/* 
   Unix SMB/CIFS implementation.
   Password and authentication handling
   Copyright (C) Andrew Bartlett         2001-2002
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_AUTH

/****************************************************************************
 Try to get a challenge out of the various authentication modules.
 Returns a const char of length 8 bytes.
****************************************************************************/

static const uint8_t *get_ntlm_challenge(struct auth_context *auth_context) 
{
	DATA_BLOB challenge = data_blob(NULL, 0);
	const char *challenge_set_by = NULL;
	struct auth_methods *auth_method;
	TALLOC_CTX *mem_ctx;

	if (auth_context->challenge.length) {
		DEBUG(5, ("get_ntlm_challenge (auth subsystem): returning previous challenge by module %s (normal)\n", 
			  auth_context->challenge_set_by));
		return auth_context->challenge.data;
	}

	auth_context->challenge_may_be_modified = False;

	for (auth_method = auth_context->auth_method_list; auth_method; auth_method = auth_method->next) {
		if (auth_method->get_chal == NULL) {
			DEBUG(5, ("auth_get_challenge: module %s did not want to specify a challenge\n", auth_method->name));
			continue;
		}

		DEBUG(5, ("auth_get_challenge: getting challenge from module %s\n", auth_method->name));
		if (challenge_set_by != NULL) {
			DEBUG(1, ("auth_get_challenge: CONFIGURATION ERROR: authentication method %s has already specified a challenge.  Challenge by %s ignored.\n", 
				  challenge_set_by, auth_method->name));
			continue;
		}

		mem_ctx = talloc_init("auth_get_challenge for module %s", auth_method->name);
		if (!mem_ctx) {
			smb_panic("talloc_init() failed!");
		}
		
		challenge = auth_method->get_chal(auth_context, &auth_method->private_data, mem_ctx);
		if (!challenge.length) {
			DEBUG(3, ("auth_get_challenge: getting challenge from authentication method %s FAILED.\n", 
				  auth_method->name));
		} else {
			DEBUG(5, ("auth_get_challenge: sucessfully got challenge from module %s\n", auth_method->name));
			auth_context->challenge = challenge;
			challenge_set_by = auth_method->name;
			auth_context->challenge_set_method = auth_method;
		}
		talloc_destroy(mem_ctx);
	}
	
	if (!challenge_set_by) {
		uint8_t chal[8];
		
		generate_random_buffer(chal, sizeof(chal), False);
		auth_context->challenge = data_blob_talloc(auth_context->mem_ctx, 
							   chal, sizeof(chal));
		
		challenge_set_by = "random";
		auth_context->challenge_may_be_modified = True;
	} 
	
	DEBUG(5, ("auth_context challenge created by %s\n", challenge_set_by));
	DEBUG(5, ("challenge is: \n"));
	dump_data(5, (const char *)auth_context->challenge.data, auth_context->challenge.length);
	
	SMB_ASSERT(auth_context->challenge.length == 8);

	auth_context->challenge_set_by=challenge_set_by;

	return auth_context->challenge.data;
}


/**
 * Check user is in correct domain (if required)
 *
 * @param user Only used to fill in the debug message
 * 
 * @param domain The domain to be verified
 *
 * @return True if the user can connect with that domain, 
 *         False otherwise.
**/

static BOOL check_domain_match(const char *user, const char *domain) 
{
	/*
	 * If we aren't serving to trusted domains, we must make sure that
	 * the validation request comes from an account in the same domain
	 * as the Samba server
	 */

	if (!lp_allow_trusted_domains() &&
	    !(strequal("", domain) || 
	      strequal(lp_workgroup(), domain) || 
	      is_myname(domain))) {
		DEBUG(1, ("check_domain_match: Attempt to connect as user %s from domain %s denied.\n", user, domain));
		return False;
	} else {
		return True;
	}
}

