1 files changed, 478 insertions, 322 deletions
diff --git a/tools/plink/wingss.c b/tools/plink/wingss.c
index 742106e88..4efad5d58 100644
--- a/tools/plink/wingss.c
+++ b/tools/plink/wingss.c
@@ -1,322 +1,478 @@
-#ifndef NO_GSSAPI
-
-#include "putty.h"
-
-#define SECURITY_WIN32
-#include <security.h>
-
-#include "sshgss.h"
-#include "misc.h"
-
-#define NOTHING
-#define DECL_SSPI_FUNCTION(linkage, rettype, name, params)	\
-  typedef rettype (WINAPI *t_##name) params;			\
-  linkage t_##name p_##name
-#define GET_SSPI_FUNCTION(module, name)					\
-  p_##name = module ? (t_##name) GetProcAddress(module, #name) : NULL
-
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   AcquireCredentialsHandleA,
-		   (SEC_CHAR *, SEC_CHAR *, ULONG, PLUID,
-		    PVOID, SEC_GET_KEY_FN, PVOID, PCredHandle, PTimeStamp));
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   InitializeSecurityContextA,
-		   (PCredHandle, PCtxtHandle, SEC_CHAR *, ULONG, ULONG,
-		   ULONG, PSecBufferDesc, ULONG, PCtxtHandle,
-		    PSecBufferDesc, PULONG, PTimeStamp));
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   FreeContextBuffer,
-		   (PVOID));
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   FreeCredentialsHandle,
-		   (PCredHandle));
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   DeleteSecurityContext,
-		   (PCtxtHandle));
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   QueryContextAttributesA,
-		   (PCtxtHandle, ULONG, PVOID));
-DECL_SSPI_FUNCTION(static, SECURITY_STATUS,
-		   MakeSignature,
-		   (PCtxtHandle, ULONG, PSecBufferDesc, ULONG));
-
-static HMODULE security_module = NULL;
-
-typedef struct winSsh_gss_ctx {
-    unsigned long maj_stat;
-    unsigned long min_stat;
-    CredHandle cred_handle;
-    CtxtHandle context;
-    PCtxtHandle context_handle;
-    TimeStamp expiry;
-} winSsh_gss_ctx;
-
-
-const Ssh_gss_buf gss_mech_krb5={9,"\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"};
-
-int ssh_gss_init(void)
-{
-    if (security_module)
-	return 1;		       /* already initialised */
-
-    security_module = LoadLibrary("secur32.dll");
-    if (security_module) {
-	GET_SSPI_FUNCTION(security_module, AcquireCredentialsHandleA);
-	GET_SSPI_FUNCTION(security_module, InitializeSecurityContextA);
-	GET_SSPI_FUNCTION(security_module, FreeContextBuffer);
-	GET_SSPI_FUNCTION(security_module, FreeCredentialsHandle);
-	GET_SSPI_FUNCTION(security_module, DeleteSecurityContext);
-	GET_SSPI_FUNCTION(security_module, QueryContextAttributesA);
-	GET_SSPI_FUNCTION(security_module, MakeSignature);
-	return 1;
-    }
-    return 0;
-}
-
-Ssh_gss_stat ssh_gss_indicate_mech(Ssh_gss_buf *mech)
-{
-    *mech = gss_mech_krb5;
-    return SSH_GSS_OK;
-}
-
-
-Ssh_gss_stat ssh_gss_import_name(char *host, Ssh_gss_name *srv_name)
-{
-    char *pStr;
-
-    /* Check hostname */
-    if (host == NULL) return SSH_GSS_FAILURE;
-    
-    /* copy it into form host/FQDN */
-    pStr = dupcat("host/", host, NULL);
-
-    *srv_name = (Ssh_gss_name) pStr;
-
-    return SSH_GSS_OK;
-}
-
-Ssh_gss_stat ssh_gss_acquire_cred(Ssh_gss_ctx *ctx)
-{
-    winSsh_gss_ctx *winctx = snew(winSsh_gss_ctx);
