vchan.c

/*
 * [MS-RDPBCGR] 3.1.5.2 Static Virtual Channels
 * http://msdn.microsoft.com/en-us/library/cc240926.aspx
 */
#include <u.h>
#include <libc.h>
#include "dat.h"
#include "fns.h"

enum
{
	/* 2.2.1.3.4.1 Channel Definition Structure */
	Inited=	1<<31,
	
	/* 2.2.6.1 Virtual Channel PDU */
	MTU=	1600,

	/* 2.2.6.1.1 Channel PDU Header */
	First=	1<<0,
	Last=	1<<1,
	Vis=  	1<<4,
};

static Vchan vctab[] =
{
	{
		.mcsid = GLOBALCHAN+1,	/* iota */
		.name = "CLIPRDR",
		.fn = clipvcfn,
		.flags = Inited,
	},
	{
		.mcsid = GLOBALCHAN+2,
		.name = "RDPSND",
		.fn = audiovcfn,
		.flags = Inited,
	},
};
static uint nvc = nelem(vctab);

void
initvc(Rdp* c)
{
	c->vc = vctab;
	c->nvc = nvc;
}

static Vchan*
lookupvc(int mcsid)
{
	int i;

	for(i=0; i<nvc; i++)
	if(vctab[i].mcsid == mcsid)
		return &vctab[i];
	return nil;
}

static Vchan*
namevc(char* name)
{
	int i;

	for(i=0; i<nvc; i++)
	if(strcmp(vctab[i].name, name) == 0)
		return &vctab[i];
	return nil;
}

int
defragvc(Rdp* c, Msg* m)
{
	Vchan* vc;
	int n;

	USED(c);
	vc = lookupvc(m->chanid);
	if(vc == nil){
		fprint(2, "defragvc: bad chanid\n");
		return -1;
	}

	if(m->flags&First)
		vc->pos = 0;

	if(m->len > vc->nb){
		vc->buf = erealloc(vc->buf, m->len);
		vc->nb = m->len;
	}
	n = m->len - vc->pos;
	if(n > m->ndata)
		n = m->ndata;
	memcpy(vc->buf+vc->pos, m->data, n);
	vc->pos += n;

	if(m->flags&Last){
		m->data = vc->buf;
		m->ndata = m->len;
		return m->len;
	}
	return 0;
}

void
callvcfunc(Rdp *c, Msg* m)
{
	Vchan* vc;
	vc = lookupvc(m->chanid);
	if(vc == nil || vc->fn==nil){
		fprint(2, "unhandled virtual channel[%d] msg\n", m->chanid);
		return;
	}
	vc->fn(c, m->data, m->ndata);
}

int
sendvc(Rdp* c, char* cname, uchar* a, int n)
{
	int sofar, chunk;
	Vchan* vc;
	Msg t;
	
	if(n < 0)
		return -1;

	vc = namevc(cname);
	if(vc == nil){
		werrstr("%s: no such vchannel", cname);
		return -1;
	}
	if(vc->mcsid < 0)
		return -1;

	t.type = Mvchan;
	t.originid = c->userchan;
	t.chanid = vc->mcsid;
	t.flags = First | Vis;
	t.len = n;
	t.data = a;

	for(sofar=0; sofar<n; sofar += chunk){
		chunk = n-sofar;
		if(chunk > MTU)
			chunk = MTU;
		else
			t.flags |= Last;

		t.data = a+sofar;
		t.ndata = chunk;
		writemsg(c, &t);

		t.flags &= ~First;
	}
	return n;
}