1 #include "std.h"
2 #include "dat.h"
3 
4 /*
5  * p9any - protocol negotiator
6  *
7  * Protocol:
8  *	S->C: v.2 proto@dom proto@dom proto@dom... NUL
9  *	C->S: proto dom NUL
10  *	[negotiated proto continues]
11  */
12 
13 static Proto* okproto[] =
14 {
15 	&p9sk1,
16 	nil,
17 };
18 
19 static int
20 rolecall(Role *r, char *name, Conv *c)
21 {
22 	for(; r->name; r++)
23 		if(strcmp(r->name, name) == 0)
24 			return (*r->fn)(c);
25 	werrstr("unknown role");
26 	return -1;
27 }
28 
29 static int
30 hasnul(void *v, int n)
31 {
32 	char *c;
33 
34 	c = v;
35 	if(n > 0 && c[n-1] == '\0')
36 		return n;
37 	else
38 		return n+1;
39 }
40 
41 static int
42 p9anyserver(Conv *c)
43 {
44 	char *s, *dom;
45 	int i, j, n, m, ret;
46 	char *tok[3];
47 	Attr *attr;
48 	Key *k;
49 
50 	ret = -1;
51 	s = estrdup("v.2");
52 	n = 0;
53 	attr = delattr(copyattr(c->attr), "proto");
54 
55 	for(i=0; i<ring.nkey; i++){
56 		k = ring.key[i];
57 		for(j=0; okproto[j]; j++)
58 			if(k->proto == okproto[j]
59 			&& (dom = strfindattr(k->attr, "dom")) != nil
60 			&& matchattr(attr, k->attr, k->privattr)){
61 				s = estrappend(s, " %s@%s", k->proto->name, dom);
62 				n++;
63 			}
64 	}
65 
66 	if(n == 0){
67 		werrstr("no valid keys");
68 		goto out;
69 	}
70 
71 	c->state = "write offer";
72 	if(convwrite(c, s, strlen(s)+1) < 0)
73 		goto out;
74 	free(s);
75 	s = nil;
76 
77 	c->state = "read choice";
78 	if(convreadfn(c, hasnul, &s) < 0)
79 		goto out;
80 
81 	m = tokenize(s, tok, nelem(tok));
82 	if(m != 2){
83 		werrstr("bad protocol message");
84 		goto out;
85 	}
86 
87 	for(i=0; okproto[i]; i++)
88 		if(strcmp(okproto[i]->name, tok[0]) == 0)
89 			break;
90 	if(!okproto[i]){
91 		werrstr("bad chosen protocol %q", tok[0]);
92 		goto out;
93 	}
94 
95 	c->state = "write ok";
96 	if(convwrite(c, "OK\0", 3) < 0)
97 		goto out;
98 
99 	c->state = "start choice";
100 	attr = addattr(attr, "proto=%q dom=%q", tok[0], tok[1]);
101 	free(c->attr);
102 	c->attr = attr;
103 	attr = nil;
104 	c->proto = okproto[i];
105 
106 	if(rolecall(c->proto->roles, "server", c) < 0){
107 		werrstr("%s: %r", tok[0]);
108 		goto out;
109 	}
110 
111 	ret = 0;
112 	
113 out:
114 	free(s);
115 	freeattr(attr);
116 	return ret;
117 }
118 
119 static int
120 p9anyclient(Conv *c)
121 {
122 	char *s, **f, *tok[20], ok[3], *q, *user, *dom;
123 	int i, n, ret, version;
124 	Key *k;
125 	Attr *attr;
126 	Proto *p;
127 
128 	ret = -1;
129 	s = nil;
130 	k = nil;
131 
132 	user = strfindattr(c->attr, "user");
133 	dom = strfindattr(c->attr, "dom");
134 
135 	/*
136 	 * if the user is the factotum owner, any key will do.
137 	 * if not, then if we have a speakfor key,
138 	 * we will only vouch for the user's local identity.
