Files
Flips/arlib/socket/socket-schannel.cpp
2016-12-20 02:10:51 +01:00

341 lines
8.9 KiB
C++

#include "socket.h"
//based on http://wayback.archive.org/web/20100528130307/http://www.coastrd.com/c-schannel-smtp
//but heavily rewritten for stability and compactness
#ifdef ARLIB_SSL_SCHANNEL
#ifndef _WIN32
#error SChannel only exists on Windows
#endif
#define SECURITY_WIN32
#undef bind
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <winsock.h>
#include <wincrypt.h>
#include <wintrust.h>
#include <schannel.h>
#include <security.h>
#include <sspi.h>
namespace {
static SecurityFunctionTable* SSPI;
static CredHandle cred;
#define SSPIFlags \
(ISC_REQ_SEQUENCE_DETECT | ISC_REQ_REPLAY_DETECT | ISC_REQ_CONFIDENTIALITY | \
ISC_RET_EXTENDED_ERROR | ISC_REQ_ALLOCATE_MEMORY | ISC_REQ_STREAM)
//my mingw headers are outdated
#ifndef SCH_USE_STRONG_CRYPTO
#define SCH_USE_STRONG_CRYPTO 0x00400000
#endif
#ifndef SP_PROT_TLS1_2_CLIENT
#define SP_PROT_TLS1_2_CLIENT 0x00000800
#endif
#ifndef SEC_Entry
#define SEC_Entry WINAPI
#endif
static void initialize()
{
if (SSPI) return;
//linking a DLL is easy, but when there's only one exported function, spending the extra effort is worth it
HMODULE secur32 = LoadLibraryA("secur32.dll");
typedef PSecurityFunctionTableA SEC_Entry (*InitSecurityInterfaceA_t)(void);
InitSecurityInterfaceA_t InitSecurityInterfaceA = (InitSecurityInterfaceA_t)GetProcAddress(secur32, SECURITY_ENTRYPOINT_ANSIA);
SSPI = InitSecurityInterfaceA();
SCHANNEL_CRED SchannelCred = {};
SchannelCred.dwVersion = SCHANNEL_CRED_VERSION;
SchannelCred.dwFlags = SCH_CRED_NO_DEFAULT_CREDS | SCH_USE_STRONG_CRYPTO;
// fun fact: IE11 doesn't use SCH_USE_STRONG_CRYPTO. I guess it favors accepting outdated servers over rejecting evil ones.
SchannelCred.grbitEnabledProtocols = SP_PROT_TLS1_2_CLIENT; // Microsoft recommends setting this to zero, but that makes it use TLS 1.0.
//howsmyssl expects session ticket support for the Good rating, but that's only supported on windows 8, according to
// https://connect.microsoft.com/IE/feedback/details/997136/internet-explorer-11-on-windows-7-does-not-support-tls-session-tickets
//and I can't find which flag enables that, anyways
SSPI->AcquireCredentialsHandleA(NULL, (char*)UNISP_NAME_A, SECPKG_CRED_OUTBOUND,
NULL, &SchannelCred, NULL, NULL, &cred, NULL);
}
class socketssl_impl : public socketssl {
public:
socket* sock;
CtxtHandle ssl;
SecPkgContext_StreamSizes bufsizes;
BYTE* recv_buf;
size_t recv_buf_len;
BYTE* ret_buf;
size_t ret_buf_len;
bool in_handshake;
bool permissive;
void fetch(bool block)
{
array<byte> retbytes;
int ret = sock->recv(retbytes, block);
if (ret<0) return error();
recv_buf = realloc(recv_buf, recv_buf_len + ret + 1024);
