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source: protocols/jabber/sasl.c @ 24b8bbb

Last change on this file since 24b8bbb was af97b23, checked in by Wilmer van der Gaast <wilmer@…>, at 2008-02-16T13:17:52Z
Improved sasl_get_part() to deal with whitespace in challenge strings, as described in RFC 2831 secion 7.1 (the #rule description). Closes bug #362.
Property mode set to `100644`
File size: 9.4 KB

Line
1	/***************************************************************************\
2	* *
3	* BitlBee - An IRC to IM gateway *
4	* Jabber module - SASL authentication *
5	* *
6	* Copyright 2006 Wilmer van der Gaast <wilmer@gaast.net> *
7	* *
8	* This program is free software; you can redistribute it and/or modify *
9	* it under the terms of the GNU General Public License as published by *
10	* the Free Software Foundation; either version 2 of the License, or *
11	* (at your option) any later version. *
12	* *
13	* This program is distributed in the hope that it will be useful, *
14	* but WITHOUT ANY WARRANTY; without even the implied warranty of *
15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16	* GNU General Public License for more details. *
17	* *
18	* You should have received a copy of the GNU General Public License along *
19	* with this program; if not, write to the Free Software Foundation, Inc., *
20	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *
21	* *
22	\***************************************************************************/
23
24	#include <ctype.h>
25
26	#include "jabber.h"
27	#include "base64.h"
28
29	xt_status sasl_pkt_mechanisms( struct xt_node *node, gpointer data )
30	{
31	struct im_connection *ic = data;
32	struct jabber_data *jd = ic->proto_data;
33	struct xt_node c, reply;
34	char *s;
35	int sup_plain = 0, sup_digest = 0;
36
37	if( !sasl_supported( ic ) )
38	{
39	/* Should abort this now, since we should already be doing
40	IQ authentication. Strange things happen when you try
41	to do both... */
42	imcb_log( ic, "XMPP 1.0 non-compliant server seems to support SASL, please report this as a BitlBee bug!" );
43	return XT_HANDLED;
44	}
45
46	s = xt_find_attr( node, "xmlns" );
47	if( !s \|\| strcmp( s, XMLNS_SASL ) != 0 )
48	{
49	imcb_log( ic, "Stream error while authenticating" );
50	imc_logout( ic, FALSE );
51	return XT_ABORT;
52	}
53
54	c = node->children;
55	while( ( c = xt_find_node( c, "mechanism" ) ) )
56	{
57	if( c->text && g_strcasecmp( c->text, "PLAIN" ) == 0 )
58	sup_plain = 1;
59	if( c->text && g_strcasecmp( c->text, "DIGEST-MD5" ) == 0 )
60	sup_digest = 1;
61
62	c = c->next;
63	}
64
65	if( !sup_plain && !sup_digest )
66	{
67	imcb_error( ic, "No known SASL authentication schemes supported" );
68	imc_logout( ic, FALSE );
69	return XT_ABORT;
70	}
71
72	reply = xt_new_node( "auth", NULL, NULL );
73	xt_add_attr( reply, "xmlns", XMLNS_SASL );
74
75	if( sup_digest )
76	{
77	xt_add_attr( reply, "mechanism", "DIGEST-MD5" );
78
79	/* The rest will be done later, when we receive a <challenge/>. */
80	}
81	else if( sup_plain )
82	{
83	int len;
84
85	xt_add_attr( reply, "mechanism", "PLAIN" );
86
87	/* With SASL PLAIN in XMPP, the text should be b64(\0user\0pass) */
88	len = strlen( jd->username ) + strlen( ic->acc->pass ) + 2;
89	s = g_malloc( len + 1 );
90	s[0] = 0;
91	strcpy( s + 1, jd->username );
92	strcpy( s + 2 + strlen( jd->username ), ic->acc->pass );
