Commit | Line | Data |
---|---|---|
c988f1f4 | 1 | /* $Cambridge: exim/src/src/auths/plaintext.c,v 1.2 2005/01/04 10:00:43 ph10 Exp $ */ |
0756eb3c PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
c988f1f4 | 7 | /* Copyright (c) University of Cambridge 1995 - 2005 */ |
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[] = { | |
17 | { "client_send", opt_stringptr, | |
18 | (void *)(offsetof(auth_plaintext_options_block, client_send)) }, | |
19 | { "server_condition", opt_stringptr, | |
20 | (void *)(offsetof(auth_plaintext_options_block, server_condition)) }, | |
21 | { "server_prompts", opt_stringptr, | |
22 | (void *)(offsetof(auth_plaintext_options_block, server_prompts)) } | |
23 | }; | |
24 | ||
25 | /* Size of the options list. An extern variable has to be used so that its | |
26 | address can appear in the tables drtables.c. */ | |
27 | ||
28 | int auth_plaintext_options_count = | |
29 | sizeof(auth_plaintext_options)/sizeof(optionlist); | |
30 | ||
31 | /* Default private options block for the plaintext authentication method. */ | |
32 | ||
33 | auth_plaintext_options_block auth_plaintext_option_defaults = { | |
34 | NULL, /* server_condition */ | |
35 | NULL, /* server_prompts */ | |
36 | NULL /* client_send */ | |
37 | }; | |
38 | ||
39 | ||
40 | /************************************************* | |
41 | * Initialization entry point * | |
42 | *************************************************/ | |
43 | ||
44 | /* Called for each instance, after its options have been read, to | |
45 | enable consistency checks to be done, or anything else that needs | |
46 | to be set up. */ | |
47 | ||
48 | void | |
49 | auth_plaintext_init(auth_instance *ablock) | |
50 | { | |
51 | auth_plaintext_options_block *ob = | |
52 | (auth_plaintext_options_block *)(ablock->options_block); | |
53 | if (ablock->public_name == NULL) ablock->public_name = ablock->name; | |
54 | if (ob->server_condition != NULL) ablock->server = TRUE; | |
55 | if (ob->client_send != NULL) ablock->client = TRUE; | |
56 | } | |
57 | ||
58 | ||
59 | ||
60 | /************************************************* | |
61 | * Server entry point * | |
62 | *************************************************/ | |
63 | ||
64 | /* For interface, see auths/README */ | |
65 | ||
66 | int | |
67 | auth_plaintext_server(auth_instance *ablock, uschar *data) | |
68 | { | |
69 | auth_plaintext_options_block *ob = | |
70 | (auth_plaintext_options_block *)(ablock->options_block); | |
71 | uschar *prompts = ob->server_prompts; | |
72 | uschar *clear, *cond, *end, *s; | |
73 | int number = 1; | |
74 | int len, rc; | |
75 | int sep = 0; | |
76 | ||
77 | /* Expand a non-empty list of prompt strings */ | |
78 | ||
79 | if (prompts != NULL) | |
80 | { | |
81 | prompts = expand_string(prompts); | |
82 | if (prompts == NULL) | |
83 | { | |
84 | auth_defer_msg = expand_string_message; | |
85 | return DEFER; | |
86 | } | |
87 | } | |
88 | ||
89 | /* If data was supplied on the AUTH command, decode it, and split it up into | |
90 | multiple items at binary zeros. If the data consists of the string "=" it | |
91 | indicates a single, empty string. */ | |
92 | ||
93 | if (*data != 0) | |
94 | { | |
95 | if (Ustrcmp(data, "=") == 0) | |
96 | { | |
97 | expand_nstring[++expand_nmax] = US""; | |
98 | expand_nlength[expand_nmax] = 0; | |
99 | } | |
100 | else | |
101 | { | |
102 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
103 | end = clear + len; | |
104 | while (clear < end && expand_nmax < EXPAND_MAXN) | |
105 | { | |
106 | expand_nstring[++expand_nmax] = clear; | |
107 | while (*clear != 0) clear++; | |
108 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
109 | } | |
110 | } | |
111 | } | |
