text: /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   * All rights reserved.
   *
   * This package is an SSL implementation written
   * by Eric Young (eay@cryptsoft.com).
   * The implementation was written so as to conform with Netscapes SSL.
   *
   * This library is free for commercial and non-commercial use as long as
   * the following conditions are aheared to.  The following conditions
   * apply to all code found in this distribution, be it the RC4, RSA,
   * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   * included with this distribution is covered by the same copyright terms
   * except that the holder is Tim Hudson (tjh@cryptsoft.com).
   *
   * Copyright remains Eric Young's, and as such any Copyright notices in
   * the code are not to be removed.
   * If this package is used in a product, Eric Young should be given attribution
   * as the author of the parts of the library used.
   * This can be in the form of a textual message at program startup or
   * in documentation (online or textual) provided with the package.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *    "This product includes cryptographic software written by
   *     Eric Young (eay@cryptsoft.com)"
   *    The word 'cryptographic' can be left out if the rouines from the library
   *    being used are not cryptographic related :-).
   * 4. If you include any Windows specific code (or a derivative thereof) from
   *    the apps directory (application code) you must include an acknowledgement:
   *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
   *
   * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   * The licence and distribution terms for any publically available version or
   * derivative of this code cannot be changed.  i.e. this code cannot simply be
   * copied and put under another distribution licence
   * [including the GNU Public Licence.]
   */
  /* ====================================================================
   * Copyright 2005 Nokia. All rights reserved.
   *
   * The portions of the attached software ("Contribution") is developed by
   * Nokia Corporation and is licensed pursuant to the OpenSSL open source
   * license.
   *
   * The Contribution, originally written by Mika Kousa and Pasi Eronen of
   * Nokia Corporation, consists of the "PSK" (Pre-Shared Key) ciphersuites
   * support (see RFC 4279) to OpenSSL.
   *
   * No patent licenses or other rights except those expressly stated in
   * the OpenSSL open source license shall be deemed granted or received
   * expressly, by implication, estoppel, or otherwise.
   *
   * No assurances are provided by Nokia that the Contribution does not
   * infringe the patent or other intellectual property rights of any third
   * party or that the license provides you with all the necessary rights
   * to make use of the Contribution.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. IN
   * ADDITION TO THE DISCLAIMERS INCLUDED IN THE LICENSE, NOKIA
   * SPECIFICALLY DISCLAIMS ANY LIABILITY FOR CLAIMS BROUGHT BY YOU OR ANY
   * OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
   * OTHERWISE. */
  
  #include <openssl/ssl.h>
  
  #include <limits.h>
  #include <string.h>
  
  #include <openssl/buf.h>
  #include <openssl/bytestring.h>
  #include <openssl/err.h>
  #include <openssl/mem.h>
  #include <openssl/x509.h>
  
  #include "../crypto/internal.h"
  #include "internal.h"
  
  
  /* An SSL_SESSION is serialized as the following ASN.1 structure:
   *
   * SSLSession ::= SEQUENCE {
   *     version                     INTEGER (1),  -- session structure version
   *     sslVersion                  INTEGER,      -- protocol version number
   *     cipher                      OCTET STRING, -- two bytes long
   *     sessionID                   OCTET STRING,
   *     masterKey                   OCTET STRING,
   *     time                    [1] INTEGER, -- seconds since UNIX epoch
   *     timeout                 [2] INTEGER, -- in seconds
   *     peer                    [3] Certificate OPTIONAL,
   *     sessionIDContext        [4] OCTET STRING OPTIONAL,
   *     verifyResult            [5] INTEGER OPTIONAL,  -- one of X509_V_* codes
   *     hostName                [6] OCTET STRING OPTIONAL,
   *                                 -- from server_name extension
   *     pskIdentity             [8] OCTET STRING OPTIONAL,
   *     ticketLifetimeHint      [9] INTEGER OPTIONAL,       -- client-only
   *     ticket                  [10] OCTET STRING OPTIONAL, -- client-only
   *     peerSHA256              [13] OCTET STRING OPTIONAL,
   *     originalHandshakeHash   [14] OCTET STRING OPTIONAL,
   *     signedCertTimestampList [15] OCTET STRING OPTIONAL,
   *                                  -- contents of SCT extension
   *     ocspResponse            [16] OCTET STRING OPTIONAL,
   *                                  -- stapled OCSP response from the server
   *     extendedMasterSecret    [17] BOOLEAN OPTIONAL,
   *     groupID                 [18] INTEGER OPTIONAL,
   *                                  -- For historical reasons, for legacy DHE or
   *                                  -- static RSA ciphers, this field contains
   *                                  -- another value to be discarded.
   *     certChain               [19] SEQUENCE OF Certificate OPTIONAL,
   *     ticketAgeAdd            [21] OCTET STRING OPTIONAL,
   *     isServer                [22] BOOLEAN DEFAULT TRUE,
   *     peerSignatureAlgorithm  [23] INTEGER OPTIONAL,
   *     ticketMaxEarlyData      [24] INTEGER OPTIONAL,
   *     authTimeout             [25] INTEGER OPTIONAL, -- defaults to timeout
   *     earlyALPN               [26] OCTET STRING OPTIONAL,
   * }
   *
   * Note: historically this serialization has included other optional
   * fields. Their presence is currently treated as a parse error:
   *
   *     keyArg                  [0] IMPLICIT OCTET STRING OPTIONAL,
   *     pskIdentityHint         [7] OCTET STRING OPTIONAL,
   *     compressionMethod       [11] OCTET STRING OPTIONAL,
   *     srpUsername             [12] OCTET STRING OPTIONAL,
   *     ticketFlags             [20] INTEGER OPTIONAL,
   */
  
