Kernel: Implement basic gateway for network interfaces

kernel/include/kernel/Networking/NetworkInterface.h

@@ -46,6 +46,9 @@ namespace Kernel
 		BAN::IPv4Address get_netmask() const { return m_netmask; }
 		void set_netmask(BAN::IPv4Address new_netmask) { m_netmask = new_netmask; }
 
+		BAN::IPv4Address get_gateway() const { return m_gateway; }
+		void set_gateway(BAN::IPv4Address new_gateway) { m_gateway = new_gateway; }
+
 		virtual bool link_up() = 0;
 		virtual int link_speed() = 0;
 
@@ -65,6 +68,7 @@ namespace Kernel
 
 		BAN::IPv4Address m_ipv4_address { 0 };
 		BAN::IPv4Address m_netmask { 0 };
+		BAN::IPv4Address m_gateway { 0 };
 	};
 
 }

kernel/kernel/Networking/ARPTable.cpp

@@ -45,6 +45,9 @@ namespace Kernel
 		if (ipv4_address == s_broadcast_ipv4)
 			return s_broadcast_mac;
 
+		if (interface.get_ipv4_address().mask(interface.get_netmask()) != ipv4_address.mask(interface.get_netmask()))
+			ipv4_address = interface.get_gateway();
+
 		{
 			LockGuard _(m_lock);
 			if (m_arp_table.contains(ipv4_address))

kernel/kernel/Networking/NetworkSocket.cpp

@@ -171,6 +171,22 @@ namespace Kernel
 				dprintln("Netmask set to {}", m_interface->get_netmask());
 				return 0;
 			}
+			case SIOCGIFGWADDR:
+			{
+				auto& ifru_gwaddr = *reinterpret_cast<sockaddr_in*>(&ifreq->ifr_ifru.ifru_gwaddr);
+				ifru_gwaddr.sin_family = AF_INET;
+				ifru_gwaddr.sin_addr.s_addr = m_interface->get_gateway().raw;
+				return 0;
+			}
+			case SIOCSIFGWADDR:
+			{
+				auto& ifru_gwaddr = *reinterpret_cast<const sockaddr_in*>(&ifreq->ifr_ifru.ifru_gwaddr);
+				if (ifru_gwaddr.sin_family != AF_INET)
+					return BAN::Error::from_errno(EADDRNOTAVAIL);
+				m_interface->set_gateway(BAN::IPv4Address { ifru_gwaddr.sin_addr.s_addr });
+				dprintln("Gateway set to {}", m_interface->get_gateway());
+				return 0;
+			}
 			case SIOCGIFHWADDR:
 			{
 				auto mac_address = m_interface->get_mac_address();