mirror of
https://github.com/mfontanini/libtins
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295 lines
9.4 KiB
C++
295 lines
9.4 KiB
C++
/*
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* Copyright (c) 2014, Matias Fontanini
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <stdexcept>
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#include <cstring>
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#ifndef _WIN32
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#include <netinet/in.h>
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#endif
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#include "rawpdu.h"
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#include "utils.h"
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#include "exceptions.h"
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#include "icmp.h"
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#include "memory_helpers.h"
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using Tins::Memory::InputMemoryStream;
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using Tins::Memory::OutputMemoryStream;
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namespace Tins {
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ICMP::ICMP(Flags flag)
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: _orig_timestamp_or_address_mask(), _recv_timestamp(), _trans_timestamp()
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{
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std::memset(&_icmp, 0, sizeof(icmphdr));
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type(flag);
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}
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ICMP::ICMP(const uint8_t *buffer, uint32_t total_sz)
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{
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InputMemoryStream stream(buffer, total_sz);
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stream.read(_icmp);
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if(type() == TIMESTAMP_REQUEST || type() == TIMESTAMP_REPLY) {
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original_timestamp(stream.read<uint32_t>());
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receive_timestamp(stream.read<uint32_t>());
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transmit_timestamp(stream.read<uint32_t>());
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}
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else if(type() == ADDRESS_MASK_REQUEST || type() == ADDRESS_MASK_REPLY) {
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address_mask(address_type(stream.read<uint32_t>()));
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}
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// Attempt to parse ICMP extensions
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try_parse_extensions(stream);
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if (stream) {
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inner_pdu(new RawPDU(stream.pointer(), stream.size()));
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}
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}
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void ICMP::code(uint8_t new_code) {
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_icmp.code = new_code;
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}
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void ICMP::type(Flags new_type) {
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_icmp.type = new_type;
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}
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void ICMP::checksum(uint16_t new_check) {
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_icmp.check = Endian::host_to_be(new_check);
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}
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void ICMP::id(uint16_t new_id) {
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_icmp.un.echo.id = Endian::host_to_be(new_id);
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}
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void ICMP::sequence(uint16_t new_seq) {
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_icmp.un.echo.sequence = Endian::host_to_be(new_seq);
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}
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void ICMP::gateway(address_type new_gw) {
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_icmp.un.gateway = Endian::host_to_be(static_cast<uint32_t>(new_gw));
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}
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void ICMP::mtu(uint16_t new_mtu) {
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_icmp.un.frag.mtu = Endian::host_to_be(new_mtu);
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}
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void ICMP::pointer(uint8_t new_pointer) {
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_icmp.un.rfc4884.pointer = new_pointer;
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}
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void ICMP::original_timestamp(uint32_t new_timestamp) {
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_orig_timestamp_or_address_mask = Endian::host_to_be(new_timestamp);
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}
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void ICMP::receive_timestamp(uint32_t new_timestamp) {
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_recv_timestamp = Endian::host_to_be(new_timestamp);
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}
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void ICMP::transmit_timestamp(uint32_t new_timestamp) {
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_trans_timestamp = Endian::host_to_be(new_timestamp);
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}
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void ICMP::address_mask(address_type new_mask) {
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_orig_timestamp_or_address_mask = Endian::host_to_be(static_cast<uint32_t>(new_mask));
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}
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uint32_t ICMP::header_size() const {
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uint32_t extra = 0;
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if(type() == TIMESTAMP_REQUEST || type() == TIMESTAMP_REPLY)
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extra = sizeof(uint32_t) * 3;
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else if(type() == ADDRESS_MASK_REQUEST || type() == ADDRESS_MASK_REPLY)
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extra = sizeof(uint32_t);
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return sizeof(icmphdr) + extra;
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}
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uint32_t ICMP::trailer_size() const {
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uint32_t output = 0;
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if (has_extensions()) {
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output += extensions_.size();
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if (inner_pdu()) {
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// This gets how much padding we'll use.
