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      1 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com)
      2  * All rights reserved.
      3  *
      4  * This package is an SSL implementation written
      5  * by Eric Young (eay (at) cryptsoft.com).
      6  * The implementation was written so as to conform with Netscapes SSL.
      7  *
      8  * This library is free for commercial and non-commercial use as long as
      9  * the following conditions are aheared to.  The following conditions
     10  * apply to all code found in this distribution, be it the RC4, RSA,
     11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
     12  * included with this distribution is covered by the same copyright terms
     13  * except that the holder is Tim Hudson (tjh (at) cryptsoft.com).
     14  *
     15  * Copyright remains Eric Young's, and as such any Copyright notices in
     16  * the code are not to be removed.
     17  * If this package is used in a product, Eric Young should be given attribution
     18  * as the author of the parts of the library used.
     19  * This can be in the form of a textual message at program startup or
     20  * in documentation (online or textual) provided with the package.
     21  *
     22  * Redistribution and use in source and binary forms, with or without
     23  * modification, are permitted provided that the following conditions
     24  * are met:
     25  * 1. Redistributions of source code must retain the copyright
     26  *    notice, this list of conditions and the following disclaimer.
     27  * 2. Redistributions in binary form must reproduce the above copyright
     28  *    notice, this list of conditions and the following disclaimer in the
     29  *    documentation and/or other materials provided with the distribution.
     30  * 3. All advertising materials mentioning features or use of this software
     31  *    must display the following acknowledgement:
     32  *    "This product includes cryptographic software written by
     33  *     Eric Young (eay (at) cryptsoft.com)"
     34  *    The word 'cryptographic' can be left out if the rouines from the library
     35  *    being used are not cryptographic related :-).
     36  * 4. If you include any Windows specific code (or a derivative thereof) from
     37  *    the apps directory (application code) you must include an acknowledgement:
     38  *    "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)"
     39  *
     40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
     41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     50  * SUCH DAMAGE.
     51  *
     52  * The licence and distribution terms for any publically available version or
     53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
     54  * copied and put under another distribution licence
     55  * [including the GNU Public Licence.]
     56  */
     57 /* ====================================================================
     58  * Copyright (c) 1998-2007 The OpenSSL Project.  All rights reserved.
     59  *
     60  * Redistribution and use in source and binary forms, with or without
     61  * modification, are permitted provided that the following conditions
     62  * are met:
     63  *
     64  * 1. Redistributions of source code must retain the above copyright
     65  *    notice, this list of conditions and the following disclaimer.
     66  *
     67  * 2. Redistributions in binary form must reproduce the above copyright
     68  *    notice, this list of conditions and the following disclaimer in
     69  *    the documentation and/or other materials provided with the
     70  *    distribution.
     71  *
     72  * 3. All advertising materials mentioning features or use of this
     73  *    software must display the following acknowledgment:
     74  *    "This product includes software developed by the OpenSSL Project
     75  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
     76  *
     77  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
     78  *    endorse or promote products derived from this software without
     79  *    prior written permission. For written permission, please contact
     80  *    openssl-core (at) openssl.org.
     81  *
     82  * 5. Products derived from this software may not be called "OpenSSL"
     83  *    nor may "OpenSSL" appear in their names without prior written
     84  *    permission of the OpenSSL Project.
     85  *
     86  * 6. Redistributions of any form whatsoever must retain the following
     87  *    acknowledgment:
     88  *    "This product includes software developed by the OpenSSL Project
     89  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
     90  *
     91  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
     92  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     93  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     94  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
     95  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     96  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     97  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     98  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     99  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    100  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    101  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
    102  * OF THE POSSIBILITY OF SUCH DAMAGE.
    103  * ====================================================================
    104  *
    105  * This product includes cryptographic software written by Eric Young
    106  * (eay (at) cryptsoft.com).  This product includes software written by Tim
    107  * Hudson (tjh (at) cryptsoft.com).
    108  *
    109  */
    110 /* ====================================================================
    111  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
    112  *
    113  * Portions of the attached software ("Contribution") are developed by
    114  * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
    115  *
    116  * The Contribution is licensed pursuant to the OpenSSL open source
    117  * license provided above.
    118  *
    119  * ECC cipher suite support in OpenSSL originally written by
    120  * Vipul Gupta and Sumit Gupta of Sun Microsystems Laboratories.
    121  *
    122  */
    123 /* ====================================================================
    124  * Copyright 2005 Nokia. All rights reserved.
    125  *
    126  * The portions of the attached software ("Contribution") is developed by
    127  * Nokia Corporation and is licensed pursuant to the OpenSSL open source
    128  * license.
    129  *
    130  * The Contribution, originally written by Mika Kousa and Pasi Eronen of
    131  * Nokia Corporation, consists of the "PSK" (Pre-Shared Key) ciphersuites
    132  * support (see RFC 4279) to OpenSSL.
    133  *
    134  * No patent licenses or other rights except those expressly stated in
    135  * the OpenSSL open source license shall be deemed granted or received
    136  * expressly, by implication, estoppel, or otherwise.
    137  *
    138  * No assurances are provided by Nokia that the Contribution does not
    139  * infringe the patent or other intellectual property rights of any third
    140  * party or that the license provides you with all the necessary rights
    141  * to make use of the Contribution.
    142  *
    143  * THE SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. IN
    144  * ADDITION TO THE DISCLAIMERS INCLUDED IN THE LICENSE, NOKIA
    145  * SPECIFICALLY DISCLAIMS ANY LIABILITY FOR CLAIMS BROUGHT BY YOU OR ANY
    146  * OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
    147  * OTHERWISE. */
    148 
    149 #include <openssl/ssl.h>
    150 
    151 #include <assert.h>
    152 #include <string.h>
    153 
    154 #include <openssl/bn.h>
    155 #include <openssl/buf.h>
    156 #include <openssl/bytestring.h>
    157 #include <openssl/cipher.h>
    158 #include <openssl/ec.h>
    159 #include <openssl/ecdsa.h>
    160 #include <openssl/err.h>
    161 #include <openssl/evp.h>
    162 #include <openssl/hmac.h>
    163 #include <openssl/md5.h>
    164 #include <openssl/mem.h>
    165 #include <openssl/nid.h>
    166 #include <openssl/rand.h>
    167 #include <openssl/x509.h>
    168 
    169 #include "internal.h"
    170 #include "../crypto/internal.h"
    171 
    172 
    173 namespace bssl {
    174 
    175 enum ssl_server_hs_state_t {
    176   state_start_accept = 0,
    177   state_read_client_hello,
    178   state_select_certificate,
    179   state_tls13,
    180   state_select_parameters,
    181   state_send_server_hello,
    182   state_send_server_certificate,
    183   state_send_server_key_exchange,
    184   state_send_server_hello_done,
    185   state_read_client_certificate,
    186   state_verify_client_certificate,
    187   state_read_client_key_exchange,
    188   state_read_client_certificate_verify,
    189   state_read_change_cipher_spec,
    190   state_process_change_cipher_spec,
    191   state_read_next_proto,
    192   state_read_channel_id,
    193   state_read_client_finished,
    194   state_send_server_finished,
    195   state_finish_server_handshake,
    196   state_done,
    197 };
    198 
    199 int ssl_client_cipher_list_contains_cipher(const SSL_CLIENT_HELLO *client_hello,
    200                                            uint16_t id) {
    201   CBS cipher_suites;
    202   CBS_init(&cipher_suites, client_hello->cipher_suites,
    203            client_hello->cipher_suites_len);
    204 
    205   while (CBS_len(&cipher_suites) > 0) {
    206     uint16_t got_id;
    207     if (!CBS_get_u16(&cipher_suites, &got_id)) {
    208       return 0;
    209     }
    210 
    211     if (got_id == id) {
    212       return 1;
    213     }
    214   }
    215 
    216   return 0;
    217 }
    218 
    219 static int negotiate_version(SSL_HANDSHAKE *hs, uint8_t *out_alert,
    220                              const SSL_CLIENT_HELLO *client_hello) {
    221   SSL *const ssl = hs->ssl;
    222   assert(!ssl->s3->have_version);
    223   CBS supported_versions, versions;
    224   if (ssl_client_hello_get_extension(client_hello, &supported_versions,
    225                                      TLSEXT_TYPE_supported_versions)) {
    226     if (!CBS_get_u8_length_prefixed(&supported_versions, &versions) ||
    227         CBS_len(&supported_versions) != 0 ||
    228         CBS_len(&versions) == 0) {
    229       OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
    230       *out_alert = SSL_AD_DECODE_ERROR;
    231       return 0;
    232     }
    233   } else {
    234     // Convert the ClientHello version to an equivalent supported_versions
    235     // extension.
