File: cramlib.c

package info (click to toggle)
courier-authlib 0.71.1-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 14,416 kB
  • sloc: ansic: 15,778; sh: 4,565; cpp: 4,205; makefile: 793; perl: 739
file content (219 lines) | stat: -rw-r--r-- 4,538 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
/*
** Copyright 1998 - 2008 Double Precision, Inc.  See COPYING for
** distribution information.
*/

#if	HAVE_CONFIG_H
#include	"courier_auth_config.h"
#endif
#include	<stdio.h>
#include	<stdlib.h>
#include	<string.h>
#include	<errno.h>
#include	"courierauthsasl.h"
#include	"courierauth.h"
#include	"courierauthdebug.h"
#include	"libhmac/hmac.h"

static int nybble(int c)
{
	if (c >= '0' && c <= '9')	return (c-'0');
	if (c >= 'a' && c <= 'f')	return (c-'a'+10);
	if (c >= 'A' && c <= 'F')	return (c-'A'+10);
	return (-1);
}

static int do_auth_verify_cram(struct hmac_hashinfo *hash,
	const char *challenge, const char *response,
	const char *hashsecret)
{
unsigned char *context;
unsigned i;

	if (strlen(hashsecret) != hash->hh_L*4 ||
		strlen(response) != hash->hh_L*2)
		return (-1);

	if ((context=malloc(hash->hh_L*3)) == 0)	return (-1);

	for (i=0; i<hash->hh_L*2; i++)
	{
	int	a=nybble(hashsecret[i*2]), b=nybble(hashsecret[i*2+1]);

		if (a < 0 || b < 0)
		{
			free(context);
			return (-1);
		}
		context[i]= a*16 + b;
	}

	hmac_hashtext(hash, challenge, strlen(challenge),
		context, context+hash->hh_L,
		context+hash->hh_L*2);

	for (i=0; i<hash->hh_L; i++)
	{
	int	a=nybble(response[i*2]), b=nybble(response[i*2+1]);

		if ( (unsigned char)(a*16+b) !=
			context[hash->hh_L*2+i])
		{
			free(context);
			return (-1);
		}
	}
	free(context);
	return (0);
}

int auth_verify_cram(struct hmac_hashinfo *hash,
	const char *challenge, const char *response,
	const char *hashsecret)
{
int rc;

	rc = do_auth_verify_cram(hash, challenge, response, hashsecret);
	DPRINTF(rc ? "cram validation failed" : "cram validation succeeded");
	return rc;
}

static int do_auth_get_cram(const char *authtype, char *authdata,
			    struct cram_callback_info *craminfo, int logerr)
{
int	i;
int	challenge_l;
int	response_l;

	if (strncmp(authtype, "cram-", 5) ||
		(craminfo->challenge=strtok(authdata, "\n")) == 0 ||
		(craminfo->response=strtok(0, "\n")) == 0)
	{
		if (logerr)
		{
			DPRINTF("Unsupported authentication type: %s", authtype);
		}
		errno=EPERM;
		return (-1);
	}

	for (i=0; hmac_list[i]; i++)
		if (strcmp(hmac_list[i]->hh_name, authtype+5) == 0)
			break;

	if (logerr)
	{
		DPRINTF("cram: challenge=%s, response=%s", craminfo->challenge,
			craminfo->response);
	}

	if (hmac_list[i] == 0
		|| (challenge_l=authsasl_frombase64(craminfo->challenge)) < 0
		|| (response_l=authsasl_frombase64(craminfo->response)) < 0)
	{
		if (logerr)
		{
			DPRINTF("cram: invalid base64 encoding, or unknown method: %s",
				authtype);
		}
		errno=EACCES;
		return (-1);
	}
	craminfo->h=hmac_list[i];

	for (i=response_l; i > 0; )
	{
		if (craminfo->response[i-1] == ' ')
			break;
		--i;
	}

	if (i == 0)
	{
		if (logerr)
		{
			DPRINTF("cram: invalid base64 encoding");
		}
		errno=EACCES;
		return (-1);
	}
	craminfo->response[i-1]=0;
	craminfo->user = craminfo->response;
	craminfo->response += i;
	response_l -= i;

	/* Since base64decoded data is always lesser in size (at least),
	** we can do the following:
	*/
	craminfo->challenge[challenge_l]=0;
	craminfo->response[response_l]=0;

	if (logerr)
	{
		/* we rely on DPRINTF doing a "safe" print here */
		DPRINTF("cram: decoded challenge/response, username '%s'",
			craminfo->user);
	}
	return (0);
}

int auth_cram_callback(struct authinfo *a, void *vp)
{
struct cram_callback_info *cci=(struct cram_callback_info *)vp;
unsigned char *hashbuf;
unsigned char *p;
unsigned i;
static const char hex[]="0123456789abcdef";
int	rc;

	if (!a->clearpasswd)
		return (-1);

	/*
		hmac->hh_L*2 will be the size of the binary hash.

		hmac->hh_L*4+1 will therefore be size of the binary hash,
		as a hexadecimal string.
	*/

	if ((hashbuf=malloc(cci->h->hh_L*6+1)) == 0)
		return (1);

	hmac_hashkey(cci->h, a->clearpasswd, strlen(a->clearpasswd),
		hashbuf, hashbuf+cci->h->hh_L);

	p=hashbuf+cci->h->hh_L*2;

	for (i=0; i<cci->h->hh_L*2; i++)
	{
	char	c;

		c = hex[ (hashbuf[i] >> 4) & 0x0F];
		*p++=c;

		c = hex[ hashbuf[i] & 0x0F];
		*p++=c;

		*p=0;
	}

	rc=auth_verify_cram(cci->h, cci->challenge, cci->response,
		(const char *)hashbuf+cci->h->hh_L*2);
	free(hashbuf);

	if (rc)	return (rc);

	return (*cci->callback_func)(a, cci->callback_arg);
}

int auth_get_cram(const char *authtype, char *authdata,
		  struct cram_callback_info *craminfo)
{
	return do_auth_get_cram(authtype, authdata, craminfo, 1);
}

int auth_get_cram_silent(const char *authtype, char *authdata,
			 struct cram_callback_info *craminfo)
{
	return do_auth_get_cram(authtype, authdata, craminfo, 0);
}