ssl/tls_srp.c

   1 /* ssl/tls_srp.c */
   2 /* Written by Christophe Renou (christophe.renou@edelweb.fr) with
   3  * the precious help of Peter Sylvester (peter.sylvester@edelweb.fr)
   4  * for the EdelKey project and contributed to the OpenSSL project 2004.
   5  */
   6 /* ====================================================================
   7  * Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  *
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in
  18  *    the documentation and/or other materials provided with the
  19  *    distribution.
  20  *
  21  * 3. All advertising materials mentioning features or use of this
  22  *    software must display the following acknowledgment:
  23  *    "This product includes software developed by the OpenSSL Project
  24  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  25  *
  26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  27  *    endorse or promote products derived from this software without
  28  *    prior written permission. For written permission, please contact
  29  *    licensing@OpenSSL.org.
  30  *
  31  * 5. Products derived from this software may not be called "OpenSSL"
  32  *    nor may "OpenSSL" appear in their names without prior written
  33  *    permission of the OpenSSL Project.
  34  *
  35  * 6. Redistributions of any form whatsoever must retain the following
  36  *    acknowledgment:
  37  *    "This product includes software developed by the OpenSSL Project
  38  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  51  * OF THE POSSIBILITY OF SUCH DAMAGE.
  52  * ====================================================================
  53  *
  54  * This product includes cryptographic software written by Eric Young
  55  * (eay@cryptsoft.com).  This product includes software written by Tim
  56  * Hudson (tjh@cryptsoft.com).
  57  *
  58  */
  59
  60 #include <openssl/crypto.h>
  61 #include <openssl/rand.h>
  62 #include <openssl/srp.h>
  63 #include <openssl/err.h>
  64 #include "ssl_locl.h"
  65
  66 #ifndef OPENSSL_NO_SRP
  67
  68 int SSL_CTX_SRP_CTX_free(struct ssl_ctx_st *ctx)
  69         {
  70         if (ctx == NULL)
  71                 return 0;
  72         OPENSSL_free(ctx->srp_ctx.login);
  73         BN_free(ctx->srp_ctx.N);
  74         BN_free(ctx->srp_ctx.g);
  75         BN_free(ctx->srp_ctx.s);
  76         BN_free(ctx->srp_ctx.B);
  77         BN_free(ctx->srp_ctx.A);
  78         BN_free(ctx->srp_ctx.a);
  79         BN_free(ctx->srp_ctx.b);
  80         BN_free(ctx->srp_ctx.v);
  81         ctx->srp_ctx.TLS_ext_srp_username_callback = NULL;
  82         ctx->srp_ctx.SRP_cb_arg = NULL;
  83         ctx->srp_ctx.SRP_verify_param_callback = NULL;
  84         ctx->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
  85         ctx->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = NULL;
  86         ctx->srp_ctx.N = NULL;
  87         ctx->srp_ctx.g = NULL;
  88         ctx->srp_ctx.s = NULL;
  89         ctx->srp_ctx.B = NULL;
  90         ctx->srp_ctx.A = NULL;
  91         ctx->srp_ctx.a = NULL;
  92         ctx->srp_ctx.b = NULL;
  93         ctx->srp_ctx.v = NULL;
  94         ctx->srp_ctx.login = NULL;
  95         ctx->srp_ctx.info = NULL;
  96         ctx->srp_ctx.strength = SRP_MINIMAL_N;
  97         ctx->srp_ctx.srp_Mask = 0;
  98         return (1);
