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0756eb3c PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
3386088d | 5 | /* Copyright (c) University of Cambridge 1995 - 2015 */ |
0756eb3c PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | #include "../exim.h" | |
9 | #include "plaintext.h" | |
10 | ||
11 | ||
12 | /* Options specific to the plaintext authentication mechanism. */ | |
13 | ||
14 | optionlist auth_plaintext_options[] = { | |
4730f942 PH |
15 | { "client_ignore_invalid_base64", opt_bool, |
16 | (void *)(offsetof(auth_plaintext_options_block, client_ignore_invalid_base64)) }, | |
0756eb3c PH |
17 | { "client_send", opt_stringptr, |
18 | (void *)(offsetof(auth_plaintext_options_block, client_send)) }, | |
0756eb3c PH |
19 | { "server_prompts", opt_stringptr, |
20 | (void *)(offsetof(auth_plaintext_options_block, server_prompts)) } | |
21 | }; | |
22 | ||
23 | /* Size of the options list. An extern variable has to be used so that its | |
24 | address can appear in the tables drtables.c. */ | |
25 | ||
26 | int auth_plaintext_options_count = | |
27 | sizeof(auth_plaintext_options)/sizeof(optionlist); | |
28 | ||
29 | /* Default private options block for the plaintext authentication method. */ | |
30 | ||
31 | auth_plaintext_options_block auth_plaintext_option_defaults = { | |
0756eb3c | 32 | NULL, /* server_prompts */ |
4730f942 PH |
33 | NULL, /* client_send */ |
34 | FALSE /* client_ignore_invalid_base64 */ | |
0756eb3c PH |
35 | }; |
36 | ||
37 | ||
38 | /************************************************* | |
39 | * Initialization entry point * | |
40 | *************************************************/ | |
41 | ||
42 | /* Called for each instance, after its options have been read, to | |
43 | enable consistency checks to be done, or anything else that needs | |
44 | to be set up. */ | |
45 | ||
46 | void | |
47 | auth_plaintext_init(auth_instance *ablock) | |
48 | { | |
49 | auth_plaintext_options_block *ob = | |
50 | (auth_plaintext_options_block *)(ablock->options_block); | |
51 | if (ablock->public_name == NULL) ablock->public_name = ablock->name; | |
16ff981e | 52 | if (ablock->server_condition != NULL) ablock->server = TRUE; |
0756eb3c PH |
53 | if (ob->client_send != NULL) ablock->client = TRUE; |
54 | } | |
55 | ||
56 | ||
57 | ||
58 | /************************************************* | |
59 | * Server entry point * | |
60 | *************************************************/ | |
61 | ||
62 | /* For interface, see auths/README */ | |
63 | ||
64 | int | |
65 | auth_plaintext_server(auth_instance *ablock, uschar *data) | |
66 | { | |
67 | auth_plaintext_options_block *ob = | |
68 | (auth_plaintext_options_block *)(ablock->options_block); | |
55414b25 | 69 | const uschar *prompts = ob->server_prompts; |
16ff981e | 70 | uschar *clear, *end, *s; |
0756eb3c PH |
71 | int number = 1; |
72 | int len, rc; | |
73 | int sep = 0; | |
74 | ||
75 | /* Expand a non-empty list of prompt strings */ | |
76 | ||
77 | if (prompts != NULL) | |
78 | { | |
55414b25 | 79 | prompts = expand_cstring(prompts); |
0756eb3c PH |
80 | if (prompts == NULL) |
81 | { | |
82 | auth_defer_msg = expand_string_message; | |
83 | return DEFER; | |
84 | } | |
85 | } | |
86 | ||
87 | /* If data was supplied on the AUTH command, decode it, and split it up into | |
f78eb7c6 PH |
88 | multiple items at binary zeros. The strings are put into $auth1, $auth2, etc, |
89 | up to a maximum. To retain backwards compatibility, they are also put int $1, | |
90 | $2, etc. If the data consists of the string "=" it indicates a single, empty | |
91 | string. */ | |
0756eb3c PH |
92 | |
93 | if (*data != 0) | |
94 | { | |
95 | if (Ustrcmp(data, "=") == 0) | |
96 | { | |
f78eb7c6 | 97 | auth_vars[0] = expand_nstring[++expand_nmax] = US""; |
0756eb3c PH |
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 | { | |
