Accept QASV for multipart 'name' field

And adjust the encoding of 'name' parameter to  always
use UTF-8 / ASCII. This aligns with how other frameworks
behave. Also amended docs to recommend ASCII for 'name'.

Found in API review.

Pick-to: 6.8
Change-Id: I54d1148bf95dece54b75c76914c49985da05e0b2
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/network/access/qformdatabuilder.cpp

@@ -28,17 +28,37 @@ QT_BEGIN_NAMESPACE
     \sa QHttpPart, QHttpMultiPart, QFormDataBuilder
 */
 
+static QByteArray nameToByteArray(QStringView view)
+{
+    return view.toUtf8();
+}
+
+static QByteArray nameToByteArray(QLatin1StringView view)
+{
+    if (!QtPrivate::isAscii(view))
+        return view.toString().toUtf8(); // ### optimize
+
+    return QByteArray::fromRawData(view.data(), view.size());
+}
+
+static QByteArray nameToByteArray(QUtf8StringView view)
+{
+    return QByteArray::fromRawData(view.data(), view.size());
+}
+
 /*!
     Constructs a QFormDataPartBuilder object and sets \a name as the name
     parameter of the form-data.
 */
-QFormDataPartBuilder::QFormDataPartBuilder(QLatin1StringView name, PrivateConstructor /*unused*/)
+QFormDataPartBuilder::QFormDataPartBuilder(QAnyStringView name, PrivateConstructor /*unused*/)
 {
     static_assert(std::is_nothrow_move_constructible_v<decltype(m_body)>);
     static_assert(std::is_nothrow_move_assignable_v<decltype(m_body)>);
 
+    const auto enc = name.visit([](auto name) { return nameToByteArray(name); });
+
     m_headerValue += "form-data; name=\"";
-    for (auto c : name) {
+    for (auto c : enc) {
         if (c == '"' || c == '\\')
             m_headerValue += '\\';
         m_headerValue += c;
@@ -292,10 +312,14 @@ QFormDataBuilder::~QFormDataBuilder()
     \a name as the name parameter of the form-data. The returned reference is
     valid until the next call to this function.
 
+    Limiting \a name characters to US-ASCII is
+    \l {https://datatracker.ietf.org/doc/html/rfc7578#section-5.1.1}{strongly recommended}
+    for interoperability reasons.
+
     \sa QFormDataPartBuilder, QHttpPart
 */
 
-QFormDataPartBuilder &QFormDataBuilder::part(QLatin1StringView name)
+QFormDataPartBuilder &QFormDataBuilder::part(QAnyStringView name)
 {
     static_assert(std::is_nothrow_move_constructible_v<decltype(m_parts)>);
     static_assert(std::is_nothrow_move_assignable_v<decltype(m_parts)>);

src/network/access/qformdatabuilder.h

@@ -32,7 +32,7 @@ class QFormDataPartBuilder
 {
     struct PrivateConstructor { explicit PrivateConstructor() = default; };
 public:
-    Q_NETWORK_EXPORT explicit QFormDataPartBuilder(QLatin1StringView name, PrivateConstructor);
+    Q_NETWORK_EXPORT explicit QFormDataPartBuilder(QAnyStringView name, PrivateConstructor);
 
     QFormDataPartBuilder(QFormDataPartBuilder &&other) noexcept
         : m_headerValue(std::move(other.m_headerValue)),
@@ -109,7 +109,7 @@ public:
     }
 
     Q_NETWORK_EXPORT ~QFormDataBuilder();
-    Q_NETWORK_EXPORT QFormDataPartBuilder &part(QLatin1StringView name);
+    Q_NETWORK_EXPORT QFormDataPartBuilder &part(QAnyStringView name);
     Q_NETWORK_EXPORT std::unique_ptr<QHttpMultiPart> buildMultiPart();
 private:
     std::vector<QFormDataPartBuilder> m_parts;

tests/auto/network/access/qformdatabuilder/tst_qformdatabuilder.cpp

@@ -29,6 +29,9 @@ private Q_SLOTS:
 
     void specifyMimeType_data();
     void specifyMimeType();
+
+    void picksUtf8NameEncodingIfAsciiDoesNotSuffice_data();
+    void picksUtf8NameEncodingIfAsciiDoesNotSuffice();
 };
 
 void tst_QFormDataBuilder::generateQHttpPartWithDevice_data()
@@ -325,6 +328,35 @@ void tst_QFormDataBuilder::specifyMimeType()
     QVERIFY(msg.contains(expected_content_type_data));
 }
 
+void tst_QFormDataBuilder::picksUtf8NameEncodingIfAsciiDoesNotSuffice_data()
+{
+    QTest::addColumn<QAnyStringView>("name_data");
+    QTest::addColumn<QString>("expected_content_disposition_data");
+
+    QTest::newRow("latin1-ascii") << QAnyStringView("text"_L1) << uR"(form-data; name="text")"_s;
+    QTest::newRow("u8-ascii") << QAnyStringView(u8"text") << uR"(form-data; name="text")"_s;
+    QTest::newRow("u-ascii") << QAnyStringView(u"text") << uR"(form-data; name="text")"_s;
+
+    // 0xF6 is 'ö', use hex value with Latin-1 to avoid interpretation as UTF-8
+    QTest::newRow("latin1-latin") << QAnyStringView("t\xF6xt"_L1) << uR"(form-data; name="töxt")"_s;
+    QTest::newRow("u8-latin") << QAnyStringView(u8"töxt") << uR"(form-data; name="töxt")"_s;
+    QTest::newRow("u-latin") << QAnyStringView(u"töxt") << uR"(form-data; name="töxt")"_s;
+
+    QTest::newRow("u8-u8") << QAnyStringView(u8"テキスト") << uR"(form-data; name="テキスト")"_s;
+}
+
+void tst_QFormDataBuilder::picksUtf8NameEncodingIfAsciiDoesNotSuffice()
+{
+    QFETCH(const QAnyStringView, name_data);
+    QFETCH(const QString, expected_content_disposition_data);
+
+    QFormDataBuilder qfdb;
+    QFormDataPartBuilder &qfdpb = qfdb.part(name_data).setBody("some"_ba);
+    auto msg = QDebug::toString(qfdpb.build());
+
+    QVERIFY2(msg.contains(expected_content_disposition_data),
+             qPrintable(u"content-disposition not found : "_s + expected_content_disposition_data));
+}
 
 QTEST_MAIN(tst_QFormDataBuilder)
 #include "tst_qformdatabuilder.moc"