Kernel: Collect IPv4 stuff in IPv4.h and ARP stuff in ARP.h.

Kernel/IPv4.h

@@ -0,0 +1,134 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <AK/Assertions.h>
+#include <AK/Types.h>
+#include <Kernel/NetworkOrdered.h>
+#include <Kernel/StdLib.h>
+
+enum class IPv4Protocol : word {
+    ICMP = 1,
+    TCP = 6,
+    UDP = 17,
+};
+
+NetworkOrdered<word> internet_checksum(const void*, size_t);
+
+class [[gnu::packed]] IPv4Address {
+public:
+    IPv4Address() { }
+    IPv4Address(const byte data[4])
+    {
+        memcpy(m_data, data, 4);
+    }
+    IPv4Address(byte a, byte b, byte c, byte d)
+    {
+        m_data[0] = a;
+        m_data[1] = b;
+        m_data[2] = c;
+        m_data[3] = d;
+    }
+    ~IPv4Address() { }
+
+    byte operator[](int i) const
+    {
+        ASSERT(i >= 0 && i < 4);
+        return m_data[i];
+    }
+
+    String to_string() const
+    {
+        return String::format("%u.%u.%u.%u", m_data[0], m_data[1], m_data[2], m_data[3]);
+    }
+
+    bool operator==(const IPv4Address& other) const { return m_data_as_dword == other.m_data_as_dword; }
+    bool operator!=(const IPv4Address& other) const { return m_data_as_dword != other.m_data_as_dword; }
+
+private:
+    union {
+        byte m_data[4];
+        dword m_data_as_dword;
+    };
+};
+
+static_assert(sizeof(IPv4Address) == 4);
+
+namespace AK {
+
+template<>
+struct Traits<IPv4Address> {
+    static unsigned hash(const IPv4Address& address) { return string_hash((const char*)&address, sizeof(address)); }
+    static void dump(const IPv4Address& address) { kprintf("%s", address.to_string().characters()); }
+};
+
+}
+
+class [[gnu::packed]] IPv4Packet {
+public:
+    byte version() const { return (m_version_and_ihl >> 4) & 0xf; }
+    void set_version(byte version) { m_version_and_ihl = (m_version_and_ihl & 0x0f) | (version << 4); }
+
+    byte internet_header_length() const { return m_version_and_ihl & 0xf; }
+    void set_internet_header_length(byte ihl) { m_version_and_ihl = (m_version_and_ihl & 0xf0) | (ihl & 0x0f); }
+
+    word length() const { return m_length; }
+    void set_length(word length) { m_length = length; }
+
+    word ident() const { return m_ident; }
+    void set_ident(word ident) { m_ident = ident; }
+
+    byte ttl() const { return m_ttl; }
+    void set_ttl(byte ttl) { m_ttl = ttl; }
+
+    byte protocol() const { return m_protocol; }
+    void set_protocol(byte protocol) { m_protocol = protocol; }
+
+    word checksum() const { return m_checksum; }
+    void set_checksum(word checksum) { m_checksum = checksum; }
+
+    const IPv4Address& source() const { return m_source; }
+    void set_source(const IPv4Address& address) { m_source = address; }
+
+    const IPv4Address& destination() const { return m_destination; }
+    void set_destination(const IPv4Address& address) { m_destination = address; }
+
+    void* payload() { return this + 1; }
+    const void* payload() const { return this + 1; }
+
+    word payload_size() const { return m_length - sizeof(IPv4Packet); }
+
+    NetworkOrdered<word> compute_checksum() const
+    {
+        ASSERT(!m_checksum);
+        return internet_checksum(this, sizeof(IPv4Packet));
+    }
+
+private:
+    byte m_version_and_ihl { 0 };
+    byte m_dscp_and_ecn { 0 };
+    NetworkOrdered<word> m_length;
+    NetworkOrdered<word> m_ident;
+    NetworkOrdered<word> m_flags_and_fragment;
+    byte m_ttl { 0 };
+    NetworkOrdered<byte> m_protocol;
+    NetworkOrdered<word> m_checksum;
+    IPv4Address m_source;
+    IPv4Address m_destination;
+};
+
+static_assert(sizeof(IPv4Packet) == 20);
+
+inline NetworkOrdered<word> internet_checksum(const void* ptr, size_t count)
+{
+    dword checksum = 0;
+    auto* w = (const word*)ptr;
+    while (count > 1) {
+        checksum += convert_between_host_and_network(*w++);
+        if (checksum & 0x80000000)
+            checksum = (checksum & 0xffff) | (checksum >> 16);
+        count -= 2;
+    }
+    while (checksum >> 16)
+        checksum = (checksum & 0xffff) + (checksum >> 16);
+    return ~checksum & 0xffff;
+}