Add tanya.network.inet.NetworkOrder

NetworkOrder converts an integral type into a bidirectional range with
big-endian byte order.

2 files changed, 293 insertions, 0 deletions

diff --git a/source/tanya/network/inet.d b/source/tanya/network/inet.d
new file mode 100644
index 0000000..97da907
--- /dev/null
+++ b/source/tanya/network/inet.d
@@ -0,0 +1,292 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Internet utilities.
+ *
+ * Copyright: Eugene Wissner 2016-2017.
+ * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
+ *                  Mozilla Public License, v. 2.0).
+ * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
+ */
+module tanya.network.inet;
+
+import std.algorithm.comparison;
+import std.traits;
+
+version (assert)
+{
+    import std.math;
+}
+
+version (unittest)
+{
+    import std.math;
+    import std.range.primitives;
+
+    version (Windows)
+    {
+        import core.sys.windows.winsock2;
+        version = PlattformUnittest;
+    }
+    else version (Posix)
+    {
+        import core.sys.posix.arpa.inet;
+        version = PlattformUnittest;
+    }
+}
+
+/**
+ * Represents an unsigned integer as an $(D_KEYWORD ubyte) range.
+ *
+ * The range is bidirectional. The byte order is always big-endian.
+ */
+struct NetworkOrder
+{
+    private uint value;
+    private size_t size;
+
+    const pure nothrow @safe @nogc invariant
+    {
+        assert(this.size <= uint.sizeof);
+    }
+
+    /**
+     * Constructs a new range.
+     *
+     * $(D_PARAM T) can be any unsigned type but $(D_PARAM value) shouldn't be
+     * larger than the maximum can be stored in $(D_PARAM length) bytes.
+     * Otherwise an assertion failure will be caused.
+     *
+     * If $(D_PARAM length) isn't specified, it is inferred from the
+     * $(D_INLINECODE T.sizeof).
+     *
+     * If $(D_PARAM T) is $(D_KEYWORD ulong), $(D_PARAM value) should be less
+     * than or equal to $(D_INLINECODE uint.max).
+     *
+     * Params:
+     *  T      = Value type.
+     *  value  = The value should be iterated over.
+     *  length = $(D_PARAM value) size in bytes.
+     *
+     * Precondition: $(D_INLINECODE length < uint.sizeof
+     *                           && value <= 2 ^ (length * 8) - 1).
+     */
+    this(T)(const T value, const size_t length)
+        if (isIntegral!T)
+    in
+    {
+        assert(length <= uint.sizeof);
+        assert(value >= 0);
+        assert(value <= pow(2, length * 8) - 1);
+    }
+    body
+    {
+        this.value = value & uint.max;
+        this.size = length;
+    }
+
+    /// Ditto.
+    this(T)(const T value)
+        if (isIntegral!T)
+    {
+        this(value, min(T.sizeof, uint.sizeof));
+    }
+
+    /**
+     * Returns: LSB.
+     *
+     * Precondition: $(D_INLINECODE length > 0).
+     */
+    @property ubyte back() const pure nothrow @safe @nogc
+    in
+    {
+        assert(this.length > 0);
+    }
+    body
+    {
+        return this.value & 0xff;
+    }
+
+    /**
+     * Returns: MSB.
+     *
+     * Precondition: $(D_INLINECODE length > 0).
+     */
+    @property ubyte front() const pure nothrow @safe @nogc
+    in
+    {
+        assert(this.length > 0);
+    }
+    body
+    {
+        return (this.value >> ((this.length - 1) * 8)) & 0xff;
+    }
+
+    /**
+     * Eliminates the LSB.
+     *
+     * Precondition: $(D_INLINECODE length > 0).
+     */
+    void popBack() pure nothrow @safe @nogc
+    in
+    {
+        assert(this.length > 0);
+    }
+    body
+    {
+        this.value >>= 8;
+        --this.size;
+    }
+
+    /**
+     * Eliminates the MSB.
+     *
+     * Precondition: $(D_INLINECODE length > 0).
+     */
+    void popFront() pure nothrow @safe @nogc
+    in
+    {
+        assert(this.length > 0);
+    }
+    body
+    {
+        this.value &= uint.max >> ((4 - this.length) * 8);
+        --this.size;
+    }
+
+    /**
+     * Returns: Copy of this range.
+     */
+    typeof(this) save() const pure nothrow @safe @nogc
+    {
+        return this;
+    }
+
+    /**
+     * Returns: Whether the range is empty.
