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),
(LPTSTR) &lpMsgBuf,
0,
NULL ))
{
return;
}
MessageBox( NULL, (LPCTSTR)lpMsgBuf, "Error", MB_OK | MB_ICONINFORMATION );
LocalFree( lpMsgBuf );
}
void CieproxyDlg::OnBnClickedOk()
{
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;
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;
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)
{
INTERNET_PER_CONN_OPTION_LIST list;
BOOL bReturn;
DWORD dwBufSize = sizeof(list);
list.dwSize = sizeof(list);
list.pszConnection = conn_name;
list.dwOptionCount = 3;
list.pOptions = new INTERNET_PER_CONN_OPTION[3];
if(NULL == list.pOptions)
{
OutputDebugString("failed to allocat memory in SetConnectionOptions()");
return FALSE;
}
list.pOptions[0].dwOption = INTERNET_PER_CONN_FLAGS;
list.pOptions[0].Value.dwValue = PROXY_TYPE_DIRECT |
PROXY_TYPE_PROXY;
list.pOptions[1].dwOption = INTERNET_PER_CONN_PROXY_SERVER;
list.pOptions[1].Value.pszValue = proxy_full_addr;
list.pOptions[2].dwOption = INTERNET_PER_CONN_PROXY_BYPASS;
list.pOptions[2].Value.pszValue = "local";
bReturn = InternetSetOption(NULL,
INTERNET_OPTION_PER_CONNECTION_OPTION, &list, dwBufSize);
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)
{
INTERNET_PER_CONN_OPTION_LIST list;
BOOL bReturn;
DWORD dwBufSize = sizeof(list);
list.dwSize = sizeof(list);
list.pszConnection = conn_name;
list.dwOptionCount = 1;
list.pOptions = new INTERNET_PER_CONN_OPTION[list.dwOptionCount];
if(NULL == list.pOptions)
{
OutputDebugString("failed to allocat memory in DisableConnectionProxy()");
return FALSE;
}
list.pOptions[0].dwOption = INTERNET_PER_CONN_FLAGS;
list.pOptions[0].Value.dwValue = PROXY_TYPE_DIRECT ;
bReturn = InternetSetOption(NULL,
INTERNET_OPTION_PER_CONNECTION_OPTION, &list, dwBufSize);
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:
const char* connection_name="Connection to adsl3";
SetConnectionOptions(connection_name,"62.81.236.23:80");
DisableConnectionProxy(connection_name);
Existing Internet Explorer instances are notified by INTERNET_OPTION_SETTINGS_CHANGED
and
INTERNET_OPTION_REFRESH