/* * 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 #include #include #ifndef WIN32 #include #endif #include "pdu.h" #include "utils.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: /** * \brief 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 }; /** * \brief Class that represents a TCP option field. */ struct TCPOption { /** * \brief Creates an instance of a TCPOption. * \param okind The option kind. * \param olength The option's data length. * \param odata The option's data(if any). */ TCPOption(uint8_t opt = 0, uint8_t length = 0, const uint8_t *value = 0) : option(opt), value(value, (value) ? (value + length) : 0) { } /** * \brief Writes the option into a buffer. * \param buffer The buffer in which to write the option. * \return The buffer pointer incremented by the size of this option. */ uint8_t *write(uint8_t *buffer); uint8_t option; std::vector value; }; /** * \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 Utils::net_to_host_s(_tcp.dport); } /** * \brief Getter for the source port field. * * \return The source port in an uint16_t. */ uint16_t sport() const { return Utils::net_to_host_s(_tcp.sport); } /** * \brief Getter for the sequence number field. * * \return The sequence number in an uint32_t. */ uint32_t seq() const { return Utils::net_to_host_l(_tcp.seq); } /** * \brief Getter for the acknowledge number field. * * \return The acknowledge number in an uint32_t. */ uint32_t ack_seq() const { return Utils::net_to_host_l(_tcp.ack_seq); } /** * \brief Getter for the window size field. * * \return The window size in an uint32_t. */ uint16_t window() const { return Utils::net_to_host_s(_tcp.window); } /** * \brief Getter for the checksum field. * * \return The checksum field in an uint16_t. */ uint16_t check() const { return Utils::net_to_host_s(_tcp.check); } /** * \brief Getter for the urgent pointer field. * * \return The urgent pointer in an uint16_t. */ uint16_t urg_ptr() const { return Utils::net_to_host_s(_tcp.urg_ptr); } /** * \brief Getter for the data offset field. * * \return Data offset in an uint8_t. */ uint8_t data_offset() const { return this->_tcp.doff; } /** * \brief Getter for the option list. * * \return The options list. */ const std::list &options() const { return _options; } /** * \brief Gets the value of a flag. * * \param tcp_flag The polled flag. * \return The value of the flag. */ uint8_t 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(uint8_t new_doff); /** * \brief Set the payload. * * Payload is NOT copied. Therefore, pointers provided as * payloads must be freed manually by the user. This actually * creates a RawPDU that holds the payload, and sets it as the * inner_pdu. Therefore, if an inner_pdu was set previously, * a call to TCP::payload will delete it. * * \param new_payload New payload. * \param new_payload_size New payload's size */ void payload(uint8_t *new_payload, uint32_t new_payload_size); /** * \brief Add a maximum segment size option. * * \param value The new maximum segment size. */ void add_mss_option(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. */ bool search_mss_option(uint16_t *value); /** * \brief Add a window scale option. * * \param value The new window scale. */ void add_winscale_option(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. */ bool search_winscale_option(uint8_t *value); /** * \brief Add a sack permitted option. */ void add_sack_permitted_option(); /** * \brief Searchs for a sack permitted option. * \return True if the option was found, false otherwise. */ bool search_sack_permitted_option(); /** * \brief Add a sack option. * * \param value The new window scale. */ void add_sack_option(const std::list &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. */ bool search_sack_option(std::list *edges); /** * \brief Add a timestamp option. * * \param value The current value of the timestamp clock. * \param reply The echo reply field. */ void add_timestamp_option(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. */ bool search_timestamp_option(uint32_t *value, uint32_t *reply); /** * \brief Add a alternate checksum option. * * \param value The new alternate checksum scale. */ void add_altchecksum_option(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. */ bool search_altchecksum_option(uint8_t *value); /** * \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, uint8_t value); /** * \brief Adds a TCP option. * * \param tcp_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 tcp_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 TCPOption *search_option(Option opt) const; /** * \sa PDU::clone_pdu */ PDU *clone_pdu() const { return do_clone_pdu(); } private: struct tcphdr { uint16_t sport; uint16_t dport; uint32_t seq; uint32_t ack_seq; #if __BYTE_ORDER == __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 __BYTE_ORDER == __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 bool generic_search(Option opt, T *value) { const TCPOption *option = search_option(opt); if(option && option->value.size() == sizeof(T)) { *value = *(const T*)(&option->value[0]); return true; } return false; } /** \brief Serialices this TCP PDU. * \param buffer The buffer in which the PDU will be serialized. * \param total_sz The size available in the buffer. * \param parent The PDU that's one level below this one on the stack. */ void write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent); tcphdr _tcp; std::list _options; uint32_t _options_size, _total_options_size; }; }; #endif // TINS_TCP_H