    236     static const uint8_t kTLSVersions[] = {
    237         0x03, 0x03,  // TLS 1.2
    238         0x03, 0x02,  // TLS 1.1
    239         0x03, 0x01,  // TLS 1
    240         0x03, 0x00,  // SSL 3
    241     };
    242 
    243     static const uint8_t kDTLSVersions[] = {
    244         0xfe, 0xfd,  // DTLS 1.2
    245         0xfe, 0xff,  // DTLS 1.0
    246     };
    247 
    248     size_t versions_len = 0;
    249     if (SSL_is_dtls(ssl)) {
    250       if (client_hello->version <= DTLS1_2_VERSION) {
    251         versions_len = 4;
    252       } else if (client_hello->version <= DTLS1_VERSION) {
    253         versions_len = 2;
    254       }
    255       CBS_init(&versions, kDTLSVersions + sizeof(kDTLSVersions) - versions_len,
    256                versions_len);
    257     } else {
    258       if (client_hello->version >= TLS1_2_VERSION) {
    259         versions_len = 8;
    260       } else if (client_hello->version >= TLS1_1_VERSION) {
    261         versions_len = 6;
    262       } else if (client_hello->version >= TLS1_VERSION) {
    263         versions_len = 4;
    264       } else if (client_hello->version >= SSL3_VERSION) {
    265         versions_len = 2;
    266       }
    267       CBS_init(&versions, kTLSVersions + sizeof(kTLSVersions) - versions_len,
    268                versions_len);
    269     }
    270   }
    271 
    272   if (!ssl_negotiate_version(hs, out_alert, &ssl->version, &versions)) {
    273     return 0;
    274   }
    275 
    276   // At this point, the connection's version is known and |ssl->version| is
    277   // fixed. Begin enforcing the record-layer version.
    278   ssl->s3->have_version = true;
    279   ssl->s3->aead_write_ctx->SetVersionIfNullCipher(ssl->version);
    280 
    281   // Handle FALLBACK_SCSV.
    282   if (ssl_client_cipher_list_contains_cipher(client_hello,
    283                                              SSL3_CK_FALLBACK_SCSV & 0xffff) &&
    284       ssl_protocol_version(ssl) < hs->max_version) {
    285     OPENSSL_PUT_ERROR(SSL, SSL_R_INAPPROPRIATE_FALLBACK);
    286     *out_alert = SSL3_AD_INAPPROPRIATE_FALLBACK;
    287     return 0;
    288   }
    289 
    290   return 1;
    291 }
    292 
    293 static UniquePtr<STACK_OF(SSL_CIPHER)> ssl_parse_client_cipher_list(
    294     const SSL_CLIENT_HELLO *client_hello) {
    295   CBS cipher_suites;
    296   CBS_init(&cipher_suites, client_hello->cipher_suites,
    297            client_hello->cipher_suites_len);
    298 
    299   UniquePtr<STACK_OF(SSL_CIPHER)> sk(sk_SSL_CIPHER_new_null());
    300   if (!sk) {
    301     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
    302     return nullptr;
    303   }
    304 
    305   while (CBS_len(&cipher_suites) > 0) {
    306     uint16_t cipher_suite;
    307 
    308     if (!CBS_get_u16(&cipher_suites, &cipher_suite)) {
    309       OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST);
    310       return nullptr;
    311     }
    312 
    313     const SSL_CIPHER *c = SSL_get_cipher_by_value(cipher_suite);
    314     if (c != NULL && !sk_SSL_CIPHER_push(sk.get(), c)) {
    315       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
    316       return nullptr;
    317     }
    318   }
    319 
    320   return sk;
    321 }
    322 
    323 // ssl_get_compatible_server_ciphers determines the key exchange and
    324 // authentication cipher suite masks compatible with the server configuration
    325 // and current ClientHello parameters of |hs|. It sets |*out_mask_k| to the key
    326 // exchange mask and |*out_mask_a| to the authentication mask.
    327 static void ssl_get_compatible_server_ciphers(SSL_HANDSHAKE *hs,
    328                                               uint32_t *out_mask_k,
    329                                               uint32_t *out_mask_a) {
    330   SSL *const ssl = hs->ssl;
    331   uint32_t mask_k = 0;
    332   uint32_t mask_a = 0;
    333 
    334   if (ssl_has_certificate(ssl)) {
    335     mask_a |= ssl_cipher_auth_mask_for_key(hs->local_pubkey.get());
    336     if (EVP_PKEY_id(hs->local_pubkey.get()) == EVP_PKEY_RSA) {
    337       mask_k |= SSL_kRSA;
    338     }
    339   }
    340 
    341   // Check for a shared group to consider ECDHE ciphers.
    342   uint16_t unused;
    343   if (tls1_get_shared_group(hs, &unused)) {
    344     mask_k |= SSL_kECDHE;
    345   }
    346 
    347   // PSK requires a server callback.
    348   if (ssl->psk_server_callback != NULL) {
    349     mask_k |= SSL_kPSK;
    350     mask_a |= SSL_aPSK;
    351   }
    352 
    353   *out_mask_k = mask_k;
    354   *out_mask_a = mask_a;
    355 }
    356 
    357 static const SSL_CIPHER *ssl3_choose_cipher(
    358     SSL_HANDSHAKE *hs, const SSL_CLIENT_HELLO *client_hello,
    359     const struct ssl_cipher_preference_list_st *server_pref) {
    360   SSL *const ssl = hs->ssl;
    361   STACK_OF(SSL_CIPHER) *prio, *allow;
    362   // in_group_flags will either be NULL, or will point to an array of bytes
    363   // which indicate equal-preference groups in the |prio| stack. See the
    364   // comment about |in_group_flags| in the |ssl_cipher_preference_list_st|
    365   // struct.
    366   const uint8_t *in_group_flags;
    367   // group_min contains the minimal index so far found in a group, or -1 if no
    368   // such value exists yet.
    369   int group_min = -1;
    370 
    371   UniquePtr<STACK_OF(SSL_CIPHER)> client_pref =
    372       ssl_parse_client_cipher_list(client_hello);
    373   if (!client_pref) {
    374     return nullptr;
    375   }
    376 
    377   if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) {
    378     prio = server_pref->ciphers;
    379     in_group_flags = server_pref->in_group_flags;
    380     allow = client_pref.get();
    381   } else {
    382     prio = client_pref.get();
    383     in_group_flags = NULL;
    384     allow = server_pref->ciphers;
    385   }
    386 
    387   uint32_t mask_k, mask_a;
    388   ssl_get_compatible_server_ciphers(hs, &mask_k, &mask_a);
    389 
    390   for (size_t i = 0; i < sk_SSL_CIPHER_num(prio); i++) {
    391     const SSL_CIPHER *c = sk_SSL_CIPHER_value(prio, i);
    392 
    393     size_t cipher_index;
    394     if (// Check if the cipher is supported for the current version.
    395         SSL_CIPHER_get_min_version(c) <= ssl_protocol_version(ssl) &&
    396         ssl_protocol_version(ssl) <= SSL_CIPHER_get_max_version(c) &&
    397         // Check the cipher is supported for the server configuration.
    398         (c->algorithm_mkey & mask_k) &&
    399         (c->algorithm_auth & mask_a) &&
    400         // Check the cipher is in the |allow| list.
    401         sk_SSL_CIPHER_find(allow, &cipher_index, c)) {
    402       if (in_group_flags != NULL && in_group_flags[i] == 1) {
    403         // This element of |prio| is in a group. Update the minimum index found
    404         // so far and continue looking.
    405         if (group_min == -1 || (size_t)group_min > cipher_index) {
    406           group_min = cipher_index;
    407         }
    408       } else {
    409         if (group_min != -1 && (size_t)group_min < cipher_index) {
    410           cipher_index = group_min;
    411         }
    412         return sk_SSL_CIPHER_value(allow, cipher_index);
    413       }
    414     }
    415 
    416     if (in_group_flags != NULL && in_group_flags[i] == 0 && group_min != -1) {
    417       // We are about to leave a group, but we found a match in it, so that's
    418       // our answer.
