[v2] Improve processRequest: Handle errors and behave more like a webserver

This also fixes that requests remain in "pending" state on
darwin if e.g. a file is not found or an error occurs during
loading of the file.

v2/internal/frontend/desktop/darwin/Application.h

@@ -41,7 +41,7 @@ void Quit(void*);
 const char* GetSize(void *ctx);
 const char* GetPos(void *ctx);
 
-void ProcessURLResponse(void *inctx, const char *url, const char *contentType, void* data, int datalength);
+void ProcessURLResponse(void *inctx, const char *url, int statusCode, const char *contentType, void* data, int datalength);
 
 /* Dialogs */
 

v2/internal/frontend/desktop/darwin/Application.m

@@ -51,13 +51,13 @@ WailsContext* Create(const char* title, int width, int height, int frameless, in
     return result;
 }
 
-void ProcessURLResponse(void *inctx, const char *url, const char *contentType, void* data, int datalength) {
+void ProcessURLResponse(void *inctx, const char *url, int statusCode, const char *contentType, void* data, int datalength) {
     WailsContext *ctx = (__bridge WailsContext*) inctx;
     NSString *nsurl = safeInit(url);
     NSString *nsContentType = safeInit(contentType);
     NSData *nsdata = [NSData dataWithBytes:data length:datalength];
     
-    [ctx processURLResponse:nsurl :nsContentType :nsdata];
+    [ctx processURLResponse:nsurl :statusCode :nsContentType :nsdata];
 
     [nsdata release];
 }

v2/internal/frontend/desktop/darwin/WailsContext.h

@@ -79,7 +79,7 @@
 - (void) SaveFileDialog :(NSString*)title :(NSString*)defaultFilename :(NSString*)defaultDirectory :(bool)canCreateDirectories :(bool)treatPackagesAsDirectories :(bool)showHiddenFiles :(NSString*)filters;
 
 - (void) loadRequest:(NSString*)url;
-- (void) processURLResponse:(NSString *)url :(NSString *)contentType :(NSData*)data;
+- (void) processURLResponse:(NSString *)url :(int)statusCode :(NSString *)contentType :(NSData*)data;
 - (void) ExecJS:(NSString*)script;
 - (NSScreen*) getCurrentScreen;
 

v2/internal/frontend/desktop/darwin/WailsContext.m

@@ -376,12 +376,14 @@
    [self.webview evaluateJavaScript:script completionHandler:nil];
 }
 
-- (void) processURLResponse:(NSString *)url :(NSString *)contentType :(NSData *)data {
+- (void) processURLResponse:(NSString *)url :(int)statusCode :(NSString *)contentType :(NSData *)data {
     id<WKURLSchemeTask> urlSchemeTask = self.urlRequests[url];
     NSURL *nsurl = [NSURL URLWithString:url];
     NSMutableDictionary *headerFields = [NSMutableDictionary new];
-    headerFields[@"content-type"] = contentType;
-    NSHTTPURLResponse *response = [[NSHTTPURLResponse new] initWithURL:nsurl statusCode:200 HTTPVersion:@"HTTP/1.1" headerFields:headerFields];
+    if ( ![contentType isEqualToString:@""] ) {
+        headerFields[@"content-type"] = contentType;
+    }
+    NSHTTPURLResponse *response = [[NSHTTPURLResponse new] initWithURL:nsurl statusCode:statusCode HTTPVersion:@"HTTP/1.1" headerFields:headerFields];
     [urlSchemeTask didReceiveResponse:response];
     [urlSchemeTask didReceiveData:data];
     [urlSchemeTask didFinish];

v2/internal/frontend/desktop/darwin/frontend.go

@@ -16,8 +16,10 @@ import "C"
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"html/template"
 	"log"
+	"os"
 	"strconv"
 	"unsafe"
 
@@ -272,21 +274,32 @@ func (f *Frontend) ExecJS(js string) {
 func (f *Frontend) processRequest(r *request) {
 	uri := C.GoString(r.url)
 
+	var _contents []byte
+	var _mimetype string
+
 	// Translate URI to file
 	file, match, err := common.TranslateUriToFile(uri, "wails", "wails")
-	if err != nil {
-		// TODO Handle errors
-		return
-	} else if !match {
-		return
+	if err == nil {
+		if !match {
+			// This should never happen on darwin, because we get only called for wails://
+			panic("Unexpected host for request on wails:// scheme")
+		}
+
+		// Load file from asset store
+		_contents, _mimetype, err = f.assets.Load(file)
 	}
 
