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libtins/include/tcp.h

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/*
* libtins is a net packet wrapper library for crafting and
* interpreting sniffed packets.
*
* Copyright (C) 2011 Nasel
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef TINS_TCP_H
#define TINS_TCP_H
#include <list>
#include <vector>
#include <stdint.h>
#include <stdexcept>
#include <utility>
#include "pdu.h"
#include "endianness.h"
#include "small_uint.h"
#include "pdu_option.h"
namespace Tins {
/**
* \brief Class that represents an TCP PDU.
*
* TCP is the representation of the TCP PDU. Instances of this class
* must be sent over a level 3 PDU, this will otherwise fail.
*/
class TCP : public PDU {
public:
/**
* This PDU's flag.
*/
static const PDU::PDUType pdu_flag = PDU::TCP;
/**
* \brief TCP flags enum.
*
* These flags identify those supported by the TCP PDU.
*/
enum Flags {
FIN,
SYN,
RST,
PSH,
ACK,
URG,
ECE,
CWR
};
/**
* \brief TCP options enum.
*
* This enum identifies valid options supported by TCP PDU.
*/
enum Option {
EOL = 0,
NOP = 1,
MSS = 2,
WSCALE = 3,
SACK_OK = 4,
SACK = 5,
TSOPT = 8,
ALTCHK = 14
};
/**
* \brief Alternate checksum enum.
*/
enum AltChecksums {
CHK_TCP,
CHK_8FLETCHER,
CHK_16FLETCHER
};
typedef PDUOption<uint8_t> tcp_option;
/**
* The type used to store the options.
*/
typedef std::list<tcp_option> options_type;
/**
* The type used to store the sack option.
*/
typedef std::vector<uint32_t> sack_type;
/**
* \brief TCP constructor.
*
* Creates an instance of TCP. Destination and source port can
* be provided, otherwise both will be 0.
* \param dport Destination port.
* \param sport Source port.
* */
TCP(uint16_t dport = 0, uint16_t sport = 0);
/**
* \brief Constructor which creates an TCP object from a buffer
* and adds all identifiable PDUs found in the buffer as children
* of this one.
* \param buffer The buffer from which this PDU will be constructed.
* \param total_sz The total size of the buffer.
*/
TCP(const uint8_t *buffer, uint32_t total_sz);
/**
* \brief Getter for the destination port field.
*
* \return The destination port in an uint16_t.
*/
uint16_t dport() const { return Endian::be_to_host(_tcp.dport); }
/**
* \brief Getter for the source port field.
*
* \return The source port in an uint16_t.
*/
uint16_t sport() const { return Endian::be_to_host(_tcp.sport); }
/**
* \brief Getter for the sequence number field.
*
* \return The sequence number in an uint32_t.
*/
uint32_t seq() const { return Endian::be_to_host(_tcp.seq); }
/**
* \brief Getter for the acknowledge number field.
*
* \return The acknowledge number in an uint32_t.
*/
uint32_t ack_seq() const { return Endian::be_to_host(_tcp.ack_seq); }
/**
* \brief Getter for the window size field.
*
* \return The window size in an uint32_t.
*/
uint16_t window() const { return Endian::be_to_host(_tcp.window); }
/**
* \brief Getter for the checksum field.
*
* \return The checksum field in an uint16_t.
*/
uint16_t check() const { return Endian::be_to_host(_tcp.check); }
/**
* \brief Getter for the urgent pointer field.
*
* \return The urgent pointer in an uint16_t.
*/
uint16_t urg_ptr() const { return Endian::be_to_host(_tcp.urg_ptr); }
/**
* \brief Getter for the data offset field.
*
* \return Data offset in an uint8_t.
*/
small_uint<4> data_offset() const { return this->_tcp.doff; }
/**
* \brief Getter for the option list.
*
* \return The options list.
*/
const options_type &options() const { return _options; }
/**
* \brief Gets the value of a flag.
*
* \param tcp_flag The polled flag.
* \return The value of the flag.
*/
small_uint<1> get_flag(Flags tcp_flag);
/* Setters */
/**
* \brief Setter for the destination port field.
*
* \param new_dport The new destination port.
*/
void dport(uint16_t new_dport);
/**
* \brief Setter for the source port field.
*
* \param new_sport The new source port.
*/
void sport(uint16_t new_sport);
/**
* \brief Setter for the sequence number.
*
* \param new_seq The new sequence number.
*/
void seq(uint32_t new_seq);
/**
* \brief Setter for the acknowledge number.
*
* \param new_ack_seq The new acknowledge number.
*/
void ack_seq(uint32_t new_ack_seq);
/**
* \brief Setter for the window size.
*
* \param new_window The new window size.
*/
void window(uint16_t new_window);
/**
* \brief Setter for the checksum field.