    419       return sk_SSL_CIPHER_value(allow, group_min);
    420     }
    421   }
    422 
    423   return nullptr;
    424 }
    425 
    426 static enum ssl_hs_wait_t do_start_accept(SSL_HANDSHAKE *hs) {
    427   ssl_do_info_callback(hs->ssl, SSL_CB_HANDSHAKE_START, 1);
    428   hs->state = state_read_client_hello;
    429   return ssl_hs_ok;
    430 }
    431 
    432 static enum ssl_hs_wait_t do_read_client_hello(SSL_HANDSHAKE *hs) {
    433   SSL *const ssl = hs->ssl;
    434 
    435   SSLMessage msg;
    436   if (!ssl->method->get_message(ssl, &msg)) {
    437     return ssl_hs_read_message;
    438   }
    439 
    440   if (!ssl_check_message_type(ssl, msg, SSL3_MT_CLIENT_HELLO)) {
    441     return ssl_hs_error;
    442   }
    443 
    444   if (ssl->handoff) {
    445     return ssl_hs_handoff;
    446   }
    447 
    448   SSL_CLIENT_HELLO client_hello;
    449   if (!ssl_client_hello_init(ssl, &client_hello, msg)) {
    450     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
    451     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
    452     return ssl_hs_error;
    453   }
    454 
    455   // Run the early callback.
    456   if (ssl->ctx->select_certificate_cb != NULL) {
    457     switch (ssl->ctx->select_certificate_cb(&client_hello)) {
    458       case ssl_select_cert_retry:
    459         return ssl_hs_certificate_selection_pending;
    460 
    461       case ssl_select_cert_error:
    462         // Connection rejected.
    463         OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
    464         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
    465         return ssl_hs_error;
    466 
    467       default:
    468         /* fallthrough */;
    469     }
    470   }
    471 
    472   // Freeze the version range after the early callback.
    473   if (!ssl_get_version_range(ssl, &hs->min_version, &hs->max_version)) {
    474     return ssl_hs_error;
    475   }
    476 
    477   uint8_t alert = SSL_AD_DECODE_ERROR;
    478   if (!negotiate_version(hs, &alert, &client_hello)) {
    479     ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
    480     return ssl_hs_error;
    481   }
    482 
    483   hs->client_version = client_hello.version;
    484   if (client_hello.random_len != SSL3_RANDOM_SIZE) {
    485     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    486     return ssl_hs_error;
    487   }
    488   OPENSSL_memcpy(ssl->s3->client_random, client_hello.random,
    489                  client_hello.random_len);
    490 
    491   // Only null compression is supported. TLS 1.3 further requires the peer
    492   // advertise no other compression.
    493   if (OPENSSL_memchr(client_hello.compression_methods, 0,
    494                      client_hello.compression_methods_len) == NULL ||
    495       (ssl_protocol_version(ssl) >= TLS1_3_VERSION &&
    496        client_hello.compression_methods_len != 1)) {
    497     OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_COMPRESSION_LIST);
    498     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
    499     return ssl_hs_error;
    500   }
    501 
    502   // TLS extensions.
    503   if (!ssl_parse_clienthello_tlsext(hs, &client_hello)) {
    504     OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
    505     return ssl_hs_error;
    506   }
    507 
    508   hs->state = state_select_certificate;
    509   return ssl_hs_ok;
    510 }
    511 
    512 static enum ssl_hs_wait_t do_select_certificate(SSL_HANDSHAKE *hs) {
    513   SSL *const ssl = hs->ssl;
    514 
    515   SSLMessage msg;
    516   if (!ssl->method->get_message(ssl, &msg)) {
    517     return ssl_hs_read_message;
    518   }
    519 
    520   // Call |cert_cb| to update server certificates if required.
    521   if (ssl->cert->cert_cb != NULL) {
    522     int rv = ssl->cert->cert_cb(ssl, ssl->cert->cert_cb_arg);
    523     if (rv == 0) {
    524       OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_CB_ERROR);
    525       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
    526       return ssl_hs_error;
    527     }
    528     if (rv < 0) {
    529       return ssl_hs_x509_lookup;
    530     }
    531   }
    532 
    533   if (!ssl_on_certificate_selected(hs)) {
    534     return ssl_hs_error;
    535   }
    536 
    537   if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
    538     // Jump to the TLS 1.3 state machine.
    539     hs->state = state_tls13;
    540     return ssl_hs_ok;
    541   }
    542 
    543   SSL_CLIENT_HELLO client_hello;
    544   if (!ssl_client_hello_init(ssl, &client_hello, msg)) {
    545     return ssl_hs_error;
    546   }
    547 
    548   // Negotiate the cipher suite. This must be done after |cert_cb| so the
    549   // certificate is finalized.
    550   hs->new_cipher =
    551       ssl3_choose_cipher(hs, &client_hello, ssl_get_cipher_preferences(ssl));
    552   if (hs->new_cipher == NULL) {
    553     OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_CIPHER);
    554     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
    555     return ssl_hs_error;
    556   }
    557 
    558   hs->state = state_select_parameters;
    559   return ssl_hs_ok;
    560 }
    561 
    562 static enum ssl_hs_wait_t do_tls13(SSL_HANDSHAKE *hs) {
    563   enum ssl_hs_wait_t wait = tls13_server_handshake(hs);
    564   if (wait == ssl_hs_ok) {
    565     hs->state = state_finish_server_handshake;
    566     return ssl_hs_ok;
    567   }
    568 
    569   return wait;
    570 }
    571 
    572 static enum ssl_hs_wait_t do_select_parameters(SSL_HANDSHAKE *hs) {
    573   SSL *const ssl = hs->ssl;
    574 
    575   SSLMessage msg;
    576   if (!ssl->method->get_message(ssl, &msg)) {
    577     return ssl_hs_read_message;
    578   }
    579 
    580   SSL_CLIENT_HELLO client_hello;
    581   if (!ssl_client_hello_init(ssl, &client_hello, msg)) {
    582     return ssl_hs_error;
    583   }
    584 
    585   // Determine whether we are doing session resumption.
    586   UniquePtr<SSL_SESSION> session;
    587   bool tickets_supported = false, renew_ticket = false;
    588   enum ssl_hs_wait_t wait = ssl_get_prev_session(
    589       ssl, &session, &tickets_supported, &renew_ticket, &client_hello);
    590   if (wait != ssl_hs_ok) {
    591     return wait;
    592   }
    593 
    594   if (session) {
    595     if (session->extended_master_secret && !hs->extended_master_secret) {
    596       // A ClientHello without EMS that attempts to resume a session with EMS
    597       // is fatal to the connection.
    598       OPENSSL_PUT_ERROR(SSL, SSL_R_RESUMED_EMS_SESSION_WITHOUT_EMS_EXTENSION);
    599       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
    600       return ssl_hs_error;
    601     }
    602 
    603     if (!ssl_session_is_resumable(hs, session.get()) ||
    604         // If the client offers the EMS extension, but the previous session
    605         // didn't use it, then negotiate a new session.
    606         hs->extended_master_secret != session->extended_master_secret) {
    607       session.reset();
    608     }
    609   }
    610 
    611   if (session) {
    612     // Use the old session.
    613     hs->ticket_expected = renew_ticket;
    614     ssl->session = session.release();
    615     ssl->s3->session_reused = true;
    616   } else {
    617     hs->ticket_expected = tickets_supported;
    618     ssl_set_session(ssl, NULL);
    619     if (!ssl_get_new_session(hs, 1 /* server */)) {
    620       return ssl_hs_error;
    621     }
    622 
    623     // Clear the session ID if we want the session to be single-use.
    624     if (!(ssl->ctx->session_cache_mode & SSL_SESS_CACHE_SERVER)) {
    625       hs->new_session->session_id_length = 0;
    626     }
    627   }
    628 
    629   if (ssl->ctx->dos_protection_cb != NULL &&
    630       ssl->ctx->dos_protection_cb(&client_hello) == 0) {
    631     // Connection rejected for DOS reasons.
    632     OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
    633     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
    634     return ssl_hs_error;
    635   }
    636 
    637   if (ssl->session == NULL) {
    638     hs->new_session->cipher = hs->new_cipher;
    639 
    640     // Determine whether to request a client certificate.
    641     hs->cert_request = !!(ssl->verify_mode & SSL_VERIFY_PEER);
    642     // Only request a certificate if Channel ID isn't negotiated.
    643     if ((ssl->verify_mode & SSL_VERIFY_PEER_IF_NO_OBC) &&
    644         ssl->s3->tlsext_channel_id_valid) {
    645       hs->cert_request = false;
    646     }
    647     // CertificateRequest may only be sent in certificate-based ciphers.
    648     if (!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
    649       hs->cert_request = false;
    650     }
    651 
    652     if (!hs->cert_request) {
    653       // OpenSSL returns X509_V_OK when no certificates are requested. This is
    654       // classed by them as a bug, but it's assumed by at least NGINX.
    655       hs->new_session->verify_result = X509_V_OK;
    656     }
    657   }
    658 
    659   // HTTP/2 negotiation depends on the cipher suite, so ALPN negotiation was
    660   // deferred. Complete it now.