/**
 * Check a user's Plaintext, LM or NTLM password.
 *
 * Check a user's password, as given in the user_info struct and return various
 * interesting details in the server_info struct.
 *
 * The return value takes precedence over the contents of the server_info 
 * struct.  When the return is other than NT_STATUS_OK the contents 
 * of that structure is undefined.
 *
 * @param user_info Contains the user supplied components, including the passwords.
 *                  Must be created with make_user_info() or one of its wrappers.
 *
 * @param auth_context Supplies the challenges and some other data. 
 *                  Must be created with make_auth_context(), and the challenges should be 
 *                  filled in, either at creation or by calling the challenge geneation 
 *                  function auth_get_challenge().  
 *
 * @param server_info If successful, contains information about the authentication, 
 *                    including a SAM_ACCOUNT struct describing the user.
 *
 * @return An NTSTATUS with NT_STATUS_OK or an appropriate error.
 *
 **/

static NTSTATUS check_ntlm_password(const struct auth_context *auth_context,
				    const struct auth_usersupplied_info *user_info, 
				    struct auth_serversupplied_info **server_info)
{
	/* if all the modules say 'not for me' this is reasonable */
	NTSTATUS nt_status = NT_STATUS_NO_SUCH_USER;
	struct auth_methods *auth_method;
	TALLOC_CTX *mem_ctx;

	if (!user_info || !auth_context || !server_info)
		return NT_STATUS_LOGON_FAILURE;

	DEBUG(3, ("check_ntlm_password:  Checking password for unmapped user [%s]\\[%s]@[%s] with the new password interface\n", 
		  user_info->client_domain.str, user_info->smb_name.str, user_info->wksta_name.str));

	DEBUG(3, ("check_ntlm_password:  mapped user is: [%s]\\[%s]@[%s]\n", 
		  user_info->domain.str, user_info->internal_username.str, user_info->wksta_name.str));

	if (auth_context->challenge.length == 0) {
		/* get a challenge, if we have not asked for one yet */
		get_ntlm_challenge(auth_context);
	}

	if (auth_context->challenge.length != 8) {
		DEBUG(0, ("check_ntlm_password:  Invalid challenge stored for this auth context - cannot continue\n"));
		return NT_STATUS_LOGON_FAILURE;
	}

	if (auth_context->challenge_set_by)
		DEBUG(10, ("check_ntlm_password: auth_context challenge created by %s\n",
					auth_context->challenge_set_by));

	DEBUG(10, ("challenge is: \n"));
	dump_data(5, (const char *)auth_context->challenge.data, auth_context->challenge.length);

#ifdef DEBUG_PASSWORD
	DEBUG(100, ("user_info has passwords of length %d and %d\n", 
		    user_info->lm_resp.length, user_info->nt_resp.length));
	DEBUG(100, ("lm:\n"));
	dump_data(100, user_info->lm_resp.data, user_info->lm_resp.length);
	DEBUG(100, ("nt:\n"));
	dump_data(100, user_info->nt_resp.data, user_info->nt_resp.length);
#endif

	/* This needs to be sorted:  If it doesn't match, what should we do? */
  	if (!check_domain_match(user_info->smb_name.str, user_info->domain.str))
		return NT_STATUS_LOGON_FAILURE;

	for (auth_method = auth_context->auth_method_list;auth_method; auth_method = auth_method->next) {
		NTSTATUS result;
		
		mem_ctx = talloc_init("%s authentication for user %s\\%s", auth_method->name, 
					    user_info->domain.str, user_info->smb_name.str);

		result = auth_method->auth(auth_context, auth_method->private_data, mem_ctx, user_info, server_info);

		/* check if the module did anything */
		if ( NT_STATUS_V(result) == NT_STATUS_V(NT_STATUS_NOT_IMPLEMENTED) ) {
			DEBUG(10,("check_ntlm_password: %s had nothing to say\n", auth_method->name));
			talloc_destroy(mem_ctx);
			continue;
		}

		nt_status = result;

		if (NT_STATUS_IS_OK(nt_status)) {
			DEBUG(3, ("check_ntlm_password: %s authentication for user [%s] succeeded\n", 
				  auth_method->name, user_info->smb_name.str));
		} else {
			DEBUG(5, ("check_ntlm_password: %s authentication for user [%s] FAILED with error %s\n", 
				  auth_method->name, user_info->smb_name.str, nt_errstr(nt_status)));
		}

