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420a0d19 CE |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
2ea97746 | 5 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
420a0d19 CE |
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[] = { | |
15 | { "client_ignore_invalid_base64", opt_bool, | |
16 | (void *)(offsetof(auth_plaintext_options_block, client_ignore_invalid_base64)) }, | |
17 | { "client_send", opt_stringptr, | |
18 | (void *)(offsetof(auth_plaintext_options_block, client_send)) }, | |
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 = { | |
32 | NULL, /* server_prompts */ | |
33 | NULL, /* client_send */ | |
34 | FALSE /* client_ignore_invalid_base64 */ | |
35 | }; | |
36 | ||
37 | ||
2ea97746 CE |
38 | #ifdef MACRO_PREDEF |
39 | ||
40 | /* Dummy values */ | |
41 | void auth_plaintext_init(auth_instance *ablock) {} | |
42 | int auth_plaintext_server(auth_instance *ablock, uschar *data) {return 0;} | |
43 | int auth_plaintext_client(auth_instance *ablock, void * sx, int timeout, | |
44 | uschar *buffer, int buffsize) {return 0;} | |
45 | ||
46 | #else /*!MACRO_PREDEF*/ | |
47 | ||
48 | ||
49 | ||
420a0d19 CE |
50 | /************************************************* |
51 | * Initialization entry point * | |
52 | *************************************************/ | |
53 | ||
54 | /* Called for each instance, after its options have been read, to | |
55 | enable consistency checks to be done, or anything else that needs | |
56 | to be set up. */ | |
57 | ||
58 | void | |
59 | auth_plaintext_init(auth_instance *ablock) | |
60 | { | |
61 | auth_plaintext_options_block *ob = | |
62 | (auth_plaintext_options_block *)(ablock->options_block); | |
63 | if (ablock->public_name == NULL) ablock->public_name = ablock->name; | |
64 | if (ablock->server_condition != NULL) ablock->server = TRUE; | |
65 | if (ob->client_send != NULL) ablock->client = TRUE; | |
66 | } | |
67 | ||
68 | ||
69 | ||
70 | /************************************************* | |
71 | * Server entry point * | |
72 | *************************************************/ | |
73 | ||
74 | /* For interface, see auths/README */ | |
75 | ||
76 | int | |
77 | auth_plaintext_server(auth_instance *ablock, uschar *data) | |
78 | { | |
79 | auth_plaintext_options_block *ob = | |
80 | (auth_plaintext_options_block *)(ablock->options_block); | |
2ea97746 | 81 | const uschar *prompts = ob->server_prompts; |
420a0d19 CE |
82 | uschar *clear, *end, *s; |
83 | int number = 1; | |
84 | int len, rc; | |
85 | int sep = 0; | |
86 | ||
87 | /* Expand a non-empty list of prompt strings */ | |
88 | ||
89 | if (prompts != NULL) | |
90 | { | |
2ea97746 | 91 | prompts = expand_cstring(prompts); |
420a0d19 CE |
92 | if (prompts == NULL) |
93 | { | |
94 | auth_defer_msg = expand_string_message; | |
95 | return DEFER; | |
96 | } | |
97 | } | |
98 | ||
99 | /* If data was supplied on the AUTH command, decode it, and split it up into | |
100 | multiple items at binary zeros. The strings are put into $auth1, $auth2, etc, | |
101 | up to a maximum. To retain backwards compatibility, they are also put int $1, | |
102 | $2, etc. If the data consists of the string "=" it indicates a single, empty | |
103 | string. */ | |
104 | ||
105 | if (*data != 0) | |
106 | { | |
107 | if (Ustrcmp(data, "=") == 0) | |
108 | { | |
109 | auth_vars[0] = expand_nstring[++expand_nmax] = US""; | |
110 | expand_nlength[expand_nmax] = 0; | |
111 | } | |
112 | else | |
113 | { | |
2ea97746 | 114 | if ((len = b64decode(data, &clear)) < 0) return BAD64; |
420a0d19 CE |
115 | end = clear + len; |
116 | while (clear < end && expand_nmax < EXPAND_MAXN) | |
117 | { | |
118 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; | |
119 | expand_nstring[++expand_nmax] = clear; | |
120 | while (*clear != 0) clear++; | |
121 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
