/****************************************************************************
 * net/utils/utils.h
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

#ifndef __NET_UTILS_UTILS_H
#define __NET_UTILS_UTILS_H

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <nuttx/net/net.h>
#include <nuttx/net/ip.h>
#include <nuttx/net/netdev.h>

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* Some utils for port selection */

#define NET_PORT_RANDOM_INIT(port) \
  do \
    { \
      net_getrandom(&(port), sizeof(port)); \
      (port) = (port) % (CONFIG_NET_DEFAULT_MAX_PORT - \
                         CONFIG_NET_DEFAULT_MIN_PORT + 1); \
      (port) += CONFIG_NET_DEFAULT_MIN_PORT; \
    } while (0)

/* Get next net port number, and make sure that the port number is within
 * range.  In host byte order.
 */

#define NET_PORT_NEXT_H(hport) \
  do \
    { \
      ++(hport); \
      if ((hport) > CONFIG_NET_DEFAULT_MAX_PORT || \
          (hport) < CONFIG_NET_DEFAULT_MIN_PORT) \
        { \
          (hport) = CONFIG_NET_DEFAULT_MIN_PORT; \
        } \
    } while (0)

/* Get next net port number, and make sure that the port number is within
 * range.  In both network & host byte order.
 */

#define NET_PORT_NEXT_NH(nport, hport) \
  do \
    { \
      NET_PORT_NEXT_H(hport); \
      (nport) = HTONS(hport); \
    } while (0)

/****************************************************************************
 * Public Types
 ****************************************************************************/

/* These values control the behavior of net_timeval2desc */

enum tv2ds_remainder_e
{
  TV2DS_TRUNC = 0, /* Truncate microsecond remainder */
  TV2DS_ROUND,     /* Round to the nearest full decisecond */
  TV2DS_CEIL       /* Force to next larger full decisecond */
};

/****************************************************************************
 * Public Data
 ****************************************************************************/

#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

struct net_driver_s;      /* Forward reference */
struct timeval;           /* Forward reference */

/****************************************************************************
 * Name: net_breaklock
 *
 * Description:
 *   Break the lock, return information needed to restore re-entrant lock
 *   state.
 *
 ****************************************************************************/

int net_breaklock(FAR unsigned int *count);

/****************************************************************************
 * Name: net_restorelock
 *
 * Description:
 *   Restore the locked state
 *
 * Returned Value:
 *   Zero (OK) is returned on success; a negated errno value is returned on
 *   failured (probably -ECANCELED).
 *
 ****************************************************************************/

int net_restorelock(unsigned int count);

/****************************************************************************
 * Name: net_dsec2timeval
 *
 * Description:
 *   Convert a decisecond value to a struct timeval.  Needed by getsockopt()
 *   to report timeout values.
 *
 * Input Parameters:
 *   dsec The decisecond value to convert
 *   tv   The struct timeval to receive the converted value
 *
 * Returned Value:
 *   None
 *
 * Assumptions:
 *
 ****************************************************************************/

void net_dsec2timeval(uint16_t dsec, FAR struct timeval *tv);

/****************************************************************************
 * Name: net_dsec2tick
 *
 * Description:
 *   Convert a decisecond value to a system clock ticks.  Used by IGMP logic.
 *
 * Input Parameters:
 *   dsec The decisecond value to convert
 *
 * Returned Value:
 *   The decisecond value expressed as system clock ticks
 *
 ****************************************************************************/

unsigned int net_dsec2tick(int dsec);

/****************************************************************************
 * Name: net_timeval2dsec
 *
 * Description:
 *   Convert a struct timeval to deciseconds.  Needed by setsockopt() to
 *   save new timeout values.
 *
 * Input Parameters:
 *   tv        - The struct timeval to convert
 *   remainder - Determines how to handler the microsecond remainder
 *
 * Returned Value:
 *   The converted value
 *
 * Assumptions:
 *
 ****************************************************************************/

unsigned int net_timeval2dsec(FAR struct timeval *tv,
                              enum tv2ds_remainder_e remainder);

/****************************************************************************
 * Name: net_getrandom
 *
 * Description:
 *   Fill a buffer of arbitrary length with randomness. This function is
 *   guaranteed to be success.
 *
 * Input Parameters:
 *   bytes  - Buffer for returned random bytes
 *   nbytes - Number of bytes requested.
 *
 ****************************************************************************/

void net_getrandom(FAR void *bytes, size_t nbytes);

