Diff: net/ip.h

Revision:

1:feaa107f56b3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/net/ip.h	Fri Apr 24 03:11:02 2015 +0000
@@ -0,0 +1,115 @@
+#ifndef IP_H
+#define IP_H
+
+#include "net.h"
+
+/**
+  \file ip.h
+  \brief IP Packet header
+  
+  This file contains the memory map and associated functions for IP packet header
+  creation and deconstruction. 
+*/
+
+#define ETHERTYPE_IPV4 0x0800
+#define ETHERTYPE_IPV6 0x86DD
+
+/// IP Address memory map
+typedef struct {
+  unsigned char octet[4]; ///< Individual address octets
+} IP_Address;
+
+/// IP Packet memory map
+typedef struct {
+  /// 4 bits that contain the version, that specifies if it's an IPv4 or IPv6 packet,
+  unsigned version:4; // Only 0x4 supported
+  /// 4 bits that contain the Internet Header Length which is the length of the header in multiples of 4 bytes (eg. 5 means 20 bytes).
+  unsigned header_bytes_div4:4;
+  /// 8 bits that contain the Type of Service, also referred to as Quality of Service (QoS), which describes what priority the packet should have,
+  unsigned tos:8;
+  /// 16 bits that contain the total length of the IP packet (datagram) in bytes,
+  u16 packet_bytes;
+  /// 16 bits that contain an identification tag to help reconstruct the packet from several fragments,
+  u16 fragment_id;
+  /// 3 bits that contain a zero, a flag that says whether the packet is allowed to be fragmented or not (DF: Don't fragment), and a flag to state whether more fragments of a packet follow (MF: More Fragments)
+  unsigned unused_0:1;
+  unsigned dont_fragment:1;
+  unsigned more_follow:1;
+  /// 13 bits that contain the fragment offset, a field to identify position of fragment within original packet
+  unsigned fragment_offset:13; ///< This and the ones above may not work properly due to endianness
+  /// 8 bits that contain the Time to live (TTL) which is the number of hops (router, computer or device along a network) the packet is allowed to pass before it dies (for example, a packet with a TTL of 16 will be allowed to go across 16 routers to get to its destination before it is discarded),
+  unsigned ttl:8;
+  /// 8 bits that contain the protocol (TCP, UDP, ICMP, etc...)
+  ///   0x01 ICMP
+  ///   0x06 TCP
+  ///   0x11 UDP
+  unsigned protocol:8;
+  /// 16 bits that contain the Header Checksum, a number used in error detection,
+  u16 header_checksum;
+  /// 32 bits that contain the source IP address,
+  IP_Address source;
+  /// 32 bits that contain the destination address.
+  IP_Address destination;
+  /// Zero-length field for memory mapping the packet data
+  unsigned char data[];
+} IP_PacketHeader;
+
+/// Convert from wire to host or host to wire endianness
+inline void fix_endian_ip(IP_PacketHeader *packet)
+{
+  packet->version ^= packet->header_bytes_div4;
+  packet->header_bytes_div4 ^= packet->version;
+  packet->version ^= packet->header_bytes_div4;
+  fix_endian_u16(&packet->packet_bytes);
+  fix_endian_u16(&packet->fragment_id);
+  // Don't fix checksums; they are done bitwise
+}
+
+/// Get a constant string of the given IP protocol (e.g. "ICMP", "TCP", "UDP") if known
+inline const char *ipproto2name(u8 proto)
+{
+  switch (proto)
+  {
+    case 0x01: return "ICMP";
+    case 0x02: return "IGMP";
+    case 0x06: return "TCP";
+    case 0x11: return "UDP";
+  }
+  return "<UNKNOWN>";
+}
+
+/// Print the IP packet
+inline void print_ip(IP_PacketHeader *packet)
+{
+  printf("IPv%d Packet: \n", packet->version);
+  if (packet->version != 4)
+  {
+    printf("Not an IPv4 packet (skipping)");
+    return;
+  }
+    
+  u8 *dst = packet->destination.octet;
+  u8 *src = packet->source.octet;
+  printf("  Source:    IP - %03d.%03d.%03d.%03d \n", src[0], src[1], src[2], src[3]);
+  printf("  Dest:      IP - %03d.%03d.%03d.%03d \n", dst[0], dst[1], dst[2], dst[3]);
+  printf("  TTL:       %d \n", packet->ttl);
+  printf("  Protocol:  0x%02X (%s) \n", packet->protocol, ipproto2name(packet->protocol));
+  printf("  ToS:       0x%02X \n", packet->tos);
+  printf("  Header:    %d bytes \n", packet->header_bytes_div4*4);
+  printf("  Packet:    %d bytes \n", packet->packet_bytes);
+  printf("  Fragment:  0x%04X DF=%d MF=%d OFFSET=0x04X", packet->fragment_id, packet->dont_fragment, packet->more_follow, packet->fragment_offset);
+  printf("  Checksum:  0x%04X \n", packet->header_checksum);
+}
+
+/// Parse the string (in decimal triple-dot notation) into the IP address structure
+inline void str2ipaddr(const char *ip, IP_Address *addr)
+{
+  static short a,b,c,d;
+  sscanf(ip, "%3hd.%3hd.%3hd.%3hd", &a, &b, &c, &d);
+  addr->octet[0] = a;
+  addr->octet[1] = b;
+  addr->octet[2] = c;
+  addr->octet[3] = d;
+}
+
+#endif
\ No newline at end of file