Revert "NSURLSession Reimplementation (#411)"

This reverts commit 07233534e6.

Source/GSEasyHandle.h

@@ -0,0 +1,236 @@
+#ifndef	INCLUDED_GSEASYHANDLE_H
+#define	INCLUDED_GSEASYHANDLE_H
+
+#import "common.h"
+#import <curl/curl.h>
+
+@class NSData;
+@class NSError;
+@class NSURL;
+@class NSURLSessionConfiguration;
+@class NSURLSessionTask;
+@class GSTimeoutSource;
+
+typedef NS_ENUM(NSUInteger, GSEasyHandleAction) {
+    GSEasyHandleActionAbort,
+    GSEasyHandleActionProceed,
+    GSEasyHandleActionPause,
+};
+
+typedef NS_ENUM(NSUInteger, GSEasyHandleWriteBufferResult) {
+    GSEasyHandleWriteBufferResultAbort,
+    GSEasyHandleWriteBufferResultPause,
+    GSEasyHandleWriteBufferResultBytes,
+};
+
+@protocol GSEasyHandleDelegate <NSObject>
+
+/* 
+ * Handle data read from the network.
+ * - returns: the action to be taken: abort, proceed, or pause.
+ */
+- (GSEasyHandleAction) didReceiveData: (NSData*)data;
+
+/*
+ * Handle header data read from the network.
+ * - returns: the action to be taken: abort, proceed, or pause.
+ */
+- (GSEasyHandleAction) didReceiveHeaderData: (NSData*)data 
+                              contentLength: (int64_t)contentLength;
+
+/*
+ * Fill a buffer with data to be sent.
+ * - parameter data: The buffer to fill
+ * - returns: the number of bytes written to the `data` buffer, or `nil` 
+ *   to stop the current transfer immediately.
+ */
+- (void) fillWriteBufferLength: (NSInteger)length
+                        result: (void (^)(GSEasyHandleWriteBufferResult result, NSInteger length, NSData *data))result;
+
+/*
+ * The transfer for this handle completed.
+ * - parameter errorCode: An NSURLError code, or `nil` if no error occurred.
+ */
+- (void) transferCompletedWithError: (NSError*)error;
+
+/*
+ * Seek the input stream to the given position
+ */
+- (BOOL) seekInputStreamToPosition: (uint64_t)position;
+
+/*
+ * Gets called during the transfer to update progress.
+ */
+- (void) updateProgressMeterWithTotalBytesSent: (int64_t)totalBytesSent 
+                      totalBytesExpectedToSend: (int64_t)totalBytesExpectedToSend 
+                            totalBytesReceived: (int64_t)totalBytesReceived 
+                   totalBytesExpectedToReceive: (int64_t)totalBytesExpectedToReceive;
+
+@end
+
+
+/* 
+ * Minimal wrapper around the curl easy interface 
+ * (https://curl.haxx.se/libcurl/c/)
+ *
+ * An *easy handle* manages the state of a transfer inside libcurl.
+ *
+ * As such the easy handle's responsibility is implementing the HTTP
+ * protocol while the *multi handle* is in charge of managing sockets and
+ * reading from / writing to these sockets.
+ *
+ * An easy handle is added to a multi handle in order to associate it with
+ * an actual socket. The multi handle will then feed bytes into the easy
+ * handle and read bytes from the easy handle. But this process is opaque
+ * to use. It is further worth noting, that with HTTP/1.1 persistent
+ * connections and with HTTP/2 there's a 1-to-many relationship between
+ * TCP streams and HTTP transfers / easy handles. A single TCP stream and
+ * its socket may be shared by multiple easy handles.
+ *
+ * A single HTTP request-response exchange (refered to here as a
+ * *transfer*) corresponds directly to an easy handle. Hence anything that
+ * needs to be configured for a specific transfer (e.g. the URL) will be
+ * configured on an easy handle.
+ *
+ * A single `NSURLSessionTask` may do multiple, consecutive transfers, and
