src/src/auths/check_serv_cond.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) University of Cambridge 1995 - 2012 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8 #include "../exim.h"
   9
  10 /* This module contains the function server_condition(), which is used
  11 by all authenticators. */
  12
  13
  14 /*************************************************
  15 *              Check server_condition            *
  16 *************************************************/
  17
  18 /* This function is called from the server code of all authenticators. For
  19 plaintext and gsasl, it is always called: the argument cannot be empty, because
  20 for those, setting server_condition is what enables it as a server
  21 authenticator. For all the other authenticators, this function is called after
  22 they have authenticated, to enable additional authorization to be done.
  23
  24 Argument:     the authenticator's instance block
  25
  26 Returns:
  27   OK          NULL argument, or success
  28   DEFER       couldn't complete the check
  29   FAIL        authentication failed
  30 */
  31
  32 int
  33 auth_check_serv_cond(auth_instance *ablock)
  34 {
  35   return auth_check_some_cond(ablock,
  36       US"server_condition", ablock->server_condition, OK);
  37 }
  38
  39
  40 /*************************************************
  41 *         Check some server condition            *
  42 *************************************************/
  43
  44 /* This underlies server_condition, but is also used for some more generic
  45  checks.
  46
  47 Arguments:
  48   ablock     the authenticator's instance block
  49   label      debugging label naming the string checked
  50   condition  the condition string to be expanded and checked
  51   unset      value to return on NULL condition
  52
  53 Returns:
  54   OK          success (or unset=OK)
  55   DEFER       couldn't complete the check
  56   FAIL        authentication failed
  57 */
  58
  59 int
  60 auth_check_some_cond(auth_instance *ablock,
  61     uschar *label, uschar *condition, int unset)
  62 {
  63 uschar *cond;
  64
  65 HDEBUG(D_auth)
  66   {
  67   debug_printf("%s authenticator %s:\n", ablock->name, label);
  68   for (int i = 0; i < AUTH_VARS; i++) if (auth_vars[i])
  69     debug_printf("  $auth%d = %s\n", i + 1, auth_vars[i]);
  70   for (int i = 1; i <= expand_nmax; i++)
  71     debug_printf("  $%d = %.*s\n", i, expand_nlength[i], expand_nstring[i]);
  72   debug_print_string(ablock->server_debug_string);    /* customized debug */
  73   }
  74
  75 /* For the plaintext authenticator, server_condition is never NULL. For the
  76 rest, an unset condition lets everything through. */
  77
  78 /* For server_condition, an unset condition lets everything through.
  79 For plaintext/gsasl authenticators, it will have been pre-checked to prevent
  80 this.  We return the unset scenario value given to us, which for
  81 server_condition will be OK and otherwise will typically be FAIL. */
  82
  83 if (!condition) return unset;
  84 cond = expand_string(condition);
  85
  86 HDEBUG(D_auth)
  87   if (!cond)
  88     debug_printf("expansion failed: %s\n", expand_string_message);
  89   else
  90     debug_printf("expanded string: %s\n", cond);
  91
  92 /* A forced expansion failure causes authentication to fail. Other expansion
  93 failures yield DEFER, which will cause a temporary error code to be returned to
  94 the AUTH command. The problem is at the server end, so the client should try
  95 again later. */
  96
  97 if (!cond)
  98   {
  99   if (f.expand_string_forcedfail) return FAIL;
 100   auth_defer_msg = expand_string_message;
 101   return DEFER;
 102   }
 103
 104 /* Return FAIL for empty string, "0", "no", and "false"; return OK for
 105 "1", "yes", and "true"; return DEFER for anything else, with the string
 106 available as an error text for the user. */
 107
 108 if (*cond == 0 ||
 109     Ustrcmp(cond, "0") == 0 ||
 110     strcmpic(cond, US"no") == 0 ||
 111     strcmpic(cond, US"false") == 0)
 112   return FAIL;
 113
 114 if (Ustrcmp(cond, "1") == 0 ||
 115     strcmpic(cond, US"yes") == 0 ||
 116     strcmpic(cond, US"true") == 0)
 117   return OK;
 118
 119 auth_defer_msg = cond;
 120 auth_defer_user_msg = string_sprintf(": %s", cond);
 121 return DEFER;
 122 }
 123
 124 /* End of check_serv_cond.c */