/****************************************************************************
 * Name: net_ipv4_mask2pref
 *
 * Description:
 *   Convert a 32-bit netmask to a prefix length.  The NuttX IPv4
 *   networking uses 32-bit network masks internally.  This function
 *   converts the IPv4 netmask to a prefix length.
 *
 *   The prefix length is the number of MS '1' bits on in the netmask.
 *   This, of course, assumes that all MS bits are '1' and all LS bits are
 *   '0' with no intermixed 1's and 0's.  This function searches from the MS
 *   bit until the first '0' is found (this does not necessary mean that
 *   there might not be additional '1' bits following the firs '0', but that
 *   will be a malformed netmask.
 *
 * Input Parameters:
 *   mask   An IPv4 netmask in the form of in_addr_t
 *
 * Returned Value:
 *   The prefix length, range 0-32 on success;  This function will not
 *   fail.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_IPv4
uint8_t net_ipv4_mask2pref(in_addr_t mask);
#endif

/****************************************************************************
 * Name: net_ipv6_common_pref
 *
 * Description:
 *   Calculate the common prefix length of two IPv6 addresses.
 *
 * Input Parameters:
 *   a1,a2   Points to IPv6 addresses in the form of uint16_t[8]
 *
 * Returned Value:
 *   The common prefix length, range 0-128 on success;  This function will
 *   not fail.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_IPv6
uint8_t net_ipv6_common_pref(FAR const uint16_t *a1, FAR const uint16_t *a2);
#endif

/****************************************************************************
 * Name: net_ipv6_mask2pref
 *
 * Description:
 *   Convert a 128-bit netmask to a prefix length.  The NuttX IPv6
 *   networking uses 128-bit network masks internally.  This function
 *   converts the IPv6 netmask to a prefix length.
 *
 *   The prefix length is the number of MS '1' bits on in the netmask.
 *   This, of course, assumes that all MS bits are '1' and all LS bits are
 *   '0' with no intermixed 1's and 0's.  This function searches from the MS
 *   bit until the first '0' is found (this does not necessary mean that
 *   there might not be additional '1' bits following the firs '0', but that
 *   will be a malformed netmask.
 *
 * Input Parameters:
 *   mask   Points to an IPv6 netmask in the form of uint16_t[8]
 *
 * Returned Value:
 *   The prefix length, range 0-128 on success;  This function will not
 *   fail.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_IPv6
uint8_t net_ipv6_mask2pref(FAR const uint16_t *mask);
#endif

/****************************************************************************
 * Name: net_ipv6_pref2mask
 *
 * Description:
 *   Convert a IPv6 prefix length to a network mask.  The prefix length
 *   specifies the number of MS bits under mask (0-128)
 *
 * Input Parameters:
 *   mask     - The location to return the netmask.
 *   preflen  - Determines the width of the netmask (in bits).  Range 0-128
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

#ifdef CONFIG_NET_IPv6
void net_ipv6_pref2mask(net_ipv6addr_t mask, uint8_t preflen);
#endif

/****************************************************************************
 * Name: net_ipv6_payload
 *
 * Description:
 *   Given a pointer to the IPv6 header, this function will return a pointer
 *   to the beginning of the L4 payload.
 *
 * Input Parameters:
 *   ipv6  - A pointer to the IPv6 header.
 *   proto - The location to return the protocol number in the IPv6 header.
 *
 * Returned Value:
 *   A pointer to the beginning of the payload.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_IPv6
FAR void *net_ipv6_payload(FAR struct ipv6_hdr_s *ipv6, FAR uint8_t *proto);
#endif

/****************************************************************************
 * Name: net_iob_concat
 *
 * Description:
 *   Concatenate iob_s chain iob2 to iob1, if CONFIG_NET_RECV_PACK is
 *   endabled, pack all data in the I/O buffer chain.
 *
 * Returned Value:
 *   The number of bytes actually buffered is returned.  This will be either
 *   zero or equal to iob1->io_pktlen.
 *
 ****************************************************************************/

#ifdef CONFIG_MM_IOB
uint16_t net_iob_concat(FAR struct iob_s **iob1, FAR struct iob_s **iob2);
#endif

/****************************************************************************
 * Name: net_chksum_adjust
 *
 * Description:
 *   Adjusts the checksum of a packet without having to completely
 *   recalculate it, as described in RFC 3022, Section 4.2, Page 9.
 *
 * Input Parameters:
 *   chksum - points to the chksum in the packet
 *   optr   - points to the old data in the packet
 *   olen   - length of old data
 *   nptr   - points to the new data in the packet
 *   nlen   - length of new data
 *
 * Limitations:
 *   The algorithm is applicable only for even offsets and even lengths.
 *
 ****************************************************************************/

void net_chksum_adjust(FAR uint16_t *chksum,
                       FAR const uint16_t *optr, ssize_t olen,
                       FAR const uint16_t *nptr, ssize_t nlen);