-    memset(winctx, 0, sizeof(winSsh_gss_ctx));
-
-    /* prepare our "wrapper" structure */
-    winctx->maj_stat =  winctx->min_stat = SEC_E_OK;
-    winctx->context_handle = NULL;
-
-    /* Specifying no principal name here means use the credentials of
-       the current logged-in user */
-
-    winctx->maj_stat = p_AcquireCredentialsHandleA(NULL,
-						   "Kerberos",
-						   SECPKG_CRED_OUTBOUND,
-						   NULL,
-						   NULL,
-						   NULL,
-						   NULL,
-						   &winctx->cred_handle,
-						   &winctx->expiry);
-
-    if (winctx->maj_stat != SEC_E_OK) return SSH_GSS_FAILURE;
-    
-    *ctx = (Ssh_gss_ctx) winctx;
-    return SSH_GSS_OK;
-}
-
-
-Ssh_gss_stat ssh_gss_init_sec_context(Ssh_gss_ctx *ctx,
-				      Ssh_gss_name srv_name,
-				      int to_deleg,
-				      Ssh_gss_buf *recv_tok,
-				      Ssh_gss_buf *send_tok)
-{
-    winSsh_gss_ctx *winctx = (winSsh_gss_ctx *) *ctx;
-    SecBuffer wsend_tok = {send_tok->length,SECBUFFER_TOKEN,send_tok->value};
-    SecBuffer wrecv_tok = {recv_tok->length,SECBUFFER_TOKEN,recv_tok->value};
-    SecBufferDesc output_desc={SECBUFFER_VERSION,1,&wsend_tok};
-    SecBufferDesc input_desc ={SECBUFFER_VERSION,1,&wrecv_tok};
-    unsigned long flags=ISC_REQ_MUTUAL_AUTH|ISC_REQ_REPLAY_DETECT|
-	ISC_REQ_CONFIDENTIALITY|ISC_REQ_ALLOCATE_MEMORY;
-    unsigned long ret_flags=0;
-    
-    /* check if we have to delegate ... */
-    if (to_deleg) flags |= ISC_REQ_DELEGATE;
-    winctx->maj_stat = p_InitializeSecurityContextA(&winctx->cred_handle,
-						    winctx->context_handle,
-						    (char*) srv_name,
-						    flags,
-						    0,          /* reserved */
-						    SECURITY_NATIVE_DREP,
-						    &input_desc,
-						    0,          /* reserved */
-						    &winctx->context,
-						    &output_desc,
-						    &ret_flags,
-						    &winctx->expiry);
-  
-    /* prepare for the next round */
-    winctx->context_handle = &winctx->context;
-    send_tok->value = wsend_tok.pvBuffer;
-    send_tok->length = wsend_tok.cbBuffer;
-  
-    /* check & return our status */
-    if (winctx->maj_stat==SEC_E_OK) return SSH_GSS_S_COMPLETE;
-    if (winctx->maj_stat==SEC_I_CONTINUE_NEEDED) return SSH_GSS_S_CONTINUE_NEEDED;
-    
-    return SSH_GSS_FAILURE;
-}
-
-Ssh_gss_stat ssh_gss_free_tok(Ssh_gss_buf *send_tok)
-{
-    /* check input */
-    if (send_tok == NULL) return SSH_GSS_FAILURE;
-
-    /* free Windows buffer */
-    p_FreeContextBuffer(send_tok->value);
-    SSH_GSS_CLEAR_BUF(send_tok);
-    
-    return SSH_GSS_OK;
-}
-
-Ssh_gss_stat ssh_gss_release_cred(Ssh_gss_ctx *ctx)
-{
-    winSsh_gss_ctx *winctx= (winSsh_gss_ctx *) *ctx;
-
-    /* check input */
-    if (winctx == NULL) return SSH_GSS_FAILURE;
-
-    /* free Windows data */
-    p_FreeCredentialsHandle(&winctx->cred_handle);
-    p_DeleteSecurityContext(&winctx->context);
-
-    /* delete our "wrapper" structure */
-    sfree(winctx);
-    *ctx = (Ssh_gss_ctx) NULL;
-
-    return SSH_GSS_OK;
-}
-
-
-Ssh_gss_stat ssh_gss_release_name(Ssh_gss_name *srv_name)
-{
-    char *pStr= (char *) *srv_name;
-
-    if (pStr == NULL) return SSH_GSS_FAILURE;