112 | ||
113 | /* Now go through the list of prompt strings. Skip over any whose data has | |
114 | already been provided as part of the AUTH command. For the rest, send them | |
115 | out as prompts, and get a data item back. If the data item is "*", abandon the | |
116 | authentication attempt. Otherwise, split it into items as above. */ | |
117 | ||
118 | while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size)) | |
119 | != NULL && expand_nmax < EXPAND_MAXN) | |
120 | { | |
121 | if (number++ <= expand_nmax) continue; | |
122 | if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc; | |
123 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
124 | end = clear + len; | |
125 | ||
126 | /* This loop must run at least once, in case the length is zero */ | |
127 | do | |
128 | { | |
129 | expand_nstring[++expand_nmax] = clear; | |
130 | while (*clear != 0) clear++; | |
131 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
132 | } | |
133 | while (clear < end && expand_nmax < EXPAND_MAXN); | |
134 | } | |
135 | ||
136 | /* We now have a number of items of data in $1, $2, etc. Match against the | |
137 | decoded data by expanding the condition. Also expand the id to set if | |
138 | authentication succeeds. */ | |
139 | ||
140 | cond = expand_string(ob->server_condition); | |
141 | ||
142 | HDEBUG(D_auth) | |
143 | { | |
144 | int i; | |
145 | debug_printf("%s authenticator:\n", ablock->name); | |
146 | for (i = 1; i <= expand_nmax; i++) | |
147 | debug_printf(" $%d = %.*s\n", i, expand_nlength[i], expand_nstring[i]); | |
148 | debug_print_string(ablock->server_debug_string); /* customized debug */ | |
149 | if (cond == NULL) | |
150 | debug_printf("expansion failed: %s\n", expand_string_message); | |
151 | else | |
152 | debug_printf("expanded string: %s\n", cond); | |
153 | } | |
154 | ||
155 | /* A forced expansion failure causes authentication to fail. Other expansion | |
156 | failures yield DEFER, which will cause a temporary error code to be returned to | |
157 | the AUTH command. The problem is at the server end, so the client should try | |
158 | again later. */ | |
159 | ||
160 | if (cond == NULL) | |
161 | { | |
162 | if (expand_string_forcedfail) return FAIL; | |
163 | auth_defer_msg = expand_string_message; | |
164 | return DEFER; | |
165 | } | |
166 | ||
167 | /* Return FAIL for empty string, "0", "no", and "false"; return OK for | |
168 | "1", "yes", and "true"; return DEFER for anything else, with the string | |
169 | available as an error text for the user. */ | |
170 | ||
171 | if (*cond == 0 || | |
172 | Ustrcmp(cond, "0") == 0 || | |
173 | strcmpic(cond, US"no") == 0 || | |
174 | strcmpic(cond, US"false") == 0) | |
175 | return FAIL; | |
176 | ||
177 | if (Ustrcmp(cond, "1") == 0 || | |
178 | strcmpic(cond, US"yes") == 0 || | |
179 | strcmpic(cond, US"true") == 0) | |
180 | return OK; | |
181 | ||
182 | auth_defer_msg = cond; | |
183 | auth_defer_user_msg = string_sprintf(": %s", cond); | |
184 | return DEFER; | |
185 | } | |
186 | ||
187 | ||
188 | ||
189 | /************************************************* | |
190 | * Client entry point * | |
191 | *************************************************/ | |
192 | ||
193 | /* For interface, see auths/README */ | |
194 | ||
195 | int | |
196 | auth_plaintext_client( | |
197 | auth_instance *ablock, /* authenticator block */ | |
198 | smtp_inblock *inblock, /* connection inblock */ | |
199 | smtp_outblock *outblock, /* connection outblock */ | |
200 | int timeout, /* command timeout */ | |
201 | uschar *buffer, /* buffer for reading response */ | |
202 | int buffsize) /* size of buffer */ | |
203 | { | |
204 | auth_plaintext_options_block *ob = | |