  99         }
 100
 101 int SSL_SRP_CTX_free(struct ssl_st *s)
 102         {
 103         if (s == NULL)
 104                 return 0;
 105         OPENSSL_free(s->srp_ctx.login);
 106         BN_free(s->srp_ctx.N);
 107         BN_free(s->srp_ctx.g);
 108         BN_free(s->srp_ctx.s);
 109         BN_free(s->srp_ctx.B);
 110         BN_free(s->srp_ctx.A);
 111         BN_free(s->srp_ctx.a);
 112         BN_free(s->srp_ctx.b);
 113         BN_free(s->srp_ctx.v);
 114         s->srp_ctx.TLS_ext_srp_username_callback = NULL;
 115         s->srp_ctx.SRP_cb_arg = NULL;
 116         s->srp_ctx.SRP_verify_param_callback = NULL;
 117         s->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
 118         s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = NULL;
 119         s->srp_ctx.N = NULL;
 120         s->srp_ctx.g = NULL;
 121         s->srp_ctx.s = NULL;
 122         s->srp_ctx.B = NULL;
 123         s->srp_ctx.A = NULL;
 124         s->srp_ctx.a = NULL;
 125         s->srp_ctx.b = NULL;
 126         s->srp_ctx.v = NULL;
 127         s->srp_ctx.login = NULL;
 128         s->srp_ctx.info = NULL;
 129         s->srp_ctx.strength = SRP_MINIMAL_N;
 130         s->srp_ctx.srp_Mask = 0;
 131         return (1);
 132         }
 133
 134 int SSL_SRP_CTX_init(struct ssl_st *s)
 135         {
 136         SSL_CTX *ctx;
 137
 138         if ((s == NULL) || ((ctx = s->ctx) == NULL))
 139                 return 0;
 140         s->srp_ctx.SRP_cb_arg = ctx->srp_ctx.SRP_cb_arg;
 141         /* set client Hello login callback */
 142         s->srp_ctx.TLS_ext_srp_username_callback = ctx->srp_ctx.TLS_ext_srp_username_callback;
 143         /* set SRP N/g param callback for verification */
 144         s->srp_ctx.SRP_verify_param_callback = ctx->srp_ctx.SRP_verify_param_callback;
 145         /* set SRP client passwd callback */
 146         s->srp_ctx.SRP_give_srp_client_pwd_callback = ctx->srp_ctx.SRP_give_srp_client_pwd_callback;
 147         s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = ctx->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback;
 148
 149         s->srp_ctx.N = NULL;
 150         s->srp_ctx.g = NULL;
 151         s->srp_ctx.s = NULL;
 152         s->srp_ctx.B = NULL;
 153         s->srp_ctx.A = NULL;
 154         s->srp_ctx.a = NULL;
 155         s->srp_ctx.b = NULL;
 156         s->srp_ctx.v = NULL;
 157         s->srp_ctx.login = NULL;
 158         s->srp_ctx.info = ctx->srp_ctx.info;
 159         s->srp_ctx.strength = ctx->srp_ctx.strength;
 160
 161         if (((ctx->srp_ctx.N != NULL) &&
 162                  ((s->srp_ctx.N = BN_dup(ctx->srp_ctx.N)) == NULL)) ||
 163                 ((ctx->srp_ctx.g != NULL) &&
 164                  ((s->srp_ctx.g = BN_dup(ctx->srp_ctx.g)) == NULL)) ||
 165                 ((ctx->srp_ctx.s != NULL) &&
 166                  ((s->srp_ctx.s = BN_dup(ctx->srp_ctx.s)) == NULL)) ||
 167                 ((ctx->srp_ctx.B != NULL) &&
 168                  ((s->srp_ctx.B = BN_dup(ctx->srp_ctx.B)) == NULL)) ||
 169                 ((ctx->srp_ctx.A != NULL) &&
 170                  ((s->srp_ctx.A = BN_dup(ctx->srp_ctx.A)) == NULL)) ||
 171                 ((ctx->srp_ctx.a != NULL) &&
 172                  ((s->srp_ctx.a = BN_dup(ctx->srp_ctx.a)) == NULL)) ||
 173                 ((ctx->srp_ctx.v != NULL) &&
