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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Sergey Bugaev <bugaevc@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "DNSName.h"
#include <AK/Random.h>
#include <AK/Vector.h>
#include <ctype.h>
namespace LookupServer {
DNSName::DNSName(const String& name)
{
if (name.ends_with('.'))
m_name = name.substring(0, name.length() - 1);
else
m_name = name;
}
DNSName DNSName::parse(const u8* data, size_t& offset, size_t max_offset, size_t recursion_level)
{
if (recursion_level > 4)
return DNSName({});
StringBuilder builder;
while (true) {
if (offset >= max_offset)
return DNSName({});
u8 b = data[offset++];
if (b == '\0') {
// This terminates the name.
return builder.to_string();
} else if ((b & 0xc0) == 0xc0) {
// The two bytes tell us the offset when to continue from.
if (offset >= max_offset)
return DNSName({});
size_t dummy = (b & 0x3f) << 8 | data[offset++];
auto rest_of_name = parse(data, dummy, max_offset, recursion_level + 1);
builder.append(rest_of_name.as_string());
return builder.to_string();
} else {
// This is the length of a part.
if (offset + b >= max_offset)
return DNSName({});
builder.append((const char*)&data[offset], (size_t)b);
builder.append('.');
offset += b;
}
}
}
size_t DNSName::serialized_size() const
{
if (m_name.is_empty())
return 1;
return m_name.length() + 2;
}
void DNSName::randomize_case()
{
StringBuilder builder;
for (char c : m_name) {
// Randomize the 0x20 bit in every ASCII character.
if (isalpha(c)) {
if (get_random_uniform(2))
c |= 0x20;
else
c &= ~0x20;
}
builder.append(c);
}
m_name = builder.to_string();
}
OutputStream& operator<<(OutputStream& stream, const DNSName& name)
{
auto parts = name.as_string().split_view('.');
for (auto& part : parts) {
stream << (u8)part.length();
stream << part.bytes();
}
stream << '\0';
return stream;
}
unsigned DNSName::Traits::hash(const DNSName& name)
{
return CaseInsensitiveStringTraits::hash(name.as_string());
}
bool DNSName::Traits::equals(const DNSName& a, const DNSName& b)
{
return CaseInsensitiveStringTraits::equals(a.as_string(), b.as_string());
}
}
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