1 056fe1ba 2003-11-23 devnull /*
  2 fa325e9b 2020-01-10 cross  * 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 fa325e9b 2020-01-10 cross  *
  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 fc638f7b 2012-01-16 rsc 	if(z == nil){
 41 fc638f7b 2012-01-16 rsc 		werrstr("not connected");
 42 fc638f7b 2012-01-16 rsc 		packetfree(p);
 43 fc638f7b 2012-01-16 rsc 		return nil;
 44 fc638f7b 2012-01-16 rsc 	}
 45 fc638f7b 2012-01-16 rsc 
 46 056fe1ba 2003-11-23 devnull 	/* must malloc because stack could be private */
 47 056fe1ba 2003-11-23 devnull 	r = vtmallocz(sizeof(Rwait));
 48 056fe1ba 2003-11-23 devnull 
 49 056fe1ba 2003-11-23 devnull 	qlock(&z->lk);
 50 056fe1ba 2003-11-23 devnull 	r->r.l = &z->lk;
 51 056fe1ba 2003-11-23 devnull 	tag = gettag(z, r);
 52 7252036f 2005-11-02 devnull 	if(tx){
 53 7252036f 2005-11-02 devnull 		/* vtfcallrpc can't print packet because it doesn't have tag */
 54 7252036f 2005-11-02 devnull 		tx->tag = tag;
 55 7252036f 2005-11-02 devnull 		if(chattyventi)
 56 7252036f 2005-11-02 devnull 			fprint(2, "%s -> %F\n", argv0, tx);
 57 7252036f 2005-11-02 devnull 	}
 58 056fe1ba 2003-11-23 devnull 
 59 056fe1ba 2003-11-23 devnull 	/* slam tag into packet */
 60 056fe1ba 2003-11-23 devnull 	top = packetpeek(p, buf, 0, 2);
 61 056fe1ba 2003-11-23 devnull 	if(top == nil){
 62 056fe1ba 2003-11-23 devnull 		packetfree(p);
 63 056fe1ba 2003-11-23 devnull 		return nil;
 64 056fe1ba 2003-11-23 devnull 	}
 65 056fe1ba 2003-11-23 devnull 	if(top == buf){
 66 056fe1ba 2003-11-23 devnull 		werrstr("first two bytes must be in same packet fragment");
 67 056fe1ba 2003-11-23 devnull 		packetfree(p);
 68 6fc7da3c 2006-10-19 devnull 		vtfree(r);
 69 056fe1ba 2003-11-23 devnull 		return nil;
 70 056fe1ba 2003-11-23 devnull 	}
 71 056fe1ba 2003-11-23 devnull 	top[1] = tag;
 72 056fe1ba 2003-11-23 devnull 	qunlock(&z->lk);
 73 6fc7da3c 2006-10-19 devnull 	if(vtsend(z, p) < 0){
 74 6fc7da3c 2006-10-19 devnull 		vtfree(r);
 75 056fe1ba 2003-11-23 devnull 		return nil;
 76 6fc7da3c 2006-10-19 devnull 	}
 77 056fe1ba 2003-11-23 devnull 
 78 056fe1ba 2003-11-23 devnull 	qlock(&z->lk);
 79 056fe1ba 2003-11-23 devnull 	/* wait for the muxer to give us our packet */
 80 056fe1ba 2003-11-23 devnull 	r->sleeping = 1;
 81 056fe1ba 2003-11-23 devnull 	z->nsleep++;
 82 056fe1ba 2003-11-23 devnull 	while(z->muxer && !r->done)
 83 056fe1ba 2003-11-23 devnull 		rsleep(&r->r);
 84 056fe1ba 2003-11-23 devnull 	z->nsleep--;
 85 056fe1ba 2003-11-23 devnull 	r->sleeping = 0;
 86 056fe1ba 2003-11-23 devnull 
 87 056fe1ba 2003-11-23 devnull 	/* if not done, there's no muxer: start muxing */
 88 056fe1ba 2003-11-23 devnull 	if(!r->done){
 89 056fe1ba 2003-11-23 devnull 		if(z->muxer)
 90 056fe1ba 2003-11-23 devnull 			abort();
 91 056fe1ba 2003-11-23 devnull 		z->muxer = 1;
 92 056fe1ba 2003-11-23 devnull 		while(!r->done){
 93 056fe1ba 2003-11-23 devnull 			qunlock(&z->lk);
 94 056fe1ba 2003-11-23 devnull 			if((p = vtrecv(z)) == nil){
 95 2e965b33 2004-05-05 devnull 				werrstr("unexpected eof on venti connection");
 96 056fe1ba 2003-11-23 devnull 				z->muxer = 0;
 97 6fc7da3c 2006-10-19 devnull 				vtfree(r);
 98 056fe1ba 2003-11-23 devnull 				return nil;
 99 056fe1ba 2003-11-23 devnull 			}
100 056fe1ba 2003-11-23 devnull 			qlock(&z->lk);
101 056fe1ba 2003-11-23 devnull 			muxrpc(z, p);
102 056fe1ba 2003-11-23 devnull 		}
103 056fe1ba 2003-11-23 devnull 		z->muxer = 0;
104 5ddc97fc 2005-02-14 devnull 		/* if there is anyone else sleeping, wake first unfinished to mux */
