text: /**
   * @file
   *
   * IPv6 addresses.
   */
  
  /*
   * Copyright (c) 2010 Inico Technologies Ltd.
   * 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: Ivan Delamer <delamer@inicotech.com>
   *
   * Functions for handling IPv6 addresses.
   *
   * Please coordinate changes and requests with Ivan Delamer
   * <delamer@inicotech.com>
   */
  
  #include <net/lwip/lwip/opt.h>
  
  #if LWIP_IPV6  /* don't build if not configured for use in lwipopts.h */
  
  #include <net/lwip/lwip/ip_addr.h>
  #include <net/lwip/lwip/def.h>
  
  //#include <string.h>
  #include <kernel/rtthread.h>
  
  #if LWIP_IPV4
  #include <net/lwip/lwip/ip4_addr.h> /* for ip6addr_aton to handle IPv4-mapped addresses */
  #endif /* LWIP_IPV4 */
  
  /* used by IP6_ADDR_ANY(6) in ip6_addr.h */
  const ip_addr_t ip6_addr_any = IPADDR6_INIT(0ul, 0ul, 0ul, 0ul);
  
  #define lwip_xchar(i)        ((char)((i) < 10 ? '0' + (i) : 'A' + (i) - 10))
  
  /**
   * Check whether "cp" is a valid ascii representation
   * of an IPv6 address and convert to a binary address.
   * Returns 1 if the address is valid, 0 if not.
   *
   * @param cp IPv6 address in ascii representation (e.g. "FF01::1")
   * @param addr pointer to which to save the ip address in network order
   * @return 1 if cp could be converted to addr, 0 on failure
   */
  int
  ip6addr_aton(const char *cp, ip6_addr_t *addr)
  {
    u32_t addr_index, zero_blocks, current_block_index, current_block_value;
    const char *s;
  #if LWIP_IPV4
    int check_ipv4_mapped = 0;
  #endif /* LWIP_IPV4 */
  
    /* Count the number of colons, to count the number of blocks in a "::" sequence
       zero_blocks may be 1 even if there are no :: sequences */
    zero_blocks = 8;
    for (s = cp; *s != 0; s++) {
      if (*s == ':') {
        zero_blocks--;
  #if LWIP_IPV4
      } else if (*s == '.') {
        if ((zero_blocks == 5) ||(zero_blocks == 2)) {
          check_ipv4_mapped = 1;
          /* last block could be the start of an IPv4 address */
          zero_blocks--;
        } else {
          /* invalid format */
          return 0;
        }
        break;
  #endif /* LWIP_IPV4 */
      } else if (!lwip_isxdigit(*s)) {
        break;
      }
    }
  
    /* parse each block */
    addr_index = 0;
    current_block_index = 0;
    current_block_value = 0;
    for (s = cp; *s != 0; s++) {
      if (*s == ':') {
        if (addr) {
          if (current_block_index & 0x1) {
            addr->addr[addr_index++] |= current_block_value;
          }
          else {
            addr->addr[addr_index] = current_block_value << 16;
          }
        }
        current_block_index++;
  #if LWIP_IPV4
        if (check_ipv4_mapped) {
          if (current_block_index == 6) {
            ip4_addr_t ip4;
            int ret = ip4addr_aton(s + 1, &ip4);
            if (ret) {
              if (addr) {
                addr->addr[3] = lwip_htonl(ip4.addr);
                current_block_index++;
                goto fix_byte_order_and_return;
              }
              return 1;
            }
          }
        }
  #endif /* LWIP_IPV4 */
        current_block_value = 0;
        if (current_block_index > 7) {
          /* address too long! */
          return 0;
        }
        if (s[1] == ':') {
          if (s[2] == ':') {
            /* invalid format: three successive colons */
            return 0;
          }
          s++;
          /* "::" found, set zeros */
          while (zero_blocks > 0) {
            zero_blocks--;
            if (current_block_index & 0x1) {
              addr_index++;
            } else {
              if (addr) {
                addr->addr[addr_index] = 0;
              }
            }
            current_block_index++;
            if (current_block_index > 7) {
              /* address too long! */
              return 0;
            }
          }
        }
      } else if (lwip_isxdigit(*s)) {
        /* add current digit */
        current_block_value = (current_block_value << 4) +
            (lwip_isdigit(*s) ? (u32_t)(*s - '0') :
            (u32_t)(10 + (lwip_islower(*s) ? *s - 'a' : *s - 'A')));
      } else {
        /* unexpected digit, space? CRLF? */
        break;
      }
    }
  
    if (addr) {
      if (current_block_index & 0x1) {
        addr->addr[addr_index++] |= current_block_value;
      }
      else {
        addr->addr[addr_index] = current_block_value << 16;
      }
  #if LWIP_IPV4
  fix_byte_order_and_return:
  #endif
      /* convert to network byte order. */
      for (addr_index = 0; addr_index < 4; addr_index++) {
        addr->addr[addr_index] = lwip_htonl(addr->addr[addr_index]);
      }
  
      ip6_addr_clear_zone(addr);
    }
  
    if (current_block_index != 7) {
      return 0;
    }
  
    return 1;
  }
  
  /**
   * Convert numeric IPv6 address into ASCII representation.
   * returns ptr to static buffer; not reentrant!
   *
   * @param addr ip6 address in network order to convert
   * @return pointer to a global static (!) buffer that holds the ASCII
   *         representation of addr
   */
  char *
  ip6addr_ntoa(const ip6_addr_t *addr)
  {
    static char str[40];
    return ip6addr_ntoa_r(addr, str, 40);
  }
  