-    sfree(pStr);
-    *srv_name = (Ssh_gss_name) NULL;
-
-    return SSH_GSS_OK;
-}
-
-Ssh_gss_stat ssh_gss_display_status(Ssh_gss_ctx ctx, Ssh_gss_buf *buf)
-{
-    winSsh_gss_ctx *winctx = (winSsh_gss_ctx *) ctx;
-    char *msg;
-
-    if (winctx == NULL) return SSH_GSS_FAILURE;
-
-    /* decode the error code */
-    switch (winctx->maj_stat) {
-      case SEC_E_OK: msg="SSPI status OK"; break;
-      case SEC_E_INVALID_HANDLE: msg="The handle passed to the function"
-	    " is invalid.";
-	break;
-      case SEC_E_TARGET_UNKNOWN: msg="The target was not recognized."; break;
-      case SEC_E_LOGON_DENIED: msg="The logon failed."; break;
-      case SEC_E_INTERNAL_ERROR: msg="The Local Security Authority cannot"
-	    " be contacted.";
-	break;
-      case SEC_E_NO_CREDENTIALS: msg="No credentials are available in the"
-	    " security package.";
-	break;
-      case SEC_E_NO_AUTHENTICATING_AUTHORITY:
-	msg="No authority could be contacted for authentication."
-	    "The domain name of the authenticating party could be wrong,"
-	    " the domain could be unreachable, or there might have been"
-	    " a trust relationship failure.";
-	break;
-      case SEC_E_INSUFFICIENT_MEMORY:
-	msg="One or more of the SecBufferDesc structures passed as"
-	    " an OUT parameter has a buffer that is too small.";
-	break;
-      case SEC_E_INVALID_TOKEN:
-	msg="The error is due to a malformed input token, such as a"
-	    " token corrupted in transit, a token"
-	    " of incorrect size, or a token passed into the wrong"
-	    " security package. Passing a token to"
-	    " the wrong package can happen if client and server did not"
-	    " negotiate the proper security package.";
-	break;
-      default:
-	msg = "Internal SSPI error";
-	break;
-    }
-
-    buf->value = dupstr(msg);
-    buf->length = strlen(buf->value);
-    
-    return SSH_GSS_OK;
-}
-
-Ssh_gss_stat ssh_gss_get_mic(Ssh_gss_ctx ctx, Ssh_gss_buf *buf,
-			     Ssh_gss_buf *hash)
-{
-    winSsh_gss_ctx *winctx= (winSsh_gss_ctx *) ctx;
-    SecPkgContext_Sizes ContextSizes;
-    SecBufferDesc InputBufferDescriptor;
-    SecBuffer InputSecurityToken[2];
-
-    if (winctx == NULL) return SSH_GSS_FAILURE;
-  
-    winctx->maj_stat = 0;
-
-    memset(&ContextSizes, 0, sizeof(ContextSizes));
-
-    winctx->maj_stat = p_QueryContextAttributesA(&winctx->context,
-						 SECPKG_ATTR_SIZES,
-						 &ContextSizes);
-    
-    if (winctx->maj_stat != SEC_E_OK ||
-	ContextSizes.cbMaxSignature == 0)
-	return winctx->maj_stat;
-
-    InputBufferDescriptor.cBuffers = 2;
-    InputBufferDescriptor.pBuffers = InputSecurityToken;
-    InputBufferDescriptor.ulVersion = SECBUFFER_VERSION;
-    InputSecurityToken[0].BufferType = SECBUFFER_DATA;
-    InputSecurityToken[0].cbBuffer = buf->length;
-    InputSecurityToken[0].pvBuffer = buf->value;
-    InputSecurityToken[1].BufferType = SECBUFFER_TOKEN;
-    InputSecurityToken[1].cbBuffer = ContextSizes.cbMaxSignature;
-    InputSecurityToken[1].pvBuffer = snewn(ContextSizes.cbMaxSignature, char);
-
-    winctx->maj_stat = p_MakeSignature(&winctx->context,
-				       0,