93	reply->text = base64_encode( (unsigned char *)s, len );
94	reply->text_len = strlen( reply->text );
95	g_free( s );
96	}
97
98	if( !jabber_write_packet( ic, reply ) )
99	{
100	xt_free_node( reply );
101	return XT_ABORT;
102	}
103	xt_free_node( reply );
104
105	/* To prevent classic authentication from happening. */
106	jd->flags \|= JFLAG_STREAM_STARTED;
107
108	return XT_HANDLED;
109	}
110
111	/* Non-static function, but not mentioned in jabber.h because it's for internal
112	use, just that the unittest should be able to reach it... */
113	char sasl_get_part( char data, char *field )
114	{
115	int i, len;
116
117	len = strlen( field );
118
119	while( isspace( data ) \|\| data == ',' )
120	data ++;
121
122	if( g_strncasecmp( data, field, len ) == 0 && data[len] == '=' )
123	{
124	i = strlen( field ) + 1;
125	}
126	else
127	{
128	for( i = 0; data[i]; i ++ )
129	{
130	/* If we have a ", skip until it's closed again. */
131	if( data[i] == '"' )
132	{
133	i ++;
134	while( data[i] != '"' \|\| data[i-1] == '\\' )
135	i ++;
136	}
137
138	/* If we got a comma, we got a new field. Check it,
139	find the next key after it. */
140	if( data[i] == ',' )
141	{
142	while( isspace( data[i] ) \|\| data[i] == ',' )
143	i ++;
144
145	if( g_strncasecmp( data + i, field, len ) == 0 &&
146	data[i+len] == '=' )
147	{
148	i += len + 1;
149	break;
150	}
151	}
152	}
153	}
154
155	if( data[i] == '"' )
156	{
157	int j;
158	char *ret;
159
160	i ++;
161	len = 0;
162	while( data[i+len] != '"' \|\| data[i+len-1] == '\\' )
163	len ++;
164
165	ret = g_strndup( data + i, len );
166	for( i = j = 0; ret[i]; i ++ )
167	{
168	if( ret[i] == '\\' )
169	{
170	ret[j++] = ret[++i];
171	}
172	else
173	{
174	ret[j++] = ret[i];
175	}
176	}
177	ret[j] = 0;
178
179	return ret;
180	}
181	else if( data[i] )
182	{
183	len = 0;
184	while( data[i+len] && data[i+len] != ',' )
185	len ++;
186
187	return g_strndup( data + i, len );
188	}
189	else
190	{
191	return NULL;
192	}
193	}
194
195	xt_status sasl_pkt_challenge( struct xt_node *node, gpointer data )
196	{
197	struct im_connection *ic = data;
198	struct jabber_data *jd = ic->proto_data;
199	struct xt_node *reply = NULL;
200	char nonce = NULL, realm = NULL, *cnonce = NULL;
201	unsigned char cnonce_bin[30];
202	char *digest_uri = NULL;
203	char *dec = NULL;
204	char *s = NULL;
205	xt_status ret = XT_ABORT;
206
207	if( node->text_len == 0 )
208	goto error;
209
210	dec = frombase64( node->text );
211
212	if( !( s = sasl_get_part( dec, "rspauth" ) ) )
213	{
214	/* See RFC 2831 for for information. */
215	md5_state_t A1, A2, H;
216	md5_byte_t A1r[16], A2r[16], Hr[16];
217	char A1h[33], A2h[33], Hh[33];
218	int i;
219
220	nonce = sasl_get_part( dec, "nonce" );
221	realm = sasl_get_part( dec, "realm" );
222
223	if( !nonce )
224	goto error;
225
226	/* Jabber.Org considers the realm part optional and doesn't
227	specify one. Oh well, actually they're right, but still,
228	don't know if this is right... */
229	if( !realm )
230	realm = g_strdup( jd->server );
231
232	random_bytes( cnonce_bin, sizeof( cnonce_bin ) );
233	cnonce = base64_encode( cnonce_bin, sizeof( cnonce_bin ) );
234	digest_uri = g_strdup_printf( "%s/%s", "xmpp", jd->server );
235
236	/* Generate the MD5 hash of username:realm:password,
237	I decided to call it H. */
238	md5_init( &H );
