pajlada
325 lines
8.5 KiB
C++
325 lines
8.5 KiB
C++
// SPDX-FileCopyrightText: 2018 Contributors to Chatterino <https://chatterino.com>
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//
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// SPDX-License-Identifier: MIT
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#define QT_NO_CAST_FROM_ASCII // avoids unexpected implicit casts
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#include "common/LinkParser.hpp"
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#include "common/QLogging.hpp"
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#include "util/QCompareTransparent.hpp"
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#include <QFile>
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#include <QString>
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#include <QStringView>
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#include <QTextStream>
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#include <set>
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namespace {
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using namespace chatterino;
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using TldSet = std::set<QString, QCompareCaseInsensitive>;
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TldSet &tlds()
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{
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static TldSet tlds = [] {
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QFile file(QStringLiteral(":/tlds.txt"));
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bool ok = file.open(QFile::ReadOnly);
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if (!ok)
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{
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assert(false && "Resources not available");
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qCWarning(chatterinoApp) << "Resources not available";
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}
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QTextStream stream(&file);
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#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
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// Default encoding of QTextStream is already UTF-8, at least in Qt6
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#else
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stream.setCodec("UTF-8");
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#endif
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TldSet set;
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while (!stream.atEnd())
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{
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set.emplace(stream.readLine());
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}
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return set;
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}();
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return tlds;
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}
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bool isValidTld(QStringView tld)
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{
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return tlds().contains(tld);
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}
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bool isValidIpv4(QStringView host)
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{
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// We don't care about the actual value,
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// we only want to verify the ip.
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char16_t sectionValue = 0; // 0..256
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uint8_t octetNumber = 0; // 0..4
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uint8_t sectionDigits = 0; // 0..3
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bool lastWasDot = true;
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for (auto c : host)
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{
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char16_t current = c.unicode();
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if (current == '.')
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{
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if (lastWasDot || octetNumber == 3)
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{
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return false;
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}
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lastWasDot = true;
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octetNumber++;
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sectionValue = 0;
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sectionDigits = 0;
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continue;
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}
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lastWasDot = false;
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if (current > u'9' || current < u'0')
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{
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return false;
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}
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sectionValue = sectionValue * 10 + (current - u'0');
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sectionDigits++;
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if (sectionValue >= 256 || sectionDigits > 3)
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{
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return false;
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}
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}
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return octetNumber == 3 && !lastWasDot;
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}
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/**
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* @brief Checks if the string starts with a port number.
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*
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* The value of the port number isn't checked. A port in this implementation
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* can be in the range 0..100'000.
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*/
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bool startsWithPort(QStringView string)
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{
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for (qsizetype i = 0; i < std::min<qsizetype>(5, string.length()); i++)
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{
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char16_t c = string[i].unicode();
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if (i >= 1 && (c == u'/' || c == u'?' || c == u'#'))
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{
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return true;
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}
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if (!string[i].isDigit())
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{
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return false;
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}
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}
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return true;
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}
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/// @brief Strips ignored characters off @a source
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///
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/// As per https://github.github.com/gfm/#autolinks-extension-:
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///
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/// '<', '*', '_', '~', and '(' are ignored at the beginning
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/// '>', '?', '!', '.', ',', ':', '*', '~', and ')' are ignored at the end.
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///
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/// A difference to GFM is that '_' isn't a valid suffix.
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///
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/// This might remove more than desired (e.g. "(a.com/(foo))" -> "a.com/(foo").
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/// Parentheses are counted after recognizing a valid IP/host.
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void strip(QStringView &source)
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{
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while (!source.isEmpty())
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{
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auto c = source.first();
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if (c == u'<' || c == u'*' || c == u'_' || c == u'~' || c == u'(')
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{
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source = source.mid(1);
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continue;
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}
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break;
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}
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while (!source.isEmpty())
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{
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auto c = source.last();
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if (c == u'>' || c == u'?' || c == u'!' || c == u'.' || c == u',' ||
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c == u':' || c == u'*' || c == u'~' || c == u')')
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{
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source.chop(1);
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continue;
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}
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break;
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}
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}
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/// @brief Checks if @a c is valid in a domain
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///
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/// Valid characters are 0-9, A-Z, a-z, '-', '_', and '.' (like in GFM)
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/// and all non-ASCII characters (unlike in GFM).