-				       &InputBufferDescriptor,
-				       0);
-
-    if (winctx->maj_stat == SEC_E_OK) {
-	hash->length = InputSecurityToken[1].cbBuffer;
-	hash->value = InputSecurityToken[1].pvBuffer;
-    }
-
-    return winctx->maj_stat;
-}
-
-Ssh_gss_stat ssh_gss_free_mic(Ssh_gss_buf *hash)
-{
-    sfree(hash->value);
-    return SSH_GSS_OK;
-}
-
-#else
-
-/* Dummy function so this source file defines something if NO_GSSAPI
-   is defined. */
-
-int ssh_gss_init(void)
-{
-    return 0;
-}
-
-#endif
+#ifndef NO_GSSAPI
+
+#include "putty.h"
+
+#include <security.h>
+
+#include "pgssapi.h"
+#include "sshgss.h"
+#include "sshgssc.h"
+
+#include "misc.h"
+
+/* Windows code to set up the GSSAPI library list. */
+
+const int ngsslibs = 3;
+const char *const gsslibnames[3] = {
+    "MIT Kerberos GSSAPI32.DLL",
+    "Microsoft SSPI SECUR32.DLL",
+    "User-specified GSSAPI DLL",
+};
+const struct keyval gsslibkeywords[] = {
+    { "gssapi32", 0 },
+    { "sspi", 1 },
+    { "custom", 2 },
+};
+
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      AcquireCredentialsHandleA,
+		      (SEC_CHAR *, SEC_CHAR *, ULONG, PLUID,
+		       PVOID, SEC_GET_KEY_FN, PVOID, PCredHandle, PTimeStamp));
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      InitializeSecurityContextA,
+		      (PCredHandle, PCtxtHandle, SEC_CHAR *, ULONG, ULONG,
+		       ULONG, PSecBufferDesc, ULONG, PCtxtHandle,
+		       PSecBufferDesc, PULONG, PTimeStamp));
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      FreeContextBuffer,
+		      (PVOID));
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      FreeCredentialsHandle,
+		      (PCredHandle));
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      DeleteSecurityContext,
+		      (PCtxtHandle));
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      QueryContextAttributesA,
+		      (PCtxtHandle, ULONG, PVOID));
+DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
+		      MakeSignature,
+		      (PCtxtHandle, ULONG, PSecBufferDesc, ULONG));
+
+typedef struct winSsh_gss_ctx {
+    unsigned long maj_stat;
+    unsigned long min_stat;
+    CredHandle cred_handle;
+    CtxtHandle context;
+    PCtxtHandle context_handle;
+    TimeStamp expiry;
+} winSsh_gss_ctx;
+
+
+const Ssh_gss_buf gss_mech_krb5={9,"\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"};
+
+const char *gsslogmsg = NULL;
+
+static void ssh_sspi_bind_fns(struct ssh_gss_library *lib);
+
+struct ssh_gss_liblist *ssh_gss_setup(const Config *cfg)
+{
+    HMODULE module;
+    HKEY regkey;
+    struct ssh_gss_liblist *list = snew(struct ssh_gss_liblist);
+
+    list->libraries = snewn(3, struct ssh_gss_library);
+    list->nlibraries = 0;
+
+    /* MIT Kerberos GSSAPI implementation */
+    /* TODO: For 64-bit builds, check for gssapi64.dll */
+    module = NULL;
+    if (RegOpenKey(HKEY_LOCAL_MACHINE, "SOFTWARE\\MIT\\Kerberos", &regkey)
+	== ERROR_SUCCESS) {
+	DWORD type, size;
+	LONG ret;
+	char *buffer;
+
+	/* Find out the string length */
+        ret = RegQueryValueEx(regkey, "InstallDir", NULL, &type, NULL, &size);
+
+	if (ret == ERROR_SUCCESS && type == REG_SZ) {
