net: loopback device

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);
+}