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.

10 files changed, 444 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);
+  }
+}
diff --git a/kernel/network/arp.h b/kernel/network/arp.h
new file mode 100644
index 0000000..c2beb94
--- /dev/null
+++ b/kernel/network/arp.h
@@ -0,0 +1,4 @@
+#include <stdint.h>
+
+int get_mac_from_ip(const uint8_t ip[4], uint8_t mac[6]);
+void handle_arp(const uint8_t *payload);
diff --git a/kernel/network/bytes.c b/kernel/network/bytes.c
new file mode 100644
index 0000000..94afa73
--- /dev/null
+++ b/kernel/network/bytes.c
@@ -0,0 +1,10 @@
+#include <network/bytes.h>
+
+uint16_t ntohs(uint16_t net) { return (net >> 8) | (net << 8); }
+
+uint16_t htons(uint16_t net) { return (net >> 8) | (net << 8); }
+
+uint32_t htonl(uint32_t net) {
+  return (((net & 0x000000FF) << 24) | ((net & 0x0000FF00) << 8) |
+          ((net & 0x00FF0000) >> 8) | ((net & 0xFF000000) >> 24));
+}
diff --git a/kernel/network/bytes.h b/kernel/network/bytes.h
new file mode 100644
index 0000000..c291589
--- /dev/null
+++ b/kernel/network/bytes.h
@@ -0,0 +1,5 @@
+#include <stdint.h>
+
+uint16_t ntohs(uint16_t net);
+uint16_t htons(uint16_t net);
+uint32_t htonl(uint32_t net);
diff --git a/kernel/network/ethernet.c b/kernel/network/ethernet.c
new file mode 100644
index 0000000..e97ccbd
--- /dev/null
+++ b/kernel/network/ethernet.c
@@ -0,0 +1,93 @@
+#include <assert.h>
+#include <drivers/rtl8139.h>
+#include <kmalloc.h>
+#include <network/arp.h>
+#include <network/bytes.h>
+#include <network/ethernet.h>
+#include <network/ipv4.h>
+#include <stdio.h>
+
+struct ETHERNET_HEADER {
+  uint8_t mac_dst[6];
+  uint8_t mac_src[6];
+  uint16_t type;
+};
+
+uint32_t crc32(const char *buf, size_t len) {
+  static uint32_t table[256];
+  static int have_table = 0;
+  uint32_t rem;
+  uint8_t octet;
+  int i, j;
+  const char *p, *q;
+
+  if (have_table == 0) {
+    for (i = 0; i < 256; i++) {
+      rem = i;
+      for (j = 0; j < 8; j++) {
+        if (rem & 1) {
+          rem >>= 1;
+          rem ^= 0xedb88320;
+        } else
+          rem >>= 1;
+      }
+      table[i] = rem;
+    }
+    have_table = 1;
+  }
+
+  uint32_t crc = 0xFFFFFFFF;
+  q = buf + len;
+  for (p = buf; p < q; p++) {
+    octet = *p;
+    crc = (crc >> 8) ^ table[(crc & 0xff) ^ octet];
+  }
+  return ~crc;
+}
+
+void handle_ethernet(const uint8_t *packet, uint64_t packet_length) {
+  struct ETHERNET_HEADER *eth_header = (struct ETHERNET_HEADER *)packet;
+  packet += sizeof(struct ETHERNET_HEADER);
+  const uint8_t *payload = packet;
+  packet += packet_length - sizeof(struct ETHERNET_HEADER);
+  uint32_t crc = *((uint32_t *)packet - 1);
+  kprintf("PACKET crc: %x\n", crc);
+  kprintf("OUR OWN CALCULATED crc: %x\n",
+          crc32((const char *)eth_header, (packet_length - 4)));
+
+  uint16_t type = ntohs(eth_header->type);
+  switch (type) {
+  case 0x0806:
+    handle_arp(payload);
+    break;
+  case 0x0800:
+    handle_ipv4(payload, packet_length - sizeof(struct ETHERNET_HEADER) - 4);
+    break;
+  default:
+    kprintf("Can't handle ethernet type\n");
+    break;
+  }
+}
+