  /**
   * Same as ipaddr_ntoa, but reentrant since a user-supplied buffer is used.
   *
   * @param addr ip6 address in network order to convert
   * @param buf target buffer where the string is stored
   * @param buflen length of buf
   * @return either pointer to buf which now holds the ASCII
   *         representation of addr or NULL if buf was too small
   */
  char *
  ip6addr_ntoa_r(const ip6_addr_t *addr, char *buf, int buflen)
  {
    u32_t current_block_index, current_block_value, next_block_value;
    s32_t i;
    u8_t zero_flag, empty_block_flag;
  
  #if LWIP_IPV4
    if (ip6_addr_isipv4mappedipv6(addr)) {
      /* This is an IPv4 mapped address */
      ip4_addr_t addr4;
      char *ret;
  #define IP4MAPPED_HEADER "::FFFF:"
      char *buf_ip4 = buf + sizeof(IP4MAPPED_HEADER) - 1;
      int buflen_ip4 = buflen - sizeof(IP4MAPPED_HEADER) + 1;
      if (buflen < (int)sizeof(IP4MAPPED_HEADER)) {
        return NULL;
      }
      rt_memcpy(buf, IP4MAPPED_HEADER, sizeof(IP4MAPPED_HEADER));
      addr4.addr = addr->addr[3];
      ret = ip4addr_ntoa_r(&addr4, buf_ip4, buflen_ip4);
      if (ret != buf_ip4) {
        return NULL;
      }
      return buf;
    }
  #endif /* LWIP_IPV4 */
    i = 0;
    empty_block_flag = 0; /* used to indicate a zero chain for "::' */
  
    for (current_block_index = 0; current_block_index < 8; current_block_index++) {
      /* get the current 16-bit block */
      current_block_value = lwip_htonl(addr->addr[current_block_index >> 1]);
      if ((current_block_index & 0x1) == 0) {
        current_block_value = current_block_value >> 16;
      }
      current_block_value &= 0xffff;
  
      /* Check for empty block. */
      if (current_block_value == 0) {
        if (current_block_index == 7 && empty_block_flag == 1) {
          /* special case, we must render a ':' for the last block. */
          buf[i++] = ':';
          if (i >= buflen) {
            return NULL;
          }
          break;
        }
        if (empty_block_flag == 0) {
          /* generate empty block "::", but only if more than one contiguous zero block,
           * according to current formatting suggestions RFC 5952. */
          next_block_value = lwip_htonl(addr->addr[(current_block_index + 1) >> 1]);
          if ((current_block_index & 0x1) == 0x01) {
              next_block_value = next_block_value >> 16;
          }
          next_block_value &= 0xffff;
          if (next_block_value == 0) {
            empty_block_flag = 1;
            buf[i++] = ':';
            if (i >= buflen) {
              return NULL;
            }
            continue; /* move on to next block. */
          }
        } else if (empty_block_flag == 1) {
          /* move on to next block. */
          continue;
        }
      } else if (empty_block_flag == 1) {
        /* Set this flag value so we don't produce multiple empty blocks. */
        empty_block_flag = 2;
      }
  
      if (current_block_index > 0) {
        buf[i++] = ':';
        if (i >= buflen) {
          return NULL;
        }
      }
  
      if ((current_block_value & 0xf000) == 0) {
        zero_flag = 1;
      } else {
        buf[i++] = lwip_xchar(((current_block_value & 0xf000) >> 12));
        zero_flag = 0;
        if (i >= buflen) {
          return NULL;
        }
      }
  
      if (((current_block_value & 0xf00) == 0) && (zero_flag)) {
        /* do nothing */
      } else {
        buf[i++] = lwip_xchar(((current_block_value & 0xf00) >> 8));
        zero_flag = 0;
        if (i >= buflen) {
          return NULL;
        }
      }
  
      if (((current_block_value & 0xf0) == 0) && (zero_flag)) {
        /* do nothing */
      }
      else {
        buf[i++] = lwip_xchar(((current_block_value & 0xf0) >> 4));
        zero_flag = 0;
        if (i >= buflen) {
          return NULL;
        }
      }
  
      buf[i++] = lwip_xchar((current_block_value & 0xf));
      if (i >= buflen) {
        return NULL;
      }
    }
  
    buf[i] = 0;
  
    return buf;
  }
  
  #endif /* LWIP_IPV6 */
  