448 lines
15 KiB
C#
448 lines
15 KiB
C#
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///////////////////////////////////////////////////////////////////////////////
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//
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// Microsoft Research Singularity
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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///////////////////////////////////////////////////////////////////////////////
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/**
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* Microsoft Research, Cambridge
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* author: Yaron Weinsberg, Richard Black
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*/
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using NetStack.Common;
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using System;
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using System.Diagnostics;
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using System.Net.IP;
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using Drivers.Net;
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#if !SINGULARITY
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using System.Net;
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using System.Net.Sockets;
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#endif
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namespace NetStack.Protocols
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{
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/**
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* A TCP formatter class
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*/
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public class TcpFormat
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{
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// size of minimum TCP header (wo options)
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public const int Size = 20;
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// default IP MSS
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public const int IP_DEFAULT_MTU=576; // wo negotiation
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public const int IP_MTU=1500;
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// available TCP MSS
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public const int TCP_MSS=IP_MTU-IPFormat.Size-Size;
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// all header fields are given in host endianness
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public struct TcpHeader
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{
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public ushort sourcePort;
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public ushort destPort;
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public uint seq;
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public uint ackSeq;
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public byte off_res1; // number of 32-bit words, min=5
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public byte res2_flags;
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public ushort window;
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public ushort checksum;
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public ushort urgPtr;
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}
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// TCP states
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public enum TCPState
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{
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TCP_ESTABLISHED = 1,
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TCP_SYN_SENT,
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TCP_SYN_RECV,
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TCP_FIN_WAIT1,
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TCP_FIN_WAIT2,
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TCP_TIME_WAIT,
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TCP_CLOSE,
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TCP_CLOSE_WAIT,
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TCP_LAST_ACK,
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TCP_LISTEN,
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TCP_CLOSING,
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TCP_MAX_STATES /* Leave at the end! */
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};
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// construct a TCP header from a packet
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// if something is wrong, return the same start value
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public static bool ReadTcpHeader(IBuffer! buf, out TcpHeader tcphdr)
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{
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// initialize an TcpHeader struct
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tcphdr = new TcpHeader();
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bool b;
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b = buf.ReadNet16(out tcphdr.sourcePort);
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b &= buf.ReadNet16(out tcphdr.destPort);
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b &= buf.ReadNet32(out tcphdr.seq);
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b &= buf.ReadNet32(out tcphdr.ackSeq);
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b &= buf.Read8(out tcphdr.off_res1);
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b &= buf.Read8(out tcphdr.res2_flags);
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b &= buf.ReadNet16(out tcphdr.window);
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b &= buf.ReadNet16(out tcphdr.checksum);
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b &= buf.ReadNet16(out tcphdr.urgPtr);
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return b;
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}
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// TCP well known server ports
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public enum ReservedPort
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{
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ECHO = 7,
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CHARGEN = 19,
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FTP_DATA = 20,
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FTP_CONTROL = 21,
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SSH = 22,
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TELNET = 23,
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SMTP = 25,
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DOMAIN = 53,
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FINGER = 79,
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HTTP = 80,
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POP3 = 110,
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SUNRPC = 111,
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NNTP = 119,
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NETBIOS_SSN = 139,
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IMAP = 111,
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BGP = 179,
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LDAP = 389,
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HTTPS = 443,
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MSDS = 445,
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SOCKS = 1080
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}
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// some getters...
