1 /*
2  * HTTPDIGEST - MD5 challenge/response authentication (RFC 2617)
3  *
4  * Client protocol:
5  *	write challenge: nonce method uri
6  *	read response: 2*MD5dlen hex digits
7  *
8  * Server protocol:
9  *	unimplemented
10  */
11 #include "std.h"
12 #include "dat.h"
13 
14 static void
15 digest(char *user, char *realm, char *passwd,
16 	char *nonce, char *method, char *uri,
17 	char *dig);
18 
19 static int
20 hdclient(Conv *c)
21 {
22 	char *realm, *passwd, *user, *f[4], *s, resp[MD5dlen*2+1];
23 	int ret;
24 	Key *k;
25 
26 	ret = -1;
27 	s = nil;
28 
29 	c->state = "keylookup";
30 	k = keyfetch(c, "%A", c->attr);
31 	if(k == nil)
32 		goto out;
33 
34 	user = strfindattr(k->attr, "user");
35 	realm = strfindattr(k->attr, "realm");
36 	passwd = strfindattr(k->attr, "!password");
37 
38 	if(convreadm(c, &s) < 0)
39 		goto out;
40 	if(tokenize(s, f, 4) != 3){
41 		werrstr("bad challenge -- want nonce method uri");
42 		goto out;
43 	}
44 
45 	digest(user, realm, passwd, f[0], f[1], f[2], resp);
46 	convwrite(c, resp, strlen(resp));
47 	ret = 0;
48 
49 out:
50 	free(s);
51 	keyclose(k);
52 	return ret;
53 }
54 
55 static void
56 strtolower(char *s)
57 {
58 	while(*s){
59 		*s = tolower((uchar)*s);
60 		s++;
61 	}
62 }
63 
64 static void
65 digest(char *user, char *realm, char *passwd,
66 	char *nonce, char *method, char *uri,
67 	char *dig)
68 {
69 	uchar b[MD5dlen];
70 	char ha1[MD5dlen*2+1];
71 	char ha2[MD5dlen*2+1];
72 	DigestState *s;
73 
74 	/*
75 	 *  H(A1) = MD5(uid + ":" + realm ":" + passwd)
76 	 */
77 	s = md5((uchar*)user, strlen(user), nil, nil);
78 	md5((uchar*)":", 1, nil, s);
79 	md5((uchar*)realm, strlen(realm), nil, s);
80 	md5((uchar*)":", 1, nil, s);
81 	md5((uchar*)passwd, strlen(passwd), b, s);
82 	enc16(ha1, sizeof(ha1), b, MD5dlen);
83 	strtolower(ha1);
84 
85 	/*
86 	 *  H(A2) = MD5(method + ":" + uri)
87 	 */
88 	s = md5((uchar*)method, strlen(method), nil, nil);
89 	md5((uchar*)":", 1, nil, s);
90 	md5((uchar*)uri, strlen(uri), b, s);
91 	enc16(ha2, sizeof(ha2), b, MD5dlen);
92 	strtolower(ha2);
93 
94 	/*
95 	 *  digest = MD5(H(A1) + ":" + nonce + ":" + H(A2))
96 	 */
97 	s = md5((uchar*)ha1, MD5dlen*2, nil, nil);
98 	md5((uchar*)":", 1, nil, s);
99 	md5((uchar*)nonce, strlen(nonce), nil, s);
100 	md5((uchar*)":", 1, nil, s);
101 	md5((uchar*)ha2, MD5dlen*2, b, s);
102 	enc16(dig, MD5dlen*2+1, b, MD5dlen);
103 	strtolower(dig);
104 }
105 
106 static Role hdroles[] =
107 {
108 	"client",	hdclient,
109 	0
110 };
111 
112 Proto httpdigest =
113 {
114 	"httpdigest",
115 	hdroles,
116 	"user? realm? !password?",
117 	0,
118 	0
119 };