I'm trying to implement an SSL handshake in C++ x64 unicode in Windows using winsock, schannel, security etc. Example host is google.com.
I created a SOCKET and could connect via WSAConnectByNameW.
I'm setting my SCHANNEL parameters as followed:
SCHANNEL_CRED *cred = new SCHANNEL_CRED;
cred->dwVersion = SCHANNEL_CRED_VERSION;
cred->dwFlags = SCH_USE_STRONG_CRYPTO | SCH_CRED_AUTO_CRED_VALIDATION| SCH_CRED_NO_DEFAULT_CREDS;
cred->grbitEnabledProtocols = SP_PROT_TLS1_2;
I want to get the handle using AcquireCredentialsHandleW (passing UNISP_NAME):
SECURITY_STATUS secstatus = AcquireCredentialsHandleW(NULL, UNISP_NAME, SECPKG_CRED_OUTBOUND, NULL, &cred, NULL, NULL, &handle, NULL);
Which fails for some reason due to incompatible data types:
""const wchar_t *"" --> ""LPWSTR""
Btw. Handle is just a CredHandle here.
I'm using unicode so I thought I could use UNISP_NAME since it's a 0 terminated string. I tried converting the string into an LPWSTR. Which is just an pointer to a 0 terminated string, right?
std::wstring service = L"Microsoft Unified Security Protocol Provider";
LPWSTR servicePtr = &service[0];
And pass it to the function:
SECURITY_STATUS secstatus = AcquireCredentialsHandleW(NULL, servicePtr, SECPKG_CRED_OUTBOUND, NULL, &cred, NULL, NULL, &handle, NULL);
But it doesn't seem to work. I don't get it. What's my problem here? Why can't I get the handle? Why does the function (AcquireCredentialsHandleW) does not accept its own pre-coded parameters even in the correct encoding?
Thanks in advance.
PS.: I want to try it without openssl or curl as far as I can make it ^^
Tried switching to multibyte. Same problem but not for wchar but chars. Tried converting the string to a pointer tried switching schannel parameter with differently encoded parameter.
The second parameter of AcquireCredentialsHandle()
expects a pointer to a non-const string (why non-const? who knows).
UNISP_NAME
is just a #define
for a string literal:
#define UNISP_NAME_A "Microsoft Unified Security Protocol Provider"
#define UNISP_NAME_W L"Microsoft Unified Security Protocol Provider"
#ifdef UNICODE
#define UNISP_NAME UNISP_NAME_W
...
#else
#define UNISP_NAME UNISP_NAME_A
...
#endif
In C++, a string literal is a const string (in this case, a const wchar_t[]
, which decays into a const wchar_t*
).
So, you will have to cast away the const
in C++, eg:
AcquireCredentialsHandleW(..., const_cast<LPWSTR>(UNISP_NAME), ...);
Alternatively, you can use a string literal to initialize a non-const character buffer, eg:
WCHAR szPackage[] = UNISP_NAME;
AcquireCredentialsHandleW(..., szPackage, ...);
Your wstring::operator[]
approach should work fine in C++11 and later, where the internal memory buffer of std::wstring
is guaranteed to be null-terminated, eg:
std::wstring package = UNISP_NAME_W;
AcquireCredentialsHandleW(..., &package[0], ...);
Or, you can cast away the const
from the pointer returned by wstring::c_str()
, eg:
std::wstring package = UNISP_NAME_W;
AcquireCredentialsHandleW(..., const_cast<LPWSTR>(package.c_str()), ...);
Or, in C++17 and later, wstring::data()
has an overload to return a non-const pointer, eg:
std::wstring package = UNISP_NAME_W;
AcquireCredentialsHandleW(..., package.data(), ...);