f78eb7c6 | 106 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; |
0756eb3c PH |
107 | expand_nstring[++expand_nmax] = clear; |
108 | while (*clear != 0) clear++; | |
109 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
110 | } | |
111 | } | |
112 | } | |
113 | ||
114 | /* Now go through the list of prompt strings. Skip over any whose data has | |
115 | already been provided as part of the AUTH command. For the rest, send them | |
116 | out as prompts, and get a data item back. If the data item is "*", abandon the | |
117 | authentication attempt. Otherwise, split it into items as above. */ | |
118 | ||
119 | while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size)) | |
120 | != NULL && expand_nmax < EXPAND_MAXN) | |
121 | { | |
122 | if (number++ <= expand_nmax) continue; | |
123 | if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc; | |
124 | if ((len = auth_b64decode(data, &clear)) < 0) return BAD64; | |
125 | end = clear + len; | |
126 | ||
127 | /* This loop must run at least once, in case the length is zero */ | |
128 | do | |
129 | { | |
f78eb7c6 | 130 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; |
0756eb3c PH |
131 | expand_nstring[++expand_nmax] = clear; |
132 | while (*clear != 0) clear++; | |
133 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
134 | } | |
135 | while (clear < end && expand_nmax < EXPAND_MAXN); | |
136 | } | |
137 | ||
f78eb7c6 | 138 | /* We now have a number of items of data in $auth1, $auth2, etc (and also, for |
16ff981e PH |
139 | compatibility, in $1, $2, etc). Authentication and authorization are handled |
140 | together for this authenticator by expanding the server_condition option. Note | |
141 | that ablock->server_condition is always non-NULL because that's what configures | |
142 | this authenticator as a server. */ | |
0756eb3c | 143 | |
16ff981e | 144 | return auth_check_serv_cond(ablock); |
0756eb3c PH |
145 | } |
146 | ||
147 | ||
148 | ||
149 | /************************************************* | |
150 | * Client entry point * | |
151 | *************************************************/ | |
152 | ||
153 | /* For interface, see auths/README */ | |
154 | ||
155 | int | |
156 | auth_plaintext_client( | |
157 | auth_instance *ablock, /* authenticator block */ | |
158 | smtp_inblock *inblock, /* connection inblock */ | |
159 | smtp_outblock *outblock, /* connection outblock */ | |
160 | int timeout, /* command timeout */ | |
161 | uschar *buffer, /* buffer for reading response */ | |
162 | int buffsize) /* size of buffer */ | |
163 | { | |
164 | auth_plaintext_options_block *ob = | |
165 | (auth_plaintext_options_block *)(ablock->options_block); | |
55414b25 | 166 | const uschar *text = ob->client_send; |
0756eb3c PH |
167 | uschar *s; |
168 | BOOL first = TRUE; | |
169 | int sep = 0; | |
4730f942 | 170 | int auth_var_idx = 0; |
0756eb3c PH |
171 | |
172 | /* The text is broken up into a number of different data items, which are | |
173 | sent one by one. The first one is sent with the AUTH command; the remainder are | |
174 | sent in response to subsequent prompts. Each is expanded before being sent. */ | |
175 | ||
176 | while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)) != NULL) | |
177 | { | |
4730f942 | 178 | int i, len, clear_len; |
0756eb3c | 179 | uschar *ss = expand_string(s); |
4730f942 | 180 | uschar *clear; |
0756eb3c PH |
181 | |
182 | /* Forced expansion failure is not an error; authentication is abandoned. On | |
183 | all but the first string, we have to abandon the authentication attempt by | |
184 | sending a line containing "*". Save the failed expansion string, because it | |
185 | is in big_buffer, and that gets used by the sending function. */ | |
186 | ||
187 | if (ss == NULL) | |
188 | { | |
189 | uschar *ssave = string_copy(s); | |
190 | if (!first) | |
191 | { | |
192 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