    661   uint8_t alert = SSL_AD_DECODE_ERROR;
    662   if (!ssl_negotiate_alpn(hs, &alert, &client_hello)) {
    663     ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
    664     return ssl_hs_error;
    665   }
    666 
    667   // Now that all parameters are known, initialize the handshake hash and hash
    668   // the ClientHello.
    669   if (!hs->transcript.InitHash(ssl_protocol_version(ssl), hs->new_cipher) ||
    670       !ssl_hash_message(hs, msg)) {
    671     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
    672     return ssl_hs_error;
    673   }
    674 
    675   // Release the handshake buffer if client authentication isn't required.
    676   if (!hs->cert_request) {
    677     hs->transcript.FreeBuffer();
    678   }
    679 
    680   ssl->method->next_message(ssl);
    681 
    682   hs->state = state_send_server_hello;
    683   return ssl_hs_ok;
    684 }
    685 
    686 static enum ssl_hs_wait_t do_send_server_hello(SSL_HANDSHAKE *hs) {
    687   SSL *const ssl = hs->ssl;
    688 
    689   // We only accept ChannelIDs on connections with ECDHE in order to avoid a
    690   // known attack while we fix ChannelID itself.
    691   if (ssl->s3->tlsext_channel_id_valid &&
    692       (hs->new_cipher->algorithm_mkey & SSL_kECDHE) == 0) {
    693     ssl->s3->tlsext_channel_id_valid = false;
    694   }
    695 
    696   // If this is a resumption and the original handshake didn't support
    697   // ChannelID then we didn't record the original handshake hashes in the
    698   // session and so cannot resume with ChannelIDs.
    699   if (ssl->session != NULL &&
    700       ssl->session->original_handshake_hash_len == 0) {
    701     ssl->s3->tlsext_channel_id_valid = false;
    702   }
    703 
    704   struct OPENSSL_timeval now;
    705   ssl_get_current_time(ssl, &now);
    706   ssl->s3->server_random[0] = now.tv_sec >> 24;
    707   ssl->s3->server_random[1] = now.tv_sec >> 16;
    708   ssl->s3->server_random[2] = now.tv_sec >> 8;
    709   ssl->s3->server_random[3] = now.tv_sec;
    710   if (!RAND_bytes(ssl->s3->server_random + 4, SSL3_RANDOM_SIZE - 4)) {
    711     return ssl_hs_error;
    712   }
    713 
    714   // Implement the TLS 1.3 anti-downgrade feature, but with a different value.
    715   //
    716   // For draft TLS 1.3 versions, it is not safe to deploy this feature. However,
    717   // some TLS terminators are non-compliant and copy the origin server's value,
    718   // so we wish to measure eventual compatibility impact.
    719   if (hs->max_version >= TLS1_3_VERSION) {
    720     OPENSSL_memcpy(ssl->s3->server_random + SSL3_RANDOM_SIZE -
    721                        sizeof(kDraftDowngradeRandom),
    722                    kDraftDowngradeRandom, sizeof(kDraftDowngradeRandom));
    723   }
    724 
    725   const SSL_SESSION *session = hs->new_session.get();
    726   if (ssl->session != NULL) {
    727     session = ssl->session;
    728   }
    729 
    730   ScopedCBB cbb;
    731   CBB body, session_id;
    732   if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) ||
    733       !CBB_add_u16(&body, ssl->version) ||
    734       !CBB_add_bytes(&body, ssl->s3->server_random, SSL3_RANDOM_SIZE) ||
    735       !CBB_add_u8_length_prefixed(&body, &session_id) ||
    736       !CBB_add_bytes(&session_id, session->session_id,
    737                      session->session_id_length) ||
    738       !CBB_add_u16(&body, ssl_cipher_get_value(hs->new_cipher)) ||
    739       !CBB_add_u8(&body, 0 /* no compression */) ||
    740       !ssl_add_serverhello_tlsext(hs, &body) ||
    741       !ssl_add_message_cbb(ssl, cbb.get())) {
    742     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    743     return ssl_hs_error;
    744   }
    745 
    746   if (ssl->session != NULL) {
    747     hs->state = state_send_server_finished;
    748   } else {
    749     hs->state = state_send_server_certificate;
    750   }
    751   return ssl_hs_ok;
    752 }
    753 
    754 static enum ssl_hs_wait_t do_send_server_certificate(SSL_HANDSHAKE *hs) {
    755   SSL *const ssl = hs->ssl;
    756   ScopedCBB cbb;
    757 
    758   if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
    759     if (!ssl_has_certificate(ssl)) {
    760       OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET);
    761       return ssl_hs_error;
    762     }
    763 
    764     if (!ssl_output_cert_chain(ssl)) {
    765       return ssl_hs_error;
    766     }
    767 
    768     if (hs->certificate_status_expected) {
    769       CBB body, ocsp_response;
    770       if (!ssl->method->init_message(ssl, cbb.get(), &body,
    771                                      SSL3_MT_CERTIFICATE_STATUS) ||
    772           !CBB_add_u8(&body, TLSEXT_STATUSTYPE_ocsp) ||
    773           !CBB_add_u24_length_prefixed(&body, &ocsp_response) ||
    774           !CBB_add_bytes(&ocsp_response,
    775                          CRYPTO_BUFFER_data(ssl->cert->ocsp_response),
    776                          CRYPTO_BUFFER_len(ssl->cert->ocsp_response)) ||
    777           !ssl_add_message_cbb(ssl, cbb.get())) {
    778         OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    779         return ssl_hs_error;
    780       }
    781     }
    782   }
    783 
    784   // Assemble ServerKeyExchange parameters if needed.
    785   uint32_t alg_k = hs->new_cipher->algorithm_mkey;
    786   uint32_t alg_a = hs->new_cipher->algorithm_auth;
    787   if (ssl_cipher_requires_server_key_exchange(hs->new_cipher) ||
    788       ((alg_a & SSL_aPSK) && ssl->psk_identity_hint)) {
    789 
    790     // Pre-allocate enough room to comfortably fit an ECDHE public key. Prepend
    791     // the client and server randoms for the signing transcript.
    792     CBB child;
    793     if (!CBB_init(cbb.get(), SSL3_RANDOM_SIZE * 2 + 128) ||
    794         !CBB_add_bytes(cbb.get(), ssl->s3->client_random, SSL3_RANDOM_SIZE) ||
    795         !CBB_add_bytes(cbb.get(), ssl->s3->server_random, SSL3_RANDOM_SIZE)) {
    796       return ssl_hs_error;
    797     }
    798 
    799     // PSK ciphers begin with an identity hint.
    800     if (alg_a & SSL_aPSK) {
    801       size_t len =
    802           (ssl->psk_identity_hint == NULL) ? 0 : strlen(ssl->psk_identity_hint);
    803       if (!CBB_add_u16_length_prefixed(cbb.get(), &child) ||
    804           !CBB_add_bytes(&child, (const uint8_t *)ssl->psk_identity_hint,
    805                          len)) {
    806         return ssl_hs_error;
    807       }
    808     }
    809 
    810     if (alg_k & SSL_kECDHE) {
    811       // Determine the group to use.
    812       uint16_t group_id;
    813       if (!tls1_get_shared_group(hs, &group_id)) {
    814         OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    815         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
    816         return ssl_hs_error;
    817        }
    818       hs->new_session->group_id = group_id;
    819 
    820       // Set up ECDH, generate a key, and emit the public half.
    821       hs->key_share = SSLKeyShare::Create(group_id);
    822       if (!hs->key_share ||
    823           !CBB_add_u8(cbb.get(), NAMED_CURVE_TYPE) ||
    824           !CBB_add_u16(cbb.get(), group_id) ||
    825           !CBB_add_u8_length_prefixed(cbb.get(), &child) ||
    826           !hs->key_share->Offer(&child)) {
    827         return ssl_hs_error;
    828       }
    829     } else {
    830       assert(alg_k & SSL_kPSK);
    831     }
    832 
    833     if (!CBBFinishArray(cbb.get(), &hs->server_params)) {
    834       return ssl_hs_error;
    835     }
    836   }
    837 
    838   hs->state = state_send_server_key_exchange;
    839   return ssl_hs_ok;
    840 }
    841 
    842 static enum ssl_hs_wait_t do_send_server_key_exchange(SSL_HANDSHAKE *hs) {
    843   SSL *const ssl = hs->ssl;
    844 
    845   if (hs->server_params.size() == 0) {
    846     hs->state = state_send_server_hello_done;
    847     return ssl_hs_ok;
    848   }
    849 
    850   ScopedCBB cbb;
    851   CBB body, child;
    852   if (!ssl->method->init_message(ssl, cbb.get(), &body,
    853                                  SSL3_MT_SERVER_KEY_EXCHANGE) ||
    854       // |hs->server_params| contains a prefix for signing.