122 | } | |
123 | } | |
124 | } | |
125 | ||
126 | /* Now go through the list of prompt strings. Skip over any whose data has | |
127 | already been provided as part of the AUTH command. For the rest, send them | |
128 | out as prompts, and get a data item back. If the data item is "*", abandon the | |
129 | authentication attempt. Otherwise, split it into items as above. */ | |
130 | ||
131 | while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size)) | |
132 | != NULL && expand_nmax < EXPAND_MAXN) | |
133 | { | |
134 | if (number++ <= expand_nmax) continue; | |
135 | if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc; | |
2ea97746 | 136 | if ((len = b64decode(data, &clear)) < 0) return BAD64; |
420a0d19 CE |
137 | end = clear + len; |
138 | ||
139 | /* This loop must run at least once, in case the length is zero */ | |
140 | do | |
141 | { | |
142 | if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear; | |
143 | expand_nstring[++expand_nmax] = clear; | |
144 | while (*clear != 0) clear++; | |
145 | expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax]; | |
146 | } | |
147 | while (clear < end && expand_nmax < EXPAND_MAXN); | |
148 | } | |
149 | ||
150 | /* We now have a number of items of data in $auth1, $auth2, etc (and also, for | |
151 | compatibility, in $1, $2, etc). Authentication and authorization are handled | |
152 | together for this authenticator by expanding the server_condition option. Note | |
153 | that ablock->server_condition is always non-NULL because that's what configures | |
154 | this authenticator as a server. */ | |
155 | ||
156 | return auth_check_serv_cond(ablock); | |
157 | } | |
158 | ||
159 | ||
160 | ||
161 | /************************************************* | |
162 | * Client entry point * | |
163 | *************************************************/ | |
164 | ||
165 | /* For interface, see auths/README */ | |
166 | ||
167 | int | |
168 | auth_plaintext_client( | |
169 | auth_instance *ablock, /* authenticator block */ | |
2ea97746 | 170 | void * sx, /* smtp connextion */ |
420a0d19 CE |
171 | int timeout, /* command timeout */ |
172 | uschar *buffer, /* buffer for reading response */ | |
173 | int buffsize) /* size of buffer */ | |
174 | { | |
175 | auth_plaintext_options_block *ob = | |
176 | (auth_plaintext_options_block *)(ablock->options_block); | |
2ea97746 | 177 | const uschar *text = ob->client_send; |
420a0d19 CE |
178 | uschar *s; |
179 | BOOL first = TRUE; | |
180 | int sep = 0; | |
181 | int auth_var_idx = 0; | |
182 | ||
183 | /* The text is broken up into a number of different data items, which are | |
184 | sent one by one. The first one is sent with the AUTH command; the remainder are | |
185 | sent in response to subsequent prompts. Each is expanded before being sent. */ | |
186 | ||
2ea97746 | 187 | while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size))) |
420a0d19 CE |
188 | { |
189 | int i, len, clear_len; | |
190 | uschar *ss = expand_string(s); | |
191 | uschar *clear; | |
192 | ||
193 | /* Forced expansion failure is not an error; authentication is abandoned. On | |
194 | all but the first string, we have to abandon the authentication attempt by | |
195 | sending a line containing "*". Save the failed expansion string, because it | |
196 | is in big_buffer, and that gets used by the sending function. */ | |
197 | ||
2ea97746 | 198 | if (!ss) |
420a0d19 CE |
199 | { |
200 | uschar *ssave = string_copy(s); | |
201 | if (!first) | |
202 | { | |
2ea97746 CE |
203 | if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0) |
204 | (void) smtp_read_response(sx, US buffer, buffsize, '2', timeout); | |
420a0d19 | 205 | } |
2ea97746 | 206 | if (f.expand_string_forcedfail) |
420a0d19 CE |
207 | { |
208 | *buffer = 0; /* No message */ | |
209 | return CANCELLED; | |