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public static byte GetOffset(ref TcpHeader hdr)
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{
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// return the header len (32 bit counter)
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return ((byte)((hdr.off_res1>>4) & 0x0F)); // 4 bits
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}
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public static byte GetReserve1(ref TcpHeader hdr)
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{
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return ((byte)(hdr.off_res1&0x0F)); // 4 bits
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}
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public static byte GetReserve2(ref TcpHeader hdr)
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{
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return ((byte)((hdr.res2_flags>>6) & 0x03)); // 2 bits
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}
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// The flags: "UAPRSF"
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// urgent pointer valid
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public static bool IsUrg(ref TcpHeader hdr)
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{
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return (((hdr.res2_flags>>5) & 0x01)==1); // 1 bits
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}
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// ack filed is valid
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public static bool IsAck(ref TcpHeader hdr)
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{
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return (((hdr.res2_flags>>4) & 0x01)==1); // 1 bits
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}
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// set ack
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public static void SetACK(ref TcpHeader hdr)
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{
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hdr.res2_flags=(byte)(hdr.res2_flags|16);
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}
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// push data
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public static bool IsPush(ref TcpHeader hdr)
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{
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return (((hdr.res2_flags>>3) & 0x01)==1); // 1 bits
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}
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// reset connection
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public static bool IsReset(ref TcpHeader hdr)
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{
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return (((hdr.res2_flags>>2) & 0x01)==1); // 1 bits
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}
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// set reset bit
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public static void SetReset(ref TcpHeader hdr)
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{
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hdr.res2_flags=(byte)(hdr.res2_flags|0x4);
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}
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// synchronize sequence numbers
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public static bool IsSync(ref TcpHeader hdr)
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{
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return (((hdr.res2_flags>>1) & 0x01)==1); // 1 bits
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}
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// set syn
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public static void SetSYN(ref TcpHeader hdr)
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{
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hdr.res2_flags=(byte)(hdr.res2_flags|2);
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}
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// set fin
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public static void SetFIN(ref TcpHeader hdr)
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{
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hdr.res2_flags=(byte)(hdr.res2_flags|1);
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}
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// no more data ; finish connection
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public static bool IsFIN(ref TcpHeader hdr)
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{
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return ((hdr.res2_flags & 0x01)==1); // 1 bits
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}
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// writes a TCP header to a packet
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// return the next place to write to
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// the checksum must be later calculated and cover the
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// pseudoheader and entire TCP segment
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public static int WriteTcpHeader(byte[]! pkt, int offset, ref TcpHeader hdr)
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{
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// check we have enough packet space
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if (pkt.Length - offset < Size)
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return offset;
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int o = offset;
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pkt[o++] = (byte)(((ushort)hdr.sourcePort) >> 8);
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pkt[o++] = (byte) (((ushort)hdr.sourcePort) & 0xff);
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pkt[o++] = (byte)(((ushort)hdr.destPort) >> 8);
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pkt[o++] = (byte) (((ushort)hdr.destPort) & 0xff);
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pkt[o++] = (byte)(((uint)hdr.seq) >> 24);
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pkt[o++] = (byte)(((uint)hdr.seq) >> 16);
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pkt[o++] = (byte)(((uint)hdr.seq) >> 8);
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pkt[o++] = (byte) (((uint)hdr.seq) & 0xff);
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pkt[o++] = (byte)(((uint)hdr.ackSeq) >> 24);
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pkt[o++] = (byte)(((uint)hdr.ackSeq) >> 16);
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pkt[o++] = (byte)(((uint)hdr.ackSeq) >> 8);
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pkt[o++] = (byte) (((uint)hdr.ackSeq) & 0xff);
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pkt[o++] = hdr.off_res1;
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pkt[o++] = hdr.res2_flags;
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pkt[o++] = (byte)(((ushort)hdr.window) >> 8);
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pkt[o++] = (byte) (((ushort)hdr.window) & 0xff);
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// checksum
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pkt[o++] = 0;
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pkt[o++] = 0;
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pkt[o++] = (byte)(((ushort)hdr.urgPtr) >> 8);
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pkt[o++] = (byte) (((ushort)hdr.urgPtr) & 0xff);
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return o;
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}
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// set the checksum field
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// offset points to the beginning of the IP header (!!!)
