Add support for IPv6 parsing and reconstructing the address

Similarly, only test against the libc function on Linux, as other OS
sometimes have different behaviour.

Change-Id: I9b8ef9a3d660a59882396d695202865ca307e528
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>

1 files changed, 215 insertions, 2 deletions

diff --git a/src/corelib/io/qipaddress.cpp b/src/corelib/io/qipaddress.cpp
index b8871fe8b9..e996c8665c 100644
--- a/src/corelib/io/qipaddress.cpp
+++ b/src/corelib/io/qipaddress.cpp
@@ -71,6 +71,7 @@ static bool checkedToAscii(Buffer &buffer, const QChar *begin, const QChar *end)
     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);
@@ -78,10 +79,19 @@ bool parseIp4(IPv4Address &address, const QChar *begin, const QChar *end)
     if (!checkedToAscii(buffer, begin, end))
         return false;
 
-    int dotCount = 0;
-    address = 0;
     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);
@@ -127,5 +137,208 @@ void toString(QString &appendTo, IPv4Address address)
                 % 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