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4730f942 | 1 | /* $Cambridge: exim/src/src/auths/plaintext.c,v 1.5 2006/02/23 12:41:22 ph10 Exp $ */ |
0756eb3c PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
d7d7b7b9 | 7 | /* Copyright (c) University of Cambridge 1995 - 2006 */ |
0756eb3c PH |
8 | /* See the file NOTICE for conditions of use and distribution. */ |
9 | ||
10 | #include "../exim.h" | |
11 | #include "plaintext.h" | |
12 | ||
13 | ||
14 | /* Options specific to the plaintext authentication mechanism. */ | |
15 | ||
16 | optionlist auth_plaintext_options[] = { | |
4730f942 PH |
17 | { "client_ignore_invalid_base64", opt_bool, |
18 | (void *)(offsetof(auth_plaintext_options_block, client_ignore_invalid_base64)) }, | |
0756eb3c PH |
19 | { "client_send", opt_stringptr, |
20 | (void *)(offsetof(auth_plaintext_options_block, client_send)) }, | |
21 | { "server_condition", opt_stringptr, | |
22 | (void *)(offsetof(auth_plaintext_options_block, server_condition)) }, | |
23 | { "server_prompts", opt_stringptr, | |
24 | (void *)(offsetof(auth_plaintext_options_block, server_prompts)) } | |
25 | }; | |
26 | ||
27 | /* Size of the options list. An extern variable has to be used so that its | |
28 | address can appear in the tables drtables.c. */ | |
29 | ||
30 | int auth_plaintext_options_count = | |
31 | sizeof(auth_plaintext_options)/sizeof(optionlist); | |
32 | ||
33 | /* Default private options block for the plaintext authentication method. */ | |
34 | ||
35 | auth_plaintext_options_block auth_plaintext_option_defaults = { | |
36 | NULL, /* server_condition */ | |
37 | NULL, /* server_prompts */ | |
4730f942 PH |
38 | NULL, /* client_send */ |
39 | FALSE /* client_ignore_invalid_base64 */ | |
0756eb3c PH |
40 | }; |
41 | ||
42 | ||
43 | /************************************************* | |
44 | * Initialization entry point * | |
45 | *************************************************/ | |
46 | ||
47 | /* Called for each instance, after its options have been read, to | |
48 | enable consistency checks to be done, or anything else that needs | |
49 | to be set up. */ | |
50 | ||
51 | void | |
52 | auth_plaintext_init(auth_instance *ablock) | |
53 | { | |
54 | auth_plaintext_options_block *ob = | |
55 | (auth_plaintext_options_block *)(ablock->options_block); | |
56 | if (ablock->public_name == NULL) ablock->public_name = ablock->name; | |
57 | if (ob->server_condition != NULL) ablock->server = TRUE; | |
58 | if (ob->client_send != NULL) ablock->client = TRUE; | |
59 | } | |
60 | ||
61 | ||
62 | ||
63 | /************************************************* | |
64 | * Server entry point * | |
65 | *************************************************/ | |
66 | ||
67 | /* For interface, see auths/README */ | |
68 | ||
69 | int | |
70 | auth_plaintext_server(auth_instance *ablock, uschar *data) | |
71 | { | |
72 | auth_plaintext_options_block *ob = | |
73 | (auth_plaintext_options_block *)(ablock->options_block); | |
74 | uschar *prompts = ob->server_prompts; | |
75 | uschar *clear, *cond, *end, *s; | |
76 | int number = 1; | |
77 | int len, rc; | |
78 | int sep = 0; | |
79 | ||
80 | /* Expand a non-empty list of prompt strings */ | |
81 | ||
82 | if (prompts != NULL) | |
83 | { | |
84 | prompts = expand_string(prompts); | |
85 | if (prompts == NULL) | |
86 | { | |
87 | auth_defer_msg = expand_string_message; | |
88 | return DEFER; | |
89 | } | |
90 | } | |
91 | ||
92 | /* If data was supplied on the AUTH command, decode it, and split it up into | |
f78eb7c6 PH |
93 | multiple items at binary zeros. The strings are put into $auth1, $auth2, etc, |
94 | up to a maximum. To retain backwards compatibility, they are also put int $1, | |
95 | $2, etc. If the data consists of the string "=" it indicates a single, empty | |
96 | string. */ | |
0756eb3c PH |
97 | |
98 | if (*data != 0) | |
99 | { | |
100 | if (Ustrcmp(data, "=") == 0) | |
101 | { | |
f78eb7c6 | 102 | auth_vars[0] = expand_nstring[++expand_nmax] = US""; |
0756eb3c PH |
103 | expand_nlength[expand_nmax] = 0; |
104 | } | |
105 | else | |
106 | { | |
107 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
108 | end = clear + len; | |
109 | while (clear < end && expand_nmax < EXPAND_MAXN) | |
110 | { | |
f78eb7c6 | 111 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; |
0756eb3c PH |
112 | expand_nstring[++expand_nmax] = clear; |
113 | while (*clear != 0) clear++; | |
114 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
115 | } | |
116 | } | |
117 | } | |
118 | ||