  static const unsigned kVersion = 1;
  
  static const int kTimeTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 1;
  static const int kTimeoutTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 2;
  static const int kPeerTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 3;
  static const int kSessionIDContextTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 4;
  static const int kVerifyResultTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 5;
  static const int kHostNameTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 6;
  static const int kPSKIdentityTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 8;
  static const int kTicketLifetimeHintTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 9;
  static const int kTicketTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 10;
  static const int kPeerSHA256Tag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 13;
  static const int kOriginalHandshakeHashTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 14;
  static const int kSignedCertTimestampListTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 15;
  static const int kOCSPResponseTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 16;
  static const int kExtendedMasterSecretTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 17;
  static const int kGroupIDTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 18;
  static const int kCertChainTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 19;
  static const int kTicketAgeAddTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 21;
  static const int kIsServerTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 22;
  static const int kPeerSignatureAlgorithmTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 23;
  static const int kTicketMaxEarlyDataTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 24;
  static const int kAuthTimeoutTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 25;
  static const int kEarlyALPNTag =
      CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 26;
  
  static int SSL_SESSION_to_bytes_full(const SSL_SESSION *in, uint8_t **out_data,
                                       size_t *out_len, int for_ticket) {
    CBB cbb, session, child, child2;
  
    if (in == NULL || in->cipher == NULL) {
      return 0;
    }
  
    CBB_zero(&cbb);
    if (!CBB_init(&cbb, 0) ||
        !CBB_add_asn1(&cbb, &session, CBS_ASN1_SEQUENCE) ||
        !CBB_add_asn1_uint64(&session, kVersion) ||
        !CBB_add_asn1_uint64(&session, in->ssl_version) ||
        !CBB_add_asn1(&session, &child, CBS_ASN1_OCTETSTRING) ||
        !CBB_add_u16(&child, (uint16_t)(in->cipher->id & 0xffff)) ||
        !CBB_add_asn1(&session, &child, CBS_ASN1_OCTETSTRING) ||
        /* The session ID is irrelevant for a session ticket. */
        !CBB_add_bytes(&child, in->session_id,
                       for_ticket ? 0 : in->session_id_length) ||
        !CBB_add_asn1(&session, &child, CBS_ASN1_OCTETSTRING) ||
        !CBB_add_bytes(&child, in->master_key, in->master_key_length)) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    if (in->time < 0) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
  
    if (!CBB_add_asn1(&session, &child, kTimeTag) ||
        !CBB_add_asn1_uint64(&child, in->time)) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    if (in->timeout < 0) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
  