205 | (auth_plaintext_options_block *)(ablock->options_block); | |
206 | uschar *text = ob->client_send; | |
207 | uschar *s; | |
208 | BOOL first = TRUE; | |
209 | int sep = 0; | |
210 | ||
211 | /* The text is broken up into a number of different data items, which are | |
212 | sent one by one. The first one is sent with the AUTH command; the remainder are | |
213 | sent in response to subsequent prompts. Each is expanded before being sent. */ | |
214 | ||
215 | while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)) != NULL) | |
216 | { | |
217 | int i, len; | |
218 | uschar *ss = expand_string(s); | |
219 | ||
220 | /* Forced expansion failure is not an error; authentication is abandoned. On | |
221 | all but the first string, we have to abandon the authentication attempt by | |
222 | sending a line containing "*". Save the failed expansion string, because it | |
223 | is in big_buffer, and that gets used by the sending function. */ | |
224 | ||
225 | if (ss == NULL) | |
226 | { | |
227 | uschar *ssave = string_copy(s); | |
228 | if (!first) | |
229 | { | |
230 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
231 | (void) smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
232 | } | |
233 | if (expand_string_forcedfail) return CANCELLED; | |
234 | string_format(buffer, buffsize, "expansion of \"%s\" failed in %s " | |
235 | "authenticator: %s", ssave, ablock->name, expand_string_message); | |
236 | return ERROR; | |
237 | } | |
238 | ||
239 | len = Ustrlen(ss); | |
240 | ||
241 | /* The character ^ is used as an escape for a binary zero character, which is | |
242 | needed for the PLAIN mechanism. It must be doubled if really needed. */ | |
243 | ||
244 | for (i = 0; i < len; i++) | |
245 | { | |
246 | if (ss[i] == '^') | |
247 | { | |
248 | if (ss[i+1] != '^') ss[i] = 0; else | |
249 | { | |
250 | i++; | |
251 | len--; | |
252 | memmove(ss + i, ss + i + 1, len - i); | |
253 | } | |
254 | } | |
255 | } | |
256 | ||
257 | /* The first string is attached to the AUTH command; others are sent | |
258 | unembelished. */ | |
259 | ||
260 | if (first) | |
261 | { | |
262 | first = FALSE; | |
263 | if (smtp_write_command(outblock, FALSE, "AUTH %s%s%s\r\n", | |
264 | ablock->public_name, (len == 0)? "" : " ", | |
265 | auth_b64encode(ss, len)) < 0) | |
266 | return FAIL_SEND; | |
267 | } | |
268 | else | |
269 | { | |
270 | if (smtp_write_command(outblock, FALSE, "%s\r\n", | |
271 | auth_b64encode(ss, len)) < 0) | |
272 | return FAIL_SEND; | |
273 | } | |
274 | ||
275 | /* If we receive a success response from the server, authentication | |
276 | has succeeded. There may be more data to send, but is there any point | |
277 | in provoking an error here? */ | |
278 | ||
279 | if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout)) return OK; | |
280 | ||
281 | /* Not a success response. If errno != 0 there is some kind of transmission | |
282 | error. Otherwise, check the response code in the buffer. If it starts with | |
283 | '3', more data is expected. */ | |
284 | ||
285 | if (errno != 0 || buffer[0] != '3') return FAIL; | |
286 | ||
287 | /* If there is no more data to send, we have to cancel the authentication | |
288 | exchange and return ERROR. */ | |
289 | ||
290 | if (text == NULL) | |
291 | { | |
292 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
293 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
294 | string_format(buffer, buffsize, "Too few items in client_send in %s " | |
295 | "authenticator", ablock->name); | |
296 | return ERROR; | |
297 | } | |
298 | } | |
299 | ||
300 | /* Control should never actually get here. */ | |
301 | ||
302 | return FAIL; | |
303 | } | |
304 | ||
305 | /* End of plaintext.c */ |