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#include "qipaddress_p.h"
#include "private/qlocale_tools_p.h"
#include "qvarlengtharray.h"

QT_BEGIN_NAMESPACE
namespace QIPAddressUtils {

static QString number(quint8 val, int base = 10)
{
    QChar zero(0x30);
    return val ? qulltoa(val, base, zero) : zero;
}

typedef QVarLengthArray<char, 64> Buffer;
static bool checkedToAscii(Buffer &buffer, const QChar *begin, const QChar *end)
{
    const ushort *const ubegin = reinterpret_cast<const ushort *>(begin);
    const ushort *const uend = reinterpret_cast<const ushort *>(end);
    const ushort *src = ubegin;

    buffer.resize(uend - ubegin + 1);
    char *dst = buffer.data();

    while (src != uend) {
        if (*src >= 0x7f)
            return false;
        *dst++ = *src++;
    }
    *dst = '\0';
    return true;
}

static bool parseIp4Internal(IPv4Address &address, const char *ptr, bool acceptLeadingZero);
bool parseIp4(IPv4Address &address, const QChar *begin, const QChar *end)
{
    Q_ASSERT(begin != end);
    Buffer buffer;
    if (!checkedToAscii(buffer, begin, end))
        return false;

    const char *ptr = buffer.data();
    return parseIp4Internal(address, ptr, true);
}

static bool parseIp4Internal(IPv4Address &address, const char *ptr, bool acceptLeadingZero)
{
    address = 0;
    int dotCount = 0;
    while (dotCount < 4) {
        if (!acceptLeadingZero && *ptr == '0' &&
                ptr[1] != '.' && ptr[1] != '\0')
            return false;

        const char *endptr;
        bool ok;
        quint64 ll = qstrtoull(ptr, &endptr, 0, &ok);
        quint32 x = ll;
        if (!ok || endptr == ptr || ll != x)
            return false;

        if (*endptr == '.' || dotCount == 3) {
            if (x & ~0xff)
                return false;
            address <<= 8;
        } else if (dotCount == 2) {
            if (x & ~0xffff)
                return false;
            address <<= 16;
        } else if (dotCount == 1) {
            if (x & ~0xffffff)
                return false;
            address <<= 24;
        }
        address |= x;

        if (dotCount == 3 && *endptr != '\0')
            return false;
        else if (dotCount == 3 || *endptr == '\0')
            return true;
        ++dotCount;
        ptr = endptr + 1;
    }
    return false;
}

void toString(QString &appendTo, IPv4Address address)
{
    // reconstructing is easy
    // use the fast operator% that pre-calculates the size
    appendTo += number(address >> 24)
                % QLatin1Char('.')
                % number(address >> 16)
                % QLatin1Char('.')
                % number(address >> 8)
                % QLatin1Char('.')
                % number(address);
}

bool parseIp6(IPv6Address &address, const QChar *begin, const QChar *end)
{
    Q_ASSERT(begin != end);
    Buffer buffer;
    if (!checkedToAscii(buffer, begin, end))
        return false;

    const char *ptr = buffer.data();

    // count the colons
    int colonCount = 0;
    int dotCount = 0;
    while (*ptr) {
        if (*ptr == ':')
            ++colonCount;
        if (*ptr == '.')
            ++dotCount;
        ++ptr;
    }
    // IPv4-in-IPv6 addresses are stricter in what they accept
    if (dotCount != 0 && dotCount != 3)
        return false;

    memset(address, 0, sizeof address);
    if (colonCount == 2 && end - begin == 2) // "::"
        return true;

    // if there's a double colon ("::"), this is how many zeroes it means
    int zeroWordsToFill;
    ptr = buffer.data();

    // there are two cases where 8 colons are allowed: at the ends
    // so test that before the colon-count test
    if ((ptr[0] == ':' && ptr[1] == ':') ||
            (ptr[end - begin - 2] == ':' && ptr[end - begin - 1] == ':')) {
        zeroWordsToFill = 9 - colonCount;
    } else if (colonCount < 2 || colonCount > 7) {
        return false;
    } else {
        zeroWordsToFill = 8 - colonCount;
    }
    if (dotCount)
        --zeroWordsToFill;

    int pos = 0;
    while (pos < 15) {
        const char *endptr;
        bool ok;
        quint64 ll = qstrtoull(ptr, &endptr, 16, &ok);
        quint16 x = ll;

        if (ptr == endptr) {
            // empty field, we hope it's "::"
            if (zeroWordsToFill < 1)
                return false;
            if (pos == 0 || pos == colonCount * 2) {
                if (ptr[0] == '\0' || ptr[1] != ':')
                    return false;
                ++ptr;
            }
            pos += zeroWordsToFill * 2;
            zeroWordsToFill = 0;
            ++ptr;
            continue;
        }
        if (!ok || ll != x)
            return false;

        if (*endptr == '.') {
            // this could be an IPv4 address
            // it's only valid in the last element
            if (pos != 12)
                return false;