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// Should be called after the TCP header + data have been written
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public static void SetTcpChecksum(byte[]! packet,
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int ipOffset,
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ref TcpHeader tcpHeader)
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{
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// sum IP pseudo
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ushort ipPayloadLength = 0;
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ushort headerSum =
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IPFormat.SumPseudoHeader(packet, ipOffset,
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ref ipPayloadLength);
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int ipHeaderSize = (packet[ipOffset] & 0xf) * 4;
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int tcpOffset = ipOffset + ipHeaderSize;
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Debug.Assert(packet[tcpOffset + 16] == 0);
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Debug.Assert(packet[tcpOffset + 17] == 0);
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// now add it to the TCP header + data
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ushort payloadSum = IPFormat.SumShortValues(packet, tcpOffset,
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ipPayloadLength);
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tcpHeader.checksum = (ushort)
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~(IPFormat.SumShortValues(headerSum, payloadSum));
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packet[tcpOffset + 16] = (byte) (tcpHeader.checksum >> 8);
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packet[tcpOffset + 17] = (byte) (tcpHeader.checksum & 0xff);
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}
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public static ushort SumHeader(TcpHeader tcpHeader)
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{
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int checksum = tcpHeader.sourcePort;
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checksum += tcpHeader.destPort;
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checksum += (int) (tcpHeader.seq >> 16);
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checksum += (int) (tcpHeader.seq & 0xffff);
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checksum += (int) (tcpHeader.ackSeq >> 16);
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checksum += (int) (tcpHeader.ackSeq & 0xffff);
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checksum += (((int)tcpHeader.off_res1) << 8) | (int)tcpHeader.res2_flags;
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checksum += (int) tcpHeader.window;
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checksum += (int) tcpHeader.urgPtr;
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// Double-wrap checksum
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checksum = (checksum & 0xFFFF) + (checksum >> 16);
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checksum = (checksum & 0xFFFF) + (checksum >> 16);
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return (ushort)checksum;
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}
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public static bool IsChecksumValid(IPFormat.IPHeader! ipHeader,
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TcpHeader tcpHeader,
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NetPacket! payload)
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{
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// Compute partial checksums of headers
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ushort checksum = IPFormat.SumPseudoHeader(ipHeader);
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checksum = IPFormat.SumShortValues(checksum,
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SumHeader(tcpHeader));
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// Checksum payload
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int length = payload.Available;
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int end = length & ~1;
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int i = 0;
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while (i != end)
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{
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int x = ((((int) payload.PeekAvailable(i++)) << 8) +
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(int) payload.PeekAvailable(i++));
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checksum = IPFormat.SumShortValues(checksum, (ushort) x);
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}
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if (i != length)
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{
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int x = (((int) payload.PeekAvailable(i++)) << 8);
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checksum = IPFormat.SumShortValues(checksum, (ushort) x);
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}
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checksum = (ushort) ~checksum;
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if (tcpHeader.checksum != checksum)
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{
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Console.WriteLine("Bad TCP checksum {0:x4} != {1:x4}",
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tcpHeader.checksum, checksum);
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}
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return tcpHeader.checksum == checksum;
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}
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// a helper method to write the TCP segment (without data)
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public static void WriteTcpSegment(byte[]! pktData,
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ushort localPort,
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ushort destPort,
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uint ackSeq,
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uint seq,
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ushort wnd,
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IPv4 sIP,
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IPv4 dIP,
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ushort dataLen,
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bool isAck,
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bool isSyn,
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bool isRst,
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bool isFin,
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bool withOptions)
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{
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// now create the IP,TCP headers!
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int start=EthernetFormat.Size;
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// prepare it...
