libcoap/include/coap/coap_io.h

/*
 * coap_io.h -- Default network I/O functions for libcoap
 *
 * Copyright (C) 2012-2013 Olaf Bergmann <bergmann@tzi.org>
 *
 * This file is part of the CoAP library libcoap. Please see README for terms
 * of use.
 */

#ifndef _COAP_IO_H_
#define _COAP_IO_H_

#include <assert.h>
#include <sys/types.h>

#include "address.h"

#ifdef WITH_LWIP
# include <lwip/udp.h>
#endif

/**
 * Abstract handle that is used to identify a local network interface.
 */
typedef int coap_if_handle_t;

/** Invalid interface handle */
#define COAP_IF_INVALID -1

struct coap_packet_t;
typedef struct coap_packet_t coap_packet_t;

struct coap_context_t;

/**
 * Abstraction of virtual endpoint that can be attached to coap_context_t. The
 * tuple (handle, addr) must uniquely identify this endpoint.
 */
typedef struct coap_endpoint_t {
  struct coap_endpoint_t *next;
#if defined(WITH_POSIX) || defined(WITH_CONTIKI)
  union {
    int fd;       /**< on POSIX systems */
    void *conn;   /**< opaque connection (e.g. uip_conn in Contiki) */
  } handle;       /**< opaque handle to identify this endpoint */
#endif /* WITH_POSIX or WITH_CONTIKI */

#ifdef WITH_LWIP
  struct udp_pcb *pcb;
#endif /* WITH_LWIP */
  struct coap_context_t *context;

  coap_address_t addr; /**< local interface address */
  int ifindex;
  int flags;
} coap_endpoint_t;

#define COAP_ENDPOINT_NOSEC 0x00
#define COAP_ENDPOINT_DTLS  0x01

coap_endpoint_t *coap_new_endpoint(const coap_address_t *addr, int flags);

void coap_free_endpoint(coap_endpoint_t *ep);

/**
 * Function interface for data transmission. This function returns the number of
 * bytes that have been transmitted, or a value less than zero on error.
 *
 * @param context          The calling CoAP context.
 * @param local_interface  The local interface to send the data.
 * @param dst              The address of the receiver.
 * @param data             The data to send.
 * @param datalen          The actual length of @p data.
 *
 * @return                 The number of bytes written on success, or a value
 *                         less than zero on error.
 */
ssize_t coap_network_send(struct coap_context_t *context,
                          const coap_endpoint_t *local_interface,
                          const coap_address_t *dst,
                          unsigned char *data, size_t datalen);

/**
 * Function interface for reading data. This function returns the number of
 * bytes that have been read, or a value less than zero on error. In case of an
 * error, @p *packet is set to NULL.
 *
 * @param ep     The endpoint that is used for reading data from the network.
 * @param packet A result parameter where a pointer to the received packet
 *               structure is stored. The caller must call coap_free_packet to
 *               release the storage used by this packet.
 *
 * @return       The number of bytes received on success, or a value less than
 *               zero on error.
 */
ssize_t coap_network_read(coap_endpoint_t *ep, coap_packet_t **packet);

#ifndef coap_mcast_interface
# define coap_mcast_interface(Local) 0
#endif

/**
 * Releases the storage allocated for @p packet.
 */
void coap_free_packet(coap_packet_t *packet);

/**
 * Populate the coap_endpoint_t *target from the incoming packet's destination
 * data.
 *
 * This is usually used to copy a packet's data into a node's local_if member.
 */
void coap_packet_populate_endpoint(coap_packet_t *packet,
                                   coap_endpoint_t *target);

/**
 * Given an incoming packet, copy its source address into an address struct.
 */
void coap_packet_copy_source(coap_packet_t *packet, coap_address_t *target);

/**
 * Given a packet, set msg and msg_len to an address and length of the packet's
 * data in memory.
 * */
void coap_packet_get_memmapped(coap_packet_t *packet,
                               unsigned char **address,
                               size_t *length);

#ifdef WITH_LWIP
/**
 * Get the pbuf of a packet. The caller takes over responsibility for freeing
 * the pbuf.
 */
struct pbuf *coap_packet_extract_pbuf(coap_packet_t *packet);
#endif

#ifdef WITH_CONTIKI
/*
 * This is only included in coap_io.h instead of .c in order to be available for
 * sizeof in mem.c.
 */
struct coap_packet_t {
  coap_if_handle_t hnd;         /**< the interface handle */
  coap_address_t src;           /**< the packet's source address */
  coap_address_t dst;           /**< the packet's destination address */
  const coap_endpoint_t *interface;
  int ifindex;
  void *session;                /**< opaque session data */
  size_t length;                /**< length of payload */
  unsigned char payload[];      /**< payload */
};
#endif

#ifdef WITH_LWIP
/*
 * This is only included in coap_io.h instead of .c in order to be available for
 * sizeof in lwippools.h.
 * Simple carry-over of the incoming pbuf that is later turned into a node.
 *
 * Source address data is currently side-banded via ip_current_dest_addr & co
 * as the packets have limited lifetime anyway.
 */
struct coap_packet_t {
  struct pbuf *pbuf;
  const coap_endpoint_t *local_interface;
  uint16_t srcport;
};
#endif

#endif /* _COAP_IO_H_ */