		talloc_destroy(mem_ctx);

		if ( NT_STATUS_IS_OK(nt_status))
		{
				break;			
		}
	}

	if (NT_STATUS_IS_OK(nt_status)) {
		if (NT_STATUS_IS_OK(nt_status)) {
			DEBUG((*server_info)->guest ? 5 : 2, 
			      ("check_ntlm_password:  %sauthentication for user [%s] -> [%s] succeeded\n", 
			       (*server_info)->guest ? "guest " : "", 
			       user_info->smb_name.str, 
			       user_info->internal_username.str));
		}
	}

	if (!NT_STATUS_IS_OK(nt_status)) {
		DEBUG(2, ("check_ntlm_password:  Authentication for user [%s] -> [%s] FAILED with error %s\n", 
			  user_info->smb_name.str, user_info->internal_username.str, 
			  nt_errstr(nt_status)));
		ZERO_STRUCTP(server_info);
	}
	return nt_status;
}

/***************************************************************************
 Clear out a auth_context, and destroy the attached TALLOC_CTX
***************************************************************************/

void free_auth_context(struct auth_context **auth_context)
{
	struct auth_methods *auth_method;
	
	if (*auth_context) {
		/* Free private data of context's authentication methods */
		for (auth_method = (*auth_context)->auth_method_list; auth_method; auth_method = auth_method->next) {
			if (auth_method->free_private_data) {
				auth_method->free_private_data (&auth_method->private_data);
				auth_method->private_data = NULL;
			}
		}

		talloc_destroy((*auth_context)->mem_ctx);
		*auth_context = NULL;
	}
}

/***************************************************************************
 Make a auth_info struct
***************************************************************************/

static NTSTATUS make_auth_context(struct auth_context **auth_context) 
{
	TALLOC_CTX *mem_ctx;

	mem_ctx = talloc_init("authentication context");
	
	*auth_context = talloc(mem_ctx, sizeof(**auth_context));
	if (!*auth_context) {
		DEBUG(0,("make_auth_context: talloc failed!\n"));
		talloc_destroy(mem_ctx);
		return NT_STATUS_NO_MEMORY;
	}
	ZERO_STRUCTP(*auth_context);

	(*auth_context)->mem_ctx = mem_ctx;
	(*auth_context)->check_ntlm_password = check_ntlm_password;
	(*auth_context)->get_ntlm_challenge = get_ntlm_challenge;
	
	return NT_STATUS_OK;
}

/***************************************************************************
 Make a auth_info struct for the auth subsystem
***************************************************************************/

static NTSTATUS make_auth_context_text_list(struct auth_context **auth_context, char **text_list) 
{
	struct auth_methods *list = NULL;
	struct auth_methods *t = NULL;
	int i;
	NTSTATUS nt_status;

	if (!text_list) {
		DEBUG(2,("make_auth_context_text_list: No auth method list!?\n"));
		return NT_STATUS_UNSUCCESSFUL;
	}
	
	if (!NT_STATUS_IS_OK(nt_status = make_auth_context(auth_context)))
		return nt_status;
	
	for (;*text_list; text_list++) {
		char *module_name = smb_xstrdup(*text_list);
		char *module_params = NULL;
		char *p;
		const struct auth_operations *ops;

		DEBUG(5,("make_auth_context_text_list: Attempting to find an auth method to match %s\n",
					*text_list));

		p = strchr(module_name, ':');
		if (p) {
			*p = 0;
			module_params = p+1;
			trim_string(module_params, " ", " ");
		}

		trim_string(module_name, " ", " ");

		ops = auth_backend_byname(module_name);
		if (!ops) {
			DEBUG(5,("make_auth_context_text_list: Found auth method %s (at pos %d)\n", *text_list, i));
			SAFE_FREE(module_name);
			break;
		}

		if (NT_STATUS_IS_OK(ops->init(*auth_context, module_params, &t))) {
			DEBUG(5,("make_auth_context_text_list: auth method %s has a valid init\n",
						*text_list));
			DLIST_ADD_END(list, t, struct auth_methods *);
		} else {
			DEBUG(0,("make_auth_context_text_list: auth method %s did not correctly init\n",
						*text_list));
		}
		SAFE_FREE(module_name);
	}
	