 174                  ((s->srp_ctx.v = BN_dup(ctx->srp_ctx.v)) == NULL)) ||
 175                 ((ctx->srp_ctx.b != NULL) &&
 176                  ((s->srp_ctx.b = BN_dup(ctx->srp_ctx.b)) == NULL)))
 177                 {
 178                 SSLerr(SSL_F_SSL_SRP_CTX_INIT,ERR_R_BN_LIB);
 179                 goto err;
 180                 }
 181         if ((ctx->srp_ctx.login != NULL) &&
 182                 ((s->srp_ctx.login = BUF_strdup(ctx->srp_ctx.login)) == NULL))
 183                 {
 184                 SSLerr(SSL_F_SSL_SRP_CTX_INIT,ERR_R_INTERNAL_ERROR);
 185                 goto err;
 186                 }
 187         s->srp_ctx.srp_Mask = ctx->srp_ctx.srp_Mask;
 188
 189         return (1);
 190 err:
 191         OPENSSL_free(s->srp_ctx.login);
 192         BN_free(s->srp_ctx.N);
 193         BN_free(s->srp_ctx.g);
 194         BN_free(s->srp_ctx.s);
 195         BN_free(s->srp_ctx.B);
 196         BN_free(s->srp_ctx.A);
 197         BN_free(s->srp_ctx.a);
 198         BN_free(s->srp_ctx.b);
 199         BN_free(s->srp_ctx.v);
 200         return (0);
 201         }
 202
 203 int SSL_CTX_SRP_CTX_init(struct ssl_ctx_st *ctx)
 204         {
 205         if (ctx == NULL)
 206                 return 0;
 207
 208         ctx->srp_ctx.SRP_cb_arg = NULL;
 209         /* set client Hello login callback */
 210         ctx->srp_ctx.TLS_ext_srp_username_callback = NULL;
 211         /* set SRP N/g param callback for verification */
 212         ctx->srp_ctx.SRP_verify_param_callback = NULL;
 213         /* set SRP client passwd callback */
 214         ctx->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
 215         ctx->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = NULL;
 216
 217         ctx->srp_ctx.N = NULL;
 218         ctx->srp_ctx.g = NULL;
 219         ctx->srp_ctx.s = NULL;
 220         ctx->srp_ctx.B = NULL;
 221         ctx->srp_ctx.A = NULL;
 222         ctx->srp_ctx.a = NULL;
 223         ctx->srp_ctx.b = NULL;
 224         ctx->srp_ctx.v = NULL;
 225         ctx->srp_ctx.login = NULL;
 226         ctx->srp_ctx.srp_Mask = 0;
 227         ctx->srp_ctx.info = NULL;
 228         ctx->srp_ctx.strength = SRP_MINIMAL_N;
 229
 230         return (1);
 231         }
 232
 233 /* server side */
 234 int SSL_srp_server_param_with_username(SSL *s, int *ad)
 235         {
 236         unsigned char b[SSL_MAX_MASTER_KEY_LENGTH];
 237         int al;
 238
 239         *ad = SSL_AD_UNKNOWN_SRP_USERNAME;
 240         if ((s->srp_ctx.TLS_ext_srp_username_callback !=NULL) &&
 241                 ((al = s->srp_ctx.TLS_ext_srp_username_callback(s, ad, s->srp_ctx.SRP_cb_arg))!=SSL_ERROR_NONE))
 242                         return al;
 243
 244         *ad = SSL_AD_INTERNAL_ERROR;
 245         if ((s->srp_ctx.N == NULL) ||
 246                 (s->srp_ctx.g == NULL) ||
 247                 (s->srp_ctx.s == NULL) ||
 248                 (s->srp_ctx.v == NULL))
 249                 return SSL3_AL_FATAL;
 250
 251         if (RAND_bytes(b, sizeof(b)) <= 0)
 252                 return SSL3_AL_FATAL;
 253         s->srp_ctx.b = BN_bin2bn(b,sizeof(b),NULL);
 254         OPENSSL_cleanse(b,sizeof(b));
 255
 256         /* Calculate:  B = (kv + g^b) % N  */
 257
 258         return ((s->srp_ctx.B = SRP_Calc_B(s->srp_ctx.b, s->srp_ctx.N, s->srp_ctx.g, s->srp_ctx.v)) != NULL)?
