1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
12 /* Options specific to the plaintext authentication mechanism. */
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)) }
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. */
26 int auth_plaintext_options_count =
27 sizeof(auth_plaintext_options)/sizeof(optionlist);
29 /* Default private options block for the plaintext authentication method. */
31 auth_plaintext_options_block auth_plaintext_option_defaults = {
32 NULL, /* server_prompts */
33 NULL, /* client_send */
34 FALSE /* client_ignore_invalid_base64 */
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;}
46 #else /*!MACRO_PREDEF*/
50 /*************************************************
51 * Initialization entry point *
52 *************************************************/
54 /* Called for each instance, after its options have been read, to
55 enable consistency checks to be done, or anything else that needs
59 auth_plaintext_init(auth_instance *ablock)
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;
70 /*************************************************
71 * Server entry point *
72 *************************************************/
74 /* For interface, see auths/README */
77 auth_plaintext_server(auth_instance *ablock, uschar *data)
79 auth_plaintext_options_block *ob =
80 (auth_plaintext_options_block *)(ablock->options_block);
81 const uschar *prompts = ob->server_prompts;
82 uschar *clear, *end, *s;
87 /* Expand a non-empty list of prompt strings */
91 prompts = expand_cstring(prompts);
94 auth_defer_msg = expand_string_message;
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
107 if (Ustrcmp(data, "=") == 0)
109 auth_vars[0] = expand_nstring[++expand_nmax] = US"";
110 expand_nlength[expand_nmax] = 0;
114 if ((len = b64decode(data, &clear)) < 0) return BAD64;
116 while (clear < end && expand_nmax < EXPAND_MAXN)
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];
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. */
131 while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size))
132 != NULL && expand_nmax < EXPAND_MAXN)
134 if (number++ <= expand_nmax) continue;
135 if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc;
136 if ((len = b64decode(data, &clear)) < 0) return BAD64;
139 /* This loop must run at least once, in case the length is zero */
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];
147 while (clear < end && expand_nmax < EXPAND_MAXN);
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. */
156 return auth_check_serv_cond(ablock);
161 /*************************************************
162 * Client entry point *
163 *************************************************/
165 /* For interface, see auths/README */
168 auth_plaintext_client(
169 auth_instance *ablock, /* authenticator block */
170 void * sx, /* smtp connextion */
171 int timeout, /* command timeout */
172 uschar *buffer, /* buffer for reading response */
173 int buffsize) /* size of buffer */
175 auth_plaintext_options_block *ob =
176 (auth_plaintext_options_block *)(ablock->options_block);
177 const uschar *text = ob->client_send;
181 int auth_var_idx = 0;
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. */
187 while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)))
190 uschar *ss = expand_string(s);
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. */
200 uschar *ssave = string_copy(s);
203 if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
204 (void) smtp_read_response(sx, US buffer, buffsize, '2', timeout);
206 if (f.expand_string_forcedfail)
208 *buffer = 0; /* No message */
211 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
212 "authenticator: %s", ssave, ablock->name, expand_string_message);
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. */
221 for (int i = 0; i < len; i++)
229 memmove(ss + i, ss + i + 1, len - i);
232 /* The first string is attached to the AUTH command; others are sent
238 if (smtp_write_command(sx, SCMD_FLUSH, "AUTH %s%s%s\r\n",
239 ablock->public_name, len == 0 ? "" : " ", b64encode(ss, len)) < 0)
244 if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", b64encode(ss, len)) < 0)
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? */
252 if (smtp_read_response(sx, US buffer, buffsize, '2', timeout)) return OK;
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. */
258 if (errno != 0 || buffer[0] != '3') return FAIL;
260 /* If there is no more data to send, we have to cancel the authentication
261 exchange and return ERROR. */
265 if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
266 (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout);
267 string_format(buffer, buffsize, "Too few items in client_send in %s "
268 "authenticator", ablock->name);
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. */
275 clear_len = b64decode(buffer+4, &clear);
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
284 uschar *save_bad = string_copy(buffer);
285 if (!ob->client_ignore_invalid_base64)
287 if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
288 (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout);
289 string_format(buffer, buffsize, "Invalid base64 string in server "
290 "response \"%s\"", save_bad);
297 if (auth_var_idx < AUTH_VARS)
298 auth_vars[auth_var_idx++] = string_copy(clear);
301 /* Control should never actually get here. */
306 #endif /*!MACRO_PREDEF*/
307 /* End of plaintext.c */