210 | } | |
211 | string_format(buffer, buffsize, "expansion of \"%s\" failed in %s " | |
212 | "authenticator: %s", ssave, ablock->name, expand_string_message); | |
213 | return ERROR; | |
214 | } | |
215 | ||
216 | len = Ustrlen(ss); | |
217 | ||
218 | /* The character ^ is used as an escape for a binary zero character, which is | |
219 | needed for the PLAIN mechanism. It must be doubled if really needed. */ | |
220 | ||
221 | for (i = 0; i < len; i++) | |
420a0d19 | 222 | if (ss[i] == '^') |
2ea97746 CE |
223 | if (ss[i+1] != '^') |
224 | ss[i] = 0; | |
225 | else | |
420a0d19 CE |
226 | { |
227 | i++; | |
228 | len--; | |
229 | memmove(ss + i, ss + i + 1, len - i); | |
230 | } | |
420a0d19 CE |
231 | |
232 | /* The first string is attached to the AUTH command; others are sent | |
2ea97746 | 233 | unembellished. */ |
420a0d19 CE |
234 | |
235 | if (first) | |
236 | { | |
237 | first = FALSE; | |
2ea97746 CE |
238 | if (smtp_write_command(sx, SCMD_FLUSH, "AUTH %s%s%s\r\n", |
239 | ablock->public_name, len == 0 ? "" : " ", b64encode(ss, len)) < 0) | |
420a0d19 CE |
240 | return FAIL_SEND; |
241 | } | |
242 | else | |
243 | { | |
2ea97746 | 244 | if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", b64encode(ss, len)) < 0) |
420a0d19 CE |
245 | return FAIL_SEND; |
246 | } | |
247 | ||
248 | /* If we receive a success response from the server, authentication | |
249 | has succeeded. There may be more data to send, but is there any point | |
250 | in provoking an error here? */ | |
251 | ||
2ea97746 | 252 | if (smtp_read_response(sx, US buffer, buffsize, '2', timeout)) return OK; |
420a0d19 CE |
253 | |
254 | /* Not a success response. If errno != 0 there is some kind of transmission | |
255 | error. Otherwise, check the response code in the buffer. If it starts with | |
256 | '3', more data is expected. */ | |
257 | ||
258 | if (errno != 0 || buffer[0] != '3') return FAIL; | |
259 | ||
260 | /* If there is no more data to send, we have to cancel the authentication | |
261 | exchange and return ERROR. */ | |
262 | ||
2ea97746 | 263 | if (!text) |
420a0d19 | 264 | { |
2ea97746 CE |
265 | if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0) |
266 | (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout); | |
420a0d19 CE |
267 | string_format(buffer, buffsize, "Too few items in client_send in %s " |
268 | "authenticator", ablock->name); | |
269 | return ERROR; | |
270 | } | |
271 | ||
272 | /* Now that we know we'll continue, we put the received data into $auth<n>, | |
273 | if possible. First, decode it: buffer+4 skips over the SMTP status code. */ | |
274 | ||
2ea97746 | 275 | clear_len = b64decode(buffer+4, &clear); |
420a0d19 CE |
276 | |
277 | /* If decoding failed, the default is to terminate the authentication, and | |
278 | return FAIL, with the SMTP response still in the buffer. However, if client_ | |
279 | ignore_invalid_base64 is set, we ignore the error, and put an empty string | |
280 | into $auth<n>. */ | |
281 | ||
282 | if (clear_len < 0) | |
283 | { | |
284 | uschar *save_bad = string_copy(buffer); | |
285 | if (!ob->client_ignore_invalid_base64) | |
286 | { | |
2ea97746 CE |
287 | if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0) |
288 | (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout); | |
420a0d19 CE |
289 | string_format(buffer, buffsize, "Invalid base64 string in server " |
290 | "response \"%s\"", save_bad); | |
291 | return CANCELLED; | |
292 | } | |
293 | clear = US""; | |
294 | clear_len = 0; | |
295 | } | |
296 | ||
297 | if (auth_var_idx < AUTH_VARS) | |
298 | auth_vars[auth_var_idx++] = string_copy(clear); | |
299 | } | |
300 | ||
301 | /* Control should never actually get here. */ | |
302 | ||
303 | return FAIL; | |
304 | } | |
305 | ||
2ea97746 | 306 | #endif /*!MACRO_PREDEF*/ |
420a0d19 | 307 | /* End of plaintext.c */ |