WinHttpSetTimeouts function (winhttp.h)

Article
01/11/2024

The WinHttpSetTimeouts function sets time-outs involved with HTTP transactions.

Syntax

WINHTTPAPI BOOL WinHttpSetTimeouts(
  [in] HINTERNET hInternet,
  [in] int       nResolveTimeout,
  [in] int       nConnectTimeout,
  [in] int       nSendTimeout,
  [in] int       nReceiveTimeout
);

Parameters

[in] hInternet

The HINTERNET handle returned by WinHttpOpen or WinHttpOpenRequest.

[in] nResolveTimeout

A value of type integer that specifies the time-out value, in milliseconds, to use for name resolution. If resolution takes longer than this time-out value, then the request is canceled. The initial value is zero, meaning no time-out (infinite).

Windows Vista and Windows XP: If DNS timeout is specified using NAME_RESOLUTION_TIMEOUT, there is an overhead of one thread per request.

[in] nConnectTimeout

A value of type integer that specifies the time-out value, in milliseconds, to use for server connection requests. If a connection request takes longer than this time-out value, the request is canceled. The initial value is 60,000 (60 seconds).

TCP/IP can time out while setting up the socket during the three leg SYN/ACK exchange, regardless of the value of this parameter.

[in] nSendTimeout

A value of type integer that specifies the time-out value, in milliseconds, to use for sending requests. If sending a request takes longer than this time-out value, the send is canceled. The initial value is 30,000 (30 seconds).

[in] nReceiveTimeout

A value of type integer that specifies the time-out value, in milliseconds, to receive a response to a request. If a response takes longer than this time-out value, the request is canceled. The initial value is 30,000 (30 seconds).

Return value

Returns TRUE if successful, or FALSE otherwise. For extended error information, call GetLastError. Among the error codes returned are the following.

Error Code	Description
ERROR_WINHTTP_INCORRECT_HANDLE_STATE	The requested operation cannot be carried out because the handle supplied is not in the correct state.
ERROR_WINHTTP_INCORRECT_HANDLE_TYPE	The type of handle supplied is incorrect for this operation.
ERROR_WINHTTP_INTERNAL_ERROR	An internal error has occurred.
ERROR_NOT_ENOUGH_MEMORY	Not enough memory was available to complete the requested operation. (Windows error code)
ERROR_INVALID_PARAMETER	One or more of the timeout parameters has a negative value other than -1.

Remarks

Even when WinHTTP is used in asynchronous mode (that is, when WINHTTP_FLAG_ASYNC has been set in WinHttpOpen), this function operates synchronously. The return value indicates success or failure. To get extended error information, call GetLastError.

A value of 0 or -1 sets a time-out to wait infinitely. A value greater than 0 sets the time-out value in milliseconds. For example, 30,000 would set the time-out to 30 seconds. All negative values other than -1 cause the function to fail with ERROR_INVALID_PARAMETER.

Important If a small timeout is set using WinHttpSetOption and WINHTTP_OPTION_RECEIVE_TIMEOUT, it can override the value set with the dwReceiveTimeout parameter, causing a response to terminate earlier than expected. To avoid this, do not set a timeout with the WINHTTP_OPTION_RECEIVE_TIMEOUT option that is smaller than the value set using dwReceiveTimeout.

Note For Windows XP and Windows 2000, see the Run-Time Requirements section of the WinHTTP start page.

Examples

This example shows how to set new time-out values using WinHttpSetTimeouts.

    // Use WinHttpOpen to obtain an HINTERNET handle.
    HINTERNET hSession = WinHttpOpen(L"A WinHTTP Example Program/1.0", 
                                    WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
                                    WINHTTP_NO_PROXY_NAME, 
                                    WINHTTP_NO_PROXY_BYPASS, 0);
    if (hSession)
    {
        // Use WinHttpSetTimeouts to set a new time-out values.
        if (!WinHttpSetTimeouts( hSession, 10000, 10000, 10000, 10000))
            printf( "Error %u in WinHttpSetTimeouts.\n", GetLastError());
              
        // PLACE ADDITIONAL CODE HERE.
    
        // When finished, release the HINTERNET handle.
        WinHttpCloseHandle(hSession);
    }
    else
    {
        printf("Error %u in WinHttpOpen.\n", GetLastError());
    }

Requirements

Requirement	Value
Minimum supported client	Windows XP, Windows 2000 Professional with SP3 [desktop apps only]
Minimum supported server	Windows Server 2003, Windows 2000 Server with SP3 [desktop apps only]
Target Platform	Windows
Header	winhttp.h
Library	Winhttp.lib
DLL	Winhttp.dll
Redistributable	WinHTTP 5.0 and Internet Explorer 5.01 or later on Windows XP and Windows 2000.

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