 259                         SSL_ERROR_NONE:SSL3_AL_FATAL;
 260         }
 261
 262 /* If the server just has the raw password, make up a verifier entry on the fly */
 263 int SSL_set_srp_server_param_pw(SSL *s, const char *user, const char *pass, const char *grp)
 264         {
 265         SRP_gN *GN = SRP_get_default_gN(grp);
 266         if(GN == NULL) return -1;
 267         s->srp_ctx.N = BN_dup(GN->N);
 268         s->srp_ctx.g = BN_dup(GN->g);
 269         if(s->srp_ctx.v != NULL)
 270                 {
 271                 BN_clear_free(s->srp_ctx.v);
 272                 s->srp_ctx.v = NULL;
 273                 }
 274         if(s->srp_ctx.s != NULL)
 275                 {
 276                 BN_clear_free(s->srp_ctx.s);
 277                 s->srp_ctx.s = NULL;
 278                 }
 279         if(!SRP_create_verifier_BN(user, pass, &s->srp_ctx.s, &s->srp_ctx.v, GN->N, GN->g)) return -1;
 280
 281         return 1;
 282         }
 283
 284 int SSL_set_srp_server_param(SSL *s, const BIGNUM *N, const BIGNUM *g,
 285                              BIGNUM *sa, BIGNUM *v, char *info)
 286         {
 287         if (N!= NULL)
 288                 {
 289                 if (s->srp_ctx.N != NULL)
 290                         {
 291                         if (!BN_copy(s->srp_ctx.N,N))
 292                                 {
 293                                 BN_free(s->srp_ctx.N);
 294                                 s->srp_ctx.N = NULL;
 295                                 }
 296                         }
 297                 else
 298                         s->srp_ctx.N = BN_dup(N);
 299                 }
 300         if (g!= NULL)
 301                 {
 302                 if (s->srp_ctx.g != NULL)
 303                         {
 304                         if (!BN_copy(s->srp_ctx.g,g))
 305                                 {
 306                                 BN_free(s->srp_ctx.g);
 307                                 s->srp_ctx.g = NULL;
 308                                 }
 309                         }
 310                 else
 311                         s->srp_ctx.g = BN_dup(g);
 312                 }
 313         if (sa!= NULL)
 314                 {
 315                 if (s->srp_ctx.s != NULL)
 316                         {
 317                         if (!BN_copy(s->srp_ctx.s,sa))
 318                                 {
 319                                 BN_free(s->srp_ctx.s);
 320                                 s->srp_ctx.s = NULL;
 321                                 }
 322                         }
 323                 else
 324                         s->srp_ctx.s = BN_dup(sa);
 325                 }
 326         if (v!= NULL)
 327                 {
 328                 if (s->srp_ctx.v != NULL)
 329                         {
 330                         if (!BN_copy(s->srp_ctx.v,v))
 331                                 {
 332                                 BN_free(s->srp_ctx.v);
 333                                 s->srp_ctx.v = NULL;
 334                                 }
 335                         }
 336                 else
 337                         s->srp_ctx.v = BN_dup(v);
 338                 }
 339         s->srp_ctx.info = info;
 340
 341         if (!(s->srp_ctx.N) ||
 342                 !(s->srp_ctx.g) ||
 343                 !(s->srp_ctx.s) ||
 344                 !(s->srp_ctx.v))
 345                 return -1;
 346
 347         return 1;
 348         }
 349
