lib/ext_srp.c

   1 /*
   2  * Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation
   3  *
   4  * Author: Nikos Mavrogiannopoulos
   5  *
   6  * This file is part of GNUTLS.
   7  *
   8  * The GNUTLS library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 2.1 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  21  * USA
  22  *
  23  */
  24
  25 #include <gnutls_int.h>
  26 #include <ext_srp.h>
  27
  28 #ifdef ENABLE_SRP
  29
  30 #include "gnutls_auth_int.h"
  31 #include "auth_srp.h"
  32 #include "gnutls_errors.h"
  33 #include "gnutls_algorithms.h"
  34 #include <gnutls_num.h>
  35
  36 int
  37 _gnutls_srp_recv_params (gnutls_session_t session, const opaque * data,
  38                          size_t _data_size)
  39 {
  40   uint8_t len;
  41   ssize_t data_size = _data_size;
  42
  43   if (session->security_parameters.entity == GNUTLS_SERVER)
  44     {
  45       if (data_size > 0)
  46         {
  47           len = data[0];
  48           DECR_LEN (data_size, len);
  49
  50           if (MAX_SRP_USERNAME < len)
  51             {
  52               gnutls_assert ();
  53               return GNUTLS_E_ILLEGAL_SRP_USERNAME;
  54             }
  55           memcpy (session->security_parameters.extensions.srp_username,
  56                   &data[1], len);
  57           /* null terminated */
  58           session->security_parameters.extensions.srp_username[len] = 0;
  59         }
  60     }
  61   return 0;
  62 }
  63
  64 /* returns data_size or a negative number on failure
  65  * data is allocated locally
  66  */
  67 int
  68 _gnutls_srp_send_params (gnutls_session_t session, opaque * data,
  69                          size_t data_size)
  70 {
  71   unsigned len;
  72
  73   if (_gnutls_kx_priority (session, GNUTLS_KX_SRP) < 0 &&
  74       _gnutls_kx_priority (session, GNUTLS_KX_SRP_DSS) < 0 &&
  75       _gnutls_kx_priority (session, GNUTLS_KX_SRP_RSA) < 0)
  76     {
  77       /* algorithm was not allowed in this session
  78        */
  79       return 0;
  80     }
  81
  82   /* this function sends the client extension data (username) */
  83   if (session->security_parameters.entity == GNUTLS_CLIENT)
  84     {
  85       gnutls_srp_client_credentials_t cred = (gnutls_srp_client_credentials_t)
  86         _gnutls_get_cred (session->key, GNUTLS_CRD_SRP, NULL);
  87
  88       if (cred == NULL)
  89         return 0;
  90
  91       if (cred->username != NULL)
  92         {                       /* send username */
  93           len = MIN (strlen (cred->username), 255);
  94
  95           if (data_size < len + 1)
  96             {
  97               gnutls_assert ();
  98               return GNUTLS_E_SHORT_MEMORY_BUFFER;
  99             }
 100
 101           data[0] = (uint8_t) len;
 102           memcpy (&data[1], cred->username, len);
 103           return len + 1;
 104         }
 105       else if (cred->get_function != NULL)
 106         {
 107           /* Try the callback
 108            */
 109           char *username = NULL, *password = NULL;
 110
 111           if (cred->get_function (session, &username, &password) < 0
 112               || username == NULL || password == NULL)
 113             {
 114                 gnutls_assert ();
 115                 return GNUTLS_E_ILLEGAL_SRP_USERNAME;
 116             }
 117
 118           len = MIN (strlen (username), 255);
 119
 120           if (data_size < len + 1)
 121             {
 122               gnutls_free (username);
 123               gnutls_free (password);
 124               gnutls_assert ();
 125               return GNUTLS_E_SHORT_MEMORY_BUFFER;
 126             }
 127
 128           session->internals.srp_username = username;
 129           session->internals.srp_password = password;
 130
 131           data[0] = (uint8_t) len;
 132           memcpy (&data[1], username, len);
 133           return len + 1;
 134         }
 135     }
 136   return 0;
 137 }
 138
 139 #endif /* ENABLE_SRP */