Diff: net/tcp.h

Revision:

1:feaa107f56b3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/net/tcp.h	Fri Apr 24 03:11:02 2015 +0000
@@ -0,0 +1,90 @@
+#ifndef TCP_H
+#define TCP_H
+
+#include "net.h"
+
+/**
+  \file tcp.h
+  \brief TCP segment header
+  
+  This file contains the memory map and associated functions for TCP segment header
+  creation and deconstruction. 
+*/
+
+#define IPPROTO_TCP 0x06
+
+/// TCP Segment memory map
+typedef struct {
+  u16 source_port;         ///< Source port (1-65535)
+  u16 destination_port;    ///< Destination port (1-65535)
+  u32 sequence_number;     ///< TCP Sequence number (initial one if SYN set)
+  u32 acknowledge_number;  ///< TCP Acknowledge number (valid if ACK set)
+  
+  unsigned data_offset_bytes_div4:4; ///< Length of this header (20) divided by 4 (should be 5)
+  unsigned unused_0:4;               ///< Unused, should be zero
+  
+  unsigned fin:1; ///< connection FINished (no more data from sender)
+  unsigned syn:1; ///< SYNchronize sequence numbers
+  unsigned rst:1; ///< ReSeT the connection
+  unsigned psh:1; ///< PuSH to receiving application
+  unsigned ack:1; ///< ACKnowledge fiend is significant
+  unsigned urg:1; ///< URGent field is significant
+  unsigned ece:1; ///< ECn Echo
+  unsigned cwr:1; ///< Congestion Window Reduced
+  
+  u16 window_size;    ///< TCP Maxumum window size (8192 is good)
+  u16 checksum;       ///< TCP checksum (computed with pseudo header)
+  u16 urgent_pointer; ///< Urgent pointer (valid if URG set)
+  
+  /// Memory map for data if no options are set
+  unsigned char data[];
+} TCP_SegmentHeader;
+
+/// Convert from wire to host or host to wire endianness
+inline void fix_endian_tcp(TCP_SegmentHeader *segment)
+{
+  segment->unused_0 ^= segment->data_offset_bytes_div4;
+  segment->data_offset_bytes_div4 ^= segment->unused_0;
+  segment->unused_0 ^= segment->data_offset_bytes_div4;
+  fix_endian_u16(&segment->source_port);
+  fix_endian_u16(&segment->destination_port);
+  fix_endian_u16(&segment->window_size);
+  // No fixing checksums
+  fix_endian_u16(&segment->urgent_pointer);
+  fix_endian_u32(&segment->sequence_number);
+  fix_endian_u32(&segment->acknowledge_number);
+}
+
+/// Print the TCP segment header
+inline void print_tcp(TCP_SegmentHeader *segment)
+{
+  printf("TCP Segment: \n");
+  printf("  Source:    PORT %d \n", segment->source_port);
+  printf("  Dest:      PORT %d \n", segment->destination_port);
+  printf("  TCP Seqno: 0x%08X \n", segment->sequence_number);
+  printf("  TCP Ackno: 0x%08X \n", segment->acknowledge_number);
+  printf("  Header:    %d bytes \n", segment->data_offset_bytes_div4*4);
+  if (segment->cwr) printf("  Flag:      CWR \n");
+  if (segment->ece) printf("  Flag:      ECE \n");
+  if (segment->urg) printf("  Flag:      URG \n");
+  if (segment->ack) printf("  Flag:      ACK \n");
+  if (segment->psh) printf("  Flag:      PSH \n");
+  if (segment->rst) printf("  Flag:      RST \n");
+  if (segment->syn) printf("  Flag:      SYN \n");
+  if (segment->fin) printf("  Flag:      FIN \n");
+}
+
+/// Compute the pseudo header checksum with the given source, destination, and length
+inline u16 pseudo_header_checksum(IP_Address source, IP_Address destination, u16 length)
+{
+  struct {
+    IP_Address src, dst;
+    u8 zeros;
+    u8 proto;
+    u16 length;
+  } pseudoheader = {source, destination, 0, IPPROTO_TCP, length};
+  fix_endian_u16(&pseudoheader.length);
+  return checksum(&pseudoheader, sizeof(pseudoheader));
+}
+
+#endif
\ No newline at end of file