mirror of
https://github.com/RGBCube/serenity
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1793f51bc6
Previously, a DNS packet containing an invalid name would be returned with an empty name. With this change, an error is returned if any error is encountered during parsing.
100 lines
2.7 KiB
C++
100 lines
2.7 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021, Sergey Bugaev <bugaevc@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "Name.h"
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#include <AK/Random.h>
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#include <AK/Stream.h>
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#include <AK/Vector.h>
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#include <ctype.h>
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namespace DNS {
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Name::Name(DeprecatedString const& name)
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{
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if (name.ends_with('.'))
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m_name = name.substring(0, name.length() - 1);
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else
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m_name = name;
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}
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ErrorOr<Name> Name::parse(ReadonlyBytes data, size_t& offset, size_t recursion_level)
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{
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if (recursion_level > 4)
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return Name {};
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StringBuilder builder;
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while (true) {
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if (offset >= data.size())
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return Error::from_string_literal("Unexpected EOF when parsing name");
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u8 b = data[offset++];
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if (b == '\0') {
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// This terminates the name.
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return builder.to_deprecated_string();
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} else if ((b & 0xc0) == 0xc0) {
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// The two bytes tell us the offset when to continue from.
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if (offset >= data.size())
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return Error::from_string_literal("Unexpected EOF when parsing name");
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size_t dummy = (b & 0x3f) << 8 | data[offset++];
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auto rest_of_name = TRY(parse(data, dummy, recursion_level + 1));
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builder.append(rest_of_name.as_string());
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return builder.to_deprecated_string();
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} else {
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// This is the length of a part.
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if (offset + b >= data.size())
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return Error::from_string_literal("Unexpected EOF when parsing name");
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builder.append({ data.offset_pointer(offset), b });
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builder.append('.');
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offset += b;
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}
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}
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}
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size_t Name::serialized_size() const
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{
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if (m_name.is_empty())
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return 1;
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return m_name.length() + 2;
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}
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void Name::randomize_case()
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{
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StringBuilder builder;
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for (char c : m_name) {
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// Randomize the 0x20 bit in every ASCII character.
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if (isalpha(c)) {
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if (get_random_uniform(2))
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c |= 0x20;
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else
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c &= ~0x20;
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}
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builder.append(c);
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}
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m_name = builder.to_deprecated_string();
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}
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ErrorOr<void> Name::write_to_stream(Stream& stream) const
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{
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auto parts = as_string().split_view('.');
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for (auto& part : parts) {
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TRY(stream.write_value<u8>(part.length()));
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TRY(stream.write_until_depleted(part.bytes()));
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}
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TRY(stream.write_value('\0'));
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return {};
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}
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unsigned Name::Traits::hash(Name const& name)
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{
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return CaseInsensitiveStringTraits::hash(name.as_string());
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}
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bool Name::Traits::equals(Name const& a, Name const& b)
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{
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return CaseInsensitiveStringTraits::equals(a.as_string(), b.as_string());
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}
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}
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