/* 
   Unix SMB/CIFS implementation.
   code to manipulate domain credentials
   Copyright (C) Andrew Tridgell 1997-1998
   Largely rewritten by Jeremy Allison 2005.
   
   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "../lib/crypto/crypto.h"
#include "libcli/auth/libcli_auth.h"

/****************************************************************************
 Represent a credential as a string.
****************************************************************************/

char *credstr(const unsigned char *cred)
{
	char *result;
	result = talloc_asprintf(talloc_tos(),
				 "%02X%02X%02X%02X%02X%02X%02X%02X",
				 cred[0], cred[1], cred[2], cred[3],
				 cred[4], cred[5], cred[6], cred[7]);
	SMB_ASSERT(result != NULL);
	return result;
}

/****************************************************************************
 Setup the session key and the client and server creds in dc.
 ADS-style 128 bit session keys.
 Used by both client and server creds setup.
****************************************************************************/

static void creds_init_128(struct dcinfo *dc,
			   const struct netr_Credential *clnt_chal_in,
			   const struct netr_Credential *srv_chal_in,
			   const unsigned char mach_pw[16])
{
	unsigned char zero[4], tmp[16];
	HMACMD5Context ctx;
	struct MD5Context md5;

	/* Just in case this isn't already there */
	memcpy(dc->mach_pw, mach_pw, 16);

	ZERO_STRUCT(dc->sess_key);

	memset(zero, 0, sizeof(zero));

	hmac_md5_init_rfc2104(mach_pw, 16, &ctx);
	MD5Init(&md5);
	MD5Update(&md5, zero, sizeof(zero));
	MD5Update(&md5, clnt_chal_in->data, 8);
	MD5Update(&md5, srv_chal_in->data, 8);
	MD5Final(tmp, &md5);
	hmac_md5_update(tmp, sizeof(tmp), &ctx);
	hmac_md5_final(dc->sess_key, &ctx);

	/* debug output */
	DEBUG(5,("creds_init_128\n"));
	DEBUG(5,("\tclnt_chal_in: %s\n", credstr(clnt_chal_in->data)));
	DEBUG(5,("\tsrv_chal_in : %s\n", credstr(srv_chal_in->data)));
	dump_data_pw("\tsession_key ", (const unsigned char *)dc->sess_key, 16);

	/* Generate the next client and server creds. */
	
	des_crypt112(dc->clnt_chal.data,		/* output */
			clnt_chal_in->data,		/* input */
			dc->sess_key,			/* input */
			1);

	des_crypt112(dc->srv_chal.data,			/* output */
			srv_chal_in->data,		/* input */
			dc->sess_key,			/* input */
			1);

	/* Seed is the client chal. */
	memcpy(dc->seed_chal.data, dc->clnt_chal.data, 8);
}

/****************************************************************************
 Setup the session key and the client and server creds in dc.
 Used by both client and server creds setup.
****************************************************************************/

static void creds_init_64(struct dcinfo *dc,
			  const struct netr_Credential *clnt_chal_in,
			  const struct netr_Credential *srv_chal_in,
			  const unsigned char mach_pw[16])
{
	uint32 sum[2];
	unsigned char sum2[8];

	/* Just in case this isn't already there */
	if (dc->mach_pw != mach_pw) {
		memcpy(dc->mach_pw, mach_pw, 16);
	}

	sum[0] = IVAL(clnt_chal_in->data, 0) + IVAL(srv_chal_in->data, 0);
	sum[1] = IVAL(clnt_chal_in->data, 4) + IVAL(srv_chal_in->data, 4);

	SIVAL(sum2,0,sum[0]);
	SIVAL(sum2,4,sum[1]);

	ZERO_STRUCT(dc->sess_key);

	des_crypt128(dc->sess_key, sum2, dc->mach_pw);

	/* debug output */
	DEBUG(5,("creds_init_64\n"));
	DEBUG(5,("\tclnt_chal_in: %s\n", credstr(clnt_chal_in->data)));
	DEBUG(5,("\tsrv_chal_in : %s\n", credstr(srv_chal_in->data)));
	DEBUG(5,("\tclnt+srv : %s\n", credstr(sum2)));
	DEBUG(5,("\tsess_key_out : %s\n", credstr(dc->sess_key)));

	/* Generate the next client and server creds. */
	
	des_crypt112(dc->clnt_chal.data,		/* output */
			clnt_chal_in->data,		/* input */
			dc->sess_key,			/* input */
			1);

	des_crypt112(dc->srv_chal.data,			/* output */
			srv_chal_in->data,		/* input */
			dc->sess_key,			/* input */
			1);

	/* Seed is the client chal. */
	memcpy(dc->seed_chal.data, dc->clnt_chal.data, 8);
}

/****************************************************************************
 Utility function to step credential chain one forward.
 Deliberately doesn't update the seed. See reseed comment below.
****************************************************************************/

static void creds_step(struct dcinfo *dc)
{
	struct netr_Credential time_chal;

	DEBUG(5,("\tsequence = 0x%x\n", (unsigned int)dc->sequence ));

	DEBUG(5,("\tseed:        %s\n", credstr(dc->seed_chal.data) ));

