text: /**
   * @file
   * UDP API (to be used from TCPIP thread)<br>
   * See also @ref udp_raw
   */
  
  /*
   * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
   * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
   * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Adam Dunkels <adam@sics.se>
   *
   */
  #ifndef LWIP_HDR_UDP_H
  #define LWIP_HDR_UDP_H
  
  #include "lwip/opt.h"
  
  #if LWIP_UDP /* don't build if not configured for use in lwipopts.h */
  
  #include "lwip/pbuf.h"
  #include "lwip/netif.h"
  #include "lwip/ip_addr.h"
  #include "lwip/ip.h"
  #include "lwip/ip6_addr.h"
  #include "lwip/prot/udp.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #define UDP_FLAGS_NOCHKSUM       0x01U
  #define UDP_FLAGS_UDPLITE        0x02U
  #define UDP_FLAGS_CONNECTED      0x04U
  #define UDP_FLAGS_MULTICAST_LOOP 0x08U
  
  struct udp_pcb;
  
  /** Function prototype for udp pcb receive callback functions
   * addr and port are in same byte order as in the pcb
   * The callback is responsible for freeing the pbuf
   * if it's not used any more.
   *
   * ATTENTION: Be aware that 'addr' might point into the pbuf 'p' so freeing this pbuf
   *            can make 'addr' invalid, too.
   *
   * @param arg user supplied argument (udp_pcb.recv_arg)
   * @param pcb the udp_pcb which received data
   * @param p the packet buffer that was received
   * @param addr the remote IP address from which the packet was received
   * @param port the remote port from which the packet was received
   */
  #if TUN2SOCKS
  typedef void (*udp_recv_fn)(void *arg, struct udp_pcb *pcb, struct pbuf *p,
      const ip_addr_t *addr, u16_t port, const ip_addr_t *dest_addr, u16_t dest_port);
  #else
  typedef void (*udp_recv_fn)(void *arg, struct udp_pcb *pcb, struct pbuf *p,
      const ip_addr_t *addr, u16_t port);
  #endif /* TUN2SOCKS */
  
  /** the UDP protocol control block */
  struct udp_pcb {
  /** Common members of all PCB types */
    IP_PCB;
  
  /* Protocol specific PCB members */
  
    struct udp_pcb *next;
  
    u8_t flags;
    /** ports are in host byte order */
    u16_t local_port, remote_port;
  
  #if LWIP_MULTICAST_TX_OPTIONS
  #if LWIP_IPV4
    /** outgoing network interface for multicast packets, by IPv4 address (if not 'any') */
    ip4_addr_t mcast_ip4;
  #endif /* LWIP_IPV4 */
    /** outgoing network interface for multicast packets, by interface index (if nonzero) */
    u8_t mcast_ifindex;
    /** TTL for outgoing multicast packets */
    u8_t mcast_ttl;
  #endif /* LWIP_MULTICAST_TX_OPTIONS */
  
  #if LWIP_UDPLITE
    /** used for UDP_LITE only */
    u16_t chksum_len_rx, chksum_len_tx;
  #endif /* LWIP_UDPLITE */
  
    /** receive callback function */
    udp_recv_fn recv;
    /** user-supplied argument for the recv callback */
    void *recv_arg;
  };
  /* udp_pcbs export for external reference (e.g. SNMP agent) */
  extern struct udp_pcb *udp_pcbs;
  
  /* The following functions is the application layer interface to the
     UDP code. */
  struct udp_pcb * udp_new        (void);
  struct udp_pcb * udp_new_ip_type(u8_t type);
  void             udp_remove     (struct udp_pcb *pcb);
  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);
  #if TUN2SOCKS
  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,
                                   const ip_addr_t *src_ip, u16_t src_port);
  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, u16_t src_port);
  err_t            udp_sendto     (struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port,
                                   const ip_addr_t *src_ip, u16_t src_port);
  #else
  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_sendto     (struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port);
  #endif /* TUN2SOCKS */
  err_t            udp_send       (struct udp_pcb *pcb, struct pbuf *p);
  
  #if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
  #if TUN2SOCKS
  err_t            udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port,
                                   struct netif *netif, u8_t have_chksum,
                                   u16_t chksum,
                                   const ip_addr_t *src_ip, u16_t src_port);
  err_t            udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port,
                                   u8_t have_chksum, u16_t chksum,
                                   const ip_addr_t *src_ip, u16_t src_port);
  #else
  err_t            udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port,
                                   struct netif *netif, u8_t have_chksum,
                                   u16_t chksum);
  err_t            udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port,
                                   u8_t have_chksum, u16_t chksum);
  #endif /* TUN2SOCKS */
  err_t            udp_send_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   u8_t have_chksum, u16_t chksum);
  #if TUN2SOCKS
  err_t            udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif,
                                   u8_t have_chksum, u16_t chksum, const ip_addr_t *src_ip, u16_t src_port);
  #else
  err_t            udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                   const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif,
                                   u8_t have_chksum, u16_t chksum, const ip_addr_t *src_ip);
  #endif /* TUN2SOCKS */
  #endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
  
  #define          udp_flags(pcb) ((pcb)->flags)
  #define          udp_setflags(pcb, f)  ((pcb)->flags = (f))
  
  #define          udp_set_flags(pcb, set_flags)     do { (pcb)->flags = (u8_t)((pcb)->flags |  (set_flags)); } while(0)
  #define          udp_clear_flags(pcb, clr_flags)   do { (pcb)->flags = (u8_t)((pcb)->flags & (u8_t)(~(clr_flags) & 0xff)); } while(0)
  #define          udp_is_flag_set(pcb, flag)        (((pcb)->flags & (flag)) != 0)
  
  /* The following functions are the lower layer interface to UDP. */
  void             udp_input      (struct pbuf *p, struct netif *inp);
  
  void             udp_init       (void);
  
  /* for compatibility with older implementation */
  #define udp_new_ip6() udp_new_ip_type(IPADDR_TYPE_V6)
  
  #if LWIP_MULTICAST_TX_OPTIONS
  #if LWIP_IPV4
  #define udp_set_multicast_netif_addr(pcb, ip4addr) ip4_addr_copy((pcb)->mcast_ip4, *(ip4addr))
  #define udp_get_multicast_netif_addr(pcb)          (&(pcb)->mcast_ip4)
  #endif /* LWIP_IPV4 */
  #define udp_set_multicast_netif_index(pcb, idx)    ((pcb)->mcast_ifindex = (idx))
  #define udp_get_multicast_netif_index(pcb)         ((pcb)->mcast_ifindex)
  #define udp_set_multicast_ttl(pcb, value)          ((pcb)->mcast_ttl = (value))
  #define udp_get_multicast_ttl(pcb)                 ((pcb)->mcast_ttl)
  #endif /* LWIP_MULTICAST_TX_OPTIONS */
  
  #if UDP_DEBUG
  void udp_debug_print(struct udp_hdr *udphdr);
  #else
  #define udp_debug_print(udphdr)
  #endif
  
  void udp_netif_ip_addr_changed(const ip_addr_t* old_addr, const ip_addr_t* new_addr);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* LWIP_UDP */
  
  #endif /* LWIP_HDR_UDP_H */
  