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Change Internet Proxy settings

, 11 Feb 2003
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Shows code snippets to programmatically change IE proxy settings

Introduction

Changing proxy settings of IE is a frequent requirement of mine. Then I got the idea of writing a tool by myself, at last. I have not found clear instructions on this. Many articles recommend to modify registry directly, but unfortunately their instruction is not enough. Most of them direct me to modify the following values in registry :-

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"ProxyEnable"=dword:00000001
"ProxyServer"=":"
"ProxyOverride"=""
"DisablePasswordCaching"=dword:00000001

Details

I tested it and find that it does not work at least on my computer.( I access internet by ADSL connection.) So I backed up registry and modified proxy settings via Internet Explorer, finding that [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections] is also changed. So I wrote the following code snippet to change proxy settings:

void ShowError(long lerr)
{
    LPVOID lpMsgBuf;
    if (!FormatMessage( 
        FORMAT_MESSAGE_ALLOCATE_BUFFER | 
        FORMAT_MESSAGE_FROM_SYSTEM | 
        FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        lerr,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
        (LPTSTR) &lpMsgBuf,
        0,
        NULL ))
    {
        return;
    }
    MessageBox( NULL, (LPCTSTR)lpMsgBuf, "Error", MB_OK | MB_ICONINFORMATION );
    LocalFree( lpMsgBuf );
}
void CieproxyDlg::OnBnClickedOk()
{//set proxy server
    UpdateData();
    GetDlgItemText(IDC_EDIT1,m_sIEProxy);
    HKEY hk;
    LONG lret=RegOpenKeyEx(HKEY_CURRENT_USER,
        "Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings",
        NULL,KEY_WRITE|KEY_SET_VALUE,&hk);
    if(lret==ERROR_SUCCESS&&NULL!=hk)
    {
        TCHAR* pbuf=m_sIEProxy.GetBuffer(1);
        lret=RegSetValueEx( hk,"ProxyServer",NULL,REG_SZ,pbuf,m_sIEProxy.GetLength());
        DWORD dwenable=1;
        lret=RegSetValueEx(hk,"ProxyEnable",NULL,REG_DWORD,
           (LPBYTE)&dwenable,sizeof(dwenable));
        RegCloseKey(hk);
    }
    const TCHAR* keyname3=_T(
      "software\\Microsoft\\windows\\currentversion\\Internet Settings\\Connections");
    lret=RegOpenKeyEx(HKEY_CURRENT_USER,keyname3,NULL,
        KEY_READ|KEY_WRITE|KEY_SET_VALUE,&hk);
    if(lret==ERROR_SUCCESS&&NULL!=hk)
    {
        DWORD dwtype;
        char pbuf[256];
        DWORD dwlen=sizeof(pbuf);
        const char* valname="Connection to adsl3";
        lret=RegQueryValueEx(hk,valname,NULL,&dwtype,pbuf,&dwlen);
        if(lret!=ERROR_SUCCESS)
        {
            ShowError(lret);
        }
        pbuf[8] = 3;//enable proxy
        pbuf[4]=pbuf[4]+1;
        const char* p=m_sIEProxy.GetBuffer(1);
        memcpy(pbuf+16,p,m_sIEProxy.GetLength());
        char c=0;
        for(int i=m_sIEProxy.GetLength();i<20;i++)
            pbuf[16+i]=c;
        m_sIEProxy.ReleaseBuffer();
        lret=RegSetValueEx(hk,valname,NULL,REG_BINARY,pbuf,dwlen);
        RegCloseKey(hk);
    }
    DWORD dwret;
    SendMessageTimeout(HWND_BROADCAST,WM_SETTINGCHANGE,NULL,NULL,
        SMTO_NORMAL,1000,&dwret);
}

