1 056fe1ba 2003-11-23 devnull /*
  2 056fe1ba 2003-11-23 devnull  * Multiplexed Venti client.  It would be nice if we 
  3 056fe1ba 2003-11-23 devnull  * could turn this into a generic library routine rather
  4 056fe1ba 2003-11-23 devnull  * than keep it Venti specific.  A user-level 9P client
  5 056fe1ba 2003-11-23 devnull  * could use something like this too.
  6 a09e80f9 2004-05-23 devnull  * 
  7 a09e80f9 2004-05-23 devnull  * (Actually it does - this should be replaced with libmux,
  8 a09e80f9 2004-05-23 devnull  * which should be renamed librpcmux.)
  9 056fe1ba 2003-11-23 devnull  *
 10 056fe1ba 2003-11-23 devnull  * This is a little more complicated than it might be
 11 056fe1ba 2003-11-23 devnull  * because we want it to work well within and without libthread.
 12 056fe1ba 2003-11-23 devnull  *
 13 056fe1ba 2003-11-23 devnull  * The mux code is inspired by tra's, which is inspired by the Plan 9 kernel.
 14 056fe1ba 2003-11-23 devnull  */
 15 056fe1ba 2003-11-23 devnull 
 16 056fe1ba 2003-11-23 devnull #include <u.h>
 17 056fe1ba 2003-11-23 devnull #include <libc.h>
 18 056fe1ba 2003-11-23 devnull #include <venti.h>
 19 056fe1ba 2003-11-23 devnull 
 20 056fe1ba 2003-11-23 devnull typedef struct Rwait Rwait;
 21 056fe1ba 2003-11-23 devnull struct Rwait
 22 056fe1ba 2003-11-23 devnull {
 23 056fe1ba 2003-11-23 devnull 	Rendez r;
 24 056fe1ba 2003-11-23 devnull 	Packet *p;
 25 056fe1ba 2003-11-23 devnull 	int done;
 26 056fe1ba 2003-11-23 devnull 	int sleeping;
 27 056fe1ba 2003-11-23 devnull };
 28 056fe1ba 2003-11-23 devnull 
 29 056fe1ba 2003-11-23 devnull static int gettag(VtConn*, Rwait*);
 30 056fe1ba 2003-11-23 devnull static void puttag(VtConn*, Rwait*, int);
 31 056fe1ba 2003-11-23 devnull static void muxrpc(VtConn*, Packet*);
 32 056fe1ba 2003-11-23 devnull 
 33 056fe1ba 2003-11-23 devnull Packet*
 34 7252036f 2005-11-02 devnull _vtrpc(VtConn *z, Packet *p, VtFcall *tx)
 35 056fe1ba 2003-11-23 devnull {
 36 056fe1ba 2003-11-23 devnull 	int i;
 37 056fe1ba 2003-11-23 devnull 	uchar tag, buf[2], *top;
 38 5ddc97fc 2005-02-14 devnull 	Rwait *r, *rr;
 39 056fe1ba 2003-11-23 devnull 
 40 056fe1ba 2003-11-23 devnull 	/* must malloc because stack could be private */
 41 056fe1ba 2003-11-23 devnull 	r = vtmallocz(sizeof(Rwait));
 42 056fe1ba 2003-11-23 devnull 
 43 056fe1ba 2003-11-23 devnull 	qlock(&z->lk);
 44 056fe1ba 2003-11-23 devnull 	r->r.l = &z->lk;
 45 056fe1ba 2003-11-23 devnull 	tag = gettag(z, r);
 46 7252036f 2005-11-02 devnull 	if(tx){
 47 7252036f 2005-11-02 devnull 		/* vtfcallrpc can't print packet because it doesn't have tag */
 48 7252036f 2005-11-02 devnull 		tx->tag = tag;
 49 7252036f 2005-11-02 devnull 		if(chattyventi)
 50 7252036f 2005-11-02 devnull 			fprint(2, "%s -> %F\n", argv0, tx);
 51 7252036f 2005-11-02 devnull 	}
 52 056fe1ba 2003-11-23 devnull 
 53 056fe1ba 2003-11-23 devnull 	/* slam tag into packet */
