Added continue / resume download support for HTTP Requests.

--HG--
branch : dev

include/eepp/network/http.hpp

@@ -168,6 +168,12 @@ class EE_API Http : NonCopyable {
 			*/
 			void setCompressedResponse(const bool& compressedResponse);
 
+			/** Resumes download if a file is already present */
+			void setContinue(const bool& resume);
+
+			/** @return If must continue a download previously started. */
+			const bool& isContinue() const;
+
 			private:
 			friend class Http;
 
@@ -194,6 +200,7 @@ class EE_API Http : NonCopyable {
 			bool                  mValidateHostname;    ///< Validates the hostname in case of an HTTPS request
 			bool                  mFollowRedirect;      ///< Follows redirect response codes
 			bool                  mCompressedResponse;  ///< Request comrpessed response
+			bool                  mContinue;            ///< Resume download
 			mutable bool          mCancel;              ///< Cancel state of current request
 			ProgressCallback      mProgressCallback;    ///< Progress callback
 			unsigned int          mMaxRedirections;     ///< Maximun number of redirections allowed
@@ -261,6 +268,9 @@ class EE_API Http : NonCopyable {
 			**  @return Value of the field, or empty string if not found */
 			const std::string& getField(const std::string& field) const;
 
+			/** @return If the field is found in the response headers. */
+			bool hasField(const std::string& field) const;
+
 			/** @brief Get the response status code
 			**  The status code should be the first thing to be checked
 			**  after receiving a response, it defines whether it is a

src/eepp/network/http.cpp

@@ -52,6 +52,7 @@ Http::Request::Request(const std::string& uri, Method method, const std::string&
 	mValidateHostname( validateHostname ),
 	mFollowRedirect( followRedirect ),
 	mCompressedResponse( compressedResponse ),
+	mContinue( false ),
 	mCancel( false ),
 	mMaxRedirections( 10 ),
 	mRedirectionCount( 0 )
@@ -161,6 +162,14 @@ std::string Http::Request::prepareTunnel(const Http& http) {
 	return out.str();
 }
 
+void Http::Request::setContinue(const bool& resume) {
+	mContinue = resume;
+}
+
+const bool& Http::Request::isContinue() const {
+	return mContinue;
+}
+
 const bool& Http::Request::isCompressedResponse() const {
 	return mCompressedResponse;
 }
@@ -273,6 +282,10 @@ const std::string& Http::Response::getField(const std::string& field) const {
 	}
 }
 
+bool Http::Response::hasField(const std::string & field) const {
+	return mFields.find(String::toLower(field)) != mFields.end();
+}
+
 Http::Response::Status Http::Response::getStatus() const {
 	return mStatus;
 }
@@ -579,6 +592,33 @@ Http::Response Http::downloadRequest(const Http::Request& request, IOStream& wri
 			}
 		}
 
+		if ( request.isContinue() ) {
+			std::size_t continueLength = writeTo.getSize();
+
+			if ( continueLength > 0 ) {
+				IOStreamString responseHeadBody;
+				Request requestHead = request;
+				requestHead.setContinue( false );
+				requestHead.setMethod( Request::Head );
+				Response responseHead = downloadRequest( requestHead, responseHeadBody );
+				std::size_t contentLength = 0;
+
+				if ( responseHead.hasField("Accept-Ranges") &&
+					 responseHead.hasField("Content-Length") &&
+					 String::fromString( contentLength, responseHead.getField("Content-Length") )  &&
+					 contentLength > 0 &&
+					 continueLength < contentLength
+					)
+				{
+					writeTo.seek( continueLength );
+					Request newRequest( request );
+					newRequest.setContinue( false );
+					newRequest.setField( "Range", String::format( "bytes=%lu-%lu", continueLength, contentLength ) );
+					return downloadRequest( newRequest, writeTo, timeout );
+				}
+			}
+		}
+
 		// Convert the request to string and send it through the connected socket
 		std::string requestStr = toSend.prepare(*this);
 
@@ -771,8 +811,8 @@ Http::Response Http::downloadRequest(const Http::Request& request, IOStream& wri
 	return received;
 }
 
-Http::Response Http::downloadRequest(const Http::Request & request, std::string writePath, Time timeout) {
-	IOStreamFile file( writePath, "wb+" );
+Http::Response Http::downloadRequest(const Http::Request& request, std::string writePath, Time timeout) {
+	IOStreamFile file( writePath, request.isContinue() ? "ab+" : "wb+" );
 	return downloadRequest( request, file, timeout );
 }
 

src/examples/http_request/http_request.cpp

@@ -17,6 +17,7 @@ void printResponseHeaders( Http::Response& response ) {
 EE_MAIN_FUNC int main (int argc, char * argv []) {
 	args::ArgumentParser parser("HTTP request program example");
 	args::HelpFlag help(parser, "help", "Display this help menu", {'h', "help"});
+	args::Flag resume(parser, "continue", "Resume getting a partially-downloaded file", {'c',"continue"});
 	args::Flag compressed(parser, "compressed", "Request compressed response", {"compressed"});
 	args::ValueFlag<std::string> postData(parser, "data", "HTTP POST data", {'d', "data"});
 	args::ValueFlagList<std::string> headers(parser, "header", "Pass custom header(s) to server", {'H', "header"});
@@ -130,7 +131,10 @@ EE_MAIN_FUNC int main (int argc, char * argv []) {
 			}
 
 			// Set the proxy for the request
-			if ( proxy ) {
+			char * http_proxy = getenv( "http_proxy" );
+			if (  !proxy && NULL != http_proxy ) {
+				http.setProxy( URI( http_proxy ) );
+			} else if ( proxy ) {
 				http.setProxy( URI( proxy.Get() ) );
 			}
 
@@ -139,6 +143,11 @@ EE_MAIN_FUNC int main (int argc, char * argv []) {
 				request.setCompressedResponse( true );
 			}
 
+			// Resume existing download
+			if ( resume ) {
+				request.setContinue( true );
+			}
+
 			if ( !output ) {
 				// Send the request
 				Http::Response response = http.sendRequest(request);