    if (!CBB_add_asn1(&session, &child, kTimeoutTag) ||
        !CBB_add_asn1_uint64(&child, in->timeout)) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    /* The peer certificate is only serialized if the SHA-256 isn't
     * serialized instead. */
    if (sk_CRYPTO_BUFFER_num(in->certs) > 0 && !in->peer_sha256_valid) {
      const CRYPTO_BUFFER *buffer = sk_CRYPTO_BUFFER_value(in->certs, 0);
      if (!CBB_add_asn1(&session, &child, kPeerTag) ||
          !CBB_add_bytes(&child, CRYPTO_BUFFER_data(buffer),
                         CRYPTO_BUFFER_len(buffer))) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    /* Although it is OPTIONAL and usually empty, OpenSSL has
     * historically always encoded the sid_ctx. */
    if (!CBB_add_asn1(&session, &child, kSessionIDContextTag) ||
        !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
        !CBB_add_bytes(&child2, in->sid_ctx, in->sid_ctx_length)) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    if (in->verify_result != X509_V_OK) {
      if (!CBB_add_asn1(&session, &child, kVerifyResultTag) ||
          !CBB_add_asn1_uint64(&child, in->verify_result)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->tlsext_hostname) {
      if (!CBB_add_asn1(&session, &child, kHostNameTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, (const uint8_t *)in->tlsext_hostname,
                         strlen(in->tlsext_hostname))) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->psk_identity) {
      if (!CBB_add_asn1(&session, &child, kPSKIdentityTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, (const uint8_t *)in->psk_identity,
                         strlen(in->psk_identity))) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->tlsext_tick_lifetime_hint > 0) {
      if (!CBB_add_asn1(&session, &child, kTicketLifetimeHintTag) ||
          !CBB_add_asn1_uint64(&child, in->tlsext_tick_lifetime_hint)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->tlsext_tick && !for_ticket) {
      if (!CBB_add_asn1(&session, &child, kTicketTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, in->tlsext_tick, in->tlsext_ticklen)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->peer_sha256_valid) {
      if (!CBB_add_asn1(&session, &child, kPeerSHA256Tag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, in->peer_sha256, sizeof(in->peer_sha256))) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->original_handshake_hash_len > 0) {
      if (!CBB_add_asn1(&session, &child, kOriginalHandshakeHashTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, in->original_handshake_hash,
                         in->original_handshake_hash_len)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->tlsext_signed_cert_timestamp_list_length > 0) {
      if (!CBB_add_asn1(&session, &child, kSignedCertTimestampListTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, in->tlsext_signed_cert_timestamp_list,
                         in->tlsext_signed_cert_timestamp_list_length)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->ocsp_response_length > 0) {
      if (!CBB_add_asn1(&session, &child, kOCSPResponseTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, in->ocsp_response, in->ocsp_response_length)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->extended_master_secret) {
      if (!CBB_add_asn1(&session, &child, kExtendedMasterSecretTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_BOOLEAN) ||
          !CBB_add_u8(&child2, 0xff)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->group_id > 0 &&
        (!CBB_add_asn1(&session, &child, kGroupIDTag) ||
         !CBB_add_asn1_uint64(&child, in->group_id))) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    /* The certificate chain is only serialized if the leaf's SHA-256 isn't
     * serialized instead. */
    if (in->certs != NULL &&
        !in->peer_sha256_valid &&
        sk_CRYPTO_BUFFER_num(in->certs) >= 2) {
      if (!CBB_add_asn1(&session, &child, kCertChainTag)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
      for (size_t i = 1; i < sk_CRYPTO_BUFFER_num(in->certs); i++) {
        const CRYPTO_BUFFER *buffer = sk_CRYPTO_BUFFER_value(in->certs, i);
        if (!CBB_add_bytes(&child, CRYPTO_BUFFER_data(buffer),
                           CRYPTO_BUFFER_len(buffer))) {
          OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
          goto err;
        }
      }
    }
  
    if (in->ticket_age_add_valid) {
      if (!CBB_add_asn1(&session, &child, kTicketAgeAddTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_u32(&child2, in->ticket_age_add)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (!in->is_server) {
      if (!CBB_add_asn1(&session, &child, kIsServerTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_BOOLEAN) ||
          !CBB_add_u8(&child2, 0x00)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (in->peer_signature_algorithm != 0 &&
        (!CBB_add_asn1(&session, &child, kPeerSignatureAlgorithmTag) ||
         !CBB_add_asn1_uint64(&child, in->peer_signature_algorithm))) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    if (in->ticket_max_early_data != 0 &&
        (!CBB_add_asn1(&session, &child, kTicketMaxEarlyDataTag) ||
         !CBB_add_asn1_uint64(&child, in->ticket_max_early_data))) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    if (in->timeout != in->auth_timeout &&
        (!CBB_add_asn1(&session, &child, kAuthTimeoutTag) ||
         !CBB_add_asn1_uint64(&child, in->auth_timeout))) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
  
    if (in->early_alpn) {
      if (!CBB_add_asn1(&session, &child, kEarlyALPNTag) ||
          !CBB_add_asn1(&child, &child2, CBS_ASN1_OCTETSTRING) ||
          !CBB_add_bytes(&child2, (const uint8_t *)in->early_alpn,
                         in->early_alpn_len)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
    }
  
    if (!CBB_finish(&cbb, out_data, out_len)) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      goto err;
    }
    return 1;
  
   err:
    CBB_cleanup(&cbb);
    return 0;
  }
  
  int SSL_SESSION_to_bytes(const SSL_SESSION *in, uint8_t **out_data,
                           size_t *out_len) {
    if (in->not_resumable) {
      /* If the caller has an unresumable session, e.g. if |SSL_get_session| were
       * called on a TLS 1.3 or False Started connection, serialize with a
       * placeholder value so it is not accidentally deserialized into a resumable
       * one. */
      static const char kNotResumableSession[] = "NOT RESUMABLE";
  