 54 056fe1ba 2003-11-23 devnull 	top = packetpeek(p, buf, 0, 2);
 55 056fe1ba 2003-11-23 devnull 	if(top == nil){
 56 056fe1ba 2003-11-23 devnull 		packetfree(p);
 57 056fe1ba 2003-11-23 devnull 		return nil;
 58 056fe1ba 2003-11-23 devnull 	}
 59 056fe1ba 2003-11-23 devnull 	if(top == buf){
 60 056fe1ba 2003-11-23 devnull 		werrstr("first two bytes must be in same packet fragment");
 61 056fe1ba 2003-11-23 devnull 		packetfree(p);
 62 6fc7da3c 2006-10-19 devnull 		vtfree(r);
 63 056fe1ba 2003-11-23 devnull 		return nil;
 64 056fe1ba 2003-11-23 devnull 	}
 65 056fe1ba 2003-11-23 devnull 	top[1] = tag;
 66 056fe1ba 2003-11-23 devnull 	qunlock(&z->lk);
 67 6fc7da3c 2006-10-19 devnull 	if(vtsend(z, p) < 0){
 68 6fc7da3c 2006-10-19 devnull 		vtfree(r);
 69 056fe1ba 2003-11-23 devnull 		return nil;
 70 6fc7da3c 2006-10-19 devnull 	}
 71 056fe1ba 2003-11-23 devnull 
 72 056fe1ba 2003-11-23 devnull 	qlock(&z->lk);
 73 056fe1ba 2003-11-23 devnull 	/* wait for the muxer to give us our packet */
 74 056fe1ba 2003-11-23 devnull 	r->sleeping = 1;
 75 056fe1ba 2003-11-23 devnull 	z->nsleep++;
 76 056fe1ba 2003-11-23 devnull 	while(z->muxer && !r->done)
 77 056fe1ba 2003-11-23 devnull 		rsleep(&r->r);
 78 056fe1ba 2003-11-23 devnull 	z->nsleep--;
 79 056fe1ba 2003-11-23 devnull 	r->sleeping = 0;
 80 056fe1ba 2003-11-23 devnull 
 81 056fe1ba 2003-11-23 devnull 	/* if not done, there's no muxer: start muxing */
 82 056fe1ba 2003-11-23 devnull 	if(!r->done){
 83 056fe1ba 2003-11-23 devnull 		if(z->muxer)
 84 056fe1ba 2003-11-23 devnull 			abort();
 85 056fe1ba 2003-11-23 devnull 		z->muxer = 1;
 86 056fe1ba 2003-11-23 devnull 		while(!r->done){
 87 056fe1ba 2003-11-23 devnull 			qunlock(&z->lk);
 88 056fe1ba 2003-11-23 devnull 			if((p = vtrecv(z)) == nil){
 89 2e965b33 2004-05-05 devnull 				werrstr("unexpected eof on venti connection");
 90 056fe1ba 2003-11-23 devnull 				z->muxer = 0;
 91 6fc7da3c 2006-10-19 devnull 				vtfree(r);
 92 056fe1ba 2003-11-23 devnull 				return nil;
 93 056fe1ba 2003-11-23 devnull 			}
 94 056fe1ba 2003-11-23 devnull 			qlock(&z->lk);
 95 056fe1ba 2003-11-23 devnull 			muxrpc(z, p);
 96 056fe1ba 2003-11-23 devnull 		}
 97 056fe1ba 2003-11-23 devnull 		z->muxer = 0;
 98 5ddc97fc 2005-02-14 devnull 		/* if there is anyone else sleeping, wake first unfinished to mux */
 99 5ddc97fc 2005-02-14 devnull 		if(z->nsleep)
100 5ddc97fc 2005-02-14 devnull 		for(i=0; i<256; i++){
101 5ddc97fc 2005-02-14 devnull 			rr = z->wait[i];
102 5ddc97fc 2005-02-14 devnull 			if(rr && rr->sleeping && !rr->done){
103 5ddc97fc 2005-02-14 devnull 				rwakeup(&rr->r);
104 5ddc97fc 2005-02-14 devnull 				break;
105 5ddc97fc 2005-02-14 devnull 			}
106 5ddc97fc 2005-02-14 devnull 		}
107 056fe1ba 2003-11-23 devnull 	}
108 056fe1ba 2003-11-23 devnull 
109 056fe1ba 2003-11-23 devnull 	p = r->p;
110 056fe1ba 2003-11-23 devnull 	puttag(z, r, tag);
