src/src/auths/external.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Jeremy Harris 2019 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8 /* This file provides an Exim authenticator driver for
   9 a server to verify a client SSL certificate, using the EXTERNAL
  10 method defined in RFC 4422 Appendix A.
  11 */
  12
  13
  14 #include "../exim.h"
  15 #include "external.h"
  16
  17 /* Options specific to the external authentication mechanism. */
  18
  19 optionlist auth_external_options[] = {
  20   { "client_send",      opt_stringptr,
  21       (void *)(offsetof(auth_external_options_block, client_send)) },
  22   { "server_param2",    opt_stringptr,
  23       (void *)(offsetof(auth_external_options_block, server_param2)) },
  24   { "server_param3",        opt_stringptr,
  25       (void *)(offsetof(auth_external_options_block, server_param3)) },
  26 };
  27
  28 /* Size of the options list. An extern variable has to be used so that its
  29 address can appear in the tables drtables.c. */
  30
  31 int auth_external_options_count = nelem(auth_external_options);
  32
  33 /* Default private options block for the authentication method. */
  34
  35 auth_external_options_block auth_external_option_defaults = {
  36     .server_param2 = NULL,
  37     .server_param3 = NULL,
  38
  39     .client_send = NULL,
  40 };
  41
  42
  43 #ifdef MACRO_PREDEF
  44
  45 /* Dummy values */
  46 void auth_external_init(auth_instance *ablock) {}
  47 int auth_external_server(auth_instance *ablock, uschar *data) {return 0;}
  48 int auth_external_client(auth_instance *ablock, void * sx,
  49   int timeout, uschar *buffer, int buffsize) {return 0;}
  50
  51 #else   /*!MACRO_PREDEF*/
  52
  53
  54
  55
  56 /*************************************************
  57 *          Initialization entry point            *
  58 *************************************************/
  59
  60 /* Called for each instance, after its options have been read, to
  61 enable consistency checks to be done, or anything else that needs
  62 to be set up. */
  63
  64 void
  65 auth_external_init(auth_instance *ablock)
  66 {
  67 auth_external_options_block * ob = (auth_external_options_block *)ablock->options_block;
  68 if (!ablock->public_name) ablock->public_name = ablock->name;
  69 if (ablock->server_condition) ablock->server = TRUE;
  70 if (ob->client_send) ablock->client = TRUE;
  71 }
  72
  73
  74
  75 /*************************************************
  76 *             Server entry point                 *
  77 *************************************************/
  78
  79 /* For interface, see auths/README */
  80
  81 int
  82 auth_external_server(auth_instance * ablock, uschar * data)
  83 {
  84 auth_external_options_block * ob = (auth_external_options_block *)ablock->options_block;
  85 int rc;
  86
  87 /* If data was supplied on the AUTH command, decode it, and split it up into
  88 multiple items at binary zeros. The strings are put into $auth1, $auth2, etc,
  89 up to a maximum. To retain backwards compatibility, they are also put int $1,
  90 $2, etc. If the data consists of the string "=" it indicates a single, empty
  91 string. */
  92
  93 if (*data)
  94   if ((rc = auth_read_input(data)) != OK)
  95     return rc;
  96
  97 /* Now go through the list of prompt strings. Skip over any whose data has
  98 already been provided as part of the AUTH command. For the rest, send them
  99 out as prompts, and get a data item back. If the data item is "*", abandon the
 100 authentication attempt. Otherwise, split it into items as above. */
 101
 102 if (expand_nmax == 0)   /* skip if rxd data */
 103   if ((rc = auth_prompt(CUS"")) != OK)
 104     return rc;
 105
 106 if (ob->server_param2)
 107   {
 108   uschar * s = expand_string(ob->server_param2);
 109   auth_vars[expand_nmax] = s;
 110   expand_nstring[++expand_nmax] = s;
 111   expand_nlength[expand_nmax] = Ustrlen(s);
 112   if (ob->server_param3)
 113     {
 114     s = expand_string(ob->server_param3);
 115     auth_vars[expand_nmax] = s;
 116     expand_nstring[++expand_nmax] = s;
 117     expand_nlength[expand_nmax] = Ustrlen(s);
 118     }
 119   }
 120
 121 return auth_check_serv_cond(ablock);
 122 }
 123
 124
 125
 126 /*************************************************
 127 *              Client entry point                *
 128 *************************************************/
 129
 130 /* For interface, see auths/README */
 131
 132 int
 133 auth_external_client(
 134   auth_instance *ablock,                 /* authenticator block */
 135   void * sx,                             /* smtp connextion */
 136   int timeout,                           /* command timeout */
 137   uschar *buffer,                        /* buffer for reading response */
 138   int buffsize)                          /* size of buffer */
 139 {
 140 auth_external_options_block *ob =
 141   (auth_external_options_block *)(ablock->options_block);
 142 const uschar * text = ob->client_send;
 143 int rc;
 144
 145 /* We output an AUTH command with one expanded argument, the client_send option */
 146
 147 if ((rc = auth_client_item(sx, ablock, &text, AUTH_ITEM_FIRST | AUTH_ITEM_LAST,
 148       timeout, buffer, buffsize)) != OK)
 149   return rc == DEFER ? FAIL : rc;
 150
 151 if (text) auth_vars[0] = string_copy(text);
 152 return OK;
 153 }
 154
 155
 156
 157 #endif   /*!MACRO_PREDEF*/
 158 /* End of external.c */