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Q_ALWAYS_INLINE bool isValidDomainChar(char16_t c)
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{
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return c >= 0x80 || (u'0' <= c && c <= u'9') || (u'A' <= c && c <= u'Z') ||
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(u'a' <= c && c <= u'z') || c == u'_' || c == u'-' || c == u'.';
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}
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} // namespace
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namespace chatterino::linkparser {
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std::optional<Parsed> parse(QStringView source) noexcept
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{
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using SizeType = QString::size_type;
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std::optional<Parsed> result;
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// This is not implemented with a regex to increase performance.
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QStringView link{source};
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strip(link);
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QStringView remaining = link;
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QStringView protocol;
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// Check protocol for https?://
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if (remaining.startsWith(u"http", Qt::CaseInsensitive) &&
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remaining.length() >= 4 + 3 + 1) // 'http' + '://' + [any]
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{
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// optimistic view assuming there's a protocol (http or https)
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auto withProto = remaining.mid(4); // 'http'
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if (withProto[0] == QChar(u's') || withProto[0] == QChar(u'S'))
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{
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withProto = withProto.mid(1);
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}
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if (withProto.startsWith(u"://"))
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{
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// there's really a protocol => consume it
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remaining = withProto.mid(3);
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protocol = {link.begin(), remaining.begin()};
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}
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}
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// Http basic auth `user:password` isn't supported for security reasons (misleading links)
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// Host `a.b.c.com`
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QStringView host = remaining;
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QStringView rest;
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bool lastWasDot = true;
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SizeType lastDotPos = -1;
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SizeType nDots = 0;
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// Extract the host
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for (SizeType i = 0; i < remaining.size(); i++)
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{
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char16_t currentChar = remaining[i].unicode();
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if (currentChar == u'.')
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{
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if (lastWasDot) // no double dots ..
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{
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return result;
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}
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lastDotPos = i;
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lastWasDot = true;
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nDots++;
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}
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else
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{
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lastWasDot = false;
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}
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// found a port
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if (currentChar == u':')
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{
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host = remaining.mid(0, i);
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rest = remaining.mid(i);
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remaining = remaining.mid(i + 1);
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if (!startsWithPort(remaining))
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{
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return result;
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}
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break;
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}
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// we accept everything in the path/query/anchor
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if (currentChar == u'/' || currentChar == u'?' || currentChar == u'#')
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{
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host = remaining.mid(0, i);
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rest = remaining.mid(i);
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break;
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}
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if (!isValidDomainChar(currentChar))
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{
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return result;
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}
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}
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if (lastWasDot || lastDotPos <= 0)
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{
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return result;
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}
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// check host/tld
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if ((nDots == 3 && isValidIpv4(host)) ||
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isValidTld(host.mid(lastDotPos + 1)))
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{
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// scan for parentheses (only if there were characters excluded)
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if (link.end() != source.end() && !rest.empty())
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{
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size_t nestingLevel = 0;
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// position after the last closing brace (i.e. the minimum characters to include)
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const auto *lastClose = link.end();
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// scan source from rest until the end:
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// lastClose
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// v
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// (example.com/foo/bar/#baz_(qox)),
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// ▏╌╌rest (before)╌ ▏
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// ▏╌╌╌╌╌╌╌link (before)╌╌╌╌╌╌╌ ▏
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// ▏╌╌rest (after)╌╌╌ ▏
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// ▏╌╌╌╌╌╌╌link (after)╌╌╌╌╌╌╌╌╌ ▏
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// ▏╌╌╌╌╌╌╌╌╌╌╌╌╌source╌╌╌╌╌╌╌╌╌╌╌╌ ▏
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// ▏╌╌╌╌╌╌╌search╌╌╌╌╌╌ ▏
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for (const auto *it = rest.begin(); it < source.end(); it++)
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{
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if (it->unicode() == u'(')
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{
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nestingLevel++;
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continue;
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}
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if (nestingLevel != 0 && it->unicode() == u')')
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{
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nestingLevel--;
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if (nestingLevel == 0)
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{
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lastClose = it + 1;
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}
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}
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}
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link = QStringView{link.begin(), std::max(link.end(), lastClose)};
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rest = QStringView{rest.begin(), std::max(rest.end(), lastClose)};
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}
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result = Parsed{
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.protocol = protocol,
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.host = host,
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.rest = rest,
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.link = link,
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};
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}
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return result;
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}
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} // namespace chatterino::linkparser
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