+	    buffer = snewn(size + 20, char);
+	    ret = RegQueryValueEx(regkey, "InstallDir", NULL,
+				  &type, buffer, &size);
+	    if (ret == ERROR_SUCCESS && type == REG_SZ) {
+		strcat(buffer, "\\bin\\gssapi32.dll");
+		module = LoadLibrary(buffer);
+	    }
+	    sfree(buffer);
+	}
+	RegCloseKey(regkey);
+    }
+    if (module) {
+	struct ssh_gss_library *lib =
+	    &list->libraries[list->nlibraries++];
+
+	lib->id = 0;
+	lib->gsslogmsg = "Using GSSAPI from GSSAPI32.DLL";
+	lib->handle = (void *)module;
+
+#define BIND_GSS_FN(name) \
+    lib->u.gssapi.name = (t_gss_##name) GetProcAddress(module, "gss_" #name)
+
+        BIND_GSS_FN(delete_sec_context);
+        BIND_GSS_FN(display_status);
+        BIND_GSS_FN(get_mic);
+        BIND_GSS_FN(import_name);
+        BIND_GSS_FN(init_sec_context);
+        BIND_GSS_FN(release_buffer);
+        BIND_GSS_FN(release_cred);
+        BIND_GSS_FN(release_name);
+
+#undef BIND_GSS_FN
+
+        ssh_gssapi_bind_fns(lib);
+    }
+
+    /* Microsoft SSPI Implementation */
+    module = load_system32_dll("secur32.dll");
+    if (module) {
+	struct ssh_gss_library *lib =
+	    &list->libraries[list->nlibraries++];
+
+	lib->id = 1;
+	lib->gsslogmsg = "Using SSPI from SECUR32.DLL";
+	lib->handle = (void *)module;
+
+	GET_WINDOWS_FUNCTION(module, AcquireCredentialsHandleA);
+	GET_WINDOWS_FUNCTION(module, InitializeSecurityContextA);
+	GET_WINDOWS_FUNCTION(module, FreeContextBuffer);
+	GET_WINDOWS_FUNCTION(module, FreeCredentialsHandle);
+	GET_WINDOWS_FUNCTION(module, DeleteSecurityContext);
+	GET_WINDOWS_FUNCTION(module, QueryContextAttributesA);
+	GET_WINDOWS_FUNCTION(module, MakeSignature);
+
+	ssh_sspi_bind_fns(lib);
+    }
+
+    /*
+     * Custom GSSAPI DLL.
+     */
+    module = NULL;
+    if (cfg->ssh_gss_custom.path[0]) {
+	module = LoadLibrary(cfg->ssh_gss_custom.path);
+    }
+    if (module) {
+	struct ssh_gss_library *lib =
+	    &list->libraries[list->nlibraries++];
+
+	lib->id = 2;
+	lib->gsslogmsg = dupprintf("Using GSSAPI from user-specified"
+				   " library '%s'", cfg->ssh_gss_custom.path);
+	lib->handle = (void *)module;
+
+#define BIND_GSS_FN(name) \
+    lib->u.gssapi.name = (t_gss_##name) GetProcAddress(module, "gss_" #name)
+
+        BIND_GSS_FN(delete_sec_context);
+        BIND_GSS_FN(display_status);
+        BIND_GSS_FN(get_mic);
+        BIND_GSS_FN(import_name);
+        BIND_GSS_FN(init_sec_context);
+        BIND_GSS_FN(release_buffer);
+        BIND_GSS_FN(release_cred);
+        BIND_GSS_FN(release_name);
+
+#undef BIND_GSS_FN
+
+        ssh_gssapi_bind_fns(lib);
+    }
+
+
+    return list;
+}
+
+void ssh_gss_cleanup(struct ssh_gss_liblist *list)
+{
+    int i;
+
+    /*
+     * LoadLibrary and FreeLibrary are defined to employ reference
+     * counting in the case where the same library is repeatedly
+     * loaded, so even in a multiple-sessions-per-process context
+     * (not that we currently expect ever to have such a thing on
+     * Windows) it's safe to naively FreeLibrary everything here
+     * without worrying about destroying it under the feet of
+     * another SSH instance still using it.