139 	 *
140 	 * this logic is duplicated in p9sk1.c
141 	 */
142 	attr = delattr(copyattr(c->attr), "role");
143 	attr = delattr(attr, "proto");
144 	if(strcmp(c->sysuser, owner) == 0)
145 		attr = addattr(attr, "role=client");
146 	else if(user==nil || strcmp(c->sysuser, user)==0){
147 		attr = delattr(attr, "user");
148 		attr = addattr(attr, "role=speakfor");
149 	}else{
150 		werrstr("will not authenticate for %q as %q", c->sysuser, user);
151 		goto out;
152 	}
153 
154 	c->state = "read offer";
155 	if(convreadfn(c, hasnul, &s) < 0)
156 		goto out;
157 
158 	c->state = "look for keys";
159 	n = tokenize(s, tok, nelem(tok));
160 	f = tok;
161 	version = 1;
162 	if(n > 0 && memcmp(f[0], "v.", 2) == 0){
163 		version = atoi(f[0]+2);
164 		if(version != 2){
165 			werrstr("unknown p9any version: %s", f[0]);
166 			goto out;
167 		}
168 		f++;
169 		n--;
170 	}
171 
172 	/* look for keys that don't need confirmation */
173 	for(i=0; i<n; i++){
174 		if((q = strchr(f[i], '@')) == nil)
175 			continue;
176 		if(dom && strcmp(q+1, dom) != 0)
177 			continue;
178 		*q++ = '\0';
179 		if((k = keylookup("%A proto=%q dom=%q", attr, f[i], q))
180 		&& strfindattr(k->attr, "confirm") == nil)
181 			goto found;
182 		*--q = '@';
183 	}
184 
185 	/* look for any keys at all */
186 	for(i=0; i<n; i++){
187 		if((q = strchr(f[i], '@')) == nil)
188 			continue;
189 		if(dom && strcmp(q+1, dom) != 0)
190 			continue;
191 		*q++ = '\0';
192 		if(k = keyfetch(c, "%A proto=%q dom=%q", attr, f[i], q))
193 			goto found;
194 		*--q = '@';
195 	}
196 
197 	/* ask for new keys */
198 	c->state = "ask for keys";
199 	for(i=0; i<n; i++){
200 		if((q = strchr(f[i], '@')) == nil)
201 			continue;
202 		if(dom && strcmp(q+1, dom) != 0)
203 			continue;
204 		*q++ = '\0';
205 		p = protolookup(f[i]);
206 		if(p == nil || p->keyprompt == nil){
207 			*--q = '@';
208 			continue;
209 		}
210 		if(k = keyfetch(c, "%A proto=%q dom=%q %s", attr, f[i], q, p->keyprompt))
211 			goto found;
212 		*--q = '@';
213 	}
214 
215 	/* nothing worked */
216 	werrstr("unable to find common key");
217 	goto out;
218 
219 found:
220 	/* f[i] is the chosen protocol, q the chosen domain */
221 	attr = addattr(attr, "proto=%q dom=%q", f[i], q);
222 	c->state = "write choice";
223 	/* have a key: go for it */
224 	if(convprint(c, "%q %q", f[i], q) < 0
225 	|| convwrite(c, "\0", 1) < 0)
226 		goto out;
227 
228 	if(version == 2){
229 		c->state = "read ok";
230 		if(convread(c, ok, 3) < 0 || memcmp(ok, "OK\0", 3) != 0)
231 			goto out;
232 	}
233 
234 	c->state = "start choice";
235 	c->proto = protolookup(f[i]);
236 	freeattr(c->attr);
237 	c->attr = attr;
238 	attr = nil;
239 
240 	if(rolecall(c->proto->roles, "client", c) < 0){
241 		werrstr("%s: %r", c->proto->name);
242 		goto out;
243 	}
244 
245 	ret = 0;
246 
247 out:
248 	keyclose(k);
249 	freeattr(attr);
250 	free(s);
251 	return ret;
252 }
253 
254 static Role
255 p9anyroles[] = 
256 {
257 	"client",	p9anyclient,
258 	"server",	p9anyserver,
259 	0
260 };
261 
262 Proto p9any = {
263 .name=		"p9any",
264 .roles=		p9anyroles,
265 };
266