/*
 * Copyright (c) 1995 The Regents of the University of California.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the Network Research
 * 	Group at Lawrence Berkeley National Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
static const char rcsid[] =
    "@(#) $Header: crypt-vat.cc,v 1.3 96/03/16 13:12:48 van Exp $ (LBL)";

#include "crypt.h"
#include "inet.h"
#include "rtp.h"

extern "C" {
extern void DesQuickInit();
extern int DesMethod(u_char* m, const u_char* k);
extern int DesQuickFipsEncrypt(u_char* dst, const u_char* m, const u_char* src);
extern int DesQuickFipsDecrypt(u_char* dst, const u_char* m, const u_char* src);
}

class CryptVAT : public Crypt {
    public:
	CryptVAT();
	~CryptVAT();
	virtual int command(int argc, const char*const* argv);
	virtual int install_key(const u_int8_t* key);
	virtual u_char* Encrypt(const u_char* in, int& len);
	virtual int Decrypt(const u_char* in, int len, u_char* out);
    protected:
	int encrypt(u_int32_t* blk, const u_char* in, int len, u_char* rh);
	int decrypt(const u_char* in, int len, u_char* out, int rtcp);
	static int didinit_;
	u_char* wrkbuf_;
	u_char mkey_[128];
};

class CryptVATctrl : public CryptVAT {
    public:
	virtual u_char* Encrypt(const u_char* in, int& len);
	virtual int Decrypt(const u_char* in, int len, u_char* out);
};

static class CryptVATMatcher : public Matcher {
    public:
	CryptVATMatcher() : Matcher("crypt") {}
	TclObject* match(const char* id) {
		if (strcmp(id, "VAT/data") == 0)
			return (new CryptVAT);
		if (strcmp(id, "VAT/ctrl") == 0)
			return (new CryptVATctrl);
		return (0);
	}
} vat_matcher;

int CryptVAT::didinit_;

CryptVAT::CryptVAT()
{
	if (didinit_ == 0) {
		DesQuickInit();
		didinit_ = 1;
	}
	/* enough extra space for padding and RTCP 4-byte random header */
	wrkbuf_ = new u_char[RTP_MTU + 8 + 4];
}

CryptVAT::~CryptVAT()
{
	delete wrkbuf_;
}

int CryptVAT::install_key(const u_int8_t* keystr)
{
	/* DES key */
	u_char key[8];
	memset((char*)key, 0, sizeof(key));
	register int i, l = strlen((const char*)keystr);
	for (i = 0; i < l; ++i)
		key[i & 7] += keystr[i];

	/* make the key odd parity */
	for (i = 0; i < 8; ++i) {
		int j = key[i];
		j ^= j >> 4;
		j ^= j >> 2;
		j ^= j >> 1;
		if ((j & 1) == 0) {
			j = 0x80;
			while (key[i] & j)
				j >>= 1;
			key[i] |= j;
		}
	}
	return (DesMethod(mkey_, key));
}

int CryptVAT::command(int argc, const char*const* argv)
{
	if (argc == 3) {
		if (strcmp(argv[1], "key") == 0) {
			Tcl& tcl = Tcl::instance();
			if (install_key((const u_char*)argv[2]) != 0)
				tcl.result("0");
			else
				tcl.result("1");
			return (TCL_OK);
		}
	}
	return (Crypt::command(argc, argv));
}

int CryptVAT::encrypt(u_int32_t* blk, const u_char* in, int len, u_char* rh)
{
	int pad = len & 7;
	if (pad != 0) {
		/* pad to an block (8 octet) boundary */
		pad = 8 - pad;
		rh[1] |= 0x40; // set vat 'pad' bit
	}

	register u_int32_t* wp = (u_int32_t*)wrkbuf_;
	const u_char* m = mkey_;
	DesQuickFipsEncrypt((u_char*)wp, m, (const u_char*)blk);

	const u_int32_t* bp = (const u_int32_t*)in;
	for (int i = len >> 3; --i >= 0; ) {
		blk[0] = bp[0] ^ wp[0];
		blk[1] = bp[1] ^ wp[1];
		wp += 2;
		DesQuickFipsEncrypt((u_char*)wp, m, (const u_char*)blk);
		bp += 2;
	}
	if (pad > 0) {
		len += pad;
		blk[0] = bp[0];
		blk[1] = bp[1];
		u_char* cp = (u_char*)blk + 7;
		*cp = pad;
		while (--pad > 0)
			*--cp = 0;
		blk[0] ^= wp[0];
		blk[1] ^= wp[1];
		wp += 2;
		DesQuickFipsEncrypt((u_char*)wp, m, (u_char*)blk);
	}
	return (len);
}

int CryptVAT::decrypt(const u_char* in, int len, u_char* out, int rtcp)
{
	register u_int32_t* wp = (u_int32_t*)out;
	const u_int32_t* bp = (const u_int32_t*)in;
	const u_char* m = mkey_;

	/* check that packet is an integral number of blocks */
	if ((len & 7) != 0) {
		++badpktlen_;
		return (-1);
	}
	int nblk = len >> 3;
	DesQuickFipsDecrypt((u_char*)wp, m, (const u_char*)bp);
	bp += 2;
	nblk -= 1;
	if (rtcp) {
		/* throw away random RTCP header */
		wp[0] = wp[1];
		wp += 1;
		len -= 4;
	} else
		wp += 2;

	while (--nblk >= 0) {
		DesQuickFipsDecrypt((u_char*)wp, m, (const u_char*)bp);
		wp[0] ^= bp[-2];
		wp[1] ^= bp[-1];
		bp += 2;
		wp += 2;
	}
	if ((out[1] & 0x40) != 0) {
		/* P bit set - trim off padding */
		int pad = out[len - 1];
		if (pad > 7 || pad == 0) {
			++badpbit_;
			return (-1);
		}
		len -= pad;
	}
	return (len);
}

u_char* CryptVAT::Encrypt(const u_char* in, int& len)
{
	u_int32_t blk[2];
	blk[0] = *(u_int32_t*)in;
	blk[1] = *(u_int32_t*)(in + 4);
	len = encrypt(blk, in + 8, len - 8, (u_char*)blk) + 8;
	return (wrkbuf_);
}

int CryptVAT::Decrypt(const u_char* in, int len, u_char* out)
{
	return (decrypt(in, len, out, 0));
}

u_char* CryptVATctrl::Encrypt(const u_char* in, int& len)
{
	if (len & 7) {
		u_char* cp = (u_char*)in + len;
		while (len & 7) {
			*cp++ = 0;
			++len;
		}
	}
	return (CryptVAT::Encrypt(in, len));
}

int CryptVATctrl::Decrypt(const u_char* in, int len, u_char* out)
{
	return (CryptVAT::Decrypt(in, len, out));
}