+     */
+    for (i = 0; i < list->nlibraries; i++) {
+	FreeLibrary((HMODULE)list->libraries[i].handle);
+	if (list->libraries[i].id == 2) {
+	    /* The 'custom' id involves a dynamically allocated message.
+	     * Note that we must cast away the 'const' to free it. */
+	    sfree((char *)list->libraries[i].gsslogmsg);
+	}
+    }
+    sfree(list->libraries);
+    sfree(list);
+}
+
+static Ssh_gss_stat ssh_sspi_indicate_mech(struct ssh_gss_library *lib,
+					   Ssh_gss_buf *mech)
+{
+    *mech = gss_mech_krb5;
+    return SSH_GSS_OK;
+}
+
+
+static Ssh_gss_stat ssh_sspi_import_name(struct ssh_gss_library *lib,
+					 char *host, Ssh_gss_name *srv_name)
+{
+    char *pStr;
+
+    /* Check hostname */
+    if (host == NULL) return SSH_GSS_FAILURE;
+    
+    /* copy it into form host/FQDN */
+    pStr = dupcat("host/", host, NULL);
+
+    *srv_name = (Ssh_gss_name) pStr;
+
+    return SSH_GSS_OK;
+}
+
+static Ssh_gss_stat ssh_sspi_acquire_cred(struct ssh_gss_library *lib,
+					  Ssh_gss_ctx *ctx)
+{
+    winSsh_gss_ctx *winctx = snew(winSsh_gss_ctx);
+    memset(winctx, 0, sizeof(winSsh_gss_ctx));
+
+    /* prepare our "wrapper" structure */
+    winctx->maj_stat =  winctx->min_stat = SEC_E_OK;
+    winctx->context_handle = NULL;
+
+    /* Specifying no principal name here means use the credentials of
+       the current logged-in user */
+
+    winctx->maj_stat = p_AcquireCredentialsHandleA(NULL,
+						   "Kerberos",
+						   SECPKG_CRED_OUTBOUND,
+						   NULL,
+						   NULL,
+						   NULL,
+						   NULL,
+						   &winctx->cred_handle,
+						   &winctx->expiry);
+
+    if (winctx->maj_stat != SEC_E_OK) return SSH_GSS_FAILURE;
+    
+    *ctx = (Ssh_gss_ctx) winctx;
+    return SSH_GSS_OK;
+}
+
+
+static Ssh_gss_stat ssh_sspi_init_sec_context(struct ssh_gss_library *lib,
+					      Ssh_gss_ctx *ctx,
+					      Ssh_gss_name srv_name,
+					      int to_deleg,
+					      Ssh_gss_buf *recv_tok,
+					      Ssh_gss_buf *send_tok)
+{
+    winSsh_gss_ctx *winctx = (winSsh_gss_ctx *) *ctx;
+    SecBuffer wsend_tok = {send_tok->length,SECBUFFER_TOKEN,send_tok->value};
+    SecBuffer wrecv_tok = {recv_tok->length,SECBUFFER_TOKEN,recv_tok->value};
+    SecBufferDesc output_desc={SECBUFFER_VERSION,1,&wsend_tok};
+    SecBufferDesc input_desc ={SECBUFFER_VERSION,1,&wrecv_tok};
+    unsigned long flags=ISC_REQ_MUTUAL_AUTH|ISC_REQ_REPLAY_DETECT|
+	ISC_REQ_CONFIDENTIALITY|ISC_REQ_ALLOCATE_MEMORY;
+    unsigned long ret_flags=0;
+    
+    /* check if we have to delegate ... */
+    if (to_deleg) flags |= ISC_REQ_DELEGATE;
+    winctx->maj_stat = p_InitializeSecurityContextA(&winctx->cred_handle,
+						    winctx->context_handle,
+						    (char*) srv_name,