239	s = g_strdup_printf( "%s:%s:%s", jd->username, realm, ic->acc->pass );
240	md5_append( &H, (unsigned char *) s, strlen( s ) );
241	g_free( s );
242	md5_finish( &H, Hr );
243
244	/* Now generate the hex. MD5 hash of H:nonce:cnonce, called A1. */
245	md5_init( &A1 );
246	s = g_strdup_printf( ":%s:%s", nonce, cnonce );
247	md5_append( &A1, Hr, 16 );
248	md5_append( &A1, (unsigned char *) s, strlen( s ) );
249	g_free( s );
250	md5_finish( &A1, A1r );
251	for( i = 0; i < 16; i ++ )
252	sprintf( A1h + i * 2, "%02x", A1r[i] );
253
254	/* A2... */
255	md5_init( &A2 );
256	s = g_strdup_printf( "%s:%s", "AUTHENTICATE", digest_uri );
257	md5_append( &A2, (unsigned char *) s, strlen( s ) );
258	g_free( s );
259	md5_finish( &A2, A2r );
260	for( i = 0; i < 16; i ++ )
261	sprintf( A2h + i * 2, "%02x", A2r[i] );
262
263	/* Final result: A1:nonce:00000001:cnonce:auth:A2. Let's reuse H for it. */
264	md5_init( &H );
265	s = g_strdup_printf( "%s:%s:%s:%s:%s:%s", A1h, nonce, "00000001", cnonce, "auth", A2h );
266	md5_append( &H, (unsigned char *) s, strlen( s ) );
267	g_free( s );
268	md5_finish( &H, Hr );
269	for( i = 0; i < 16; i ++ )
270	sprintf( Hh + i * 2, "%02x", Hr[i] );
271
272	/* Now build the SASL response string: */
273	g_free( dec );
274	dec = g_strdup_printf( "username=\"%s\",realm=\"%s\",nonce=\"%s\",cnonce=\"%s\","
275	"nc=%08x,qop=auth,digest-uri=\"%s\",response=%s,charset=%s",
276	jd->username, realm, nonce, cnonce, 1, digest_uri, Hh, "utf-8" );
277	s = tobase64( dec );
278	}
279	else
280	{
281	/* We found rspauth, but don't really care... */
282	g_free( s );
283	s = NULL;
284	}
285
286	reply = xt_new_node( "response", s, NULL );
287	xt_add_attr( reply, "xmlns", XMLNS_SASL );
288
289	if( !jabber_write_packet( ic, reply ) )
290	goto silent_error;
291
292	ret = XT_HANDLED;
293	goto silent_error;
294
295	error:
296	imcb_error( ic, "Incorrect SASL challenge received" );
297	imc_logout( ic, FALSE );
298
299	silent_error:
300	g_free( digest_uri );
301	g_free( cnonce );
302	g_free( nonce );
303	g_free( realm );
304	g_free( dec );
305	g_free( s );
306	xt_free_node( reply );
307
308	return ret;
309	}
310
311	xt_status sasl_pkt_result( struct xt_node *node, gpointer data )
312	{
313	struct im_connection *ic = data;
314	struct jabber_data *jd = ic->proto_data;
315	char *s;
316
317	s = xt_find_attr( node, "xmlns" );
318	if( !s \|\| strcmp( s, XMLNS_SASL ) != 0 )
319	{
320	imcb_log( ic, "Stream error while authenticating" );
321	imc_logout( ic, FALSE );
322	return XT_ABORT;
323	}
324
325	if( strcmp( node->name, "success" ) == 0 )
326	{
327	imcb_log( ic, "Authentication finished" );
328	jd->flags \|= JFLAG_AUTHENTICATED \| JFLAG_STREAM_RESTART;
329	}
330	else if( strcmp( node->name, "failure" ) == 0 )
331	{
332	imcb_error( ic, "Authentication failure" );
333	imc_logout( ic, FALSE );
334	return XT_ABORT;
335	}
336
337	return XT_HANDLED;
338	}
339
340	/* This one is needed to judge if we'll do authentication using IQ or SASL.
341	It's done by checking if the <stream:stream> from the server has a
342	version attribute. I don't know if this is the right way though... */
343	gboolean sasl_supported( struct im_connection *ic )
344	{
345	struct jabber_data *jd = ic->proto_data;
346
347	return ( jd->xt && jd->xt->root && xt_find_attr( jd->xt->root, "version" ) ) != 0;
348	}

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