    855       hs->server_params.size() < 2 * SSL3_RANDOM_SIZE ||
    856       !CBB_add_bytes(&body, hs->server_params.data() + 2 * SSL3_RANDOM_SIZE,
    857                      hs->server_params.size() - 2 * SSL3_RANDOM_SIZE)) {
    858     return ssl_hs_error;
    859   }
    860 
    861   // Add a signature.
    862   if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
    863     if (!ssl_has_private_key(ssl)) {
    864       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
    865       return ssl_hs_error;
    866     }
    867 
    868     // Determine the signature algorithm.
    869     uint16_t signature_algorithm;
    870     if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
    871       return ssl_hs_error;
    872     }
    873     if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) {
    874       if (!CBB_add_u16(&body, signature_algorithm)) {
    875         OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    876         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
    877         return ssl_hs_error;
    878       }
    879     }
    880 
    881     // Add space for the signature.
    882     const size_t max_sig_len = EVP_PKEY_size(hs->local_pubkey.get());
    883     uint8_t *ptr;
    884     if (!CBB_add_u16_length_prefixed(&body, &child) ||
    885         !CBB_reserve(&child, &ptr, max_sig_len)) {
    886       return ssl_hs_error;
    887     }
    888 
    889     size_t sig_len;
    890     switch (ssl_private_key_sign(hs, ptr, &sig_len, max_sig_len,
    891                                  signature_algorithm, hs->server_params)) {
    892       case ssl_private_key_success:
    893         if (!CBB_did_write(&child, sig_len)) {
    894           return ssl_hs_error;
    895         }
    896         break;
    897       case ssl_private_key_failure:
    898         return ssl_hs_error;
    899       case ssl_private_key_retry:
    900         return ssl_hs_private_key_operation;
    901     }
    902   }
    903 
    904   if (!ssl_add_message_cbb(ssl, cbb.get())) {
    905     return ssl_hs_error;
    906   }
    907 
    908   hs->server_params.Reset();
    909 
    910   hs->state = state_send_server_hello_done;
    911   return ssl_hs_ok;
    912 }
    913 
    914 static enum ssl_hs_wait_t do_send_server_hello_done(SSL_HANDSHAKE *hs) {
    915   SSL *const ssl = hs->ssl;
    916 
    917   ScopedCBB cbb;
    918   CBB body;
    919 
    920   if (hs->cert_request) {
    921     CBB cert_types, sigalgs_cbb;
    922     if (!ssl->method->init_message(ssl, cbb.get(), &body,
    923                                    SSL3_MT_CERTIFICATE_REQUEST) ||
    924         !CBB_add_u8_length_prefixed(&body, &cert_types) ||
    925         !CBB_add_u8(&cert_types, SSL3_CT_RSA_SIGN) ||
    926         (ssl_protocol_version(ssl) >= TLS1_VERSION &&
    927          !CBB_add_u8(&cert_types, TLS_CT_ECDSA_SIGN)) ||
    928         (ssl_protocol_version(ssl) >= TLS1_2_VERSION &&
    929          (!CBB_add_u16_length_prefixed(&body, &sigalgs_cbb) ||
    930           !tls12_add_verify_sigalgs(ssl, &sigalgs_cbb))) ||
    931         !ssl_add_client_CA_list(ssl, &body) ||
    932         !ssl_add_message_cbb(ssl, cbb.get())) {
    933       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    934       return ssl_hs_error;
    935     }
    936   }
    937 
    938   if (!ssl->method->init_message(ssl, cbb.get(), &body,
    939                                  SSL3_MT_SERVER_HELLO_DONE) ||
    940       !ssl_add_message_cbb(ssl, cbb.get())) {
    941     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    942     return ssl_hs_error;
    943   }
    944 
    945   hs->state = state_read_client_certificate;
    946   return ssl_hs_flush;
    947 }
    948 
    949 static enum ssl_hs_wait_t do_read_client_certificate(SSL_HANDSHAKE *hs) {
    950   SSL *const ssl = hs->ssl;
    951 
    952   if (!hs->cert_request) {
    953     hs->state = state_verify_client_certificate;
    954     return ssl_hs_ok;
    955   }
    956 
    957   SSLMessage msg;
    958   if (!ssl->method->get_message(ssl, &msg)) {
    959     return ssl_hs_read_message;
    960   }
    961 
    962   if (msg.type != SSL3_MT_CERTIFICATE) {
    963     if (ssl->version == SSL3_VERSION &&
    964         msg.type == SSL3_MT_CLIENT_KEY_EXCHANGE) {
    965       // In SSL 3.0, the Certificate message is omitted to signal no
    966       // certificate.
    967       if (ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) {
    968         OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
    969         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
    970         return ssl_hs_error;
    971       }
    972 
    973       // OpenSSL returns X509_V_OK when no certificates are received. This is
    974       // classed by them as a bug, but it's assumed by at least NGINX.
    975       hs->new_session->verify_result = X509_V_OK;
    976       hs->state = state_verify_client_certificate;
    977       return ssl_hs_ok;
    978     }
    979 
    980     OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
    981     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
    982     return ssl_hs_error;
    983   }
    984 
    985   if (!ssl_hash_message(hs, msg)) {
    986     return ssl_hs_error;
    987   }
    988 
    989   CBS certificate_msg = msg.body;
    990   uint8_t alert = SSL_AD_DECODE_ERROR;
    991   UniquePtr<STACK_OF(CRYPTO_BUFFER)> chain;
    992   if (!ssl_parse_cert_chain(&alert, &chain, &hs->peer_pubkey,
    993                             ssl->retain_only_sha256_of_client_certs
    994                                 ? hs->new_session->peer_sha256
    995                                 : NULL,
    996                             &certificate_msg, ssl->ctx->pool)) {
    997     ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
    998     return ssl_hs_error;
    999   }
   1000   sk_CRYPTO_BUFFER_pop_free(hs->new_session->certs, CRYPTO_BUFFER_free);
   1001   hs->new_session->certs = chain.release();
   1002 
   1003   if (CBS_len(&certificate_msg) != 0 ||
   1004       !ssl->ctx->x509_method->session_cache_objects(hs->new_session.get())) {
   1005     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1006     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1007     return ssl_hs_error;
   1008   }
   1009 
   1010   if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) == 0) {
   1011     // No client certificate so the handshake buffer may be discarded.
   1012     hs->transcript.FreeBuffer();
   1013 
   1014     // In SSL 3.0, sending no certificate is signaled by omitting the
   1015     // Certificate message.
   1016     if (ssl->version == SSL3_VERSION) {
   1017       OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATES_RETURNED);
   1018       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
   1019       return ssl_hs_error;
   1020     }
   1021 
   1022     if (ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) {
   1023       // Fail for TLS only if we required a certificate
   1024       OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
   1025       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
   1026       return ssl_hs_error;
   1027     }
   1028 
   1029     // OpenSSL returns X509_V_OK when no certificates are received. This is
   1030     // classed by them as a bug, but it's assumed by at least NGINX.
   1031     hs->new_session->verify_result = X509_V_OK;
   1032   } else if (ssl->retain_only_sha256_of_client_certs) {
   1033     // The hash will have been filled in.
   1034     hs->new_session->peer_sha256_valid = 1;
   1035   }
   1036 
   1037   ssl->method->next_message(ssl);
   1038   hs->state = state_verify_client_certificate;
   1039   return ssl_hs_ok;
   1040 }
   1041 
   1042 static enum ssl_hs_wait_t do_verify_client_certificate(SSL_HANDSHAKE *hs) {
   1043   if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) > 0) {
   1044     switch (ssl_verify_peer_cert(hs)) {
   1045       case ssl_verify_ok:
   1046         break;
   1047       case ssl_verify_invalid:
   1048         return ssl_hs_error;
   1049       case ssl_verify_retry:
   1050         return ssl_hs_certificate_verify;
   1051     }
   1052   }
   1053 
   1054   hs->state = state_read_client_key_exchange;
   1055   return ssl_hs_ok;
   1056 }
   1057 
   1058 static enum ssl_hs_wait_t do_read_client_key_exchange(SSL_HANDSHAKE *hs) {
   1059   SSL *const ssl = hs->ssl;
   1060   SSLMessage msg;
   1061   if (!ssl->method->get_message(ssl, &msg)) {
   1062     return ssl_hs_read_message;
   1063   }
   1064 
   1065   if (!ssl_check_message_type(ssl, msg, SSL3_MT_CLIENT_KEY_EXCHANGE)) {
   1066     return ssl_hs_error;
   1067   }
   1068 
   1069   CBS client_key_exchange = msg.body;
   1070   uint32_t alg_k = hs->new_cipher->algorithm_mkey;
   1071   uint32_t alg_a = hs->new_cipher->algorithm_auth;
   1072 
   1073   // If using a PSK key exchange, parse the PSK identity.