      *out_len = strlen(kNotResumableSession);
      *out_data = BUF_memdup(kNotResumableSession, *out_len);
      if (*out_data == NULL) {
        return 0;
      }
  
      return 1;
    }
  
    return SSL_SESSION_to_bytes_full(in, out_data, out_len, 0);
  }
  
  int SSL_SESSION_to_bytes_for_ticket(const SSL_SESSION *in, uint8_t **out_data,
                                      size_t *out_len) {
    return SSL_SESSION_to_bytes_full(in, out_data, out_len, 1);
  }
  
  int i2d_SSL_SESSION(SSL_SESSION *in, uint8_t **pp) {
    uint8_t *out;
    size_t len;
  
    if (!SSL_SESSION_to_bytes(in, &out, &len)) {
      return -1;
    }
  
    if (len > INT_MAX) {
      OPENSSL_free(out);
      OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
      return -1;
    }
  
    if (pp) {
      OPENSSL_memcpy(*pp, out, len);
      *pp += len;
    }
    OPENSSL_free(out);
  
    return len;
  }
  
  /* SSL_SESSION_parse_string gets an optional ASN.1 OCTET STRING
   * explicitly tagged with |tag| from |cbs| and saves it in |*out|. On
   * entry, if |*out| is not NULL, it frees the existing contents. If
   * the element was not found, it sets |*out| to NULL. It returns one
   * on success, whether or not the element was found, and zero on
   * decode error. */
  static int SSL_SESSION_parse_string(CBS *cbs, char **out, unsigned tag) {
    CBS value;
    int present;
    if (!CBS_get_optional_asn1_octet_string(cbs, &value, &present, tag)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      return 0;
    }
    if (present) {
      if (CBS_contains_zero_byte(&value)) {
        OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
        return 0;
      }
      if (!CBS_strdup(&value, out)) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        return 0;
      }
    } else {
      OPENSSL_free(*out);
      *out = NULL;
    }
    return 1;
  }
  
  /* SSL_SESSION_parse_string gets an optional ASN.1 OCTET STRING
   * explicitly tagged with |tag| from |cbs| and stows it in |*out_ptr|
   * and |*out_len|. If |*out_ptr| is not NULL, it frees the existing
   * contents. On entry, if the element was not found, it sets
   * |*out_ptr| to NULL. It returns one on success, whether or not the
   * element was found, and zero on decode error. */
  static int SSL_SESSION_parse_octet_string(CBS *cbs, uint8_t **out_ptr,
                                            size_t *out_len, unsigned tag) {
    CBS value;
    if (!CBS_get_optional_asn1_octet_string(cbs, &value, NULL, tag)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      return 0;
    }
    if (!CBS_stow(&value, out_ptr, out_len)) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
      return 0;
    }
    return 1;
  }
  
  /* SSL_SESSION_parse_bounded_octet_string parses an optional ASN.1 OCTET STRING
   * explicitly tagged with |tag| of size at most |max_out|. */
  static int SSL_SESSION_parse_bounded_octet_string(
      CBS *cbs, uint8_t *out, uint8_t *out_len, uint8_t max_out, unsigned tag) {
    CBS value;
    if (!CBS_get_optional_asn1_octet_string(cbs, &value, NULL, tag) ||
        CBS_len(&value) > max_out) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      return 0;
    }
    OPENSSL_memcpy(out, CBS_data(&value), CBS_len(&value));
    *out_len = (uint8_t)CBS_len(&value);
    return 1;
  }
  
  static int SSL_SESSION_parse_long(CBS *cbs, long *out, unsigned tag,
                                    long default_value) {
    uint64_t value;
    if (!CBS_get_optional_asn1_uint64(cbs, &value, tag,
                                      (uint64_t)default_value) ||
        value > LONG_MAX) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      return 0;
    }
    *out = (long)value;
    return 1;
  }
  
  static int SSL_SESSION_parse_u32(CBS *cbs, uint32_t *out, unsigned tag,
                                   uint32_t default_value) {
    uint64_t value;
    if (!CBS_get_optional_asn1_uint64(cbs, &value, tag,
                                      (uint64_t)default_value) ||
        value > 0xffffffff) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      return 0;
    }
    *out = (uint32_t)value;
    return 1;
  }
  
  static int SSL_SESSION_parse_u16(CBS *cbs, uint16_t *out, unsigned tag,
                                   uint16_t default_value) {
    uint64_t value;
    if (!CBS_get_optional_asn1_uint64(cbs, &value, tag,
                                      (uint64_t)default_value) ||
        value > 0xffff) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      return 0;
    }
    *out = (uint16_t)value;
    return 1;
  }
  