+						    flags,
+						    0,          /* reserved */
+						    SECURITY_NATIVE_DREP,
+						    &input_desc,
+						    0,          /* reserved */
+						    &winctx->context,
+						    &output_desc,
+						    &ret_flags,
+						    &winctx->expiry);
+  
+    /* prepare for the next round */
+    winctx->context_handle = &winctx->context;
+    send_tok->value = wsend_tok.pvBuffer;
+    send_tok->length = wsend_tok.cbBuffer;
+  
+    /* check & return our status */
+    if (winctx->maj_stat==SEC_E_OK) return SSH_GSS_S_COMPLETE;
+    if (winctx->maj_stat==SEC_I_CONTINUE_NEEDED) return SSH_GSS_S_CONTINUE_NEEDED;
+    
+    return SSH_GSS_FAILURE;
+}
+
+static Ssh_gss_stat ssh_sspi_free_tok(struct ssh_gss_library *lib,
+				      Ssh_gss_buf *send_tok)
+{
+    /* check input */
+    if (send_tok == NULL) return SSH_GSS_FAILURE;
+
+    /* free Windows buffer */
+    p_FreeContextBuffer(send_tok->value);
+    SSH_GSS_CLEAR_BUF(send_tok);
+    
+    return SSH_GSS_OK;
+}
+
+static Ssh_gss_stat ssh_sspi_release_cred(struct ssh_gss_library *lib,
+					  Ssh_gss_ctx *ctx)
+{
+    winSsh_gss_ctx *winctx= (winSsh_gss_ctx *) *ctx;
+
+    /* check input */
+    if (winctx == NULL) return SSH_GSS_FAILURE;
+
+    /* free Windows data */
+    p_FreeCredentialsHandle(&winctx->cred_handle);
+    p_DeleteSecurityContext(&winctx->context);
+
+    /* delete our "wrapper" structure */
+    sfree(winctx);
+    *ctx = (Ssh_gss_ctx) NULL;
+
+    return SSH_GSS_OK;
+}
+
+
+static Ssh_gss_stat ssh_sspi_release_name(struct ssh_gss_library *lib,
+					  Ssh_gss_name *srv_name)
+{
+    char *pStr= (char *) *srv_name;
+
+    if (pStr == NULL) return SSH_GSS_FAILURE;
+    sfree(pStr);
+    *srv_name = (Ssh_gss_name) NULL;
+
+    return SSH_GSS_OK;
+}
+
+static Ssh_gss_stat ssh_sspi_display_status(struct ssh_gss_library *lib,
+					    Ssh_gss_ctx ctx, Ssh_gss_buf *buf)
+{
+    winSsh_gss_ctx *winctx = (winSsh_gss_ctx *) ctx;
+    char *msg;
+
+    if (winctx == NULL) return SSH_GSS_FAILURE;
+
+    /* decode the error code */
+    switch (winctx->maj_stat) {
+      case SEC_E_OK: msg="SSPI status OK"; break;
+      case SEC_E_INVALID_HANDLE: msg="The handle passed to the function"
+	    " is invalid.";
+	break;
+      case SEC_E_TARGET_UNKNOWN: msg="The target was not recognized."; break;
+      case SEC_E_LOGON_DENIED: msg="The logon failed."; break;
+      case SEC_E_INTERNAL_ERROR: msg="The Local Security Authority cannot"
+	    " be contacted.";
+	break;
+      case SEC_E_NO_CREDENTIALS: msg="No credentials are available in the"
+	    " security package.";
+	break;
+      case SEC_E_NO_AUTHENTICATING_AUTHORITY:
+	msg="No authority could be contacted for authentication."