   1074   if (alg_a & SSL_aPSK) {
   1075     CBS psk_identity;
   1076 
   1077     // If using PSK, the ClientKeyExchange contains a psk_identity. If PSK,
   1078     // then this is the only field in the message.
   1079     if (!CBS_get_u16_length_prefixed(&client_key_exchange, &psk_identity) ||
   1080         ((alg_k & SSL_kPSK) && CBS_len(&client_key_exchange) != 0)) {
   1081       OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1082       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1083       return ssl_hs_error;
   1084     }
   1085 
   1086     if (CBS_len(&psk_identity) > PSK_MAX_IDENTITY_LEN ||
   1087         CBS_contains_zero_byte(&psk_identity)) {
   1088       OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG);
   1089       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
   1090       return ssl_hs_error;
   1091     }
   1092 
   1093     if (!CBS_strdup(&psk_identity, &hs->new_session->psk_identity)) {
   1094       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
   1095       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
   1096       return ssl_hs_error;
   1097     }
   1098   }
   1099 
   1100   // Depending on the key exchange method, compute |premaster_secret|.
   1101   Array<uint8_t> premaster_secret;
   1102   if (alg_k & SSL_kRSA) {
   1103     CBS encrypted_premaster_secret;
   1104     if (ssl->version > SSL3_VERSION) {
   1105       if (!CBS_get_u16_length_prefixed(&client_key_exchange,
   1106                                        &encrypted_premaster_secret) ||
   1107           CBS_len(&client_key_exchange) != 0) {
   1108         OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1109         ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1110         return ssl_hs_error;
   1111       }
   1112     } else {
   1113       encrypted_premaster_secret = client_key_exchange;
   1114     }
   1115 
   1116     // Allocate a buffer large enough for an RSA decryption.
   1117     Array<uint8_t> decrypt_buf;
   1118     if (!decrypt_buf.Init(EVP_PKEY_size(hs->local_pubkey.get()))) {
   1119       return ssl_hs_error;
   1120     }
   1121 
   1122     // Decrypt with no padding. PKCS#1 padding will be removed as part of the
   1123     // timing-sensitive code below.
   1124     size_t decrypt_len;
   1125     switch (ssl_private_key_decrypt(hs, decrypt_buf.data(), &decrypt_len,
   1126                                     decrypt_buf.size(),
   1127                                     encrypted_premaster_secret)) {
   1128       case ssl_private_key_success:
   1129         break;
   1130       case ssl_private_key_failure:
   1131         return ssl_hs_error;
   1132       case ssl_private_key_retry:
   1133         return ssl_hs_private_key_operation;
   1134     }
   1135 
   1136     if (decrypt_len != decrypt_buf.size()) {
   1137       OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
   1138       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
   1139       return ssl_hs_error;
   1140     }
   1141 
   1142     // Prepare a random premaster, to be used on invalid padding. See RFC 5246,
   1143     // section 7.4.7.1.
   1144     if (!premaster_secret.Init(SSL_MAX_MASTER_KEY_LENGTH) ||
   1145         !RAND_bytes(premaster_secret.data(), premaster_secret.size())) {
   1146       return ssl_hs_error;
   1147     }
   1148 
   1149     // The smallest padded premaster is 11 bytes of overhead. Small keys are
   1150     // publicly invalid.
   1151     if (decrypt_len < 11 + premaster_secret.size()) {
   1152       OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
   1153       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
   1154       return ssl_hs_error;
   1155     }
   1156 
   1157     // Check the padding. See RFC 3447, section 7.2.2.
   1158     size_t padding_len = decrypt_len - premaster_secret.size();
   1159     uint8_t good = constant_time_eq_int_8(decrypt_buf[0], 0) &
   1160                    constant_time_eq_int_8(decrypt_buf[1], 2);
   1161     for (size_t i = 2; i < padding_len - 1; i++) {
   1162       good &= ~constant_time_is_zero_8(decrypt_buf[i]);
   1163     }
   1164     good &= constant_time_is_zero_8(decrypt_buf[padding_len - 1]);
   1165 
   1166     // The premaster secret must begin with |client_version|. This too must be
   1167     // checked in constant time (http://eprint.iacr.org/2003/052/).
   1168     good &= constant_time_eq_8(decrypt_buf[padding_len],
   1169                                (unsigned)(hs->client_version >> 8));
   1170     good &= constant_time_eq_8(decrypt_buf[padding_len + 1],
   1171                                (unsigned)(hs->client_version & 0xff));
   1172 
   1173     // Select, in constant time, either the decrypted premaster or the random
   1174     // premaster based on |good|.
   1175     for (size_t i = 0; i < premaster_secret.size(); i++) {
   1176       premaster_secret[i] = constant_time_select_8(
   1177           good, decrypt_buf[padding_len + i], premaster_secret[i]);
   1178     }
   1179   } else if (alg_k & SSL_kECDHE) {
   1180     // Parse the ClientKeyExchange.
   1181     CBS peer_key;
   1182     if (!CBS_get_u8_length_prefixed(&client_key_exchange, &peer_key) ||
   1183         CBS_len(&client_key_exchange) != 0) {
   1184       OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1185       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1186       return ssl_hs_error;
   1187     }
   1188 
   1189     // Compute the premaster.
   1190     uint8_t alert = SSL_AD_DECODE_ERROR;
   1191     if (!hs->key_share->Finish(&premaster_secret, &alert, peer_key)) {
   1192       ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
   1193       return ssl_hs_error;
   1194     }
   1195 
   1196     // The key exchange state may now be discarded.
   1197     hs->key_share.reset();
   1198   } else if (!(alg_k & SSL_kPSK)) {
   1199     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
   1200     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
   1201     return ssl_hs_error;
   1202   }
   1203 
   1204   // For a PSK cipher suite, the actual pre-master secret is combined with the
   1205   // pre-shared key.
   1206   if (alg_a & SSL_aPSK) {
   1207     if (ssl->psk_server_callback == NULL) {
   1208       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
   1209       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
   1210       return ssl_hs_error;
   1211     }
   1212 
   1213     // Look up the key for the identity.
   1214     uint8_t psk[PSK_MAX_PSK_LEN];
   1215     unsigned psk_len = ssl->psk_server_callback(
   1216         ssl, hs->new_session->psk_identity, psk, sizeof(psk));
   1217     if (psk_len > PSK_MAX_PSK_LEN) {
   1218       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
   1219       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
   1220       return ssl_hs_error;
   1221     } else if (psk_len == 0) {
   1222       // PSK related to the given identity not found.
   1223       OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND);
   1224       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNKNOWN_PSK_IDENTITY);
   1225       return ssl_hs_error;
   1226     }
   1227 
   1228     if (alg_k & SSL_kPSK) {
   1229       // In plain PSK, other_secret is a block of 0s with the same length as the
   1230       // pre-shared key.
   1231       if (!premaster_secret.Init(psk_len)) {
   1232         return ssl_hs_error;
   1233       }
   1234       OPENSSL_memset(premaster_secret.data(), 0, premaster_secret.size());
   1235     }
   1236 
   1237     ScopedCBB new_premaster;
   1238     CBB child;
   1239     if (!CBB_init(new_premaster.get(),
   1240                   2 + psk_len + 2 + premaster_secret.size()) ||
   1241         !CBB_add_u16_length_prefixed(new_premaster.get(), &child) ||
   1242         !CBB_add_bytes(&child, premaster_secret.data(),
   1243                        premaster_secret.size()) ||
   1244         !CBB_add_u16_length_prefixed(new_premaster.get(), &child) ||
   1245         !CBB_add_bytes(&child, psk, psk_len) ||
   1246         !CBBFinishArray(new_premaster.get(), &premaster_secret)) {
   1247       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
   1248       return ssl_hs_error;
   1249     }
   1250   }
   1251 
   1252   if (!ssl_hash_message(hs, msg)) {
   1253     return ssl_hs_error;
   1254   }
   1255 
   1256   // Compute the master secret.