memcpy(recv_buf+recv_buf_len, retbytes.ptr(), ret);
recv_buf_len += ret;
}
void fetch() { fetch(true); }
void fetchnb() { fetch(false); }
void ret_realloc(int bytes)
{
if (bytes > 0)
{
ret_buf_len += bytes;
if (ret_buf_len > 1024)
{
ret_buf = realloc(ret_buf, ret_buf_len + 1024);
}
}
}
BYTE* tmpptr()
{
return recv_buf + recv_buf_len;
}
void error()
{
SSPI->DeleteSecurityContext(&ssl);
delete sock;
sock = NULL;
in_handshake = false;
}
void handshake()
{
if (!in_handshake) return;
SecBuffer InBuffers[2] = { { recv_buf_len, SECBUFFER_TOKEN, recv_buf }, { 0, SECBUFFER_EMPTY, NULL } };
SecBufferDesc InBufferDesc = { SECBUFFER_VERSION, 2, InBuffers };
SecBuffer OutBuffer = { 0, SECBUFFER_TOKEN, NULL };
SecBufferDesc OutBufferDesc = { SECBUFFER_VERSION, 1, &OutBuffer };
DWORD ignore;
SECURITY_STATUS scRet;
ULONG flags = SSPIFlags;
if (this->permissive) flags |= ISC_REQ_MANUAL_CRED_VALIDATION; // +1 for defaulting to secure
scRet = SSPI->InitializeSecurityContextA(&cred, &ssl, NULL, flags, 0, SECURITY_NATIVE_DREP,
&InBufferDesc, 0, NULL, &OutBufferDesc, &ignore, NULL);
// according to the original program, extended errors are success
// but they also hit the error handler below, so I guess it just sends an error to the server?
// either way, ignore
if (scRet == SEC_E_OK || scRet == SEC_I_CONTINUE_NEEDED)
{
if (OutBuffer.cbBuffer != 0 && OutBuffer.pvBuffer != NULL)
{
if (sock->send(arrayview<byte>((BYTE*)OutBuffer.pvBuffer, OutBuffer.cbBuffer)) < 0)
{
SSPI->FreeContextBuffer(OutBuffer.pvBuffer);
error();
return;
}
SSPI->FreeContextBuffer(OutBuffer.pvBuffer);
}
}
if (scRet == SEC_E_INCOMPLETE_MESSAGE) return;
if (scRet == SEC_E_OK)
{
in_handshake = false;
}
if (FAILED(scRet))
{
error();
return;
}
// SEC_I_INCOMPLETE_CREDENTIALS is possible and means server requested client authentication
// we don't support that, just ignore it
if (InBuffers[1].BufferType == SECBUFFER_EXTRA)
{
memmove(recv_buf, recv_buf + (recv_buf_len - InBuffers[1].cbBuffer), InBuffers[1].cbBuffer);
recv_buf_len = InBuffers[1].cbBuffer;
}
else recv_buf_len = 0;
}
bool handshake_first(const char * domain)
{
SecBuffer OutBuffer = { 0, SECBUFFER_TOKEN, NULL };
SecBufferDesc OutBufferDesc = { SECBUFFER_VERSION, 1, &OutBuffer };
DWORD ignore;
if (SSPI->InitializeSecurityContextA(&cred, NULL, (char*)domain, SSPIFlags, 0, SECURITY_NATIVE_DREP,
NULL, 0, &ssl, &OutBufferDesc, &ignore, NULL)
!= SEC_I_CONTINUE_NEEDED)
{
return false;
}
if (OutBuffer.cbBuffer != 0)
{
if (sock->send(arrayview<byte>((BYTE*)OutBuffer.pvBuffer, OutBuffer.cbBuffer)) < 0)
{
SSPI->FreeContextBuffer(OutBuffer.pvBuffer);
error();
return false;
}
SSPI->FreeContextBuffer(OutBuffer.pvBuffer); // Free output buffer.