193 | (void) smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
194 | } | |
4730f942 PH |
195 | if (expand_string_forcedfail) |
196 | { | |
197 | *buffer = 0; /* No message */ | |
198 | return CANCELLED; | |
199 | } | |
0756eb3c PH |
200 | string_format(buffer, buffsize, "expansion of \"%s\" failed in %s " |
201 | "authenticator: %s", ssave, ablock->name, expand_string_message); | |
202 | return ERROR; | |
203 | } | |
204 | ||
205 | len = Ustrlen(ss); | |
206 | ||
207 | /* The character ^ is used as an escape for a binary zero character, which is | |
208 | needed for the PLAIN mechanism. It must be doubled if really needed. */ | |
209 | ||
210 | for (i = 0; i < len; i++) | |
211 | { | |
212 | if (ss[i] == '^') | |
213 | { | |
214 | if (ss[i+1] != '^') ss[i] = 0; else | |
215 | { | |
216 | i++; | |
217 | len--; | |
218 | memmove(ss + i, ss + i + 1, len - i); | |
219 | } | |
220 | } | |
221 | } | |
222 | ||
223 | /* The first string is attached to the AUTH command; others are sent | |
224 | unembelished. */ | |
225 | ||
226 | if (first) | |
227 | { | |
228 | first = FALSE; | |
229 | if (smtp_write_command(outblock, FALSE, "AUTH %s%s%s\r\n", | |
230 | ablock->public_name, (len == 0)? "" : " ", | |
231 | auth_b64encode(ss, len)) < 0) | |
232 | return FAIL_SEND; | |
233 | } | |
234 | else | |
235 | { | |
236 | if (smtp_write_command(outblock, FALSE, "%s\r\n", | |
237 | auth_b64encode(ss, len)) < 0) | |
238 | return FAIL_SEND; | |
239 | } | |
240 | ||
241 | /* If we receive a success response from the server, authentication | |
242 | has succeeded. There may be more data to send, but is there any point | |
243 | in provoking an error here? */ | |
244 | ||
245 | if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout)) return OK; | |
246 | ||
247 | /* Not a success response. If errno != 0 there is some kind of transmission | |
248 | error. Otherwise, check the response code in the buffer. If it starts with | |
249 | '3', more data is expected. */ | |
250 | ||
251 | if (errno != 0 || buffer[0] != '3') return FAIL; | |
252 | ||
253 | /* If there is no more data to send, we have to cancel the authentication | |
254 | exchange and return ERROR. */ | |
255 | ||
256 | if (text == NULL) | |
257 | { | |
258 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
259 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
260 | string_format(buffer, buffsize, "Too few items in client_send in %s " | |
261 | "authenticator", ablock->name); | |
262 | return ERROR; | |
263 | } | |
4730f942 PH |
264 | |
265 | /* Now that we know we'll continue, we put the received data into $auth<n>, | |
266 | if possible. First, decode it: buffer+4 skips over the SMTP status code. */ | |
267 | ||
268 | clear_len = auth_b64decode(buffer+4, &clear); | |
269 | ||
270 | /* If decoding failed, the default is to terminate the authentication, and | |
271 | return FAIL, with the SMTP response still in the buffer. However, if client_ | |
272 | ignore_invalid_base64 is set, we ignore the error, and put an empty string | |
273 | into $auth<n>. */ | |
274 | ||
275 | if (clear_len < 0) | |
276 | { | |
277 | uschar *save_bad = string_copy(buffer); | |
278 | if (!ob->client_ignore_invalid_base64) | |
279 | { | |
280 | if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0) | |
281 | (void)smtp_read_response(inblock, US buffer, buffsize, '2', timeout); | |
282 | string_format(buffer, buffsize, "Invalid base64 string in server " | |
283 | "response \"%s\"", save_bad); | |
284 | return CANCELLED; | |
285 | } | |
286 | clear = US""; | |
287 | clear_len = 0; | |
288 | } | |
289 | ||
290 | if (auth_var_idx < AUTH_VARS) | |
291 | auth_vars[auth_var_idx++] = string_copy(clear); | |
0756eb3c PH |
292 | } |
293 | ||
294 | /* Control should never actually get here. */ | |
295 | ||
296 | return FAIL; | |
297 | } | |
298 | ||
299 | /* End of plaintext.c */ |