111 056fe1ba 2003-11-23 devnull 	vtfree(r);
112 056fe1ba 2003-11-23 devnull 	qunlock(&z->lk);
113 056fe1ba 2003-11-23 devnull 	return p;
114 056fe1ba 2003-11-23 devnull }
115 056fe1ba 2003-11-23 devnull 
116 7252036f 2005-11-02 devnull Packet*
117 7252036f 2005-11-02 devnull vtrpc(VtConn *z, Packet *p)
118 7252036f 2005-11-02 devnull {
119 7252036f 2005-11-02 devnull 	return _vtrpc(z, p, nil);
120 7252036f 2005-11-02 devnull }
121 7252036f 2005-11-02 devnull 
122 056fe1ba 2003-11-23 devnull static int 
123 056fe1ba 2003-11-23 devnull gettag(VtConn *z, Rwait *r)
124 056fe1ba 2003-11-23 devnull {
125 056fe1ba 2003-11-23 devnull 	int i;
126 056fe1ba 2003-11-23 devnull 
127 056fe1ba 2003-11-23 devnull Again:
128 056fe1ba 2003-11-23 devnull 	while(z->ntag == 256)
129 056fe1ba 2003-11-23 devnull 		rsleep(&z->tagrend);
130 056fe1ba 2003-11-23 devnull 	for(i=0; i<256; i++)
131 056fe1ba 2003-11-23 devnull 		if(z->wait[i] == 0){
132 056fe1ba 2003-11-23 devnull 			z->ntag++;
133 056fe1ba 2003-11-23 devnull 			z->wait[i] = r;
134 056fe1ba 2003-11-23 devnull 			return i;
135 056fe1ba 2003-11-23 devnull 		}
136 056fe1ba 2003-11-23 devnull 	fprint(2, "libventi: ntag botch\n");
137 056fe1ba 2003-11-23 devnull 	goto Again;
138 056fe1ba 2003-11-23 devnull }
139 056fe1ba 2003-11-23 devnull 
140 056fe1ba 2003-11-23 devnull static void
141 056fe1ba 2003-11-23 devnull puttag(VtConn *z, Rwait *r, int tag)
142 056fe1ba 2003-11-23 devnull {
143 056fe1ba 2003-11-23 devnull 	assert(z->wait[tag] == r);
144 056fe1ba 2003-11-23 devnull 	z->wait[tag] = nil;
145 056fe1ba 2003-11-23 devnull 	z->ntag--;
146 056fe1ba 2003-11-23 devnull 	rwakeup(&z->tagrend);
147 056fe1ba 2003-11-23 devnull }
148 056fe1ba 2003-11-23 devnull 
149 056fe1ba 2003-11-23 devnull static void
150 056fe1ba 2003-11-23 devnull muxrpc(VtConn *z, Packet *p)
151 056fe1ba 2003-11-23 devnull {
152 056fe1ba 2003-11-23 devnull 	uchar tag, buf[2], *top;
153 056fe1ba 2003-11-23 devnull 	Rwait *r;
154 056fe1ba 2003-11-23 devnull 
155 056fe1ba 2003-11-23 devnull 	if((top = packetpeek(p, buf, 0, 2)) == nil){
156 056fe1ba 2003-11-23 devnull 		fprint(2, "libventi: short packet in vtrpc\n");
157 056fe1ba 2003-11-23 devnull 		packetfree(p);
158 056fe1ba 2003-11-23 devnull 		return;
159 056fe1ba 2003-11-23 devnull 	}
160 056fe1ba 2003-11-23 devnull 
161 056fe1ba 2003-11-23 devnull 	tag = top[1];
162 056fe1ba 2003-11-23 devnull 	if((r = z->wait[tag]) == nil){
163 056fe1ba 2003-11-23 devnull 		fprint(2, "libventi: unexpected packet tag %d in vtrpc\n", tag);
164 056fe1ba 2003-11-23 devnull abort();
165 056fe1ba 2003-11-23 devnull 		packetfree(p);
166 056fe1ba 2003-11-23 devnull 		return;
167 056fe1ba 2003-11-23 devnull 	}
168 056fe1ba 2003-11-23 devnull 
169 056fe1ba 2003-11-23 devnull 	r->p = p;
170 056fe1ba 2003-11-23 devnull 	r->done = 1;
171 056fe1ba 2003-11-23 devnull 	rwakeup(&r->r);
172 056fe1ba 2003-11-23 devnull }
173 056fe1ba 2003-11-23 devnull