   1257   hs->new_session->master_key_length = tls1_generate_master_secret(
   1258       hs, hs->new_session->master_key, premaster_secret);
   1259   if (hs->new_session->master_key_length == 0) {
   1260     return ssl_hs_error;
   1261   }
   1262   hs->new_session->extended_master_secret = hs->extended_master_secret;
   1263 
   1264   ssl->method->next_message(ssl);
   1265   hs->state = state_read_client_certificate_verify;
   1266   return ssl_hs_ok;
   1267 }
   1268 
   1269 static enum ssl_hs_wait_t do_read_client_certificate_verify(SSL_HANDSHAKE *hs) {
   1270   SSL *const ssl = hs->ssl;
   1271 
   1272   // Only RSA and ECDSA client certificates are supported, so a
   1273   // CertificateVerify is required if and only if there's a client certificate.
   1274   if (!hs->peer_pubkey) {
   1275     hs->transcript.FreeBuffer();
   1276     hs->state = state_read_change_cipher_spec;
   1277     return ssl_hs_ok;
   1278   }
   1279 
   1280   SSLMessage msg;
   1281   if (!ssl->method->get_message(ssl, &msg)) {
   1282     return ssl_hs_read_message;
   1283   }
   1284 
   1285   if (!ssl_check_message_type(ssl, msg, SSL3_MT_CERTIFICATE_VERIFY)) {
   1286     return ssl_hs_error;
   1287   }
   1288 
   1289   CBS certificate_verify = msg.body, signature;
   1290 
   1291   // Determine the signature algorithm.
   1292   uint16_t signature_algorithm = 0;
   1293   if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) {
   1294     if (!CBS_get_u16(&certificate_verify, &signature_algorithm)) {
   1295       OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1296       ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1297       return ssl_hs_error;
   1298     }
   1299     uint8_t alert = SSL_AD_DECODE_ERROR;
   1300     if (!tls12_check_peer_sigalg(ssl, &alert, signature_algorithm)) {
   1301       ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
   1302       return ssl_hs_error;
   1303     }
   1304     hs->new_session->peer_signature_algorithm = signature_algorithm;
   1305   } else if (!tls1_get_legacy_signature_algorithm(&signature_algorithm,
   1306                                                   hs->peer_pubkey.get())) {
   1307     OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_ERROR_UNSUPPORTED_CERTIFICATE_TYPE);
   1308     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_CERTIFICATE);
   1309     return ssl_hs_error;
   1310   }
   1311 
   1312   // Parse and verify the signature.
   1313   if (!CBS_get_u16_length_prefixed(&certificate_verify, &signature) ||
   1314       CBS_len(&certificate_verify) != 0) {
   1315     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1316     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1317     return ssl_hs_error;
   1318   }
   1319 
   1320   bool sig_ok;
   1321   // The SSL3 construction for CertificateVerify does not decompose into a
   1322   // single final digest and signature, and must be special-cased.
   1323   if (ssl_protocol_version(ssl) == SSL3_VERSION) {
   1324     uint8_t digest[EVP_MAX_MD_SIZE];
   1325     size_t digest_len;
   1326     if (!hs->transcript.GetSSL3CertVerifyHash(
   1327             digest, &digest_len, hs->new_session.get(), signature_algorithm)) {
   1328       return ssl_hs_error;
   1329     }
   1330 
   1331     UniquePtr<EVP_PKEY_CTX> pctx(
   1332         EVP_PKEY_CTX_new(hs->peer_pubkey.get(), nullptr));
   1333     sig_ok = pctx &&
   1334              EVP_PKEY_verify_init(pctx.get()) &&
   1335              EVP_PKEY_verify(pctx.get(), CBS_data(&signature),
   1336                              CBS_len(&signature), digest, digest_len);
   1337   } else {
   1338     sig_ok =
   1339         ssl_public_key_verify(ssl, signature, signature_algorithm,
   1340                               hs->peer_pubkey.get(), hs->transcript.buffer());
   1341   }
   1342 
   1343 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   1344   sig_ok = true;
   1345   ERR_clear_error();
   1346 #endif
   1347   if (!sig_ok) {
   1348     OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
   1349     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
   1350     return ssl_hs_error;
   1351   }
   1352 
   1353   // The handshake buffer is no longer necessary, and we may hash the current
   1354   // message.
   1355   hs->transcript.FreeBuffer();
   1356   if (!ssl_hash_message(hs, msg)) {
   1357     return ssl_hs_error;
   1358   }
   1359 
   1360   ssl->method->next_message(ssl);
   1361   hs->state = state_read_change_cipher_spec;
   1362   return ssl_hs_ok;
   1363 }
   1364 
   1365 static enum ssl_hs_wait_t do_read_change_cipher_spec(SSL_HANDSHAKE *hs) {
   1366   hs->state = state_process_change_cipher_spec;
   1367   return ssl_hs_read_change_cipher_spec;
   1368 }
   1369 
   1370 static enum ssl_hs_wait_t do_process_change_cipher_spec(SSL_HANDSHAKE *hs) {
   1371   if (!tls1_change_cipher_state(hs, evp_aead_open)) {
   1372     return ssl_hs_error;
   1373   }
   1374 
   1375   hs->state = state_read_next_proto;
   1376   return ssl_hs_ok;
   1377 }
   1378 
   1379 static enum ssl_hs_wait_t do_read_next_proto(SSL_HANDSHAKE *hs) {
   1380   SSL *const ssl = hs->ssl;
   1381 
   1382   if (!hs->next_proto_neg_seen) {
   1383     hs->state = state_read_channel_id;
   1384     return ssl_hs_ok;
   1385   }
   1386 
   1387   SSLMessage msg;
   1388   if (!ssl->method->get_message(ssl, &msg)) {
   1389     return ssl_hs_read_message;
   1390   }
   1391 
   1392   if (!ssl_check_message_type(ssl, msg, SSL3_MT_NEXT_PROTO) ||
   1393       !ssl_hash_message(hs, msg)) {
   1394     return ssl_hs_error;
   1395   }
   1396 
   1397   CBS next_protocol = msg.body, selected_protocol, padding;
   1398   if (!CBS_get_u8_length_prefixed(&next_protocol, &selected_protocol) ||
   1399       !CBS_get_u8_length_prefixed(&next_protocol, &padding) ||
   1400       CBS_len(&next_protocol) != 0) {
   1401     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
   1402     ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
   1403     return ssl_hs_error;
   1404   }
   1405 
   1406   if (!ssl->s3->next_proto_negotiated.CopyFrom(selected_protocol)) {
   1407     return ssl_hs_error;
   1408   }
   1409 
   1410   ssl->method->next_message(ssl);
   1411   hs->state = state_read_channel_id;
   1412   return ssl_hs_ok;
   1413 }
   1414 
   1415 static enum ssl_hs_wait_t do_read_channel_id(SSL_HANDSHAKE *hs) {
   1416   SSL *const ssl = hs->ssl;
   1417 
   1418   if (!ssl->s3->tlsext_channel_id_valid) {
   1419     hs->state = state_read_client_finished;
   1420     return ssl_hs_ok;
   1421   }
   1422 
   1423   SSLMessage msg;
   1424   if (!ssl->method->get_message(ssl, &msg)) {
   1425     return ssl_hs_read_message;
   1426   }
   1427 
   1428   if (!ssl_check_message_type(ssl, msg, SSL3_MT_CHANNEL_ID) ||
   1429       !tls1_verify_channel_id(hs, msg) ||
   1430       !ssl_hash_message(hs, msg)) {
   1431     return ssl_hs_error;
   1432   }
   1433 
   1434   ssl->method->next_message(ssl);
   1435   hs->state = state_read_client_finished;
   1436   return ssl_hs_ok;
   1437 }
   1438 
   1439 static enum ssl_hs_wait_t do_read_client_finished(SSL_HANDSHAKE *hs) {
   1440   SSL *const ssl = hs->ssl;
   1441   enum ssl_hs_wait_t wait = ssl_get_finished(hs);
   1442   if (wait != ssl_hs_ok) {
   1443     return wait;
   1444   }
   1445 
   1446   if (ssl->session != NULL) {
   1447     hs->state = state_finish_server_handshake;
   1448   } else {
   1449     hs->state = state_send_server_finished;
   1450   }
   1451 
   1452   // If this is a full handshake with ChannelID then record the handshake
   1453   // hashes in |hs->new_session| in case we need them to verify a
   1454   // ChannelID signature on a resumption of this session in the future.
   1455   if (ssl->session == NULL && ssl->s3->tlsext_channel_id_valid &&
   1456       !tls1_record_handshake_hashes_for_channel_id(hs)) {
   1457     return ssl_hs_error;
   1458   }
   1459 
   1460   return ssl_hs_ok;
   1461 }
   1462 
   1463 static enum ssl_hs_wait_t do_send_server_finished(SSL_HANDSHAKE *hs) {
   1464   SSL *const ssl = hs->ssl;
   1465 
   1466   if (hs->ticket_expected) {
   1467     const SSL_SESSION *session;
   1468     UniquePtr<SSL_SESSION> session_copy;
   1469     if (ssl->session == NULL) {
   1470       // Fix the timeout to measure from the ticket issuance time.
