1 #include <u.h>
2 #include <libc.h>
3 #include <venti.h>
4 
5 static char *okvers[] = {
6 	"04",
7 	"02",
8 	nil,
9 };
10 
11 /*
12 static char EBigString[] = "string too long";
13 static char EBigPacket[] = "packet too long";
14 static char ENullString[] = "missing string";
15 */
16 static char EBadVersion[] = "bad format in version string";
17 
18 static int
19 vtreadversion(VtConn *z, char *q, char *v, int nv)
20 {
21 	int n;
22 
23 	for(;;){
24 		if(nv <= 1){
25 			werrstr("version too long");
26 			return -1;
27 		}
28 		n = read(z->infd, v, 1);
29 		if(n <= 0){
30 			if(n == 0)
31 				werrstr("unexpected eof");
32 			return -1;
33 		}
34 		if(*v == '\n'){
35 			*v = 0;
36 			break;
37 		}
38 		if((uchar)*v < ' ' || (uchar)*v > 0x7f || (*q && *v != *q)){
39 			werrstr(EBadVersion);
40 			return -1;
41 		}
42 		v++;
43 		nv--;
44 		if(*q)
45 			q++;
46 	}
47 	return 0;
48 }
49 
50 int
51 vtversion(VtConn *z)
52 {
53 	char buf[VtMaxStringSize], *p, *ep, *prefix, *pp;
54 	int i;
55 
56 	qlock(&z->lk);
57 	if(z->state != VtStateAlloc){
58 		werrstr("bad session state");
59 		qunlock(&z->lk);
60 		return -1;
61 	}
62 
63 	qlock(&z->inlk);
64 	qlock(&z->outlk);
65 
66 	p = buf;
67 	ep = buf + sizeof buf;
68 	prefix = "venti-";
69 	p = seprint(p, ep, "%s", prefix);
70 	p += strlen(p);
71 	for(i=0; okvers[i]; i++)
72 		p = seprint(p, ep, "%s%s", i ? ":" : "", okvers[i]);
73 	p = seprint(p, ep, "-libventi\n");
74 	assert(p-buf < sizeof buf);
75 
76 	if(write(z->outfd, buf, p-buf) != p-buf)
77 		goto Err;
78 	vtdebug(z, "version string out: %s", buf);
79 
80 	if(vtreadversion(z, prefix, buf, sizeof buf) < 0)
81 		goto Err;
82 	vtdebug(z, "version string in: %s", buf);
83 
84 	p = buf+strlen(prefix);
85 	for(; *p; p=pp){
86 		if(*p == ':' || *p == '-')
87 			p++;
88 		pp = strpbrk(p, ":-");
89 		if(pp == nil)
90 			pp = p+strlen(p);
91 		for(i=0; okvers[i]; i++)
92 			if(strlen(okvers[i]) == pp-p && memcmp(okvers[i], p, pp-p) == 0){
93 				*pp = 0;
94 				z->version = vtstrdup(p);
95 				goto Okay;
96 			}
97 	}
98 	werrstr("unable to negotiate version");
99 	goto Err;
100 
101 Okay:
102 	z->state = VtStateConnected;
103 	qunlock(&z->inlk);
104 	qunlock(&z->outlk);
105 	qunlock(&z->lk);
106 	return 0;
107 
108 Err:
109 	werrstr("vtversion: %r");
110 	if(z->infd >= 0)
111 		close(z->infd);
112 	if(z->outfd >= 0 && z->outfd != z->infd)
113 		close(z->outfd);
114 	z->infd = -1;
115 	z->outfd = -1;
116 	z->state = VtStateClosed;
117 	qunlock(&z->inlk);
118 	qunlock(&z->outlk);
119 	qunlock(&z->lk);
120 	return -1;
121 }