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16ff981e | 1 | /* $Cambridge: exim/src/src/auths/plaintext.c,v 1.6 2006/10/16 15:44:36 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)) }, | |
0756eb3c PH |
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 = { | |
0756eb3c | 34 | NULL, /* server_prompts */ |
4730f942 PH |
35 | NULL, /* client_send */ |
36 | FALSE /* client_ignore_invalid_base64 */ | |
0756eb3c PH |
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; | |
16ff981e | 54 | if (ablock->server_condition != NULL) ablock->server = TRUE; |
0756eb3c PH |
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; | |
16ff981e | 72 | uschar *clear, *end, *s; |
0756eb3c PH |
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 | |
f78eb7c6 PH |
90 | multiple items at binary zeros. The strings are put into $auth1, $auth2, etc, |
91 | up to a maximum. To retain backwards compatibility, they are also put int $1, | |
92 | $2, etc. If the data consists of the string "=" it indicates a single, empty | |
93 | string. */ | |
0756eb3c PH |
94 | |
95 | if (*data != 0) | |
96 | { | |
97 | if (Ustrcmp(data, "=") == 0) | |
98 | { | |
f78eb7c6 | 99 | auth_vars[0] = expand_nstring[++expand_nmax] = US""; |
0756eb3c PH |
100 | expand_nlength[expand_nmax] = 0; |
101 | } | |
102 | else | |
103 | { | |
104 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
105 | end = clear + len; | |
106 | while (clear < end && expand_nmax < EXPAND_MAXN) | |
107 | { | |
f78eb7c6 | 108 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; |
0756eb3c PH |
109 | expand_nstring[++expand_nmax] = clear; |
110 | while (*clear != 0) clear++; | |
111 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
112 | } | |
113 | } | |
114 | } | |
115 | ||
116 | /* Now go through the list of prompt strings. Skip over any whose data has | |
117 | already been provided as part of the AUTH command. For the rest, send them | |
118 | out as prompts, and get a data item back. If the data item is "*", abandon the | |
119 | authentication attempt. Otherwise, split it into items as above. */ | |
120 | ||
121 | while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size)) | |
122 | != NULL && expand_nmax < EXPAND_MAXN) | |
123 | { | |
124 | if (number++ <= expand_nmax) continue; | |
125 | if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc; | |
126 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
127 | end = clear + len; | |
128 | ||
129 | /* This loop must run at least once, in case the length is zero */ | |
130 | do | |
131 | { | |
f78eb7c6 | 132 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; |
0756eb3c PH |
133 | expand_nstring[++expand_nmax] = clear; |
134 | while (*clear != 0) clear++; | |
135 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
136 | } | |
137 | while (clear < end && expand_nmax < EXPAND_MAXN); | |
138 | } | |
139 | ||
f78eb7c6 | 140 | /* We now have a number of items of data in $auth1, $auth2, etc (and also, for |
16ff981e PH |
141 | compatibility, in $1, $2, etc). Authentication and authorization are handled |
142 | together for this authenticator by expanding the server_condition option. Note | |
143 | that ablock->server_condition is always non-NULL because that's what configures | |
144 | this authenticator as a server. */ | |
0756eb3c | 145 | |
16ff981e | 146 | return auth_check_serv_cond(ablock); |
0756eb3c PH |
147 | } |
148 | ||
149 | ||
150 | ||
151 | /************************************************* | |
152 | * Client entry point * | |
153 | *************************************************/ | |
154 | ||
155 | /* For interface, see auths/README */ | |
156 | ||
157 | int | |
158 | auth_plaintext_client( | |
159 | auth_instance *ablock, /* authenticator block */ | |
160 | smtp_inblock *inblock, /* connection inblock */ | |
161 | smtp_outblock *outblock, /* connection outblock */ | |
162 | int timeout, /* command timeout */ | |
163 | uschar *buffer, /* buffer for reading response */ | |
164 | int buffsize) /* size of buffer */ | |
165 | { | |
166 | auth_plaintext_options_block *ob = | |
167 | (auth_plaintext_options_block *)(ablock->options_block); | |
168 | uschar *text = ob->client_send; | |
169 | uschar *s; | |
170 | BOOL first = TRUE; | |
171 | int sep = 0; | |
4730f942 | 172 | int auth_var_idx = 0; |
0756eb3c PH |
173 | |
174 | /* The text is broken up into a number of different data items, which are | |
175 | sent one by one. The first one is sent with the AUTH command; the remainder are | |
176 | sent in response to subsequent prompts. Each is expanded before being sent. */ | |
177 | ||