+ * as a result it will have to reconfigure its easy handle between
+ * transfers. An easy handle can be re-used once its transfer has
+ * completed.
+ *
+ * Note: All code assumes that it is being called on a single thread,
+ * it is intentionally **not** thread safe.
+ */
+@interface GSEasyHandle : NSObject
+{
+  CURL                      *_rawHandle;
+  char                      *_errorBuffer;
+  id<GSEasyHandleDelegate>  _delegate;
+  GSTimeoutSource           *_timeoutTimer;
+  NSURL                     *_URL;
+}
+
+- (CURL*) rawHandle;
+
+- (char*) errorBuffer;
+
+/*
+ * Set error buffer for error messages
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_ERRORBUFFER.html
+ */
+- (void) setErrorBuffer: (char*)buffer;
+
+- (GSTimeoutSource*) timeoutTimer;
+
+- (void) setTimeoutTimer: (GSTimeoutSource*)timer;
+
+- (NSURL*) URL;
+
+/*
+ * URL to use in the request
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_URL.html
+ */
+- (void) setURL: (NSURL*)URL;
+
+- (void) setPipeWait: (BOOL)flag;
+
+- (instancetype) initWithDelegate: (id<GSEasyHandleDelegate>)delegate;
+
+- (void) transferCompletedWithError: (NSError*)error;
+
+- (int) urlErrorCodeWithEasyCode: (int)easyCode;
+
+- (void) setVerboseMode: (BOOL)flag;
+
+- (void) setDebugOutput: (BOOL)flag 
+                   task: (NSURLSessionTask*)task;
+
+- (void) setPassHeadersToDataStream: (BOOL)flag;
+
+/*
+ * Follow any Location: header that the server sends as part of a HTTP header 
+ * in a 3xx response
+ */
+- (void) setFollowLocation: (BOOL)flag;
+
+/*
+ * Switch off the progress meter. 
+ */
+- (void) setProgressMeterOff: (BOOL)flag;
+
+/*
+ * Skip all signal handling
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_NOSIGNAL.html
+ */
+- (void) setSkipAllSignalHandling: (BOOL)flag;
+
+/* 
+ * Request failure on HTTP response >= 400
+ */
+- (void) setFailOnHTTPErrorCode: (BOOL)flag;
+
+- (void) setConnectToHost: (NSString*)host 
+                     port: (NSInteger)port;
+
+- (void) setSessionConfig: (NSURLSessionConfiguration*)config;
+
+- (void) setAllowedProtocolsToHTTPAndHTTPS;
+
+/*
+ * set preferred receive buffer size
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_BUFFERSIZE.html
+ */
+- (void) setPreferredReceiveBufferSize: (NSInteger)size;
+
+/*
+ * Set custom HTTP headers
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_HTTPHEADER.html
+ */
+- (void) setCustomHeaders: (NSArray*)headers;
+
+/*
+ * Enable automatic decompression of HTTP downloads
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_ACCEPT_ENCODING.html
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_HTTP_CONTENT_DECODING.html
+ */
+- (void) setAutomaticBodyDecompression: (BOOL)flag;
+
+/*
+ * Set request method
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_CUSTOMREQUEST.html
+ */
+- (void) setRequestMethod:(NSString*)method;
+
+/*
+ * Download request without body
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_NOBODY.html
+ */
+- (void) setNoBody: (BOOL)flag;
+
+/*
+ * Enable data upload
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_UPLOAD.html
+ */
+- (void) setUpload: (BOOL)flag;
+
+/*
+ * Set size of the request body to send
+ * - SeeAlso: https://curl.haxx.se/libcurl/c/CURLOPT_INFILESIZE_LARGE.html
+ */
+- (void) setRequestBodyLength: (int64_t)length;
+
+- (void) setTimeout: (NSInteger)timeout;
+
+- (void) setProxy;
+
+- (double) getTimeoutIntervalSpent;
+
+
+- (void) pauseReceive;
+- (void) unpauseReceive;
+
+- (void) pauseSend;
+- (void) unpauseSend;
+
+@end
+
+#endif