1 /* $Cambridge: exim/src/src/auths/plaintext.c,v 1.5 2006/02/23 12:41:22 ph10 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) University of Cambridge 1995 - 2006 */
8 /* See the file NOTICE for conditions of use and distribution. */
11 #include "plaintext.h"
14 /* Options specific to the plaintext authentication mechanism. */
16 optionlist auth_plaintext_options[] = {
17 { "client_ignore_invalid_base64", opt_bool,
18 (void *)(offsetof(auth_plaintext_options_block, client_ignore_invalid_base64)) },
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)) }
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. */
30 int auth_plaintext_options_count =
31 sizeof(auth_plaintext_options)/sizeof(optionlist);
33 /* Default private options block for the plaintext authentication method. */
35 auth_plaintext_options_block auth_plaintext_option_defaults = {
36 NULL, /* server_condition */
37 NULL, /* server_prompts */
38 NULL, /* client_send */
39 FALSE /* client_ignore_invalid_base64 */
43 /*************************************************
44 * Initialization entry point *
45 *************************************************/
47 /* Called for each instance, after its options have been read, to
48 enable consistency checks to be done, or anything else that needs
52 auth_plaintext_init(auth_instance *ablock)
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;
63 /*************************************************
64 * Server entry point *
65 *************************************************/
67 /* For interface, see auths/README */
70 auth_plaintext_server(auth_instance *ablock, uschar *data)
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;
80 /* Expand a non-empty list of prompt strings */
84 prompts = expand_string(prompts);
87 auth_defer_msg = expand_string_message;
92 /* If data was supplied on the AUTH command, decode it, and split it up into
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
100 if (Ustrcmp(data, "=") == 0)
102 auth_vars[0] = expand_nstring[++expand_nmax] = US"";
103 expand_nlength[expand_nmax] = 0;
107 if ((len = auth_b64decode(data, &clear)) < 0) return BAD64;
109 while (clear < end && expand_nmax < EXPAND_MAXN)
111 if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear;
112 expand_nstring[++expand_nmax] = clear;
113 while (*clear != 0) clear++;
114 expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax];
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. */
124 while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size))
125 != NULL && expand_nmax < EXPAND_MAXN)
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;
132 /* This loop must run at least once, in case the length is zero */
135 if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear;
136 expand_nstring[++expand_nmax] = clear;
137 while (*clear != 0) clear++;
138 expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax];
140 while (clear < end && expand_nmax < EXPAND_MAXN);
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
147 cond = expand_string(ob->server_condition);
152 debug_printf("%s authenticator:\n", ablock->name);
153 for (i = 0; i < AUTH_VARS; i++)
155 if (auth_vars[i] != NULL)
156 debug_printf(" $auth%d = %s\n", i + 1, auth_vars[i]);
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 */
162 debug_printf("expansion failed: %s\n", expand_string_message);
164 debug_printf("expanded string: %s\n", cond);
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
174 if (expand_string_forcedfail) return FAIL;
175 auth_defer_msg = expand_string_message;
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. */
184 Ustrcmp(cond, "0") == 0 ||
185 strcmpic(cond, US"no") == 0 ||
186 strcmpic(cond, US"false") == 0)
189 if (Ustrcmp(cond, "1") == 0 ||
190 strcmpic(cond, US"yes") == 0 ||
191 strcmpic(cond, US"true") == 0)
194 auth_defer_msg = cond;
195 auth_defer_user_msg = string_sprintf(": %s", cond);
201 /*************************************************
202 * Client entry point *
203 *************************************************/
205 /* For interface, see auths/README */
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 */
216 auth_plaintext_options_block *ob =
217 (auth_plaintext_options_block *)(ablock->options_block);
218 uschar *text = ob->client_send;
222 int auth_var_idx = 0;
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. */
228 while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)) != NULL)
230 int i, len, clear_len;
231 uschar *ss = expand_string(s);
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. */
241 uschar *ssave = string_copy(s);
244 if (smtp_write_command(outblock, FALSE, "*\r\n") >= 0)
245 (void) smtp_read_response(inblock, US buffer, buffsize, '2', timeout);
247 if (expand_string_forcedfail)
249 *buffer = 0; /* No message */
252 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
253 "authenticator: %s", ssave, ablock->name, expand_string_message);
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. */
262 for (i = 0; i < len; i++)
266 if (ss[i+1] != '^') ss[i] = 0; else
270 memmove(ss + i, ss + i + 1, len - i);
275 /* The first string is attached to the AUTH command; others are sent
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)
288 if (smtp_write_command(outblock, FALSE, "%s\r\n",
289 auth_b64encode(ss, len)) < 0)
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? */
297 if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout)) return OK;
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. */
303 if (errno != 0 || buffer[0] != '3') return FAIL;
305 /* If there is no more data to send, we have to cancel the authentication
306 exchange and return ERROR. */
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);
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. */
320 clear_len = auth_b64decode(buffer+4, &clear);
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
329 uschar *save_bad = string_copy(buffer);
330 if (!ob->client_ignore_invalid_base64)
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);
342 if (auth_var_idx < AUTH_VARS)
343 auth_vars[auth_var_idx++] = string_copy(clear);
346 /* Control should never actually get here. */
351 /* End of plaintext.c */