EXTERNAL authenticator

[exim.git] / src / src / auths / external.c

diff --git a/src/src/auths/external.c b/src/src/auths/external.c
new file mode 100644 (file)
index 0000000..10e1366
--- /dev/null
+++ b/src/src/auths/external.c
@@ -0,0 +1,158 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 2019 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file provides an Exim authenticator driver for
+a server to verify a client SSL certificate, using the EXTERNAL
+method defined in RFC 4422 Appendix A.
+*/
+
+
+#include "../exim.h"
+#include "external.h"
+
+/* Options specific to the external authentication mechanism. */
+
+optionlist auth_external_options[] = {
+  { "client_send",     opt_stringptr,
+      (void *)(offsetof(auth_external_options_block, client_send)) },
+  { "server_param2",   opt_stringptr,
+      (void *)(offsetof(auth_external_options_block, server_param2)) },
+  { "server_param3",       opt_stringptr,
+      (void *)(offsetof(auth_external_options_block, server_param3)) },
+};
+
+/* 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_external_options_count = nelem(auth_external_options);
+
+/* Default private options block for the authentication method. */
+
+auth_external_options_block auth_external_option_defaults = {
+    .server_param2 = NULL,
+    .server_param3 = NULL,
+
+    .client_send = NULL,
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_external_init(auth_instance *ablock) {}
+int auth_external_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_external_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_external_init(auth_instance *ablock)
+{
+auth_external_options_block * ob = (auth_external_options_block *)ablock->options_block;
+if (!ablock->public_name) ablock->public_name = ablock->name;
+if (ablock->server_condition) ablock->server = TRUE;
+if (ob->client_send) ablock->client = TRUE;
+}
+
+
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_external_server(auth_instance * ablock, uschar * data)
+{
+auth_external_options_block * ob = (auth_external_options_block *)ablock->options_block;
+int rc;
+
+/* 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)
+  if ((rc = auth_read_input(data)) != OK)
+    return rc;
+
+/* 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. */
+
+if (expand_nmax == 0)  /* skip if rxd data */
+  if ((rc = auth_prompt(CUS"")) != OK)
+    return rc;
+
+if (ob->server_param2)
+  {
+  uschar * s = expand_string(ob->server_param2);
+  auth_vars[expand_nmax] = s;
+  expand_nstring[++expand_nmax] = s;
+  expand_nlength[expand_nmax] = Ustrlen(s);
+  if (ob->server_param3)
+    {
+    s = expand_string(ob->server_param3);
+    auth_vars[expand_nmax] = s;
+    expand_nstring[++expand_nmax] = s;
+    expand_nlength[expand_nmax] = Ustrlen(s);
+    }
+  }
+
+return auth_check_serv_cond(ablock);
+}
+
+
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_external_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_external_options_block *ob =
+  (auth_external_options_block *)(ablock->options_block);
+const uschar * text = ob->client_send;
+int rc;
+
+/* We output an AUTH command with one expanded argument, the client_send option */
+
+if ((rc = auth_client_item(sx, ablock, &text, AUTH_ITEM_FIRST | AUTH_ITEM_LAST,
+      timeout, buffer, buffsize)) != OK)
+  return rc == DEFER ? FAIL : rc;
+
+if (text) auth_vars[0] = string_copy(text);
+return OK;
+}
+
+
+
+#endif   /*!MACRO_PREDEF*/
+/* End of external.c */