Implement eTag support for static content

2 files changed, 69 insertions, 12 deletions

diff --git a/src/webclientserver.cpp b/src/webclientserver.cpp
index 664e04e..a8bee77 100644
--- a/src/webclientserver.cpp
+++ b/src/webclientserver.cpp
@@ -2,6 +2,8 @@
 #include "webclientserver.h"
 #include <time.h>
 
+const QByteArray &eTagVersion = "v1-";
+
 HttpRequest::HttpRequest()
 {
 }
@@ -63,12 +65,14 @@ void HttpRequest::parseText()
             QByteArray hostline = line.split(' ').at(1); // ###
             hostline.chop(2); // remove newline
             m_hostName = hostline;
+        } else if (line.startsWith("If-None-Match:")){
+            m_ifNoneMatch = line.mid(18).simplified(); // remove "If-None-Match: vX-", where X is the integer version number
         }
     }
 }
 
 HttpResponse::HttpResponse()
-: contentType("text/html") { }
+: contentType("text/html"), response304(false) { }
 
 void HttpResponse::setBody(const QByteArray &body)
 {
@@ -85,21 +89,49 @@ void HttpResponse::setContentType(const QByteArray &contentType)
     this->contentType = contentType;
 }
 
+void HttpResponse::seteTag(const QByteArray &eTag)
+{
+    this->eTag = eTagVersion + eTag;
+}
+
+void HttpResponse::set304Response()
+{
+    response304 = true;
+}
+
+bool HttpResponse::isHandled() const
+{
+    return response304 || body.isEmpty() == false;
+}
+
 QByteArray HttpResponse::toText()
 {
     time_t currentTime = time(0);
 
-    QByteArray text = 
-    QByteArray("HTTP/1.1 200 OK \r\n")
-    + QByteArray("Date: ") + QByteArray(asctime(gmtime(&currentTime))) + QByteArray("")
+    QByteArray text;
+
+    if (response304) {
+        text += QByteArray("HTTP/1.1 304 Not Modified\r\n");
+        text+= QByteArray("\r\n");
+        return text;
+    }
+
+    text += QByteArray("HTTP/1.1 200 OK \r\n");
+    text += QByteArray("Date: ") + QByteArray(asctime(gmtime(&currentTime))) + QByteArray("")
     + QByteArray("Content-Type: " + contentType + " \r\n")
-    + QByteArray("Content-Length: " + QByteArray::number(body.length())  + "\r\n")
-    + QByteArray("Cace-control: no-cache \r\n");
+    + QByteArray("Content-Length: " + QByteArray::number(body.length())  + "\r\n");
     
     if (cookie.isEmpty() == false) {
         text+= "Set-Cookie: " + cookie + "\r\n";
     }
     
+    if (eTag.isEmpty() == false) {
+        text += "eTag: " + eTag + "\r\n";
+    } else {
+        text += QByteArray("Cace-control: no-cache \r\n");
+        text += QByteArray("max-age: 0 \r\n");
+    }
+
     text+= QByteArray("\r\n")
     + body;
     return text;
@@ -257,7 +289,7 @@ void Server::dataOnSocket()
     }
 */
     session->emitRequestContent(&request, &response);
-    if (response.body.isEmpty() == false) {
+    if (response.isHandled()) {
         QByteArray responseText = response.toText();
         dynamicBytesWritten += responseText.count();
         socket->write(responseText);
@@ -271,7 +303,7 @@ void Server::dataOnSocket()
 
 //    if (path == "/idle")
 //        DEBUG << response.body;
-    if (path.startsWith("/idle") && response.body == QByteArray()) {
+    if (path.startsWith("/idle") && response.isHandled() == false) {
         // Keep one socket for each connection, the html spec allows
         // only two connections between a web browser and a server.
         if (session->m_idleSocket == 0) {
@@ -284,7 +316,7 @@ void Server::dataOnSocket()
         return;
     } else if (path.startsWith("/statistics")) {
         response.setBody(createStatiticsPage());
-    } else if (response.body == QByteArray()) {
+    } else if (response.isHandled() == false) {
         fileServer.handleRequest(&request, &response);
         QByteArray responseText = response.toText();
         staticBytesWritten += responseText.count();
@@ -327,7 +359,7 @@ FileServer::FileServer()
 
 void FileServer::handleRequest(HttpRequest *request, HttpResponse *response)
 {
-    if (response->body != QByteArray())
+    if (response->isHandled())
         return;
 
     const QByteArray path = request->path();
@@ -335,7 +367,7 @@ void FileServer::handleRequest(HttpRequest *request, HttpResponse *response)
             
     DEBUG << "file server handle request" << path <<  filePath;
 
-    if (filePath == "")
+    if (filePath == "" || filePath == "index.html")
         filePath = ":index.html";
 
     if (allowedFileNames.contains(filePath) == false)
@@ -347,6 +379,17 @@ void FileServer::handleRequest(HttpRequest *request, HttpResponse *response)
         return;
     }
 
+    // Check if the client sends an If-None-Match, return
+    // 304 Not Modified if it matches the server's eTag
+    // for the file path.
+    if (request->m_ifNoneMatch.isEmpty() == false) {
+        if (request->m_ifNoneMatch == eTags.value(filePath)) {
+            response->set304Response();
+            response->seteTag(request->m_ifNoneMatch);
+            return;
+        }
+    }
+
     file.open(QIODevice::ReadOnly);
     QByteArray fileContents = file.readAll();
     fileContents.replace("INSERT_HOSTNAME", request->hostName());
@@ -356,5 +399,12 @@ void FileServer::handleRequest(HttpRequest *request, HttpResponse *response)
     if (fileContents.contains("INSERT_PAGE_ID"))
         fileContents.replace("INSERT_PAGE_ID", QByteArray::number(++pageId));
 */
+    QByteArray eTag = eTags[filePath];
+    if (eTag.isEmpty()) {
+        eTag = QByteArray::number(qHash(fileContents));
+        eTags[filePath] = eTag;
+    }
+
+    response->seteTag(eTag);
     response->setBody(fileContents);
 }
diff --git a/src/webclientserver.h b/src/webclientserver.h
index 6a29f1e..1f231c9 100644
--- a/src/webclientserver.h
+++ b/src/webclientserver.h
@@ -24,6 +24,7 @@ public:
     QByteArray m_hostName;
     QList<QByteArray> m_text;
     QTcpSocket *m_socket;
+    QByteArray m_ifNoneMatch;
 };
 
 class HttpResponse
@@ -33,12 +34,17 @@ public:
     void setBody(const QByteArray &body);
     void setCookie(const QByteArray &name, const QByteArray &value);
     void setContentType(const QByteArray &contentType);
-//    void setLastModified(QDateTime lastModified, QDateTime expires);
+    void seteTag(const QByteArray &eTag);
+    void set304Response();
+
+    bool isHandled() const;
     QByteArray toText();
 
     QByteArray body;
     QByteArray cookie;
     QByteArray contentType;
+    QByteArray eTag;
+    bool response304;
 };
 
 class Server;
@@ -75,6 +81,7 @@ public slots:
     virtual void handleRequest(HttpRequest *request, HttpResponse *response);
 private:
     QSet<QString> allowedFileNames;
+    QHash<QString, QByteArray> eTags;
 };
 
 class Server : public QTcpServer