Patch for WinInet error handling

SynCrtSock.pas.diff

Index: SynCrtSock.pas
===================================================================
--- SynCrtSock.pas  (revision 53301)
+++ SynCrtSock.pas	(working copy)
@@ -900,9 +900,12 @@
 
   /// WinINet exception type
   EWinINet = class(Exception)
+  private
+    fCode: Cardinal;
   public
     /// create a WinINet exception, with the error message as text
     constructor Create;
+    property ErrorCode: cardinal read fCode;
   end;
 
   {/ a class to handle HTTP/1.1 request using the WinHTTP API
@@ -4103,17 +4106,33 @@
 { EWinINet }
 
 constructor EWinINet.Create;
-var tmp: array[byte] of Char;
+var err: PChar;
     dwError, tmpLen: DWORD;
-    msg: string;
-    lastError: cardinal;
+    msg, tmp: string;
 begin
-  lastError := GetLastError;
-  tmpLen := 255;
-  if InternetGetLastResponseInfo({$ifdef FPC}@{$endif}dwError,tmp,tmpLen) and (tmpLen>0) then
-    SetString(msg,tmp,tmpLen) else
-    msg := 'Error';
-  inherited CreateFmt('%s (%d)',[msg,lastError]);
+  fCode := GetLastError;
+  msg := 'Error';
+
+  tmpLen := FormatMessage(FORMAT_MESSAGE_FROM_HMODULE or FORMAT_MESSAGE_ALLOCATE_BUFFER,
+    Pointer(GetModuleHandle('wininet.dll')), fCode, 0, @err, 0, nil);
+  // See SysUtils.SysErrorMessage
+  try
+    while (tmpLen > 0) and (CharInSet(err[tmpLen - 1], [#0..#32, '.'])) do Dec(tmpLen);
+    SetString(msg, err, tmpLen);
+  finally
+    LocalFree(HLOCAL(err));
+  end;
+
+  if fCode = ERROR_INTERNET_EXTENDED_ERROR then begin
+    InternetGetLastResponseInfo({$ifdef FPC}@{$endif}dwError,nil,tmpLen);
+    if tmpLen > 0 then begin
+      SetLength(tmp, tmpLen);
+      InternetGetLastResponseInfo({$ifdef FPC}@{$endif}dwError,PChar(tmp),tmpLen);
+      msg := msg + ' [' + tmp + ']';
+    end;
+  end;
+
+  inherited CreateFmt('%s (%d)',[msg,fCode]);
 end;
 
 
@@ -4132,7 +4151,7 @@
 begin
   if (hdr<>'') and not HttpAddRequestHeadersA(fRequest,
      Pointer(hdr), length(hdr), HTTP_ADDREQ_FLAG_COALESCE) then
-    EWinINet.Create;
+    raise EWinINet.Create;
 end;
 
 procedure TWinINet.InternalCloseRequest;
@@ -4200,13 +4219,13 @@
   FRequest := HttpOpenRequestA(FConnection, Pointer(method), Pointer(aURL), nil,
     nil, @ALL_ACCEPT, Flags,0);
   if FRequest=nil then
-    EWinINet.Create;
+    raise EWinINet.Create;
 end;
 
 procedure TWinINet.InternalSendRequest(const aData: RawByteString);
 begin
   if not HttpSendRequestA(fRequest, nil, 0, pointer(aData), length(aData)) then
-    EWinINet.Create;
+    raise EWinINet.Create;
 end;