Replace QHttpHeaders::toListOfPairs() usage with iteration

... as a more computationally effective way, which was not present at
the time those usages were introduced.

As a drive-by add spaces around a binary operator

Task-number: QTBUG-122017
Pick-to: 6.7
Change-Id: I0528c995d1a3c1fe171486c5c313697d1706ee10
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

3 files changed, 26 insertions, 20 deletions

diff --git a/src/network/access/qhttp2protocolhandler.cpp b/src/network/access/qhttp2protocolhandler.cpp
index f69390e47a..08dfa02624 100644
--- a/src/network/access/qhttp2protocolhandler.cpp
+++ b/src/network/access/qhttp2protocolhandler.cpp
@@ -60,9 +60,11 @@ HPack::HttpHeader build_headers(const QHttpNetworkRequest &request, quint32 maxH
     if (size.second > maxHeaderListSize)
         return HttpHeader(); // Bad, we cannot send this request ...
 
-    const auto requestHeader = request.header().toListOfPairs();
-    for (const auto &field : requestHeader) {
-        const HeaderSize delta = entry_size(field.first, field.second);
+    const QHttpHeaders requestHeader = request.header();
+    for (qsizetype i = 0; i < requestHeader.size(); ++i) {
+        const auto name = requestHeader.nameAt(i);
+        const auto value = requestHeader.valueAt(i);
+        const HeaderSize delta = entry_size(name, value);
         if (!delta.first) // Overflow???
             break;
         if (std::numeric_limits<quint32>::max() - delta.second < size.second)
@@ -71,18 +73,19 @@ HPack::HttpHeader build_headers(const QHttpNetworkRequest &request, quint32 maxH
         if (size.second > maxHeaderListSize)
             break;
 
-        if (field.first.compare("connection", Qt::CaseInsensitive) == 0 ||
-                field.first.compare("host", Qt::CaseInsensitive) == 0 ||
-                field.first.compare("keep-alive", Qt::CaseInsensitive) == 0 ||
-                field.first.compare("proxy-connection", Qt::CaseInsensitive) == 0 ||
-                field.first.compare("transfer-encoding", Qt::CaseInsensitive) == 0)
+        if (name.compare("connection", Qt::CaseInsensitive) == 0 ||
+                name.compare("host", Qt::CaseInsensitive) == 0 ||
+                name.compare("keep-alive", Qt::CaseInsensitive) == 0 ||
+                name.compare("proxy-connection", Qt::CaseInsensitive) == 0 ||
+                name.compare("transfer-encoding", Qt::CaseInsensitive) == 0)
             continue; // Those headers are not valid (section 3.2.1) - from QSpdyProtocolHandler
         // TODO: verify with specs, which fields are valid to send ....
-        // toLower - 8.1.2 .... "header field names MUST be converted to lowercase prior
-        // to their encoding in HTTP/2.
-        // A request or response containing uppercase header field names
-        // MUST be treated as malformed (Section 8.1.2.6)".
-        header.emplace_back(field.first.toLower(), field.second);
+        //
+        // Note: RFC 7450 8.1.2 (HTTP/2) states that header field names must be lower-cased
+        // prior to their encoding in HTTP/2; header name fields in QHttpHeaders are already
+        // lower-cased
+        header.emplace_back(QByteArray{name.data(), name.size()},
+                            QByteArray{value.data(), value.size()});
     }
 
     return header;
diff --git a/src/network/access/qhttpnetworkrequest.cpp b/src/network/access/qhttpnetworkrequest.cpp
index bc3eb67adc..7a4ffb1684 100644
--- a/src/network/access/qhttpnetworkrequest.cpp
+++ b/src/network/access/qhttpnetworkrequest.cpp
@@ -112,9 +112,9 @@ QByteArray QHttpNetworkRequest::uri(bool throughProxy) const
 
 QByteArray QHttpNetworkRequestPrivate::header(const QHttpNetworkRequest &request, bool throughProxy)
 {
-    const QList<QPair<QByteArray, QByteArray> > fields = request.header().toListOfPairs();
+    const QHttpHeaders headers = request.header();
     QByteArray ba;
-    ba.reserve(40 + fields.size()*25); // very rough lower bound estimation
+    ba.reserve(40 + headers.size() * 25); // very rough lower bound estimation
 
     ba += request.methodName();
     ba += ' ';
@@ -126,10 +126,10 @@ QByteArray QHttpNetworkRequestPrivate::header(const QHttpNetworkRequest &request
     ba += QByteArray::number(request.minorVersion());
     ba += "\r\n";
 
-    for (const auto& [name, value] : fields) {
-        ba += name;
+    for (qsizetype i = 0; i < headers.size(); ++i) {
+        ba += headers.nameAt(i);
         ba += ": ";
-        ba += value;
+        ba += headers.valueAt(i);
         ba += "\r\n";
     }
     if (request.d->operation == QHttpNetworkRequest::Post) {
diff --git a/src/network/access/qnetworkreplyhttpimpl.cpp b/src/network/access/qnetworkreplyhttpimpl.cpp
index 84d9e08b91..a5f2d91f0d 100644
--- a/src/network/access/qnetworkreplyhttpimpl.cpp
+++ b/src/network/access/qnetworkreplyhttpimpl.cpp
@@ -1364,7 +1364,10 @@ void QNetworkReplyHttpImplPrivate::replyDownloadMetaData(const QHttpHeaders &hm,
     const bool autoDecompress = request.rawHeader("accept-encoding").isEmpty();
     const bool shouldDecompress = isCompressed && autoDecompress;
     // reconstruct the HTTP header
-    for (const auto &[key, originValue] : hm.toListOfPairs()) {
+    for (qsizetype i = 0; i < hm.size(); ++i) {
+        const auto key = hm.nameAt(i);
+        const auto originValue = hm.valueAt(i);
+
         QByteArray value = q->rawHeader(key);
 
         // Reset any previous "location" header set in the reply. In case of
@@ -1398,7 +1401,7 @@ void QNetworkReplyHttpImplPrivate::replyDownloadMetaData(const QHttpHeaders &hm,
                 value += ", ";
         }
         value += originValue;
-        q->setRawHeader(key, value);
+        q->setRawHeader({key.data(), key.size()}, value);
     }
 
     q->setAttribute(QNetworkRequest::HttpStatusCodeAttribute, statusCode);