            IPv4Address ip4;
            if (!parseIp4Internal(ip4, ptr, false))
                return false;

            address[12] = ip4 >> 24;
            address[13] = ip4 >> 16;
            address[14] = ip4 >> 8;
            address[15] = ip4;
            return true;
        }

        address[pos++] = x >> 8;
        address[pos++] = x & 0xff;

        if (*endptr == '\0')
            break;
        if (*endptr != ':')
            return false;
        ptr = endptr + 1;
    }
    return pos == 16;
}

static inline QChar toHex(uchar c)
{
    return ushort(c > 9 ? c + 'a' - 0xA : c + '0');
}

void toString(QString &appendTo, IPv6Address address)
{
    // the longest IPv6 address possible is:
    //   "1111:2222:3333:4444:5555:6666:255.255.255.255"
    // however, this function never generates that. The longest it does
    // generate without an IPv4 address is:
    //   "1111:2222:3333:4444:5555:6666:7777:8888"
    // and the longest with an IPv4 address is:
    //   "::ffff:255.255.255.255"
    static const int Ip6AddressMaxLen = sizeof "1111:2222:3333:4444:5555:6666:7777:8888";
    static const int Ip6WithIp4AddressMaxLen = sizeof "::ffff:255.255.255.255";

    // check for the special cases
    const quint64 zeroes[] = { 0, 0 };
    bool embeddedIp4 = false;

    // we consider embedded IPv4 for:
    //  ::ffff:x.x.x.x
    //  ::x.x.x.y  except if the x are 0 too
    if (memcmp(address, zeroes, 10) == 0) {
        if (address[10] == 0xff && address[11] == 0xff) {
            embeddedIp4 = true;
        } else if (address[10] == 0 && address[11] == 0) {
            if (address[12] != 0 || address[13] != 0 || address[14] != 0) {
                embeddedIp4 = true;
            } else if (address[15] == 0) {
                appendTo.append(QLatin1String("::"));
                return;
            }
        }
    }

    // QString::reserve doesn't shrink, so it's fine to us
    appendTo.reserve(appendTo.size() +
                     (embeddedIp4 ? Ip6WithIp4AddressMaxLen : Ip6AddressMaxLen));

    // for finding where to place the "::"
    int zeroRunLength = 0; // in octets
    int zeroRunOffset = 0; // in octets
    for (int i = 0; i < 16; i += 2) {
        if (address[i] == 0 && address[i + 1] == 0) {
            // found a zero, scan forward to see how many more there are
            int j;
            for (j = i; j < 16; j += 2) {
                if (address[j] != 0 || address[j+1] != 0)
                    break;
            }

            if (j - i > zeroRunLength) {
                zeroRunLength = j - i;
                zeroRunOffset = i;
                i = j;
            }
        }
    }

    const QChar colon = ushort(':');
    if (zeroRunLength < 4)
        zeroRunOffset = -1;
    else if (zeroRunOffset == 0)
        appendTo.append(colon);

    for (int i = 0; i < 16; i += 2) {
        if (i == zeroRunOffset) {
            appendTo.append(colon);
            i += zeroRunLength - 2;
            continue;
        }

        if (i == 12 && embeddedIp4) {
            IPv4Address ip4 = address[12] << 24 |
                              address[13] << 16 |
                              address[14] << 8 |
                              address[15];
            toString(appendTo, ip4);
            return;
        }

        if (address[i]) {
            if (address[i] >> 4) {
                appendTo.append(toHex(address[i] >> 4));
                appendTo.append(toHex(address[i] & 0xf));
                appendTo.append(toHex(address[i + 1] >> 4));
                appendTo.append(toHex(address[i + 1] & 0xf));
            } else if (address[i] & 0xf) {
                appendTo.append(toHex(address[i] & 0xf));
                appendTo.append(toHex(address[i + 1] >> 4));
                appendTo.append(toHex(address[i + 1] & 0xf));
            }
        } else if (address[i + 1] >> 4) {
            appendTo.append(toHex(address[i + 1] >> 4));
            appendTo.append(toHex(address[i + 1] & 0xf));
        } else {
            appendTo.append(toHex(address[i + 1] & 0xf));
        }

        if (i != 14)
            appendTo.append(colon);
    }
}

}
QT_END_NAMESPACE