   1471       ssl_session_rebase_time(ssl, hs->new_session.get());
   1472       session = hs->new_session.get();
   1473     } else {
   1474       // We are renewing an existing session. Duplicate the session to adjust
   1475       // the timeout.
   1476       session_copy = SSL_SESSION_dup(ssl->session, SSL_SESSION_INCLUDE_NONAUTH);
   1477       if (!session_copy) {
   1478         return ssl_hs_error;
   1479       }
   1480 
   1481       ssl_session_rebase_time(ssl, session_copy.get());
   1482       session = session_copy.get();
   1483     }
   1484 
   1485     ScopedCBB cbb;
   1486     CBB body, ticket;
   1487     if (!ssl->method->init_message(ssl, cbb.get(), &body,
   1488                                    SSL3_MT_NEW_SESSION_TICKET) ||
   1489         !CBB_add_u32(&body, session->timeout) ||
   1490         !CBB_add_u16_length_prefixed(&body, &ticket) ||
   1491         !ssl_encrypt_ticket(ssl, &ticket, session) ||
   1492         !ssl_add_message_cbb(ssl, cbb.get())) {
   1493       return ssl_hs_error;
   1494     }
   1495   }
   1496 
   1497   if (!ssl->method->add_change_cipher_spec(ssl) ||
   1498       !tls1_change_cipher_state(hs, evp_aead_seal) ||
   1499       !ssl_send_finished(hs)) {
   1500     return ssl_hs_error;
   1501   }
   1502 
   1503   if (ssl->session != NULL) {
   1504     hs->state = state_read_change_cipher_spec;
   1505   } else {
   1506     hs->state = state_finish_server_handshake;
   1507   }
   1508   return ssl_hs_flush;
   1509 }
   1510 
   1511 static enum ssl_hs_wait_t do_finish_server_handshake(SSL_HANDSHAKE *hs) {
   1512   SSL *const ssl = hs->ssl;
   1513 
   1514   ssl->method->on_handshake_complete(ssl);
   1515 
   1516   // If we aren't retaining peer certificates then we can discard it now.
   1517   if (hs->new_session != NULL && ssl->retain_only_sha256_of_client_certs) {
   1518     sk_CRYPTO_BUFFER_pop_free(hs->new_session->certs, CRYPTO_BUFFER_free);
   1519     hs->new_session->certs = NULL;
   1520     ssl->ctx->x509_method->session_clear(hs->new_session.get());
   1521   }
   1522 
   1523   if (ssl->session != NULL) {
   1524     SSL_SESSION_up_ref(ssl->session);
   1525     ssl->s3->established_session.reset(ssl->session);
   1526   } else {
   1527     ssl->s3->established_session = std::move(hs->new_session);
   1528     ssl->s3->established_session->not_resumable = 0;
   1529   }
   1530 
   1531   hs->handshake_finalized = true;
   1532   ssl->s3->initial_handshake_complete = true;
   1533   ssl_update_cache(hs, SSL_SESS_CACHE_SERVER);
   1534 
   1535   hs->state = state_done;
   1536   return ssl_hs_ok;
   1537 }
   1538 
   1539 enum ssl_hs_wait_t ssl_server_handshake(SSL_HANDSHAKE *hs) {
   1540   while (hs->state != state_done) {
   1541     enum ssl_hs_wait_t ret = ssl_hs_error;
   1542     enum ssl_server_hs_state_t state =
   1543         static_cast<enum ssl_server_hs_state_t>(hs->state);
   1544     switch (state) {
   1545       case state_start_accept:
   1546         ret = do_start_accept(hs);
   1547         break;
   1548       case state_read_client_hello:
   1549         ret = do_read_client_hello(hs);
   1550         break;
   1551       case state_select_certificate:
   1552         ret = do_select_certificate(hs);
   1553         break;
   1554       case state_tls13:
   1555         ret = do_tls13(hs);
   1556         break;
   1557       case state_select_parameters:
   1558         ret = do_select_parameters(hs);
   1559         break;
   1560       case state_send_server_hello:
   1561         ret = do_send_server_hello(hs);
   1562         break;
   1563       case state_send_server_certificate:
   1564         ret = do_send_server_certificate(hs);
   1565         break;
   1566       case state_send_server_key_exchange:
   1567         ret = do_send_server_key_exchange(hs);
   1568         break;
   1569       case state_send_server_hello_done:
   1570         ret = do_send_server_hello_done(hs);
   1571         break;
   1572       case state_read_client_certificate:
   1573         ret = do_read_client_certificate(hs);
   1574         break;
   1575       case state_verify_client_certificate:
   1576         ret = do_verify_client_certificate(hs);
   1577         break;
   1578       case state_read_client_key_exchange:
   1579         ret = do_read_client_key_exchange(hs);
   1580         break;
   1581       case state_read_client_certificate_verify:
   1582         ret = do_read_client_certificate_verify(hs);
   1583         break;
   1584       case state_read_change_cipher_spec:
   1585         ret = do_read_change_cipher_spec(hs);
   1586         break;
   1587       case state_process_change_cipher_spec:
   1588         ret = do_process_change_cipher_spec(hs);
   1589         break;
   1590       case state_read_next_proto:
   1591         ret = do_read_next_proto(hs);
   1592         break;
   1593       case state_read_channel_id:
   1594         ret = do_read_channel_id(hs);
   1595         break;
   1596       case state_read_client_finished:
   1597         ret = do_read_client_finished(hs);
   1598         break;
   1599       case state_send_server_finished:
   1600         ret = do_send_server_finished(hs);
   1601         break;
   1602       case state_finish_server_handshake:
   1603         ret = do_finish_server_handshake(hs);
   1604         break;
   1605       case state_done:
   1606         ret = ssl_hs_ok;
   1607         break;
   1608     }
   1609 
   1610     if (hs->state != state) {
   1611       ssl_do_info_callback(hs->ssl, SSL_CB_ACCEPT_LOOP, 1);
   1612     }
   1613 
   1614     if (ret != ssl_hs_ok) {
   1615       return ret;
   1616     }
   1617   }
   1618 
   1619   ssl_do_info_callback(hs->ssl, SSL_CB_HANDSHAKE_DONE, 1);
   1620   return ssl_hs_ok;
   1621 }
   1622 
   1623 const char *ssl_server_handshake_state(SSL_HANDSHAKE *hs) {
   1624   enum ssl_server_hs_state_t state =
   1625       static_cast<enum ssl_server_hs_state_t>(hs->state);
   1626   switch (state) {
   1627     case state_start_accept:
   1628       return "TLS server start_accept";
   1629     case state_read_client_hello:
   1630       return "TLS server read_client_hello";
   1631     case state_select_certificate:
   1632       return "TLS server select_certificate";
   1633     case state_tls13:
   1634       return tls13_server_handshake_state(hs);
   1635     case state_select_parameters:
   1636       return "TLS server select_parameters";
   1637     case state_send_server_hello:
   1638       return "TLS server send_server_hello";
   1639     case state_send_server_certificate:
   1640       return "TLS server send_server_certificate";
   1641     case state_send_server_key_exchange:
   1642       return "TLS server send_server_key_exchange";
   1643     case state_send_server_hello_done:
   1644       return "TLS server send_server_hello_done";
   1645     case state_read_client_certificate:
   1646       return "TLS server read_client_certificate";
   1647     case state_verify_client_certificate:
   1648       return "TLS server verify_client_certificate";
   1649     case state_read_client_key_exchange:
   1650       return "TLS server read_client_key_exchange";
   1651     case state_read_client_certificate_verify:
   1652       return "TLS server read_client_certificate_verify";
   1653     case state_read_change_cipher_spec:
   1654       return "TLS server read_change_cipher_spec";
   1655     case state_process_change_cipher_spec:
   1656       return "TLS server process_change_cipher_spec";
   1657     case state_read_next_proto:
   1658       return "TLS server read_next_proto";
   1659     case state_read_channel_id:
   1660       return "TLS server read_channel_id";
   1661     case state_read_client_finished:
   1662       return "TLS server read_client_finished";
   1663     case state_send_server_finished:
   1664       return "TLS server send_server_finished";
   1665     case state_finish_server_handshake:
   1666       return "TLS server finish_server_handshake";
   1667     case state_done:
   1668       return "TLS server done";
   1669   }
   1670 
   1671   return "TLS server unknown";
   1672 }
   1673 
   1674 }
   1675