178 | while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)) != NULL) | |
179 | { | |
4730f942 | 180 | int i, len, clear_len; |
0756eb3c | 181 | uschar *ss = expand_string(s); |
4730f942 | 182 | uschar *clear; |
0756eb3c PH |
183 | |
184 | /* Forced expansion failure is not an error; authentication is abandoned. On | |
185 | all but the first string, we have to abandon the authentication attempt by | |
186 | sending a line containing "*". Save the failed expansion string, because it | |
187 | is in big_buffer, and that gets used by the sending function. */ | |
188 | ||
189 | if (ss == NULL) | |
190 | { | |
191 | uschar *ssave = string_copy(s); | |
192 | if (!first) | |
193 | { | |
194 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
195 | (void) smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
196 | } | |
4730f942 PH |
197 | if (expand_string_forcedfail) |
198 | { | |
199 | *buffer = 0; /* No message */ | |
200 | return CANCELLED; | |
201 | } | |
0756eb3c PH |
202 | string_format(buffer, buffsize, "expansion of \"%s\" failed in %s " |
203 | "authenticator: %s", ssave, ablock->name, expand_string_message); | |
204 | return ERROR; | |
205 | } | |
206 | ||
207 | len = Ustrlen(ss); | |
208 | ||
209 | /* The character ^ is used as an escape for a binary zero character, which is | |
210 | needed for the PLAIN mechanism. It must be doubled if really needed. */ | |
211 | ||
212 | for (i = 0; i < len; i++) | |
213 | { | |
214 | if (ss[i] == '^') | |
215 | { | |
216 | if (ss[i+1] != '^') ss[i] = 0; else | |
217 | { | |
218 | i++; | |
219 | len--; | |
220 | memmove(ss + i, ss + i + 1, len - i); | |
221 | } | |
222 | } | |
223 | } | |
224 | ||
225 | /* The first string is attached to the AUTH command; others are sent | |
226 | unembelished. */ | |
227 | ||
228 | if (first) | |
229 | { | |
230 | first = FALSE; | |
231 | if (smtp_write_command(outblock, FALSE, "AUTH %s%s%s\r\n", | |
232 | ablock->public_name, (len == 0)? "" : " ", | |
233 | auth_b64encode(ss, len)) < 0) | |
234 | return FAIL_SEND; | |
235 | } | |
236 | else | |
237 | { | |
238 | if (smtp_write_command(outblock, FALSE, "%s\r\n", | |
239 | auth_b64encode(ss, len)) < 0) | |
240 | return FAIL_SEND; | |
241 | } | |
242 | ||
243 | /* If we receive a success response from the server, authentication | |
244 | has succeeded. There may be more data to send, but is there any point | |
245 | in provoking an error here? */ | |
246 | ||
247 | if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout)) return OK; | |
248 | ||
249 | /* Not a success response. If errno != 0 there is some kind of transmission | |
250 | error. Otherwise, check the response code in the buffer. If it starts with | |
251 | '3', more data is expected. */ | |
252 | ||
253 | if (errno != 0 || buffer[0] != '3') return FAIL; | |
254 | ||
255 | /* If there is no more data to send, we have to cancel the authentication | |
256 | exchange and return ERROR. */ | |
257 | ||
258 | if (text == NULL) | |
259 | { | |
260 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
261 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
262 | string_format(buffer, buffsize, "Too few items in client_send in %s " | |
263 | "authenticator", ablock->name); | |
264 | return ERROR; | |
265 | } | |
4730f942 PH |
266 | |
267 | /* Now that we know we'll continue, we put the received data into $auth<n>, | |
268 | if possible. First, decode it: buffer+4 skips over the SMTP status code. */ | |
269 | ||
270 | clear_len = auth_b64decode(buffer+4, &clear); | |
271 | ||
272 | /* If decoding failed, the default is to terminate the authentication, and | |
273 | return FAIL, with the SMTP response still in the buffer. However, if client_ | |
274 | ignore_invalid_base64 is set, we ignore the error, and put an empty string | |
275 | into $auth<n>. */ | |
276 | ||
277 | if (clear_len < 0) | |
278 | { | |
279 | uschar *save_bad = string_copy(buffer); | |
280 | if (!ob->client_ignore_invalid_base64) | |
281 | { | |
282 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
283 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
284 | string_format(buffer, buffsize, "Invalid base64 string in server " | |
285 | "response \"%s\"", save_bad); | |
286 | return CANCELLED; | |
287 | } | |
288 | clear = US""; | |
289 | clear_len = 0; | |
290 | } | |
291 | ||
292 | if (auth_var_idx < AUTH_VARS) | |
293 | auth_vars[auth_var_idx++] = string_copy(clear); | |
0756eb3c PH |
294 | } |
295 | ||
296 | /* Control should never actually get here. */ | |
297 | ||
298 | return FAIL; | |
299 | } | |
300 | ||
301 | /* End of plaintext.c */ |