net: loopback device

kernel-src/arch/x86-64/main.c

@@ -69,6 +69,7 @@ void kernel_entry() {
 	ext2_init();
 
 	netdev_init();
+	loopback_init();
 	arp_init();
 	ipv4_init();
 	udp_init();

kernel-src/include/kernel/net.h

@@ -29,6 +29,7 @@ typedef struct netdev_t {
 	size_t mtu;
 	uint32_t ip;
 	hashtable_t arpcache;
+	bool doarp;
 	int (*allocdesc)(size_t requestedsize, netdesc_t *desc);
 	int (*sendpacket)(struct netdev_t *_internal, netdesc_t desc, mac_t targetmac, int proto);
 } netdev_t;
@@ -76,6 +77,8 @@ void arp_init();
 void ipv4_init();
 void udp_init();
 void netdev_init();
+void loopback_init();
+netdev_t *loopback_device();
 void udp_process(netdev_t *netdev, void *buffer, uint32_t ip);
 void arp_process(netdev_t *netdev, void *buffer);
 int arp_lookup(netdev_t *netdev, uint32_t ip, mac_t *mac);

kernel-src/io/net/ipv4.c

@@ -168,9 +168,11 @@ int ipv4_sendpacket(void *buffer, size_t packetsize, uint32_t ip, int proto, net
 		if (entry.netdev == NULL)
 			return 0; // if a packet can't be routed to anywhere just pretend it was sent somewhere
 
-		int error = arp_lookup(entry.netdev, entry.gateway ? entry.gateway : ip, &mac);
-		if (error)
-			return error;
+		if (entry.netdev->doarp) {
+			int error = arp_lookup(entry.netdev, entry.gateway ? entry.gateway : ip, &mac);
+			if (error)
+				return error;
+		}
 
 		netdev = entry.netdev;
 	} else {
@@ -207,4 +209,5 @@ void ipv4_init() {
 	MUTEX_INIT(&routingtablelock);
 	routingtable = alloc(sizeof(routingentry_t));
 	__assert(routingtable);
+	__assert(ipv4_addroute(loopback_device(), 0x7f000001, 0, 0xff000000, 10000) == 0);
 }

kernel-src/io/net/loopback.c

@@ -0,0 +1,61 @@
+#include <kernel/virtio.h>
+#include <logging.h>
+#include <kernel/pmm.h>
+#include <kernel/eth.h>
+#include <kernel/net.h>
+#include <event.h>
+#include <hashtable.h>
+#include <arch/cpu.h>
+
+static netdev_t loopbacknetdev;
+
+static void rx_dpc(context_t *context, dpcarg_t arg) {
+	eth_process(&loopbacknetdev, arg);
+}
+
+// requested size doesn't account for ethernet header or the virtio header
+static int loopback_allocdesc(size_t requestedsize, netdesc_t *desc) {
+	desc->address = alloc(requestedsize + sizeof(ethframe_t));
+	if (desc->address == NULL)
+		return ENOMEM;
+
+	desc->size = requestedsize + sizeof(ethframe_t);
+	desc->curroffset = sizeof(ethframe_t);
+	return 0;
+}
+
+static int loopback_sendpacket(netdev_t *netdev, netdesc_t desc, mac_t targetmac, int proto) {
+	desc.curroffset = 0;
+	ethframe_t ethframe = {
+		.type = cpu_to_be_w(proto)
+	};
+
+	mac_t broadcast = NET_BROADCAST_MAC;
+
+	memcpy(&ethframe.source, &netdev->mac, sizeof(mac_t));
+	memcpy(&ethframe.destination, &broadcast, sizeof(mac_t));
+	memcpy(desc.address, &ethframe, sizeof(ethframe_t));
+
+	dpc_t dpc = {0};
+	dpc_enqueue(&dpc, rx_dpc, desc.address);
+
+	return 0;
+}
+
+netdev_t *loopback_device() {
+	return &loopbacknetdev;
+}
+
+void loopback_init() {
+	loopbacknetdev.mtu = 30000;
+	loopbacknetdev.sendpacket = loopback_sendpacket;
+	loopbacknetdev.allocdesc = loopback_allocdesc;
+	loopbacknetdev.ip = 0x7f000001;
+	loopbacknetdev.doarp = false;
+	__assert(hashtable_init(&loopbacknetdev.arpcache, 30) == 0);
+
+	for (int i = 0; i < 6; ++i)
+		loopbacknetdev.mac.address[i] = 0;
+
+	__assert(netdev_register(&loopbacknetdev, "lo") == 0);
+}

kernel-src/io/net/vionet.c

@@ -179,6 +179,7 @@ int vionet_newdevice(viodevice_t *viodevice) {
 	netdev->netdev.mtu = 1500;
 	netdev->netdev.sendpacket = vionet_sendpacket;
 	netdev->netdev.allocdesc = vionet_allocdesc;
+	netdev->netdev.doarp = true;
 	__assert(hashtable_init(&netdev->netdev.arpcache, 30) == 0);
 
 	// initialize queues