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-rw-r--r--src/auths/plaintext.c307
1 files changed, 307 insertions, 0 deletions
diff --git a/src/auths/plaintext.c b/src/auths/plaintext.c
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+++ b/src/auths/plaintext.c
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+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+#include "plaintext.h"
+
+
+/* Options specific to the plaintext authentication mechanism. */
+
+optionlist auth_plaintext_options[] = {
+ { "client_ignore_invalid_base64", opt_bool,
+ (void *)(offsetof(auth_plaintext_options_block, client_ignore_invalid_base64)) },
+ { "client_send", opt_stringptr,
+ (void *)(offsetof(auth_plaintext_options_block, client_send)) },
+ { "server_prompts", opt_stringptr,
+ (void *)(offsetof(auth_plaintext_options_block, server_prompts)) }
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_plaintext_options_count =
+ sizeof(auth_plaintext_options)/sizeof(optionlist);
+
+/* Default private options block for the plaintext authentication method. */
+
+auth_plaintext_options_block auth_plaintext_option_defaults = {
+ NULL, /* server_prompts */
+ NULL, /* client_send */
+ FALSE /* client_ignore_invalid_base64 */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_plaintext_init(auth_instance *ablock) {}
+int auth_plaintext_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_plaintext_client(auth_instance *ablock, void * sx, int timeout,
+ uschar *buffer, int buffsize) {return 0;}
+
+#else /*!MACRO_PREDEF*/
+
+
+
+/*************************************************
+* Initialization entry point *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_plaintext_init(auth_instance *ablock)
+{
+auth_plaintext_options_block *ob =
+ (auth_plaintext_options_block *)(ablock->options_block);
+if (ablock->public_name == NULL) ablock->public_name = ablock->name;
+if (ablock->server_condition != NULL) ablock->server = TRUE;
+if (ob->client_send != NULL) ablock->client = TRUE;
+}
+
+
+
+/*************************************************
+* Server entry point *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_plaintext_server(auth_instance *ablock, uschar *data)
+{
+auth_plaintext_options_block *ob =
+ (auth_plaintext_options_block *)(ablock->options_block);
+const uschar *prompts = ob->server_prompts;
+uschar *clear, *end, *s;
+int number = 1;
+int len, rc;
+int sep = 0;
+
+/* Expand a non-empty list of prompt strings */
+
+if (prompts != NULL)
+ {
+ prompts = expand_cstring(prompts);
+ if (prompts == NULL)
+ {
+ auth_defer_msg = expand_string_message;
+ return DEFER;
+ }
+ }
+
+/* If data was supplied on the AUTH command, decode it, and split it up into
+multiple items at binary zeros. The strings are put into $auth1, $auth2, etc,
+up to a maximum. To retain backwards compatibility, they are also put int $1,
+$2, etc. If the data consists of the string "=" it indicates a single, empty
+string. */
+
+if (*data != 0)
+ {
+ if (Ustrcmp(data, "=") == 0)
+ {
+ auth_vars[0] = expand_nstring[++expand_nmax] = US"";
+ expand_nlength[expand_nmax] = 0;
+ }
+ else
+ {
+ if ((len = b64decode(data, &clear)) < 0) return BAD64;
+ end = clear + len;
+ while (clear < end && expand_nmax < EXPAND_MAXN)
+ {
+ if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear;
+ expand_nstring[++expand_nmax] = clear;
+ while (*clear != 0) clear++;
+ expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax];
+ }
+ }
+ }
+
+/* Now go through the list of prompt strings. Skip over any whose data has
+already been provided as part of the AUTH command. For the rest, send them
+out as prompts, and get a data item back. If the data item is "*", abandon the
+authentication attempt. Otherwise, split it into items as above. */
+
+while ((s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size))
+ != NULL && expand_nmax < EXPAND_MAXN)
+ {
+ if (number++ <= expand_nmax) continue;
+ if ((rc = auth_get_data(&data, s, Ustrlen(s))) != OK) return rc;
+ if ((len = b64decode(data, &clear)) < 0) return BAD64;
+ end = clear + len;
+
+ /* This loop must run at least once, in case the length is zero */
+ do
+ {
+ if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear;
+ expand_nstring[++expand_nmax] = clear;
+ while (*clear != 0) clear++;
+ expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax];
+ }
+ while (clear < end && expand_nmax < EXPAND_MAXN);
+ }
+
+/* We now have a number of items of data in $auth1, $auth2, etc (and also, for
+compatibility, in $1, $2, etc). Authentication and authorization are handled
+together for this authenticator by expanding the server_condition option. Note
