/*++

Copyright (c) 2001  Microsoft Corporation

Module Name:

    add2strt.h

Abstract:

    Code for IP address-to-string translation routines.

Author:

    Dave Thaler (dthaler)   3-28-2001

Revision History:

    IPv6 conversion code originally by Rich Draves (richdr)

--*/

struct in6_addr {
    union {
        UCHAR Byte[16];
        USHORT Word[8];
    } u;
};
#define s6_bytes   u.Byte
#define s6_words   u.Word

struct in_addr {
        union {
                struct { UCHAR s_b1,s_b2,s_b3,s_b4; } S_un_b;
                struct { USHORT s_w1,s_w2; } S_un_w;
                ULONG S_addr;
        } S_un;
};
#define s_addr  S_un.S_addr

LPTSTR
RtlIpv6AddressToStringT(
    IN const struct in6_addr *Addr,
    OUT LPTSTR S
    )

/*++

Routine Description:

    Generates an IPv6 string literal corresponding to the address Addr.
    The shortened canonical forms are used (RFC 1884 etc).
    The basic string representation consists of 8 hex numbers
    separated by colons, with a couple embellishments:
    - a string of zero numbers (at most one) is replaced
    with a double-colon.
    - the last 32 bits are represented in IPv4-style dotted-octet notation
    if the address is a v4-compatible or ISATAP address.

    For example,
        ::
        ::1
        ::157.56.138.30
        ::ffff:156.56.136.75
        ff01::
        ff02::2
        0:1:2:3:4:5:6:7

Arguments:

    S - Receives a pointer to the buffer in which to place the
        string literal.

    Addr - Receives the IPv6 address.

Return Value:

    Pointer to the null byte at the end of the string inserted.
    This can be used by the caller to easily append more information.

--*/

{
    int maxFirst, maxLast;
    int curFirst, curLast;
    int i;
    int endHex = 8;

    // Check for IPv6-compatible, IPv4-mapped, and IPv4-translated
    // addresses
    if ((Addr->s6_words[0] == 0) && (Addr->s6_words[1] == 0) &&
        (Addr->s6_words[2] == 0) && (Addr->s6_words[3] == 0) &&
        (Addr->s6_words[6] != 0)) {
        if ((Addr->s6_words[4] == 0) &&
             ((Addr->s6_words[5] == 0) || (Addr->s6_words[5] == 0xffff)))
        {
            // compatible or mapped
            S += _stprintf(S, _T("::%hs%u.%u.%u.%u"),
                           Addr->s6_words[5] == 0 ? "" : "ffff:",
                           Addr->s6_bytes[12], Addr->s6_bytes[13],
                           Addr->s6_bytes[14], Addr->s6_bytes[15]);
            return S;
        }
        else if ((Addr->s6_words[4] == 0xffff) && (Addr->s6_words[5] == 0)) {
            // translated
            S += _stprintf(S, _T("::ffff:0:%u.%u.%u.%u"),
                           Addr->s6_bytes[12], Addr->s6_bytes[13],
                           Addr->s6_bytes[14], Addr->s6_bytes[15]);
            return S;
        }
    }


    // Find largest contiguous substring of zeroes
    // A substring is [First, Last), so it's empty if First == Last.

    maxFirst = maxLast = 0;
    curFirst = curLast = 0;

    // ISATAP EUI64 starts with 00005EFE (or 02005EFE)...
    if (((Addr->s6_words[4] & 0xfffd) == 0) && (Addr->s6_words[5] == 0xfe5e)) {
        endHex = 6;
    }

    for (i = 0; i < endHex; i++) {

        if (Addr->s6_words[i] == 0) {
            // Extend current substring
            curLast = i+1;

            // Check if current is now largest
            if (curLast - curFirst > maxLast - maxFirst) {

                maxFirst = curFirst;
                maxLast = curLast;
            }
        }
        else {
            // Start a new substring
            curFirst = curLast = i+1;
        }
    }

    // Ignore a substring of length 1.
    if (maxLast - maxFirst <= 1)
        maxFirst = maxLast = 0;

        // Write colon-separated words.
        // A double-colon takes the place of the longest string of zeroes.
        // All zeroes is just "::".

    for (i = 0; i < endHex; i++) {

        // Skip over string of zeroes
        if ((maxFirst <= i) && (i < maxLast)) {

            S += _stprintf(S, _T("::"));
            i = maxLast-1;
            continue;
        }

        // Need colon separator if not at beginning
        if ((i != 0) && (i != maxLast))
            S += _stprintf(S, _T(":"));

        S += _stprintf(S, _T("%x"), RtlUshortByteSwap(Addr->s6_words[i]));
    }

    if (endHex < 8) {
        S += _stprintf(S, _T(":%u.%u.%u.%u"),
                       Addr->s6_bytes[12], Addr->s6_bytes[13],
                       Addr->s6_bytes[14], Addr->s6_bytes[15]);
    }

    return S;
}

LPTSTR
RtlIpv4AddressToStringT(
    IN const struct in_addr *Addr,
    OUT LPTSTR S
    )

/*++

Routine Description:

    Generates an IPv4 string literal corresponding to the address Addr.

Arguments:

    S - Receives a pointer to the buffer in which to place the
        string literal.

    Addr - Receives the IPv4 address.

Return Value:

    Pointer to the null byte at the end of the string inserted.
    This can be used by the caller to easily append more information.

--*/

{
    S += _stprintf(S, _T("%u.%u.%u.%u"),
                  ( Addr->s_addr >>  0 ) & 0xFF,
                  ( Addr->s_addr >>  8 ) & 0xFF,
                  ( Addr->s_addr >> 16 ) & 0xFF,
                  ( Addr->s_addr >> 24 ) & 0xFF );

    return S;
}