/****************************************************************************
 * Name: tcp_chksum, tcp_ipv4_chksum, and tcp_ipv6_chksum
 *
 * Description:
 *   Calculate the TCP checksum of the packet in d_buf and d_appdata.
 *
 *   The TCP checksum is the Internet checksum of data contents of the
 *   TCP segment, and a pseudo-header as defined in RFC793.
 *
 *   Note: The d_appdata pointer that points to the packet data may
 *   point anywhere in memory, so it is not possible to simply calculate
 *   the Internet checksum of the contents of the d_buf buffer.
 *
 * Returned Value:
 *   The TCP checksum of the TCP segment in d_buf and pointed to by
 *   d_appdata.
 *
 ****************************************************************************/

#ifdef CONFIG_NET_IPv4
uint16_t tcp_ipv4_chksum(FAR struct net_driver_s *dev);
#endif

#ifdef CONFIG_NET_IPv6
uint16_t tcp_ipv6_chksum(FAR struct net_driver_s *dev);
#endif

#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
uint16_t tcp_chksum(FAR struct net_driver_s *dev);
#elif defined(CONFIG_NET_IPv4)
#  define tcp_chksum(d) tcp_ipv4_chksum(d)
#else /* if defined(CONFIG_NET_IPv6) */
#  define tcp_chksum(d) tcp_ipv6_chksum(d)
#endif

/****************************************************************************
 * Name: udp_ipv4_chksum
 *
 * Description:
 *   Calculate the UDP/IPv4 checksum of the packet in d_buf and d_appdata.
 *
 ****************************************************************************/

#if defined(CONFIG_NET_UDP_CHECKSUMS) && defined(CONFIG_NET_IPv4)
uint16_t udp_ipv4_chksum(FAR struct net_driver_s *dev);
#endif

/****************************************************************************
 * Name: udp_ipv6_chksum
 *
 * Description:
 *   Calculate the UDP/IPv6 checksum of the packet in d_buf and d_appdata.
 *
 ****************************************************************************/

#if defined(CONFIG_NET_UDP_CHECKSUMS) && defined(CONFIG_NET_IPv6)
uint16_t udp_ipv6_chksum(FAR struct net_driver_s *dev);
#endif

/****************************************************************************
 * Name: icmp_chksum
 *
 * Description:
 *   Calculate the checksum of the IPv4 ICMP message
 *
 ****************************************************************************/

#ifdef CONFIG_NET_ICMP
uint16_t icmp_chksum(FAR struct net_driver_s *dev, int len);
#endif

/****************************************************************************
 * Name: icmp_chksum_iob
 *
 * Description:
 *   Calculate the checksum of the ICMP message, the input can be an I/O
 *   buffer chain
 *
 ****************************************************************************/

#if defined(CONFIG_NET_ICMP) && defined(CONFIG_MM_IOB)
uint16_t icmp_chksum_iob(FAR struct iob_s *iob);
#endif /* CONFIG_NET_ICMP && CONFIG_MM_IOB */

/****************************************************************************
 * Name: icmpv6_chksum
 *
 * Description:
 *   Calculate the checksum of the ICMPv6 message
 *
 ****************************************************************************/

#ifdef CONFIG_NET_ICMPv6
uint16_t icmpv6_chksum(FAR struct net_driver_s *dev, unsigned int iplen);
#endif

/****************************************************************************
 * Name: cmsg_append
 *
 * Description:
 *   Append specified data into the control message, msg_control and
 *   msg_controllen will be changed to the appropriate value when success
 *
 * Input Parameters:
 *   msg       - Buffer to receive the message.
 *   level     - The level of control message.
 *   type      - The type of control message.
 *   value     - If the value is not NULL, this interface copies the data
 *               to the appropriate location in msg_control, and modify
 *               msg_control and msg_controllen.
 *               If the value is NULL, just modify the corresponding value
 *               of msg.
 *   value_len - The value length of control message.
 *
 * Returned Value:
 *   On success, a pointer to the start address of control message data,
 *               the caller can copy the data in.
 *   On failure, return NULL, because of msg_controllen is not enough
 *
 ****************************************************************************/

FAR void *cmsg_append(FAR struct msghdr *msg, int level, int type,
                      FAR void *value, int value_len);

#undef EXTERN
#ifdef __cplusplus
}
#endif

#endif /* __NET_UTILS_UTILS_H */