119 | /* Now go through the list of prompt strings. Skip over any whose data has | |
120 | already been provided as part of the AUTH command. For the rest, send them | |
121 | out as prompts, and get a data item back. If the data item is "*", abandon the | |
122 | authentication attempt. Otherwise, split it into items as above. */ | |
123 | ||
124 | while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size)) | |
125 | != NULL && expand_nmax < EXPAND_MAXN) | |
126 | { | |
127 | if (number++ <= expand_nmax) continue; | |
128 | if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc; | |
129 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
130 | end = clear + len; | |
131 | ||
132 | /* This loop must run at least once, in case the length is zero */ | |
133 | do | |
134 | { | |
f78eb7c6 | 135 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; |
0756eb3c PH |
136 | expand_nstring[++expand_nmax] = clear; |
137 | while (*clear != 0) clear++; | |
138 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
139 | } | |
140 | while (clear < end && expand_nmax < EXPAND_MAXN); | |
141 | } | |
142 | ||
f78eb7c6 PH |
143 | /* We now have a number of items of data in $auth1, $auth2, etc (and also, for |
144 | compatibility, in $1, $2, etc). Match against the decoded data by expanding the | |
145 | condition. */ | |
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146 | |
147 | cond = expand_string(ob->server_condition); | |
148 | ||
149 | HDEBUG(D_auth) | |
150 | { | |
151 | int i; | |
152 | debug_printf("%s authenticator:\n", ablock->name); | |
f78eb7c6 PH |
153 | for (i = 0; i < AUTH_VARS; i++) |
154 | { | |
155 | if (auth_vars[i] != NULL) | |
156 | debug_printf(" $auth%d = %s\n", i + 1, auth_vars[i]); | |
157 | } | |
0756eb3c PH |
158 | for (i = 1; i <= expand_nmax; i++) |
159 | debug_printf(" $%d = %.*s\n", i, expand_nlength[i], expand_nstring[i]); | |
160 | debug_print_string(ablock->server_debug_string); /* customized debug */ | |
161 | if (cond == NULL) | |
162 | debug_printf("expansion failed: %s\n", expand_string_message); | |
163 | else | |
164 | debug_printf("expanded string: %s\n", cond); | |
165 | } | |
166 | ||
167 | /* A forced expansion failure causes authentication to fail. Other expansion | |
168 | failures yield DEFER, which will cause a temporary error code to be returned to | |
169 | the AUTH command. The problem is at the server end, so the client should try | |
170 | again later. */ | |
171 | ||
172 | if (cond == NULL) | |
173 | { | |
174 | if (expand_string_forcedfail) return FAIL; | |
175 | auth_defer_msg = expand_string_message; | |
176 | return DEFER; | |
177 | } | |
178 | ||
179 | /* Return FAIL for empty string, "0", "no", and "false"; return OK for | |
180 | "1", "yes", and "true"; return DEFER for anything else, with the string | |
181 | available as an error text for the user. */ | |
182 | ||
183 | if (*cond == 0 || | |
184 | Ustrcmp(cond, "0") == 0 || | |
185 | strcmpic(cond, US"no") == 0 || | |
186 | strcmpic(cond, US"false") == 0) | |
187 | return FAIL; | |
188 | ||
189 | if (Ustrcmp(cond, "1") == 0 || | |
190 | strcmpic(cond, US"yes") == 0 || | |
191 | strcmpic(cond, US"true") == 0) | |
192 | return OK; | |
193 | ||
194 | auth_defer_msg = cond; | |
195 | auth_defer_user_msg = string_sprintf(": %s", cond); | |
196 | return DEFER; | |
197 | } | |
198 | ||
199 | ||
200 | ||
201 | /************************************************* | |
202 | * Client entry point * | |
203 | *************************************************/ | |
204 | ||
205 | /* For interface, see auths/README */ | |
206 | ||
207 | int | |
208 | auth_plaintext_client( | |
209 | auth_instance *ablock, /* authenticator block */ | |
210 | smtp_inblock *inblock, /* connection inblock */ | |
211 | smtp_outblock *outblock, /* connection outblock */ | |
212 | int timeout, /* command timeout */ | |
213 | uschar *buffer, /* buffer for reading response */ | |
214 | int buffsize) /* size of buffer */ | |
215 | { | |
216 | auth_plaintext_options_block *ob = | |
217 | (auth_plaintext_options_block *)(ablock->options_block); | |
218 | uschar *text = ob->client_send; | |
219 | uschar *s; | |
220 | BOOL first = TRUE; | |
221 | int sep = 0; | |
4730f942 | 222 | int auth_var_idx = 0; |
0756eb3c PH |
223 | |
224 | /* The text is broken up into a number of different data items, which are | |
225 | sent one by one. The first one is sent with the AUTH command; the remainder are | |
226 | sent in response to subsequent prompts. Each is expanded before being sent. */ | |
227 | ||
228 | while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)) != NULL) | |
