#include "rdp.h"

/* TPDUs over stream protocols like TCP are prepended with TPKT
to delimit message boundaries -- T.123 clause 8; RFC 1006. */

int
readtpdu(int fd, void *abuf, uint n)
{
	int m, mgc, len;
	uchar *buf;

	buf = abuf;

	/* read TPKT header */
	m = readn(fd, buf, TPKTFIXLEN);
	if(m != TPKTFIXLEN)
		return -1;
	mgc = GBIT8(buf); /* 0x03 octet; followed one is reserved */
	if(mgc != 0x03)
		return -1;
	
	len = GBE16(buf+BIT8SZ+BIT8SZ);
	if(len <= TPKTFIXLEN || len > n){
		werrstr("bad length in TPKT header: %d", len);
		return -1;
	}

	len -= TPKTFIXLEN;
	m = readn(fd, buf+TPKTFIXLEN, len);
	if(m < len)
		return 0;
	return m +TPKTFIXLEN;
};

/* fixme: the following two are incosistent in what they do return */

int
mktpcr(uchar* buf, int nbuf, int ndata)	/* connect request */
{
	int size;
	uchar *p;

	p = buf;
	size = TPKTFIXLEN + 2*BIT8SZ + 2*BIT16SZ + 1*BIT8SZ + ndata;
	if(size > nbuf){
		werrstr("buffer too small");
		return -1;
	}

	/* format TPKT header */
	PBIT8(p, 0x03); /* 0x03 octet */;
	p += BIT8SZ;
	PBIT8(p, 0); /* reserved */
	p += BIT8SZ;
	PBE16(p, size);
	p += BIT16SZ;

	PBIT8(p, size - TPKTFIXLEN - BIT8SZ); /* length indicator */
	p += BIT8SZ;
	PBIT8(p, TPDUCR); /* TPDU code */
	p += BIT8SZ;
	PBE16(p, 0); /* DST-REF */
	p += BIT16SZ;
	PBE16(p, 0); /* SRC-REF */
	p += BIT16SZ;
	PBIT8(p, 0); /* CLASS OPTION: class 0 */
	p += BIT8SZ;

	USED(p);
	return size;
}

int
mktpdata(uchar* buf, int nbuf, int ndata)		/* data transfer */
{
	int size;
	uchar *p;

	p = buf;
	size = TPDATAFIXLEN + ndata;
	if(size > nbuf){
		werrstr("buffer too small");
		return -1;
	}

	/* format TPKT header */
	PBIT8(p, 0x03); /* 0x03 octet */;
	p += BIT8SZ;
	PBIT8(p, 0); /* reserved */
	p += BIT8SZ;
	PBE16(p, size);
	p += BIT16SZ;

	PBIT8(p, 2*BIT8SZ); /* length indicator */
	p += BIT8SZ;
	PBIT8(p, TPDUDT); /* TPDU code */
	p += BIT8SZ;
	PBIT8(p, 0x80); /* TPDU send sequence number (0 in Class 0) + EOT mark (1<<7) */

	return TPDATAFIXLEN;
}