+that ablock->server_condition is always non-NULL because that's what configures
+this authenticator as a server. */
+
+return auth_check_serv_cond(ablock);
+}
+
+
+
+/*************************************************
+* Client entry point *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_plaintext_client(
+ auth_instance *ablock, /* authenticator block */
+ void * sx, /* smtp connextion */
+ int timeout, /* command timeout */
+ uschar *buffer, /* buffer for reading response */
+ int buffsize) /* size of buffer */
+{
+auth_plaintext_options_block *ob =
+ (auth_plaintext_options_block *)(ablock->options_block);
+const uschar *text = ob->client_send;
+uschar *s;
+BOOL first = TRUE;
+int sep = 0;
+int auth_var_idx = 0;
+
+/* The text is broken up into a number of different data items, which are
+sent one by one. The first one is sent with the AUTH command; the remainder are
+sent in response to subsequent prompts. Each is expanded before being sent. */
+
+while ((s = string_nextinlist(&text, &sep, big_buffer, big_buffer_size)))
+ {
+ int i, len, clear_len;
+ uschar *ss = expand_string(s);
+ uschar *clear;
+
+ /* Forced expansion failure is not an error; authentication is abandoned. On
+ all but the first string, we have to abandon the authentication attempt by
+ sending a line containing "*". Save the failed expansion string, because it
+ is in big_buffer, and that gets used by the sending function. */
+
+ if (!ss)
+ {
+ uschar *ssave = string_copy(s);
+ if (!first)
+ {
+ if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
+ (void) smtp_read_response(sx, US buffer, buffsize, '2', timeout);
+ }
+ if (f.expand_string_forcedfail)
+ {
+ *buffer = 0; /* No message */
+ return CANCELLED;
+ }
+ string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
+ "authenticator: %s", ssave, ablock->name, expand_string_message);
+ return ERROR;
+ }
+
+ len = Ustrlen(ss);
+
+ /* The character ^ is used as an escape for a binary zero character, which is
+ needed for the PLAIN mechanism. It must be doubled if really needed. */
+
+ for (i = 0; i < len; i++)
+ if (ss[i] == '^')
+ if (ss[i+1] != '^')
+ ss[i] = 0;
+ else
+ {
+ i++;
+ len--;
+ memmove(ss + i, ss + i + 1, len - i);
+ }
+
+ /* The first string is attached to the AUTH command; others are sent
+ unembellished. */
+
+ if (first)
+ {
+ first = FALSE;
+ if (smtp_write_command(sx, SCMD_FLUSH, "AUTH %s%s%s\r\n",
+ ablock->public_name, len == 0 ? "" : " ", b64encode(ss, len)) < 0)
+ return FAIL_SEND;
+ }
+ else
+ {
+ if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", b64encode(ss, len)) < 0)
+ return FAIL_SEND;
+ }
+
+ /* If we receive a success response from the server, authentication
+ has succeeded. There may be more data to send, but is there any point
+ in provoking an error here? */
+
+ if (smtp_read_response(sx, US buffer, buffsize, '2', timeout)) return OK;
+
+ /* Not a success response. If errno != 0 there is some kind of transmission
+ error. Otherwise, check the response code in the buffer. If it starts with
+ '3', more data is expected. */
+
+ if (errno != 0 || buffer[0] != '3') return FAIL;
+
+ /* If there is no more data to send, we have to cancel the authentication
+ exchange and return ERROR. */
+
+ if (!text)
+ {
+ if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
+ (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout);
+ string_format(buffer, buffsize, "Too few items in client_send in %s "
+ "authenticator", ablock->name);
+ return ERROR;
+ }
+
+ /* Now that we know we'll continue, we put the received data into $auth<n>,
+ if possible. First, decode it: buffer+4 skips over the SMTP status code. */
+
+ clear_len = b64decode(buffer+4, &clear);
+
+ /* If decoding failed, the default is to terminate the authentication, and
+ return FAIL, with the SMTP response still in the buffer. However, if client_
+ ignore_invalid_base64 is set, we ignore the error, and put an empty string
+ into $auth<n>. */
+
+ if (clear_len < 0)
+ {
+ uschar *save_bad = string_copy(buffer);
+ if (!ob->client_ignore_invalid_base64)
+ {
+ if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
+ (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout);
+ string_format(buffer, buffsize, "Invalid base64 string in server "
+ "response \"%s\"", save_bad);
+ return CANCELLED;
+ }
+ clear = US"";
+ clear_len = 0;
+ }
+
+ if (auth_var_idx < AUTH_VARS)
+ auth_vars[auth_var_idx++] = string_copy(clear);
+ }
+
+/* Control should never actually get here. */
+
+return FAIL;
+}
+
+#endif /*!MACRO_PREDEF*/
+/* End of plaintext.c */
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