229 | { | |
4730f942 | 230 | int i, len, clear_len; |
0756eb3c | 231 | uschar *ss = expand_string(s); |
4730f942 | 232 | uschar *clear; |
0756eb3c PH |
233 | |
234 | /* Forced expansion failure is not an error; authentication is abandoned. On | |
235 | all but the first string, we have to abandon the authentication attempt by | |
236 | sending a line containing "*". Save the failed expansion string, because it | |
237 | is in big_buffer, and that gets used by the sending function. */ | |
238 | ||
239 | if (ss == NULL) | |
240 | { | |
241 | uschar *ssave = string_copy(s); | |
242 | if (!first) | |
243 | { | |
244 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
245 | (void) smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
246 | } | |
4730f942 PH |
247 | if (expand_string_forcedfail) |
248 | { | |
249 | *buffer = 0; /* No message */ | |
250 | return CANCELLED; | |
251 | } | |
0756eb3c PH |
252 | string_format(buffer, buffsize, "expansion of \"%s\" failed in %s " |
253 | "authenticator: %s", ssave, ablock->name, expand_string_message); | |
254 | return ERROR; | |
255 | } | |
256 | ||
257 | len = Ustrlen(ss); | |
258 | ||
259 | /* The character ^ is used as an escape for a binary zero character, which is | |
260 | needed for the PLAIN mechanism. It must be doubled if really needed. */ | |
261 | ||
262 | for (i = 0; i < len; i++) | |
263 | { | |
264 | if (ss[i] == '^') | |
265 | { | |
266 | if (ss[i+1] != '^') ss[i] = 0; else | |
267 | { | |
268 | i++; | |
269 | len--; | |
270 | memmove(ss + i, ss + i + 1, len - i); | |
271 | } | |
272 | } | |
273 | } | |
274 | ||
275 | /* The first string is attached to the AUTH command; others are sent | |
276 | unembelished. */ | |
277 | ||
278 | if (first) | |
279 | { | |
280 | first = FALSE; | |
281 | if (smtp_write_command(outblock, FALSE, "AUTH %s%s%s\r\n", | |
282 | ablock->public_name, (len == 0)? "" : " ", | |
283 | auth_b64encode(ss, len)) < 0) | |
284 | return FAIL_SEND; | |
285 | } | |
286 | else | |
287 | { | |
288 | if (smtp_write_command(outblock, FALSE, "%s\r\n", | |
289 | auth_b64encode(ss, len)) < 0) | |
290 | return FAIL_SEND; | |
291 | } | |
292 | ||
293 | /* If we receive a success response from the server, authentication | |
294 | has succeeded. There may be more data to send, but is there any point | |
295 | in provoking an error here? */ | |
296 | ||
297 | if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout)) return OK; | |
298 | ||
299 | /* Not a success response. If errno != 0 there is some kind of transmission | |
300 | error. Otherwise, check the response code in the buffer. If it starts with | |
301 | '3', more data is expected. */ | |
302 | ||
303 | if (errno != 0 || buffer[0] != '3') return FAIL; | |
304 | ||
305 | /* If there is no more data to send, we have to cancel the authentication | |
306 | exchange and return ERROR. */ | |
307 | ||
308 | if (text == NULL) | |
309 | { | |
310 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
311 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
312 | string_format(buffer, buffsize, "Too few items in client_send in %s " | |
313 | "authenticator", ablock->name); | |
314 | return ERROR; | |
315 | } | |
4730f942 PH |
316 | |
317 | /* Now that we know we'll continue, we put the received data into $auth<n>, | |
318 | if possible. First, decode it: buffer+4 skips over the SMTP status code. */ | |
319 | ||
320 | clear_len = auth_b64decode(buffer+4, &clear); | |
321 | ||
322 | /* If decoding failed, the default is to terminate the authentication, and | |
323 | return FAIL, with the SMTP response still in the buffer. However, if client_ | |
324 | ignore_invalid_base64 is set, we ignore the error, and put an empty string | |
325 | into $auth<n>. */ | |
326 | ||
327 | if (clear_len < 0) | |
328 | { | |
329 | uschar *save_bad = string_copy(buffer); | |
330 | if (!ob->client_ignore_invalid_base64) | |
331 | { | |
332 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
333 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
334 | string_format(buffer, buffsize, "Invalid base64 string in server " | |
335 | "response \"%s\"", save_bad); | |
336 | return CANCELLED; | |
337 | } | |
338 | clear = US""; | |
339 | clear_len = 0; | |
340 | } | |
341 | ||
342 | if (auth_var_idx < AUTH_VARS) | |
343 | auth_vars[auth_var_idx++] = string_copy(clear); | |
0756eb3c PH |
344 | } |
345 | ||
346 | /* Control should never actually get here. */ | |
347 | ||
348 | return FAIL; | |
349 | } | |
350 | ||
351 | /* End of plaintext.c */ |