}
in_handshake = true;
while (in_handshake) { fetch(); handshake(); }
return true;
}
bool init(socket* parent, const char * domain, bool permissive)
{
if (!parent) return false;
this->sock = parent;
this->fd = parent->get_fd();
this->recv_buf = malloc(2048);
this->recv_buf_len = 0;
this->ret_buf = malloc(2048);
this->ret_buf_len = 0;
this->permissive = permissive;
if (!handshake_first(domain)) return false;
SSPI->QueryContextAttributes(&ssl, SECPKG_ATTR_STREAM_SIZES, &bufsizes);
return (sock);
}
void process()
{
handshake();
bool again = true;
while (again)
{
again = false;
SecBuffer Buffers[4] = {
{ recv_buf_len, SECBUFFER_DATA, recv_buf },
{ 0, SECBUFFER_EMPTY, NULL },
{ 0, SECBUFFER_EMPTY, NULL },
{ 0, SECBUFFER_EMPTY, NULL },
};
SecBufferDesc Message = { SECBUFFER_VERSION, 4, Buffers };
SECURITY_STATUS scRet = SSPI->DecryptMessage(&ssl, &Message, 0, NULL);
if (scRet == SEC_E_INCOMPLETE_MESSAGE) return;
else if (scRet == SEC_I_RENEGOTIATE)
{
in_handshake = true;
}
else if (scRet != SEC_E_OK)
{
error();
return;
}
recv_buf_len = 0;
// Locate data and (optional) extra buffers.
for (int i=0;i<4;i++)
{
if (Buffers[i].BufferType == SECBUFFER_DATA)
{
memcpy(ret_buf+ret_buf_len, Buffers[i].pvBuffer, Buffers[i].cbBuffer);
ret_realloc(Buffers[i].cbBuffer);
again = true;
}
if (Buffers[i].BufferType == SECBUFFER_EXTRA)
{
memmove(recv_buf, Buffers[i].pvBuffer, Buffers[i].cbBuffer);
recv_buf_len = Buffers[i].cbBuffer;
}
}
}
}
int recv(arrayvieww<byte> data, bool block = false)
{
if (!sock) return -1;
fetch(block);
process();
size_t bytes_ret = ret_buf_len;
if (bytes_ret > data.size()) bytes_ret = data.size();
memcpy(data.ptr(), ret_buf, bytes_ret);
memmove(ret_buf, ret_buf+bytes_ret, ret_buf_len-bytes_ret);
ret_buf_len -= bytes_ret;
return bytes_ret;
}
int sendp(arrayview<byte> bytes, bool block = true)
{
if (!sock) return -1;
const byte* data = bytes.ptr();
unsigned int len = bytes.size();
fetchnb();
process();
BYTE* sendbuf = tmpptr(); // let's reuse this
unsigned int maxmsglen = 0x1000 - bufsizes.cbHeader - bufsizes.cbTrailer;
if (len > maxmsglen) len = maxmsglen;
memcpy(sendbuf+bufsizes.cbHeader, data, len);
SecBuffer Buffers[4] = {
{ bufsizes.cbHeader, SECBUFFER_STREAM_HEADER, sendbuf },
{ len, SECBUFFER_DATA, sendbuf+bufsizes.cbHeader },
{ bufsizes.cbTrailer, SECBUFFER_STREAM_TRAILER, sendbuf+bufsizes.cbHeader+len },
{ 0, SECBUFFER_EMPTY, NULL },
};
SecBufferDesc Message = { SECBUFFER_VERSION, 4, Buffers };
if (FAILED(SSPI->EncryptMessage(&ssl, 0, &Message, 0))) { error(); return -1; }
if (sock->send(arrayview<byte>(sendbuf, Buffers[0].cbBuffer + Buffers[1].cbBuffer + Buffers[2].cbBuffer)) < 0) error();
return len;
}
~socketssl_impl()
{
error();
free(recv_buf);
free(ret_buf);
}
};
}
socketssl* socketssl::create(socket* parent, cstring domain, bool permissive)
{
initialize();
socketssl_impl* ret = new socketssl_impl();
if (!ret->init(parent, domain, permissive)) { delete ret; return NULL; }
else return ret;
}
#endif