 350 int SRP_generate_server_master_secret(SSL *s,unsigned char *master_key)
 351         {
 352         BIGNUM *K = NULL, *u = NULL;
 353         int ret = -1, tmp_len;
 354         unsigned char *tmp = NULL;
 355
 356         if (!SRP_Verify_A_mod_N(s->srp_ctx.A,s->srp_ctx.N))
 357                 goto err;
 358         if (!(u = SRP_Calc_u(s->srp_ctx.A,s->srp_ctx.B,s->srp_ctx.N)))
 359                 goto err;
 360         if (!(K = SRP_Calc_server_key(s->srp_ctx.A, s->srp_ctx.v, u, s->srp_ctx.b, s->srp_ctx.N)))
 361                 goto err;
 362
 363         tmp_len = BN_num_bytes(K);
 364         if ((tmp = OPENSSL_malloc(tmp_len)) == NULL)
 365                 goto err;
 366         BN_bn2bin(K, tmp);
 367         ret = s->method->ssl3_enc->generate_master_secret(s,master_key,tmp,tmp_len);
 368 err:
 369         if (tmp)
 370                 {
 371                 OPENSSL_cleanse(tmp,tmp_len) ;
 372                 OPENSSL_free(tmp);
 373                 }
 374         BN_clear_free(K);
 375         BN_clear_free(u);
 376         return ret;
 377         }
 378
 379 /* client side */
 380 int SRP_generate_client_master_secret(SSL *s,unsigned char *master_key)
 381         {
 382         BIGNUM *x = NULL, *u = NULL, *K = NULL;
 383         int ret = -1, tmp_len;
 384         char *passwd = NULL;
 385         unsigned char *tmp = NULL;
 386
 387         /* Checks if b % n == 0
 388          */
 389         if (SRP_Verify_B_mod_N(s->srp_ctx.B,s->srp_ctx.N)==0) goto err;
 390         if (!(u = SRP_Calc_u(s->srp_ctx.A,s->srp_ctx.B,s->srp_ctx.N))) goto err;
 391         if (s->srp_ctx.SRP_give_srp_client_pwd_callback == NULL) goto err;
 392         if (!(passwd = s->srp_ctx.SRP_give_srp_client_pwd_callback(s, s->srp_ctx.SRP_cb_arg))) goto err;
 393         if (!(x = SRP_Calc_x(s->srp_ctx.s,s->srp_ctx.login,passwd))) goto err;
 394         if (!(K = SRP_Calc_client_key(s->srp_ctx.N, s->srp_ctx.B, s->srp_ctx.g, x, s->srp_ctx.a, u))) goto err;
 395
 396         tmp_len = BN_num_bytes(K);
 397         if ((tmp = OPENSSL_malloc(tmp_len)) == NULL) goto err;
 398         BN_bn2bin(K, tmp);
 399         ret = s->method->ssl3_enc->generate_master_secret(s,master_key,tmp,tmp_len);
 400 err:
 401         if (tmp)
 402                 {
 403                 OPENSSL_cleanse(tmp,tmp_len) ;
 404                 OPENSSL_free(tmp);
 405                 }
 406         BN_clear_free(K);
 407         BN_clear_free(x);
 408         if (passwd)
 409                 {
 410                 OPENSSL_cleanse(passwd,strlen(passwd)) ;
 411                 OPENSSL_free(passwd);
 412                 }
 413         BN_clear_free(u);
 414         return ret;
 415         }
 416
 417 int SRP_Calc_A_param(SSL *s)
 418         {
 419         unsigned char rnd[SSL_MAX_MASTER_KEY_LENGTH];
 420
 421         if (BN_num_bits(s->srp_ctx.N) < s->srp_ctx.strength)
 422                 return 0;
 423
 424         if (s->srp_ctx.SRP_verify_param_callback ==NULL &&
 425                 !SRP_check_known_gN_param(s->srp_ctx.g,s->srp_ctx.N))
 426                 return 0;
 427
 428         if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
 429                 return 0;
 430         s->srp_ctx.a = BN_bin2bn(rnd,sizeof(rnd), s->srp_ctx.a);
 431         OPENSSL_cleanse(rnd,sizeof(rnd));
 432
 433         if (!(s->srp_ctx.A = SRP_Calc_A(s->srp_ctx.a,s->srp_ctx.N,s->srp_ctx.g)))
 434                 return 0;
 435
 436         /* We can have a callback to verify SRP param!! */