+void send_ethernet_packet(uint8_t mac_dst[6], uint16_t type, uint8_t *payload,
+                          uint64_t payload_length) {
+  // FIXME: Janky allocation, do this better
+  uint64_t buffer_size =
+      sizeof(struct ETHERNET_HEADER) + payload_length + sizeof(uint32_t);
+  uint8_t *buffer = kmalloc(buffer_size);
+  uint8_t *buffer_start = buffer;
+  struct ETHERNET_HEADER *eth_header = (struct ETHERNET_HEADER *)buffer;
+  buffer += sizeof(struct ETHERNET_HEADER);
+  memcpy(buffer, payload, payload_length);
+  buffer += payload_length;
+
+  memcpy(eth_header->mac_dst, mac_dst, sizeof(uint8_t[6]));
+  get_mac_address(eth_header->mac_src);
+  eth_header->type = htons(type);
+  *(uint32_t *)(buffer) =
+      htonl(crc32((const char *)buffer_start, buffer_size - 4));
+
+  assert(rtl8139_send_data(buffer_start, buffer_size));
+  kfree(buffer_start);
+  kprintf("sent data\n");
+}
diff --git a/kernel/network/ethernet.h b/kernel/network/ethernet.h
new file mode 100644
index 0000000..0fdcee3
--- /dev/null
+++ b/kernel/network/ethernet.h
@@ -0,0 +1,5 @@
+#include <stdint.h>
+
+void handle_ethernet(const uint8_t *packet, uint64_t packet_length);
+void send_ethernet_packet(uint8_t mac_dst[6], uint16_t type, uint8_t *payload,
+                          uint64_t payload_length);
diff --git a/kernel/network/ipv4.c b/kernel/network/ipv4.c
new file mode 100644
index 0000000..099aa0d
--- /dev/null
+++ b/kernel/network/ipv4.c
@@ -0,0 +1,98 @@
+#include <assert.h>
+#include <kmalloc.h>
+#include <network/arp.h>
+#include <network/bytes.h>
+#include <network/ethernet.h>
+#include <network/ipv4.h>
+#include <network/udp.h>
+#include <string.h>
+
+uint16_t ip_checksum(void *vdata, size_t length) {
+  // Cast the data pointer to one that can be indexed.
+  char *data = (char *)vdata;
+
+  // Initialise the accumulator.
+  uint32_t acc = 0xffff;
+
+  // Handle complete 16-bit blocks.
+  for (size_t i = 0; i + 1 < length; i += 2) {
+    uint16_t word;
+    memcpy(&word, data + i, 2);
+    acc += ntohs(word);
+    if (acc > 0xffff) {
+      acc -= 0xffff;
+    }
+  }
+
+  // Handle any partial block at the end of the data.
+  if (length & 1) {
+    uint16_t word = 0;
+    memcpy(&word, data + length - 1, 1);
+    acc += ntohs(word);
+    if (acc > 0xffff) {
+      acc -= 0xffff;
+    }
+  }
+
+  // Return the checksum in network byte order.
+  return htons(~acc);
+}
+
+extern uint8_t ip_address[4];
+void send_ipv4_packet(uint32_t ip, uint8_t protocol, const uint8_t *payload,
+                      uint16_t length) {
+  uint8_t header[20] = {0};
+  header[0] = (4 /*version*/ << 4) | (5 /*IHL*/);
+  *((uint16_t *)(header + 2)) = htons(length + 20);
+  header[8 /*TTL*/] = 0xF8;
+  header[9] = protocol;
+
+  memcpy(header + 12 /*src_ip*/, ip_address, sizeof(uint8_t[4]));
+  memcpy(header + 16, &ip, sizeof(uint8_t[4]));
+
+  *((uint16_t *)(header + 10 /*checksum*/)) = ip_checksum(header, 20);
+  uint16_t packet_length = length + 20;
+  uint8_t *packet = kmalloc(packet_length);
+  memcpy(packet, header, 20);
+  memcpy(packet + 20, payload, length);
+
+  uint8_t mac[6];
+  uint8_t ip_copy[4]; // TODO: Do I need to do this?
