_disconnect | ( | struct udp_pcb * | pcb | ) |

Remove the remote end of the pcb. This function does not generate any network traffic, but only removes the remote address of the pcb.

Parameters

  pcb | the udp pcb to disconnect.

## ◆ udp_new()

struct udp_pcb* udp_new | ( | void |  | ) |

Creates a new UDP pcb which can be used for UDP communication. The pcb is not active until it has either been bound to a local address or connected to a remote address.

See also
  MEMP_NUM_UDP_PCB

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

See also
  udp_remove()

## ◆ udp_new_ip_type()

struct udp_pcb* udp_new_ip_type | ( | u8_t | type | ) |

Create a UDP PCB for specific IP type. The pcb is not active until it has either been bound to a local address or connected to a remote address.

See also
  MEMP_NUM_UDP_PCB

Parameters

  type | IP address type, see lwip_ip_addr_type definitions. If you want to listen to IPv4 and IPv6 (dual-stack) packets, supply IPADDR_TYPE_ANY as argument and bind to IP_ANY_TYPE.

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

See also
  udp_remove()

## ◆ udp_recv()

void udp_recv | ( | struct udp_pcb * | pcb,
|  | udp_recv_fn | recv,
|  | void * | recv_arg
| ) |  |

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 which to set the recv callback
  recv | function pointer of the callback function
  recv_arg | additional argument to pass to the callback function

## ◆ udp_remove()

void udp_remove | ( | struct udp_pcb * | pcb | ) |

Removes and deallocates the 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()

## ◆ udp_send()

err_t udp_send | ( | struct udp_pcb * | pcb,
|  | struct pbuf * | p
| ) |  |

Sends the pbuf p using UDP. The pbuf is not deallocated.

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 occurred.
  - ERR_MEM. Out of memory.
  - ERR_RTE. Could not find route to destination address.
  - ERR_VAL. No PCB or PCB is dual-stack
  - More errors could be returned by lower protocol layers.

See also
  udp_disconnect() udp_sendto()

## ◆ udp_sendto()

err_t udp_sendto | ( | struct udp_pcb * | pcb,
|  | struct pbuf * | p,
|  | const ip_addr_t * | dst_ip,
|  | u16_t | dst_port
| ) |  |

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()

## ◆ udp_sendto_if()

err_t udp_sendto_if | ( | struct udp_pcb * | pcb,
|  | struct pbuf * | p,
|  | const ip_addr_t * | dst_ip,
|  | u16_t | dst_port,
|  | struct netif * | netif
| ) |  |

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()

## ◆ udp_sendto_if_src()

err_t udp_sendto_if_src | ( | struct udp_pcb * | pcb,
|  | struct pbuf * | p,
|  | const ip_addr_t * | dst_ip,
|  | u16_t | dst_port,
|  | struct netif * | netif,
|  | const ip_addr_t * | src_ip
| ) |  |

Same as udp_sendto_if, but with source address