+	    "The domain name of the authenticating party could be wrong,"
+	    " the domain could be unreachable, or there might have been"
+	    " a trust relationship failure.";
+	break;
+      case SEC_E_INSUFFICIENT_MEMORY:
+	msg="One or more of the SecBufferDesc structures passed as"
+	    " an OUT parameter has a buffer that is too small.";
+	break;
+      case SEC_E_INVALID_TOKEN:
+	msg="The error is due to a malformed input token, such as a"
+	    " token corrupted in transit, a token"
+	    " of incorrect size, or a token passed into the wrong"
+	    " security package. Passing a token to"
+	    " the wrong package can happen if client and server did not"
+	    " negotiate the proper security package.";
+	break;
+      default:
+	msg = "Internal SSPI error";
+	break;
+    }
+
+    buf->value = dupstr(msg);
+    buf->length = strlen(buf->value);
+    
+    return SSH_GSS_OK;
+}
+
+static Ssh_gss_stat ssh_sspi_get_mic(struct ssh_gss_library *lib,
+				     Ssh_gss_ctx ctx, Ssh_gss_buf *buf,
+				     Ssh_gss_buf *hash)
+{
+    winSsh_gss_ctx *winctx= (winSsh_gss_ctx *) ctx;
+    SecPkgContext_Sizes ContextSizes;
+    SecBufferDesc InputBufferDescriptor;
+    SecBuffer InputSecurityToken[2];
+
+    if (winctx == NULL) return SSH_GSS_FAILURE;
+  
+    winctx->maj_stat = 0;
+
+    memset(&ContextSizes, 0, sizeof(ContextSizes));
+
+    winctx->maj_stat = p_QueryContextAttributesA(&winctx->context,
+						 SECPKG_ATTR_SIZES,
+						 &ContextSizes);
+    
+    if (winctx->maj_stat != SEC_E_OK ||
+	ContextSizes.cbMaxSignature == 0)
+	return winctx->maj_stat;
+
+    InputBufferDescriptor.cBuffers = 2;
+    InputBufferDescriptor.pBuffers = InputSecurityToken;
+    InputBufferDescriptor.ulVersion = SECBUFFER_VERSION;
+    InputSecurityToken[0].BufferType = SECBUFFER_DATA;
+    InputSecurityToken[0].cbBuffer = buf->length;
+    InputSecurityToken[0].pvBuffer = buf->value;
+    InputSecurityToken[1].BufferType = SECBUFFER_TOKEN;
+    InputSecurityToken[1].cbBuffer = ContextSizes.cbMaxSignature;
+    InputSecurityToken[1].pvBuffer = snewn(ContextSizes.cbMaxSignature, char);
+
+    winctx->maj_stat = p_MakeSignature(&winctx->context,
+				       0,
+				       &InputBufferDescriptor,
+				       0);
+
+    if (winctx->maj_stat == SEC_E_OK) {
+	hash->length = InputSecurityToken[1].cbBuffer;
+	hash->value = InputSecurityToken[1].pvBuffer;
+    }
+
+    return winctx->maj_stat;
+}
+
+static Ssh_gss_stat ssh_sspi_free_mic(struct ssh_gss_library *lib,
+				      Ssh_gss_buf *hash)
+{
+    sfree(hash->value);
+    return SSH_GSS_OK;
+}
+
+static void ssh_sspi_bind_fns(struct ssh_gss_library *lib)
+{
+    lib->indicate_mech = ssh_sspi_indicate_mech;
+    lib->import_name = ssh_sspi_import_name;
+    lib->release_name = ssh_sspi_release_name;
+    lib->init_sec_context = ssh_sspi_init_sec_context;
+    lib->free_tok = ssh_sspi_free_tok;
+    lib->acquire_cred = ssh_sspi_acquire_cred;
+    lib->release_cred = ssh_sspi_release_cred;
+    lib->get_mic = ssh_sspi_get_mic;
+    lib->free_mic = ssh_sspi_free_mic;
+    lib->display_status = ssh_sspi_display_status;
+}
+
+#else
+
+/* Dummy function so this source file defines something if NO_GSSAPI
+   is defined. */
+
+void ssh_gss_init(void)
+{
+}
+
+#endif