105 5ddc97fc 2005-02-14 devnull 		if(z->nsleep)
106 5ddc97fc 2005-02-14 devnull 		for(i=0; i<256; i++){
107 5ddc97fc 2005-02-14 devnull 			rr = z->wait[i];
108 5ddc97fc 2005-02-14 devnull 			if(rr && rr->sleeping && !rr->done){
109 5ddc97fc 2005-02-14 devnull 				rwakeup(&rr->r);
110 5ddc97fc 2005-02-14 devnull 				break;
111 5ddc97fc 2005-02-14 devnull 			}
112 5ddc97fc 2005-02-14 devnull 		}
113 056fe1ba 2003-11-23 devnull 	}
114 056fe1ba 2003-11-23 devnull 
115 056fe1ba 2003-11-23 devnull 	p = r->p;
116 056fe1ba 2003-11-23 devnull 	puttag(z, r, tag);
117 056fe1ba 2003-11-23 devnull 	vtfree(r);
118 056fe1ba 2003-11-23 devnull 	qunlock(&z->lk);
119 056fe1ba 2003-11-23 devnull 	return p;
120 056fe1ba 2003-11-23 devnull }
121 056fe1ba 2003-11-23 devnull 
122 7252036f 2005-11-02 devnull Packet*
123 7252036f 2005-11-02 devnull vtrpc(VtConn *z, Packet *p)
124 7252036f 2005-11-02 devnull {
125 7252036f 2005-11-02 devnull 	return _vtrpc(z, p, nil);
126 7252036f 2005-11-02 devnull }
127 7252036f 2005-11-02 devnull 
128 fa325e9b 2020-01-10 cross static int
129 056fe1ba 2003-11-23 devnull gettag(VtConn *z, Rwait *r)
130 056fe1ba 2003-11-23 devnull {
131 056fe1ba 2003-11-23 devnull 	int i;
132 056fe1ba 2003-11-23 devnull 
133 056fe1ba 2003-11-23 devnull Again:
134 056fe1ba 2003-11-23 devnull 	while(z->ntag == 256)
135 056fe1ba 2003-11-23 devnull 		rsleep(&z->tagrend);
136 056fe1ba 2003-11-23 devnull 	for(i=0; i<256; i++)
137 056fe1ba 2003-11-23 devnull 		if(z->wait[i] == 0){
138 056fe1ba 2003-11-23 devnull 			z->ntag++;
139 056fe1ba 2003-11-23 devnull 			z->wait[i] = r;
140 056fe1ba 2003-11-23 devnull 			return i;
141 056fe1ba 2003-11-23 devnull 		}
142 056fe1ba 2003-11-23 devnull 	fprint(2, "libventi: ntag botch\n");
143 056fe1ba 2003-11-23 devnull 	goto Again;
144 056fe1ba 2003-11-23 devnull }
145 056fe1ba 2003-11-23 devnull 
146 056fe1ba 2003-11-23 devnull static void
147 056fe1ba 2003-11-23 devnull puttag(VtConn *z, Rwait *r, int tag)
148 056fe1ba 2003-11-23 devnull {
149 056fe1ba 2003-11-23 devnull 	assert(z->wait[tag] == r);
150 056fe1ba 2003-11-23 devnull 	z->wait[tag] = nil;
151 056fe1ba 2003-11-23 devnull 	z->ntag--;
152 056fe1ba 2003-11-23 devnull 	rwakeup(&z->tagrend);
153 056fe1ba 2003-11-23 devnull }
154 056fe1ba 2003-11-23 devnull 
155 056fe1ba 2003-11-23 devnull static void
156 056fe1ba 2003-11-23 devnull muxrpc(VtConn *z, Packet *p)
157 056fe1ba 2003-11-23 devnull {
158 056fe1ba 2003-11-23 devnull 	uchar tag, buf[2], *top;
159 056fe1ba 2003-11-23 devnull 	Rwait *r;
160 056fe1ba 2003-11-23 devnull 
161 056fe1ba 2003-11-23 devnull 	if((top = packetpeek(p, buf, 0, 2)) == nil){
162 056fe1ba 2003-11-23 devnull 		fprint(2, "libventi: short packet in vtrpc\n");
163 056fe1ba 2003-11-23 devnull 		packetfree(p);
164 056fe1ba 2003-11-23 devnull 		return;
165 056fe1ba 2003-11-23 devnull 	}
166 056fe1ba 2003-11-23 devnull 
167 056fe1ba 2003-11-23 devnull 	tag = top[1];
168 056fe1ba 2003-11-23 devnull 	if((r = z->wait[tag]) == nil){
169 056fe1ba 2003-11-23 devnull 		fprint(2, "libventi: unexpected packet tag %d in vtrpc\n", tag);
170 056fe1ba 2003-11-23 devnull abort();
171 056fe1ba 2003-11-23 devnull 		packetfree(p);
172 056fe1ba 2003-11-23 devnull 		return;
173 056fe1ba 2003-11-23 devnull 	}
174 056fe1ba 2003-11-23 devnull 
175 056fe1ba 2003-11-23 devnull 	r->p = p;
176 056fe1ba 2003-11-23 devnull 	r->done = 1;
177 056fe1ba 2003-11-23 devnull 	rwakeup(&r->r);
178 056fe1ba 2003-11-23 devnull }