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// If the next pdu size is lower than 128 bytes, then padding = 128 - pdu size
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// If the next pdu size is greater than 128 bytes,
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// then padding = pdu size padded to next 32 bit boundary - pdu size
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const uint32_t upper_bound = std::max(get_adjusted_inner_pdu_size(), 128U);
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output += upper_bound - inner_pdu()->size();
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}
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}
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return output;
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}
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void ICMP::set_echo_request(uint16_t id, uint16_t seq) {
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type(ECHO_REQUEST);
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this->id(id);
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sequence(seq);
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}
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void ICMP::set_echo_reply(uint16_t id, uint16_t seq) {
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type(ECHO_REPLY);
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this->id(id);
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sequence(seq);
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}
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void ICMP::set_info_request(uint16_t id, uint16_t seq) {
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type(INFO_REQUEST);
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code(0);
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this->id(id);
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sequence(seq);
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}
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void ICMP::set_info_reply(uint16_t id, uint16_t seq) {
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type(INFO_REPLY);
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code(0);
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this->id(id);
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sequence(seq);
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}
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void ICMP::set_dest_unreachable() {
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type(DEST_UNREACHABLE);
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}
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void ICMP::set_time_exceeded(bool ttl_exceeded) {
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type(TIME_EXCEEDED);
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code((ttl_exceeded) ? 0 : 1);
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}
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void ICMP::set_param_problem(bool set_pointer, uint8_t bad_octet) {
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type(PARAM_PROBLEM);
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if(set_pointer) {
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code(0);
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pointer(bad_octet);
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}
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else
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code(1);
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}
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void ICMP::set_source_quench() {
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type(SOURCE_QUENCH);
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}
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void ICMP::set_redirect(uint8_t icode, address_type address) {
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type(REDIRECT);
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code(icode);
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gateway(address);
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}
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void ICMP::use_length_field(bool value) {
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// We just need a non 0 value here, we'll use the right value on
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// write_serialization
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_icmp.un.rfc4884.length = value ? 1 : 0;
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}
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void ICMP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *) {
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OutputMemoryStream stream(buffer, total_sz);
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// If extensions are allowed and we have to set the length field
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if (are_extensions_allowed()) {
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uint32_t length_value = get_adjusted_inner_pdu_size();
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// If the next pdu size is greater than 128, we are forced to set the length field
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if (length() != 0 || length_value > 128) {
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length_value = length_value ? std::max(length_value, 128U) : 0;
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// This field uses 32 bit words as the unit
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_icmp.un.rfc4884.length = length_value / sizeof(uint32_t);
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}
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}
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// Write the header using checksum 0
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_icmp.check = 0;
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stream.write(_icmp);
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if(type() == TIMESTAMP_REQUEST || type() == TIMESTAMP_REPLY) {
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stream.write(original_timestamp());
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stream.write(receive_timestamp());
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stream.write(transmit_timestamp());
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}
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else if(type() == ADDRESS_MASK_REQUEST || type() == ADDRESS_MASK_REPLY) {
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stream.write(address_mask());
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}
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if (has_extensions()) {
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uint8_t* extensions_ptr = buffer + sizeof(icmphdr);
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if (inner_pdu()) {
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// Get the size of the next pdu, padded to the next 32 bit boundary
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uint32_t inner_pdu_size = get_adjusted_inner_pdu_size();
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// If it's lower than 128, we need to padd enough zeroes to make it 128 bytes long
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if (inner_pdu_size < 128) {
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memset(extensions_ptr + inner_pdu_size, 0, 128 - inner_pdu_size);
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inner_pdu_size = 128;
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}
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else {
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// If the packet has to be padded to 32 bits, append the amount
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// of zeroes we need
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uint32_t diff = inner_pdu_size - inner_pdu()->size();
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memset(extensions_ptr + inner_pdu_size, 0, diff);
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}
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extensions_ptr += inner_pdu_size;
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}
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// Now serialize the exensions where they should be
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extensions_.serialize(extensions_ptr, total_sz - (extensions_ptr - buffer));
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}
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// Calculate checksum
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uint32_t checksum = Utils::do_checksum(buffer, buffer + total_sz);
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while (checksum >> 16) {
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checksum = (checksum & 0xffff) + (checksum >> 16);
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}
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// Write back only the 2 checksum bytes
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_icmp.check = Endian::host_to_be<uint16_t>(~checksum);
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memcpy(buffer + 2, &_icmp.check, sizeof(uint16_t));
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}
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uint32_t ICMP::get_adjusted_inner_pdu_size() const {
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// This gets the size of the next pdu, padded to the next 32 bit word boundary
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return Internals::get_padded_icmp_inner_pdu_size(inner_pdu(), sizeof(uint32_t));
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}
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void ICMP::try_parse_extensions(InputMemoryStream& stream) {
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// Check if this is one of the types defined in RFC 4884
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if (are_extensions_allowed()) {
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Internals::try_parse_icmp_extensions(stream, length() * sizeof(uint32_t),
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extensions_);
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}
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}
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bool ICMP::are_extensions_allowed() const {
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return type() == DEST_UNREACHABLE || type() == TIME_EXCEEDED || type() == PARAM_PROBLEM;
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}
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bool ICMP::matches_response(const uint8_t *ptr, uint32_t total_sz) const {
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if(total_sz < sizeof(icmphdr))
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return false;
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const icmphdr *icmp_ptr = (const icmphdr*)ptr;
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if((_icmp.type == ECHO_REQUEST && icmp_ptr->type == ECHO_REPLY) ||
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(_icmp.type == TIMESTAMP_REQUEST && icmp_ptr->type == TIMESTAMP_REPLY) ||
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(_icmp.type == ADDRESS_MASK_REQUEST && icmp_ptr->type == ADDRESS_MASK_REPLY)) {
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return icmp_ptr->un.echo.id == _icmp.un.echo.id && icmp_ptr->un.echo.sequence == _icmp.un.echo.sequence;
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}
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return false;
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}
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} // namespace Tins
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