-	_contents, _mimetype, err := f.assets.Load(file)
+	statusCode := 200
 	if err != nil {
-		f.logger.Error(err.Error())
-		//TODO: Handle errors
-		return
+		if os.IsNotExist(err) {
+			statusCode = 404
+		} else {
+			err = fmt.Errorf("Error processing request %s: %w", uri, err)
+			f.logger.Error(err.Error())
+			statusCode = 500
+		}
 	}
+
 	var data unsafe.Pointer
 	if _contents != nil {
 		data = unsafe.Pointer(&_contents[0])
@@ -294,7 +307,7 @@ func (f *Frontend) processRequest(r *request) {
 	mimetype := C.CString(_mimetype)
 	defer C.free(unsafe.Pointer(mimetype))
 
-	C.ProcessURLResponse(r.ctx, r.url, mimetype, data, C.int(len(_contents)))
+	C.ProcessURLResponse(r.ctx, r.url, C.int(statusCode), mimetype, data, C.int(len(_contents)))
 }
 
 //func (f *Frontend) processSystemEvent(message string) {

v2/internal/frontend/desktop/linux/frontend.go

@@ -333,7 +333,8 @@ func (f *Frontend) processRequest(request unsafe.Pointer) {
 		// TODO Handle errors
 		return
 	} else if !match {
-		return
+		// This should never happen on linux, because we get only called for wails://
+		panic("Unexpected host for request on wails:// scheme")
 	}
 
 	// Load file from asset store
@@ -342,6 +343,8 @@ func (f *Frontend) processRequest(request unsafe.Pointer) {
 		return
 	}
 
+	// TODO How to return 404/500 errors to webkit?
+
 	cContent := C.CString(string(content))
 	defer C.free(unsafe.Pointer(cContent))
 	cMimeType := C.CString(mimeType)

v2/internal/frontend/desktop/windows/frontend.go

@@ -8,6 +8,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"os"
 	"runtime"
 	"strconv"
 	"strings"
@@ -336,26 +337,45 @@ func (f *Frontend) processRequest(req *edge.ICoreWebView2WebResourceRequest, arg
 	//Get the request
 	uri, _ := req.GetUri()
 
+	var content []byte
+	var mimeType string
+
+	// Translate URI to file
 	file, match, err := common.TranslateUriToFile(uri, "file", "wails")
-	if err != nil {
-		// TODO Handle errors
-		return
-	} else if !match {
-		return
+	if err == nil {
+		if !match {
+			// In this case we should let the WebView2 handle the request with it's default handler
+			return
+		}
+
+		// Load file from asset store
+		content, mimeType, err = f.assets.Load(file)
 	}
 
-	// Load file from asset store
-	content, mimeType, err := f.assets.Load(file)
+	statusCode := 200
+	reasonPhrase := "OK"
 	if err != nil {
-		return
+		if os.IsNotExist(err) {
+			statusCode = 404
+			reasonPhrase = "Not Found"
+		} else {
+			err = fmt.Errorf("Error processing request %s: %w", uri, err)
+			f.logger.Error(err.Error())
+			statusCode = 500
+			reasonPhrase = "Internal Server Error"
+		}
+	}
+
+	headers := []string{}
+	if mimeType != "" {
+		headers = append(headers, "Content-Type: "+mimeType)
+	}
+	if content != nil && f.servingFromDisk {
+		headers = append(headers, "Pragma: no-cache")
 	}
 
 	env := f.chromium.Environment()
-	headers := "Content-Type: " + mimeType
-	if f.servingFromDisk {
-		headers += "\nPragma: no-cache"
-	}
-	response, err := env.CreateWebResourceResponse(content, 200, "OK", headers)
+	response, err := env.CreateWebResourceResponse(content, statusCode, reasonPhrase, strings.Join(headers, "\n"))
 	if err != nil {
 		return
 	}
@@ -366,7 +386,6 @@ func (f *Frontend) processRequest(req *edge.ICoreWebView2WebResourceRequest, arg
 	if err != nil {
 		return
 	}
-	return
 }
 
 var edgeMap = map[string]uintptr{