+     */
+    @property bool empty() const pure nothrow @safe @nogc
+    {
+        return this.length == 0;
+    }
+
+    /**
+     * Returns: Byte length.
+     */
+    @property size_t length() const pure nothrow @safe @nogc
+    {
+        return this.size;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    auto networkOrder = NetworkOrder(0xae34e2u, 3);
+    assert(!networkOrder.empty);
+    assert(networkOrder.front == 0xae);
+
+    networkOrder.popFront();
+    assert(networkOrder.length == 2);
+    assert(networkOrder.front == 0x34);
+    assert(networkOrder.back == 0xe2);
+
+    networkOrder.popBack();
+    assert(networkOrder.length == 1);
+    assert(networkOrder.front == 0x34);
+    assert(networkOrder.front == 0x34);
+
+    networkOrder.popFront();
+    assert(networkOrder.empty);
+}
+
+// Static.
+private unittest
+{
+    static assert(isBidirectionalRange!NetworkOrder);
+}
+
+// Tests against the system's htonl, htons.
+version (PlattformUnittest)
+{
+    private unittest
+    {
+        for (uint counter; counter <= 8 * uint.sizeof; ++counter)
+        {
+            const value = pow(2, counter) - 1;
+            const inNetworkOrder = htonl(value);
+            const p = cast(ubyte*) &inNetworkOrder;
+            auto networkOrder = NetworkOrder(value);
+
+            assert(networkOrder.length == 4);
+            assert(!networkOrder.empty);
+            assert(networkOrder.front == *p);
+            assert(networkOrder.back == *(p + 3));
+
+            networkOrder.popBack();
+            assert(networkOrder.length == 3);
+            assert(networkOrder.front == *p);
+            assert(networkOrder.back == *(p + 2));
+
+            networkOrder.popFront();
+            assert(networkOrder.length == 2);
+            assert(networkOrder.front == *(p + 1));
+            assert(networkOrder.back == *(p + 2));
+
+            networkOrder.popFront();
+            assert(networkOrder.length == 1);
+            assert(networkOrder.front == *(p + 2));
+            assert(networkOrder.back == *(p + 2));
+
+            networkOrder.popBack();
+            assert(networkOrder.length == 0);
+            assert(networkOrder.empty);
+        }
+
+        for (ushort counter; counter <= 8 * ushort.sizeof; ++counter)
+        {
+            const value = cast(ushort) (pow(2, counter) - 1);
+            const inNetworkOrder = htons(value);
+            const p = cast(ubyte*) &inNetworkOrder;
+
+            auto networkOrder = NetworkOrder(value);
+
+            assert(networkOrder.length == 2);
+            assert(!networkOrder.empty);
+            assert(networkOrder.front == *p);
+            assert(networkOrder.back == *(p + 1));
+
+            networkOrder.popBack();
+            assert(networkOrder.length == 1);
+            assert(networkOrder.front == *p);
+            assert(networkOrder.back == *p);
+
+            networkOrder.popBack();
+            assert(networkOrder.length == 0);
+            assert(networkOrder.empty);
+
+            networkOrder = NetworkOrder(value);
+
+            networkOrder.popFront();
+            assert(networkOrder.length == 1);
+            assert(networkOrder.front == *(p + 1));
+            assert(networkOrder.back == *(p + 1));
+
+            networkOrder.popFront();
+            assert(networkOrder.length == 0);
+            assert(networkOrder.empty);
+        }
+
+        auto networkOrder = NetworkOrder(255u, 1);
+        assert(networkOrder.length == 1);
+        assert(!networkOrder.empty);
+        assert(networkOrder.front == 0xff);
+        assert(networkOrder.back == 0xff);
+
+        networkOrder.popFront();
+        assert(networkOrder.length == 0);
+        assert(networkOrder.empty);
+    }
+}
diff --git a/source/tanya/network/package.d b/source/tanya/network/package.d
index 96b987c..14a6752 100644
--- a/source/tanya/network/package.d
+++ b/source/tanya/network/package.d
@@ -12,5 +12,6 @@
  */
 module tanya.network;
 
+public import tanya.network.inet;
 public import tanya.network.socket;
 public import tanya.network.url;