+  memcpy(ip_copy, &ip, sizeof(uint8_t[4]));
+  get_mac_from_ip(ip_copy, mac);
+  send_ethernet_packet(mac, 0x0800, packet, packet_length);
+  kfree(packet);
+}
+
+void handle_ipv4(const uint8_t *payload, uint32_t packet_length) {
+  assert(packet_length > 4);
+
+  uint16_t saved_checksum = *(uint16_t *)(payload + 10);
+  *(uint16_t *)(payload + 10) = 0;
+  uint16_t calc_checksum = ip_checksum((uint8_t *)payload, 20);
+  *(uint16_t *)(payload + 10) = saved_checksum;
+  assert(calc_checksum == saved_checksum);
+
+  uint8_t version = (*payload & 0xF0) >> 4;
+  uint8_t IHL = (*payload & 0xF);
+  kprintf("version: %x\n", version);
+  assert(4 == version);
+  assert(5 == IHL);
+  uint16_t ipv4_total_length = ntohs(*(uint16_t *)(payload + 2));
+  assert(ipv4_total_length >= 20);
+  // Make sure the ipv4 header is not trying to get uninitalized memory
+  assert(ipv4_total_length <= packet_length);
+
+  uint8_t src_ip[4];
+  memcpy(src_ip, payload + 12, sizeof(uint8_t[4]));
+
+  uint8_t protocol = *(payload + 9);
+  switch (protocol) {
+  case 0x11:
+    handle_udp(src_ip, payload + 20, ipv4_total_length - 20);
+    break;
+  default:
+    kprintf("Protocol given in IPv4 header not handeld: %x\n", protocol);
+    break;
+  }
+}
diff --git a/kernel/network/ipv4.h b/kernel/network/ipv4.h
new file mode 100644
index 0000000..f578202
--- /dev/null
+++ b/kernel/network/ipv4.h
@@ -0,0 +1,5 @@
+#include <stdint.h>
+
+void handle_ipv4(const uint8_t *payload, uint32_t packet_length);
+void send_ipv4_packet(uint32_t ip, uint8_t protocol, const uint8_t *payload,
+                      uint16_t length);
diff --git a/kernel/network/udp.c b/kernel/network/udp.c
new file mode 100644
index 0000000..23411da
--- /dev/null
+++ b/kernel/network/udp.c
@@ -0,0 +1,64 @@
+#include <assert.h>
+#include <network/bytes.h>
+#include <network/ipv4.h>
+#include <network/udp.h>
+#include <socket.h>
+
+void send_udp_packet(struct sockaddr_in *src, const struct sockaddr_in *dst,
+                     const uint8_t *payload, uint16_t payload_length) {
+  uint16_t header[4] = {0};
+  header[0] = src->sin_port;
+  header[1] = dst->sin_port;
+  header[2] = htons(payload_length + 8);
+
+  uint16_t packet_length = sizeof(header) + payload_length;
+  uint8_t *packet = kmalloc(packet_length);
+  memcpy(packet, header, sizeof(header));
+  memcpy(packet + sizeof(header), payload, payload_length);
+  send_ipv4_packet(dst->sin_addr.s_addr, 0x11, packet, packet_length);
+  kfree(packet);
+}
+
+void handle_udp(uint8_t src_ip[4], const uint8_t *payload,
+                uint32_t packet_length) {
+  assert(packet_length >= 8);
+  // n_.* means network format(big endian)
+  // h_.* means host format((probably) little endian)
+  uint16_t n_source_port = *(uint16_t *)payload;
+  uint16_t h_source_port = ntohs(n_source_port);
+  (void)h_source_port;
+  uint16_t h_dst_port = ntohs(*(uint16_t *)(payload + 2));
+  uint16_t h_length = ntohs(*(uint16_t *)(payload + 4));
+  assert(h_length == packet_length);
+  uint16_t data_length = h_length - 8;
+  const uint8_t *data = payload + 8;
+
+  // Find the open port
+  OPEN_INET_SOCKET *in_s = find_open_udp_port(htons(h_dst_port));
+  assert(in_s);
+  SOCKET *s = in_s->s;
+  vfs_fd_t *fifo_file = s->ptr_socket_fd;
+
+  // Write the sockaddr struct such that it can later be
+  // given to userland if asked.
+  struct sockaddr_in /*{
+    sa_family_t sin_family;
+    union {
+      uint32_t s_addr;
+    } sin_addr;
+    uint16_t sin_port;
+  }*/ in;
+  in.sin_family = AF_INET;
+  memcpy(&in.sin_addr.s_addr, src_ip, sizeof(uint32_t));
+  in.sin_port = n_source_port;
+  socklen_t sock_length = sizeof(struct sockaddr_in);
+
+  raw_vfs_pwrite(fifo_file, &sock_length, sizeof(sock_length), 0);
+  raw_vfs_pwrite(fifo_file, &in, sizeof(in), 0);
+
+  // Write the UDP payload length(not including header)
+  raw_vfs_pwrite(fifo_file, &data_length, sizeof(uint16_t), 0);
+
+  // Write the UDP payload
+  raw_vfs_pwrite(fifo_file, (char *)data, data_length, 0);
+}
diff --git a/kernel/network/udp.h b/kernel/network/udp.h
new file mode 100644
index 0000000..c30b8c8
--- /dev/null
+++ b/kernel/network/udp.h
@@ -0,0 +1,7 @@
+#include <socket.h>
+#include <stdint.h>
+
+void handle_udp(uint8_t src_ip[4], const uint8_t *payload,
+                uint32_t packet_length);
+void send_udp_packet(struct sockaddr_in *src, const struct sockaddr_in *dst,
+                     const uint8_t *payload, uint16_t payload_length);