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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "DNSRequest.h"
#include "DNSPacket.h"
#include <AK/MemoryStream.h>
#include <AK/StringBuilder.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <stdlib.h>
const u16 C_IN = 1;
DNSRequest::DNSRequest()
: m_id(arc4random_uniform(UINT16_MAX))
{
}
void DNSRequest::add_question(const String& name, u16 record_type, ShouldRandomizeCase should_randomize_case)
{
ASSERT(m_questions.size() <= UINT16_MAX);
if (name.is_empty())
return;
StringBuilder builder;
for (size_t i = 0; i < name.length(); ++i) {
u8 ch = name[i];
if (should_randomize_case == ShouldRandomizeCase::Yes) {
// Randomize the 0x20 bit in every ASCII character.
if (isalpha(ch)) {
if (arc4random_uniform(2))
ch |= 0x20;
else
ch &= ~0x20;
}
}
builder.append(ch);
}
if (name[name.length() - 1] != '.')
builder.append('.');
m_questions.empend(builder.to_string(), record_type, C_IN);
}
ByteBuffer DNSRequest::to_byte_buffer() const
{
DNSPacket request_header;
request_header.set_id(m_id);
request_header.set_is_query();
request_header.set_opcode(0);
request_header.set_truncated(false);
request_header.set_recursion_desired(true);
request_header.set_question_count(m_questions.size());
DuplexMemoryStream stream;
stream << ReadonlyBytes { &request_header, sizeof(request_header) };
for (auto& question : m_questions) {
auto parts = question.name().split('.');
for (auto& part : parts) {
stream << (u8)part.length();
stream << part.bytes();
}
stream << '\0';
stream << htons(question.record_type());
stream << htons(question.class_code());
}
return stream.copy_into_contiguous_buffer();
}
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