Meta: Move kernel and userland to their own folders.

This is to allow both the kernel and the userland to share certain
header files and to make the folder structure a bit more clear.

1 files changed, 153 insertions, 0 deletions

diff --git a/kernel/network/arp.c b/kernel/network/arp.c
new file mode 100644
index 0000000..de6d898
--- /dev/null
+++ b/kernel/network/arp.c
@@ -0,0 +1,153 @@
+#include <assert.h>
+#include <drivers/rtl8139.h>
+#include <network/arp.h>
+#include <network/bytes.h>
+#include <network/ethernet.h>
+#include <stdio.h>
+#include <string.h>
+
+struct ARP_DATA {
+  uint16_t htype;   // Hardware type
+  uint16_t ptype;   // Protocol type
+  uint8_t hlen;     // Hardware address length (Ethernet = 6)
+  uint8_t plen;     // Protocol address length (IPv4 = 4)
+  uint16_t opcode;  // ARP Operation Code
+  uint8_t srchw[6]; // Source hardware address - hlen bytes (see above)
+  uint8_t srcpr[4]; // Source protocol address - plen bytes (see above).
+                    // If IPv4 can just be a "u32" type.
+  uint8_t dsthw[6]; // Destination hardware address - hlen bytes (see above)
+  uint8_t dstpr[4]; // Destination protocol address - plen bytes (see
+                    // above). If IPv4 can just be a "u32" type.
+};
+
+struct ARP_TABLE_ENTRY {
+  uint8_t is_used;
+  uint8_t mac[6];
+  uint8_t ip[4];
+};
+
+struct ARP_TABLE_ENTRY arp_table[10] = {0};
+
+// FIXME: This is hardcoded, don't do this.
+uint8_t ip_address[4] = {10, 0, 2, 15};
+
+struct ARP_TABLE_ENTRY *find_arp_entry_to_use(void) {
+  // This does not need to find a "free" entry as a ARP table is
+  // just a cache, it just has to pick a entry efficently.
+  for (int i = 0; i < 10; i++) {
+    if (!arp_table[i].is_used) {
+      return &arp_table[i];
+    }
+  }
+  return &arp_table[0];
+}
+
+void print_mac(const char *str, uint8_t *mac) {
+  kprintf("%s: ", str);
+  for (int i = 0; i < 6; i++) {
+    kprintf("%x", mac[i]);
+    if (5 != i)
+      kprintf(":");
+  }
+  kprintf("\n");
+}
+
+void print_ip(const char *str, const uint8_t *ip) {
+  kprintf("%s: ", str);
+  for (int i = 0; i < 4; i++) {
+    kprintf("%d", ip[i]);
+    if (3 != i)
+      kprintf(".");
+  }
+  kprintf("\n");
+}
+
+void send_arp_request(const uint8_t ip[4]) {
+  struct ARP_DATA data;
+  data.htype = htons(1);
+  data.ptype = htons(0x0800);
+
+  data.hlen = 6;
+  data.plen = 4;
+
+  data.opcode = htons(0x0001);
+  get_mac_address(data.srchw);
+  memcpy(data.srcpr, ip_address, sizeof(uint8_t[4]));
+
+  memset(data.dsthw, 0, sizeof(uint8_t[6]));
+  memcpy(data.dstpr, ip, sizeof(uint8_t[4]));
+
+  uint8_t broadcast[6];
+  memset(broadcast, 0xFF, sizeof(broadcast));
+  send_ethernet_packet(broadcast, 0x0806, (uint8_t *)&data, sizeof(data));
+}
+
+int get_mac_from_ip(const uint8_t ip[4], uint8_t mac[6]) {
+  print_ip("ARP GETTING MAC FROM IP: ", ip);
+  for (int i = 0; i < 10; i++) {
+    if (0 != memcmp(arp_table[i].ip, ip, sizeof(uint8_t[4])))
+      continue;
+    memcpy(mac, arp_table[i].mac, sizeof(uint8_t[6]));
+    return 1;
+  }
+  klog("ARP cache miss", LOG_NOTE);
+  asm("sti");
+  send_arp_request(ip);
+  // TODO: Maybe wait a bit?
+  for (int i = 0; i < 10; i++) {
+    if (0 != memcmp(arp_table[i].ip, ip, sizeof(uint8_t[4])))
+      continue;
+    memcpy(mac, arp_table[i].mac, sizeof(uint8_t[6]));
+    return 1;
+  }
+  assert(0);
+  return 0;
+}
+
+void handle_arp(const uint8_t *payload) {
+  struct ARP_DATA *data = (struct ARP_DATA *)payload;
+
+  // Assert that communication is over ethernet
+  assert(1 == ntohs(data->htype));
+  // Assert that request uses IP
+  assert(0x0800 == ntohs(data->ptype));
+
+  assert(6 == data->hlen);
+  assert(4 == data->plen);
+  // Assert it is a request
+  if (0x0001 /*arp_request*/ == ntohs(data->opcode)) {
+    print_mac("srchw: ", data->srchw);
+    print_ip("srcpr: ", data->srcpr);
+
+    print_mac("dsthw: ", data->dsthw);
+    print_ip("dstpr: ", data->dstpr);
+
+    assert(0 == memcmp(data->dstpr, ip_address, sizeof(uint8_t[4])));
+
+    // Now we have to construct a ARP response
+    struct ARP_DATA response;
+    response.htype = htons(1);
+    response.ptype = htons(0x0800);
+    response.opcode = htons(0x00002);
+    response.hlen = 6;
+    response.plen = 4;
+    get_mac_address(response.srchw);
+    memcpy(response.srcpr, ip_address, sizeof(uint8_t[4]));
+
+    memcpy(response.dsthw, data->srchw, sizeof(uint8_t[6]));
+    memcpy(response.dstpr, data->srcpr, sizeof(uint8_t[4]));
+
+    send_ethernet_packet(data->srchw, 0x0806, (uint8_t *)&response,
+                         sizeof(response));
+  } else if (0x0002 /*arp_response*/ == ntohs(data->opcode)) {
+    // Find a entry to fill
+    struct ARP_TABLE_ENTRY *entry = find_arp_entry_to_use();
+    entry->is_used = 1;
+    memcpy(entry->mac, data->srchw, sizeof(uint8_t[6]));
+    memcpy(entry->ip, data->srcpr, sizeof(uint8_t[4]));
+    print_ip("Added ip: ", entry->ip);
+  } else {
+    kprintf("GOT A ARP REQEUST WITH TYPE: %x\n", ntohs(data->opcode));
+    assert(0);
+  }
+}