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TcpFormat.TcpHeader tcpHeader = new TcpFormat.TcpHeader();
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tcpHeader.sourcePort = localPort;
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tcpHeader.destPort = destPort;
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if (withOptions)
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{
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tcpHeader.off_res1 = 0x60;
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}
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else
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{
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tcpHeader.off_res1 = 0x50;
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}
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tcpHeader.ackSeq = ackSeq;
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tcpHeader.seq = seq;
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tcpHeader.window = wnd;
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if (isFin)
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{
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TcpFormat.SetFIN(ref tcpHeader);
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}
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if (isSyn)
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{
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TcpFormat.SetSYN(ref tcpHeader);
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}
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if (isAck)
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{
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TcpFormat.SetACK(ref tcpHeader);
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}
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if (isRst)
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{
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TcpFormat.SetReset(ref tcpHeader);
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}
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IPFormat.IPHeader ipHeader = new IPFormat.IPHeader();
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ipHeader.SetDefaults(IPFormat.Protocol.TCP);
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ipHeader.totalLength = (ushort)(IPFormat.Size + TcpFormat.Size+dataLen);
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ipHeader.srcAddr = sIP;
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ipHeader.destAddr = dIP;
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IPFormat.SetDontFragBit(ipHeader);
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// write the ip header + ip checksum
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start = IPFormat.WriteIPHeader(pktData, start, ipHeader);
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// write TCP header, no checksum
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||
|
|
start = TcpFormat.WriteTcpHeader(pktData, start, ref tcpHeader);
|
||
|
|
|
||
|
|
// calc the checksum...
|
||
|
|
TcpFormat.SetTcpChecksum(pktData, EthernetFormat.Size, ref tcpHeader);
|
||
|
|
}
|
||
|
|
|
||
|
|
#if SINGULARITY
|
||
|
|
private static long snBase = 133413;
|
||
|
|
|
||
|
|
public static int GenerateSequenceNumber(IPv4 localHost,
|
||
|
|
IPv4 remoteHost,
|
||
|
|
ushort localPort,
|
||
|
|
ushort remotePort)
|
||
|
|
{
|
||
|
|
// No MD5 for now so perform a weak hash
|
||
|
|
long isn = DateTime.UtcNow.Ticks;
|
||
|
|
|
||
|
|
snBase = snBase + 2287 * snBase;
|
||
|
|
isn += snBase;
|
||
|
|
|
||
|
|
int i = 0;
|
||
|
|
foreach (byte b in localHost.GetAddressBytes()) {
|
||
|
|
isn ^= ((long)b) << i;
|
||
|
|
i += 8;
|
||
|
|
}
|
||
|
|
|
||
|
|
foreach (byte b in localHost.GetAddressBytes()) {
|
||
|
|
isn ^= ((long)b) << i;
|
||
|
|
i += 8;
|
||
|
|
}
|
||
|
|
|
||
|
|
isn += (localPort << 16) | remotePort;
|
||
|
|
return (int)((isn >> 32) ^ isn);
|
||
|
|
}
|
||
|
|
#else
|
||
|
|
public static int GenerateSequenceNumber(IPAddress localHost,IPAddress remoteHost,
|
||
|
|
ushort localPort,ushort remotePort)
|
||
|
|
{
|
||
|
|
// generate safer initial sequence numbers (RFC 1948)
|
||
|
|
// ISN = M + F(localhost, localport, remotehost, remoteport).
|
||
|
|
|
||
|
|
byte[] data=new byte[12];
|
||
|
|
Array.Copy(localHost.GetAddressBytes(),0,data,0,4);
|
||
|
|
Array.Copy(remoteHost.GetAddressBytes(),0,data,4,4);
|
||
|
|
data[8]=(byte)(localPort>>8);
|
||
|
|
data[9]=(byte)localPort;
|
||
|
|
data[10]=(byte)(remotePort>>8);
|
||
|
|
data[11]=(byte)remotePort;
|
||
|
|
|
||
|
|
System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
|
||
|
|
byte[] result = md5.ComputeHash(data);
|
||
|
|
string hashString = Convert.ToBase64String(result);
|
||
|
|
return (int)(Convert.ToInt64(hashString,10)+(uint)DateTime.UtcNow.Ticks);
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
}
|