void CieproxyDlg::OnBnClickedDisableProxy()
{
    UpdateData();
    GetDlgItemText(IDC_EDIT1,m_sIEProxy);
    HKEY hk;
    LONG lret=RegOpenKeyEx(HKEY_CURRENT_USER,
        "Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings",
        NULL,KEY_WRITE|KEY_SET_VALUE,&hk);
    if(lret==ERROR_SUCCESS&&NULL!=hk)
    {
        DWORD dwenable=0;
        lret=RegSetValueEx(hk,"ProxyEnable",NULL,REG_DWORD,
            (LPBYTE)&dwenable,sizeof(dwenable));
        RegCloseKey(hk);
    }
    const TCHAR* keyname3=_T(
      "software\\Microsoft\\windows\\currentversion\\Internet Settings\\Connections");
    lret=RegOpenKeyEx(HKEY_CURRENT_USER,keyname3,
        NULL,KEY_READ|KEY_WRITE|KEY_SET_VALUE,&hk);
    if(lret==ERROR_SUCCESS&&NULL!=hk)
    {
        DWORD dwtype;
        char pbuf[256];
        DWORD dwlen=sizeof(pbuf);
        const char* valname="Connection to adsl3";
        lret=RegQueryValueEx(hk,valname,NULL,&dwtype,pbuf,&dwlen);
        if(lret!=ERROR_SUCCESS)
        {
            ShowError(lret);
        }
        pbuf[8] = 1;//enable proxy
        pbuf[4]=pbuf[4]+1;
        lret=RegSetValueEx(hk,valname,NULL,REG_BINARY,pbuf,dwlen);
        RegCloseKey(hk);
    }
    DWORD dwret;
    SendMessageTimeout(HWND_BROADCAST,WM_SETTINGCHANGE,NULL,NULL,SMTO_NORMAL,
        1000,&dwret);
}

Problem with above code is that existing Internet Explorer instances don't know the change of settings. What is more, changing registry directly is not an elegant method. Then the following must be more attractive :

BOOL SetConnectionOptions(LPCTSTR conn_name,LPCTSTR proxy_full_addr)
{
    //conn_name: active connection name. 
    //proxy_full_addr : eg "210.78.22.87:8000"
    INTERNET_PER_CONN_OPTION_LIST list;
    BOOL    bReturn;
    DWORD   dwBufSize = sizeof(list);
    // Fill out list struct.
    list.dwSize = sizeof(list);
    // NULL == LAN, otherwise connectoid name.
    list.pszConnection = conn_name;
    // Set three options.
    list.dwOptionCount = 3;
    list.pOptions = new INTERNET_PER_CONN_OPTION[3];
    // Make sure the memory was allocated.
    if(NULL == list.pOptions)
    {
        // Return FALSE if the memory wasn't allocated.
        OutputDebugString("failed to allocat memory in SetConnectionOptions()");
        return FALSE;
    }
    // Set flags.
    list.pOptions[0].dwOption = INTERNET_PER_CONN_FLAGS;
    list.pOptions[0].Value.dwValue = PROXY_TYPE_DIRECT |
        PROXY_TYPE_PROXY;

    // Set proxy name.
    list.pOptions[1].dwOption = INTERNET_PER_CONN_PROXY_SERVER;
    list.pOptions[1].Value.pszValue = proxy_full_addr;//"http://proxy:80";

    // Set proxy override.
    list.pOptions[2].dwOption = INTERNET_PER_CONN_PROXY_BYPASS;
    list.pOptions[2].Value.pszValue = "local";

    // Set the options on the connection.
    bReturn = InternetSetOption(NULL,
        INTERNET_OPTION_PER_CONNECTION_OPTION, &list, dwBufSize);