	(*auth_context)->auth_method_list = list;
	
	return nt_status;
}

/***************************************************************************
 Make a auth_context struct for the auth subsystem
***************************************************************************/

NTSTATUS make_auth_context_subsystem(struct auth_context **auth_context) 
{
	char **auth_method_list = NULL; 
	NTSTATUS nt_status;

	if (lp_auth_methods() && !str_list_copy(&auth_method_list, lp_auth_methods())) {
		return NT_STATUS_NO_MEMORY;
	}

	if (!NT_STATUS_IS_OK(nt_status = make_auth_context_text_list(auth_context, auth_method_list))) {
		str_list_free(&auth_method_list);
		return nt_status;
	}
	
	str_list_free(&auth_method_list);
	return nt_status;
}

/***************************************************************************
 Make a auth_info struct with a fixed challenge
***************************************************************************/

NTSTATUS make_auth_context_fixed(struct auth_context **auth_context, uint8_t chal[8]) 
{
	NTSTATUS nt_status;
	if (!NT_STATUS_IS_OK(nt_status = make_auth_context_subsystem(auth_context))) {
		return nt_status;
	}
	
	(*auth_context)->challenge = data_blob_talloc((*auth_context)->mem_ctx, chal, 8);
	(*auth_context)->challenge_set_by = "fixed";
	return nt_status;
}

/* the list of currently registered AUTH backends */
static struct {
	const struct auth_operations *ops;
} *backends = NULL;
static int num_backends;

/*
  register a AUTH backend. 

  The 'name' can be later used by other backends to find the operations
  structure for this backend.
*/
static NTSTATUS auth_register(void *_ops)
{
	const struct auth_operations *ops = _ops;
	struct auth_operations *new_ops;
	
	if (auth_backend_byname(ops->name) != NULL) {
		/* its already registered! */
		DEBUG(0,("AUTH backend '%s' already registered\n", 
			 ops->name));
		return NT_STATUS_OBJECT_NAME_COLLISION;
	}

	backends = Realloc(backends, sizeof(backends[0]) * (num_backends+1));
	if (!backends) {
		smb_panic("out of memory in auth_register");
	}

	new_ops = smb_xmemdup(ops, sizeof(*ops));
	new_ops->name = smb_xstrdup(ops->name);

	backends[num_backends].ops = new_ops;

	num_backends++;

	DEBUG(3,("AUTH backend '%s' registered\n", 
		 ops->name));

	return NT_STATUS_OK;
}

/*
  return the operations structure for a named backend of the specified type
*/
const struct auth_operations *auth_backend_byname(const char *name)
{
	int i;

	for (i=0;i<num_backends;i++) {
		if (strcmp(backends[i].ops->name, name) == 0) {
			return backends[i].ops;
		}
	}

	return NULL;
}

/*
  return the AUTH interface version, and the size of some critical types
  This can be used by backends to either detect compilation errors, or provide
  multiple implementations for different smbd compilation options in one module
*/
const struct auth_critical_sizes *auth_interface_version(void)
{
	static const struct auth_critical_sizes critical_sizes = {
		AUTH_INTERFACE_VERSION,
		sizeof(struct auth_operations),
		sizeof(struct auth_methods),
		sizeof(struct auth_context),
		sizeof(struct auth_ntlmssp_state),
		sizeof(struct auth_usersupplied_info),
		sizeof(struct auth_serversupplied_info),
		sizeof(struct auth_str),
	};

	return &critical_sizes;
}

/*
  initialise the AUTH subsystem
*/
BOOL auth_init(void)
{
	NTSTATUS status;

	status = register_subsystem("auth", auth_register); 
	if (!NT_STATUS_IS_OK(status)) {
		return False;
	}

	/* FIXME: Perhaps panic if a basic backend, such as SAM, fails to initialise? */
	static_init_auth;

	DEBUG(3,("AUTH subsystem version %d initialised\n", AUTH_INTERFACE_VERSION));
	return True;
}