 437         if (s->srp_ctx.SRP_verify_param_callback !=NULL)
 438                 return s->srp_ctx.SRP_verify_param_callback(s,s->srp_ctx.SRP_cb_arg);
 439
 440         return 1;
 441         }
 442
 443 int SRP_have_to_put_srp_username(SSL *s)
 444         {
 445         if (s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback == NULL)
 446                 return 0;
 447         if ((s->srp_ctx.login = s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback(s,s->srp_ctx.SRP_cb_arg)) == NULL)
 448                 return 0;
 449         s->srp_ctx.srp_Mask|=SSL_kSRP;
 450         return 1;
 451         }
 452
 453 BIGNUM *SSL_get_srp_g(SSL *s)
 454         {
 455         if (s->srp_ctx.g != NULL)
 456                 return s->srp_ctx.g;
 457         return s->ctx->srp_ctx.g;
 458         }
 459
 460 BIGNUM *SSL_get_srp_N(SSL *s)
 461         {
 462         if (s->srp_ctx.N != NULL)
 463                 return s->srp_ctx.N;
 464         return s->ctx->srp_ctx.N;
 465         }
 466
 467 char *SSL_get_srp_username(SSL *s)
 468         {
 469         if (s->srp_ctx.login != NULL)
 470                 return s->srp_ctx.login;
 471         return s->ctx->srp_ctx.login;
 472         }
 473
 474 char *SSL_get_srp_userinfo(SSL *s)
 475         {
 476         if (s->srp_ctx.info != NULL)
 477                 return s->srp_ctx.info;
 478         return s->ctx->srp_ctx.info;
 479         }
 480
 481 #define tls1_ctx_ctrl ssl3_ctx_ctrl
 482 #define tls1_ctx_callback_ctrl ssl3_ctx_callback_ctrl
 483
 484 int SSL_CTX_set_srp_username(SSL_CTX *ctx,char *name)
 485         {
 486         return tls1_ctx_ctrl(ctx,SSL_CTRL_SET_TLS_EXT_SRP_USERNAME,0,name);
 487         }
 488
 489 int SSL_CTX_set_srp_password(SSL_CTX *ctx,char *password)
 490         {
 491         return tls1_ctx_ctrl(ctx,SSL_CTRL_SET_TLS_EXT_SRP_PASSWORD,0,password);
 492         }
 493
 494 int SSL_CTX_set_srp_strength(SSL_CTX *ctx, int strength)
 495         {
 496         return tls1_ctx_ctrl(ctx, SSL_CTRL_SET_TLS_EXT_SRP_STRENGTH, strength,
 497                              NULL);
 498         }
 499
 500 int SSL_CTX_set_srp_verify_param_callback(SSL_CTX *ctx, int (*cb)(SSL *,void *))
 501         {
 502         return tls1_ctx_callback_ctrl(ctx,SSL_CTRL_SET_SRP_VERIFY_PARAM_CB,
 503                                       (void (*)(void))cb);
 504         }
 505
 506 int SSL_CTX_set_srp_cb_arg(SSL_CTX *ctx, void *arg)
 507         {
 508         return tls1_ctx_ctrl(ctx,SSL_CTRL_SET_SRP_ARG,0,arg);
 509         }
 510
 511 int SSL_CTX_set_srp_username_callback(SSL_CTX *ctx,
 512                                       int (*cb)(SSL *,int *,void *))
 513         {
 514         return tls1_ctx_callback_ctrl(ctx,SSL_CTRL_SET_TLS_EXT_SRP_USERNAME_CB,
 515                                       (void (*)(void))cb);
 516         }
 517
 518 int SSL_CTX_set_srp_client_pwd_callback(SSL_CTX *ctx, char *(*cb)(SSL *,void *))
 519         {
 520         return tls1_ctx_callback_ctrl(ctx,SSL_CTRL_SET_SRP_GIVE_CLIENT_PWD_CB,
 521                                       (void (*)(void))cb);
 522         }
 523
 524 int SSL_CTX_set_srp_missing_srp_username_callback(SSL_CTX *ctx,
 525                                                   char *(*cb)(SSL *,void *))
 526         {
 527         return tls1_ctx_callback_ctrl(ctx,
 528                             SSL_CTRL_SET_TLS_EXT_SRP_MISSING_CLIENT_USERNAME_CB,
 529                                       (void (*)(void))cb);
 530         }
 531 #endif