    // Free the allocated memory.
    delete [] list.pOptions;
    InternetSetOption(NULL, INTERNET_OPTION_SETTINGS_CHANGED, NULL, 0);
    InternetSetOption(NULL, INTERNET_OPTION_REFRESH , NULL, 0);
    return bReturn;
}
BOOL DisableConnectionProxy(LPCTSTR conn_name)
{
    //conn_name: active connection name. 
    INTERNET_PER_CONN_OPTION_LIST list;
    BOOL    bReturn;
    DWORD   dwBufSize = sizeof(list);
    // Fill out list struct.
    list.dwSize = sizeof(list);
    // NULL == LAN, otherwise connectoid name.
    list.pszConnection = conn_name;
    // Set three options.
    list.dwOptionCount = 1;
    list.pOptions = new INTERNET_PER_CONN_OPTION[list.dwOptionCount];
    // Make sure the memory was allocated.
    if(NULL == list.pOptions)
    {
        // Return FALSE if the memory wasn't allocated.
        OutputDebugString("failed to allocat memory in DisableConnectionProxy()");
        return FALSE;
    }
    // Set flags.
    list.pOptions[0].dwOption = INTERNET_PER_CONN_FLAGS;
    list.pOptions[0].Value.dwValue = PROXY_TYPE_DIRECT  ;
    // Set the options on the connection.
    bReturn = InternetSetOption(NULL,
        INTERNET_OPTION_PER_CONNECTION_OPTION, &list, dwBufSize);
    // Free the allocated memory.
    delete [] list.pOptions;
    InternetSetOption(NULL, INTERNET_OPTION_SETTINGS_CHANGED, NULL, 0);
    InternetSetOption(NULL, INTERNET_OPTION_REFRESH , NULL, 0);
    return bReturn;
}

The usage is very straightforward:

//set proxy
    const char* connection_name="Connection to adsl3";
    SetConnectionOptions(connection_name,"62.81.236.23:80");
//disable proxy 
    DisableConnectionProxy(connection_name);
    

Existing Internet Explorer instances are notified by INTERNET_OPTION_SETTINGS_CHANGED and INTERNET_OPTION_REFRESH

License

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About the Author

onega
Web Developer
China China
No Biography provided

Comments and Discussions

 
GeneralCool ! And a helpfull tip. PinmemberETA11-Sep-08 8:44 
QuestionHow to set "Enable integrated windows authentication" Pinmembervishnuteja18-Apr-07 2:03 
GeneralHelp needed PinmemberKrishhh16-Apr-07 1:43 
GeneralINTERNET_PER_CONN_OPTION' : undeclared identifier PinmemberShashikant_200627-Apr-06 22:09 
GeneralRe: INTERNET_PER_CONN_OPTION' : undeclared identifier Pinmemberchristsiav26-Jun-06 5:50 
GeneralRe: INTERNET_PER_CONN_OPTION' : undeclared identifier Pinmemberchristsiav26-Jun-06 6:12 
GeneralRe: INTERNET_PER_CONN_OPTION' : undeclared identifier Pinmemberalboori27-Jul-06 1:49 
GeneralRe: INTERNET_PER_CONN_OPTION' : undeclared identifier Pinmemberdekdimaya10-Sep-06 21:49 
GeneralRe: INTERNET_PER_CONN_OPTION' : undeclared identifier Pinmemberaren37216-Sep-06 15:24 
QuestionHello, can someone help me here? PinmemberShimshonthegever4-Apr-06 2:02 
QuestionProblem with ProxyServer value Pinsussexpander2k25-Sep-05 0:49 
AnswerRe: Problem with ProxyServer value PinmemberOZambrano17-Dec-08 12:21 
Generalschool blockers Pinsussshwoggie16-Sep-05 2:58 
QuestionHow to get the default (active) connection name directly from the registry? PinmemberAirstriker18-May-05 1:59 
AnswerRe: How to get the default (active) connection name directly from the registry? PinmemberAirstriker18-May-05 2:25 
GeneralRe: How to get the default (active) connection name directly from the registry? Pinmemberchristsiav26-Jun-06 5:25 
GeneralRe: How to get the default (active) connection name directly from the registry? PinmemberAirstriker11-Sep-06 3:06 
GeneralRe: How to get the default (active) connection name directly from the registry? Pinmembertaxtdod2-Dec-06 20:02 
Generalyou went a little overboard PinmemberPyro Joe22-Apr-05 4:01 
GeneralGet it to work in vc++ PinmemberDimitris Vassiliades26-Mar-05 22:26 
GeneralSolution to get it to work in vc++ Pinmemberspdr87027-Aug-04 7:54 
Generalspecific rules for ProxyOvveride Pinmembertyounsi11-Jul-04 8:13 
Generalcompiling problem!! PinsussMayrit31-May-04 9:46 
Generalcompiling problem!! PinsussAnonymous31-May-04 9:37 
QuestionWhat about different browsers? PinsussAnonymous28-Apr-04 9:36 

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Article Copyright 2003 by onega
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