eclip.c

/*
 * [MS-RDPECLIP]: Remote Desktop Protocol: Clipboard Virtual Channel Extension
 * http://msdn.microsoft.com/en-us/library/cc241066.aspx
 * 
 * Standard Clipboard Formats
 * http://msdn.microsoft.com/en-us/library/windows/desktop/ff729168(v=vs.85).aspx
 */
#include <u.h>
#include <libc.h>
#include "dat.h"
#include "fns.h"

static char	cliprdr[]				= "CLIPRDR";

enum
{
	FmtUnicode=	13,

	Fok= 	1<<0,
	Ferr=	1<<1,

	Cready=	1,
	Cannounce=	2,
	Cnoted=	3,
	Crq=	4,
	Crx=	5,
};

typedef	struct	Clipmsg Clipmsg;
struct Clipmsg
{
	uint		type;
	uint		flags;
	uint		fmtid;
	uchar	*data;
	uint		ndata;
};
static	int	clipputmsg(uchar*,int,Clipmsg*);
static	int	clipgetmsg(Clipmsg*,uchar*,int);

static	void	clipattached(Rdp*,Clipmsg*);
static	void	clipnoted(Rdp*,Clipmsg*);
static	void	cliprequested(Rdp*,Clipmsg*);
static	void	clipprovided(Rdp*,Clipmsg*);

static	void	(*clipcall[])(Rdp*,Clipmsg*) =
{
	[Cready]=		clipattached,
	[Cannounce]=	clipnoted,
	[Crq]=		cliprequested,
	[Crx]=		clipprovided,
};

static void		cliprequest(Rdp*);

void
clipvcfn(Rdp* c, uchar* p, uint nb)
{
	Clipmsg r;

	if(clipgetmsg(&r, p, nb) < 0)
		return;
	if(r.flags&Ferr)
		return;
	if(r.type >= nelem(clipcall))
		return;
	if(clipcall[r.type] == nil)
		return;
	clipcall[r.type](c, &r);
}

void
clipannounce(Rdp* c)
{
	Clipmsg t;
	uchar a[44];
	int n;

	t.type = Cannounce;
	t.flags = 0;
	t.fmtid = FmtUnicode;
	t.ndata = 0;
	n = clipputmsg(a, sizeof(a), &t);
	if(sendvc(c, cliprdr, a, n) < 0)
		fprint(2, "clipannounce: %r\n");
}

static void
cliprequest(Rdp* c)
{
	Clipmsg t;
	uchar a[12];
	int n;

	t.type = Crq;
	t.flags = 0;
	t.fmtid = FmtUnicode;
	t.ndata = 0;
	n = clipputmsg(a, sizeof(a), &t);
	if(sendvc(c, cliprdr, a, n) < 0)
		fprint(2, "cliprequest: %r\n");
}

static void
clipattached(Rdp* c, Clipmsg *m)
{
	USED(m);
	clipannounce(c);
}

static void
clipnoted(Rdp* c, Clipmsg *m)
{
	Clipmsg t;
	uchar a[8];
	int n;

	if(m->fmtid == FmtUnicode)
		cliprequest(c);

	t.type = Cnoted;
	t.flags = Fok;
	t.ndata = 0;
	n = clipputmsg(a, sizeof(a), &t);
	if(sendvc(c, cliprdr, a, n) < 0)
		fprint(2, "clipnoted: %r\n");
}

static void
cliprequested(Rdp* c, Clipmsg *m)
{
	Clipmsg t;
	char* s;
	uchar *b;
	int n, ns, nb;

	b = emalloc(8);
	nb = 0;

	t.type = Crx;
	t.flags = Fok;
	if(m->fmtid != FmtUnicode){
		t.flags = Ferr;
		goto Respond;
	}

	s = getsnarfn(&ns);
	if(s == nil)
		goto Respond;
	nb = ns*4;
	b = erealloc(b, nb+8);
	nb = toutf16(b+8, nb, s, ns);
	free(s);
  Respond:
	t.data = b+8;
	t.ndata = nb;
	n = clipputmsg(b, nb+8, &t);
	if(sendvc(c, cliprdr, b, n) < 0)
		fprint(2, "cliprequested: %r\n");
	free(b);
}

static void
clipprovided(Rdp* c, Clipmsg *m)
{
	char *s;
	int n, ns;

	USED(c);
	ns = m->ndata*UTFmax/2;
	s = emalloc(ns);
	n = fromutf16(s, ns, m->data, m->ndata);
	putsnarfn(s, n);
	free(s);
	return;
}

static int
clipputmsg(uchar *a, int n, Clipmsg *m)
{
	if(n < 8){
		werrstr(Esmall);
		return -1;
	}
	iputs(a+0, m->type);
	iputs(a+2, m->flags);
	switch(m->type){
	case Cannounce:
		m->data = a+8;
		m->ndata = 4+32;
		if(8 + m->ndata > n){
			werrstr(Esmall);
			return -1;
		}
		iputl(a+8, m->fmtid);
		memset(a+12, 0, 32);	/* fmt name - who cares? */
		break;
	case Crq:
		m->data = a+8;
		m->ndata = 4;
		if(8 + m->ndata > n){
			werrstr(Esmall);
			return -1;
		}
		iputl(a+8, m->fmtid);
		break;
	case Cnoted:
		m->ndata = 0;
		m->data = a+8;
		break;
	}
	if(8 + m->ndata > n){
		werrstr(Esmall);
		return -1;
	}
	iputl(a+4, m->ndata);
	memcpy(a+8, m->data, m->ndata);
	return 8+m->ndata;
}

static int
clipgetmsg(Clipmsg *m, uchar *p, int n)
{
	uint len;
	uchar *ep;

	if(8 > n){
		werrstr(Eshort);
		return -1;
	}
	m->type = igets(p);
	m->flags = igets(p+2);
	len = igetl(p+4);
	if(8+len > n){
		werrstr(Eshort);
		return -1;
	}
	m->ndata = len;
	m->data = p+8;

	switch(m->type){
	case Crq:
		if(len < 4){
			werrstr(Eshort);
			return -1;
		}
		m->fmtid = igetl(m->data);
		break;
	case Cannounce:
		m->fmtid = 0;
		p += 8;
		ep = p+len;
		while(p < ep){
			m->fmtid = igetl(p);
			if(m->fmtid == FmtUnicode)
				break;
			p += 4+32*1;
		}
		break;
	}
	return 8+len;
}