Kernel/LibC: Implement SYS_SENDTO

kernel/kernel/Networking/NetworkInterface.cpp

@@ -1,3 +1,4 @@
+#include <BAN/Endianness.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/Networking/NetworkInterface.h>
 
@@ -7,6 +8,14 @@
 namespace Kernel
 {
 
+	struct EthernetHeader
+	{
+		uint8_t dst_mac[6];
+		uint8_t src_mac[6];
+		BAN::NetworkEndian<uint16_t> ether_type;
+	};
+	static_assert(sizeof(EthernetHeader) == 14);
+
 	static dev_t get_network_rdev_major()
 	{
 		static dev_t major = DevFileSystem::get().get_next_dev();
@@ -31,4 +40,19 @@ namespace Kernel
 		m_name[3] = minor(m_rdev) + '0';
 	}
 
+	BAN::ErrorOr<void> NetworkInterface::add_interface_header(BAN::Vector<uint8_t>& packet, uint8_t destination_mac[6])
+	{
+		ASSERT(m_type == Type::Ethernet);
+
+		TRY(packet.resize(packet.size() + sizeof(EthernetHeader)));
+		memmove(packet.data() + sizeof(EthernetHeader), packet.data(), packet.size() - sizeof(EthernetHeader));
+
+		auto* header = reinterpret_cast<EthernetHeader*>(packet.data());
+		memcpy(header->dst_mac, destination_mac, 6);
+		memcpy(header->src_mac, get_mac_address(), 6);
+		header->ether_type = 0x0800; // ipv4
+
+		return {};
+	}
+
 }