	SIVAL(time_chal.data, 0, IVAL(dc->seed_chal.data, 0) + dc->sequence);
	SIVAL(time_chal.data, 4, IVAL(dc->seed_chal.data, 4));
                                                                                                   
	DEBUG(5,("\tseed+seq   %s\n", credstr(time_chal.data) ));

	des_crypt112(dc->clnt_chal.data, time_chal.data, dc->sess_key, 1);

	DEBUG(5,("\tCLIENT      %s\n", credstr(dc->clnt_chal.data) ));

	SIVAL(time_chal.data, 0, IVAL(dc->seed_chal.data, 0) + dc->sequence + 1);
	SIVAL(time_chal.data, 4, IVAL(dc->seed_chal.data, 4));

	DEBUG(5,("\tseed+seq+1   %s\n", credstr(time_chal.data) ));

	des_crypt112(dc->srv_chal.data, time_chal.data, dc->sess_key, 1);

	DEBUG(5,("\tSERVER      %s\n", credstr(dc->srv_chal.data) ));
}

/****************************************************************************
 Create a server credential struct.
****************************************************************************/

void creds_server_init(uint32 neg_flags,
			struct dcinfo *dc,
			struct netr_Credential *clnt_chal,
			struct netr_Credential *srv_chal,
			const unsigned char mach_pw[16],
			struct netr_Credential *init_chal_out)
{
	DEBUG(10,("creds_server_init: neg_flags : %x\n", (unsigned int)neg_flags));
	DEBUG(10,("creds_server_init: client chal : %s\n", credstr(clnt_chal->data) ));
	DEBUG(10,("creds_server_init: server chal : %s\n", credstr(srv_chal->data) ));
	dump_data_pw("creds_server_init: machine pass", mach_pw, 16);

	/* Generate the session key and the next client and server creds. */
	if (neg_flags & NETLOGON_NEG_128BIT) {
		creds_init_128(dc,
			clnt_chal,
			srv_chal,
			mach_pw);
	} else {
		creds_init_64(dc,
			clnt_chal,
			srv_chal,
			mach_pw);
	}

	dump_data_pw("creds_server_init: session key", dc->sess_key, 16);

	DEBUG(10,("creds_server_init: clnt : %s\n", credstr(dc->clnt_chal.data) ));
	DEBUG(10,("creds_server_init: server : %s\n", credstr(dc->srv_chal.data) ));
	DEBUG(10,("creds_server_init: seed : %s\n", credstr(dc->seed_chal.data) ));

	memcpy(init_chal_out->data, dc->srv_chal.data, 8);
}

/****************************************************************************
 Check a credential sent by the client.
****************************************************************************/

bool netlogon_creds_server_check(const struct dcinfo *dc,
				 const struct netr_Credential *rcv_cli_chal_in)
{
	if (memcmp(dc->clnt_chal.data, rcv_cli_chal_in->data, 8)) {
		DEBUG(5,("netlogon_creds_server_check: challenge : %s\n",
			credstr(rcv_cli_chal_in->data)));
		DEBUG(5,("calculated: %s\n", credstr(dc->clnt_chal.data)));
		DEBUG(2,("netlogon_creds_server_check: credentials check failed.\n"));
		return false;
	}

	DEBUG(10,("netlogon_creds_server_check: credentials check OK.\n"));

	return true;
}
/****************************************************************************
 Replace current seed chal. Internal function - due to split server step below.
****************************************************************************/

static void creds_reseed(struct dcinfo *dc)
{
	struct netr_Credential time_chal;

	SIVAL(time_chal.data, 0, IVAL(dc->seed_chal.data, 0) + dc->sequence + 1);
	SIVAL(time_chal.data, 4, IVAL(dc->seed_chal.data, 4));

	dc->seed_chal = time_chal;

	DEBUG(5,("cred_reseed: seed %s\n", credstr(dc->seed_chal.data) ));
}

/****************************************************************************
 Step the server credential chain one forward. 
****************************************************************************/

bool netlogon_creds_server_step(struct dcinfo *dc,
				const struct netr_Authenticator *received_cred,
				struct netr_Authenticator *cred_out)
{
	bool ret;
	struct dcinfo tmp_dc = *dc;

	if (!received_cred || !cred_out) {
		return false;
	}

	/* Do all operations on a temporary copy of the dc,
	   which we throw away if the checks fail. */

	tmp_dc.sequence = received_cred->timestamp;

	creds_step(&tmp_dc);

	/* Create the outgoing credentials */
	cred_out->timestamp = tmp_dc.sequence + 1;
	memcpy(&cred_out->cred, &tmp_dc.srv_chal, sizeof(cred_out->cred));

	creds_reseed(&tmp_dc);

	ret = netlogon_creds_server_check(&tmp_dc, &received_cred->cred);
	if (!ret) {
		return false;
	}

	/* creds step succeeded - replace the current creds. */
	*dc = tmp_dc;
	return true;
}

void cred_hash3(unsigned char *out, const unsigned char *in, const unsigned char *key, int forw)
{
        unsigned char key2[8];

	memset(key2,'\0',8);
        des_crypt56(out, in, key, forw);
        key2[0] = key[7];
        des_crypt56(out + 8, in + 8, key2, forw);
}