*
* \param new_check The new checksum.
*/
void check(uint16_t new_check);
/**
* \brief Setter for the urgent pointer field.
*
* \param new_urg_ptr The new urgent pointer.
*/
void urg_ptr(uint16_t new_urg_ptr);
/**
* \brief Setter for the data offset pointer field.
*
* \param new_doff The new data offset pointer.
*/
void data_offset(small_uint<4> new_doff);
// Options
/**
* \brief Add a maximum segment size option.
*
* \param value The new maximum segment size.
*/
void mss(uint16_t value);
/**
* \brief Searchs for a maximum segment size option.
* \param value A pointer in which the option's value will be stored.
* \return True if the option was found, false otherwise.
*/
uint16_t mss() const;
/**
* \brief Add a window scale option.
*
* \param value The new window scale.
*/
void winscale(uint8_t value);
/**
* \brief Searchs for a window scale option.
* \param value A pointer in which the option's value will be stored.
* \return True if the option was found, false otherwise.
*/
uint8_t winscale() const;
/**
* \brief Add a sack permitted option.
*/
void sack_permitted();
/**
* \brief Searchs for a sack permitted option.
* \return True if the option was found, false otherwise.
*/
bool has_sack_permitted() const;
/**
* \brief Add a sack option.
*
* \param value The new window scale.
*/
void sack(const sack_type &edges);
/**
* \brief Searchs for a sack option.
* \param value A pointer in which the option's value will be stored.
* \return True if the option was found, false otherwise.
*/
sack_type sack() const;
/**
* \brief Add a timestamp option.
*
* \param value The current value of the timestamp clock.
* \param reply The echo reply field.
*/
void timestamp(uint32_t value, uint32_t reply);
/**
* \brief Searchs for a timestamp option.
* \param value A pointer in which the option's value will be stored.
* \param reply A pointer in which the option's reply value will be stored.
* \return True if the option was found, false otherwise.
*/
std::pair<uint32_t, uint32_t> timestamp() const;
/**
* \brief Add a alternate checksum option.
*
* \param value The new alternate checksum scale.
*/
void altchecksum(AltChecksums value);
/**
* \brief Searchs for a alternate checksum option.
* \param value A pointer in which the option's value will be stored.
* \return True if the option was found, false otherwise.
*/
AltChecksums altchecksum() const;
/**
* \brief Set a TCP flag value.
*
* \param tcp_flag The flag to be set.
* \param value The new value for this flag. Must be 0 or 1.
*/
void set_flag(Flags tcp_flag, small_uint<1> value);
/**
* \brief Adds a TCP option.
*
* \param option The option type flag to be set.
* \param length The length of this option(optional).
* \param data Pointer to this option's data(optional).
*/
void add_option(Option option, uint8_t length = 0, const uint8_t *data = 0);
/**
* \brief Returns the header size.
*
* This metod overrides PDU::header_size. This size includes the
* payload and options size.
*
* \sa PDU::header_size
*/
uint32_t header_size() const;
/**
* \brief Getter for the PDU's type.
*
* \sa PDU::pdu_type
*/
PDUType pdu_type() const { return PDU::TCP; }
/**
* \brief Searchs for an option that matchs the given flag.
* \param opt_flag The flag to be searched.
* \return A pointer to the option, or 0 if it was not found.
*/
const tcp_option *search_option(Option opt) const;
/**
* \sa PDU::clone_pdu
*/
TCP *clone_pdu() const {
return new TCP(*this);
}
private:
struct tcphdr {
uint16_t sport;
uint16_t dport;
uint32_t seq;
uint32_t ack_seq;
#if TINS_IS_LITTLE_ENDIAN
uint16_t res1:4,
doff:4,
fin:1,
syn:1,
rst:1,
psh:1,
ack:1,
urg:1,
ece:1,
cwr:1;
#elif TINS_IS_BIG_ENDIAN
uint16_t doff:4,
res1:4,
cwr:1,
ece:1,
urg:1,
ack:1,
psh:1,
rst:1,
syn:1,
fin:1;
#else
#error "Endian is not LE nor BE..."
#endif
uint16_t window;
uint16_t check;
uint16_t urg_ptr;
} __attribute__((packed));
static const uint16_t DEFAULT_WINDOW;
template<class T>
T generic_search(Option opt) const {
const tcp_option *option = search_option(opt);
if(option && option->data_size() == sizeof(T))
return *(const T*)(&option->data_ptr()[0]);
throw option_not_found();
}
void write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent);
uint8_t *write_option(const tcp_option &opt, uint8_t *buffer);
tcphdr _tcp;
options_type _options;
uint32_t _options_size, _total_options_size;
};
};
#endif // TINS_TCP_H
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