  SSL_SESSION *SSL_SESSION_parse(CBS *cbs, const SSL_X509_METHOD *x509_method,
                                 CRYPTO_BUFFER_POOL *pool) {
    SSL_SESSION *ret = ssl_session_new(x509_method);
    if (ret == NULL) {
      goto err;
    }
  
    CBS session;
    uint64_t version, ssl_version;
    if (!CBS_get_asn1(cbs, &session, CBS_ASN1_SEQUENCE) ||
        !CBS_get_asn1_uint64(&session, &version) ||
        version != kVersion ||
        !CBS_get_asn1_uint64(&session, &ssl_version)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    ret->ssl_version = ssl_version;
  
    CBS cipher;
    uint16_t cipher_value;
    if (!CBS_get_asn1(&session, &cipher, CBS_ASN1_OCTETSTRING) ||
        !CBS_get_u16(&cipher, &cipher_value) ||
        CBS_len(&cipher) != 0) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    ret->cipher = SSL_get_cipher_by_value(cipher_value);
    if (ret->cipher == NULL) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_CIPHER);
      goto err;
    }
  
    CBS session_id, master_key;
    if (!CBS_get_asn1(&session, &session_id, CBS_ASN1_OCTETSTRING) ||
        CBS_len(&session_id) > SSL3_MAX_SSL_SESSION_ID_LENGTH ||
        !CBS_get_asn1(&session, &master_key, CBS_ASN1_OCTETSTRING) ||
        CBS_len(&master_key) > SSL_MAX_MASTER_KEY_LENGTH) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    OPENSSL_memcpy(ret->session_id, CBS_data(&session_id), CBS_len(&session_id));
    ret->session_id_length = CBS_len(&session_id);
    OPENSSL_memcpy(ret->master_key, CBS_data(&master_key), CBS_len(&master_key));
    ret->master_key_length = CBS_len(&master_key);
  
    CBS child;
    uint64_t time, timeout;
    if (!CBS_get_asn1(&session, &child, kTimeTag) ||
        !CBS_get_asn1_uint64(&child, &time) ||
        time > LONG_MAX ||
        !CBS_get_asn1(&session, &child, kTimeoutTag) ||
        !CBS_get_asn1_uint64(&child, &timeout) ||
        timeout > LONG_MAX) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
  
    ret->time = (long)time;
    ret->timeout = (long)timeout;
  
    CBS peer;
    int has_peer;
    if (!CBS_get_optional_asn1(&session, &peer, &has_peer, kPeerTag) ||
        (has_peer && CBS_len(&peer) == 0)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    /* |peer| is processed with the certificate chain. */
  
    if (!SSL_SESSION_parse_bounded_octet_string(
            &session, ret->sid_ctx, &ret->sid_ctx_length, sizeof(ret->sid_ctx),
            kSessionIDContextTag) ||
        !SSL_SESSION_parse_long(&session, &ret->verify_result, kVerifyResultTag,
                                X509_V_OK) ||
        !SSL_SESSION_parse_string(&session, &ret->tlsext_hostname,
                                  kHostNameTag) ||
        !SSL_SESSION_parse_string(&session, &ret->psk_identity,
                                  kPSKIdentityTag) ||
        !SSL_SESSION_parse_u32(&session, &ret->tlsext_tick_lifetime_hint,
                               kTicketLifetimeHintTag, 0) ||
        !SSL_SESSION_parse_octet_string(&session, &ret->tlsext_tick,
                                        &ret->tlsext_ticklen, kTicketTag)) {
      goto err;
    }
  
    if (CBS_peek_asn1_tag(&session, kPeerSHA256Tag)) {
      CBS peer_sha256;
      if (!CBS_get_asn1(&session, &child, kPeerSHA256Tag) ||
          !CBS_get_asn1(&child, &peer_sha256, CBS_ASN1_OCTETSTRING) ||
          CBS_len(&peer_sha256) != sizeof(ret->peer_sha256) ||
          CBS_len(&child) != 0) {
        OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
        goto err;
      }
      OPENSSL_memcpy(ret->peer_sha256, CBS_data(&peer_sha256),
                     sizeof(ret->peer_sha256));
      ret->peer_sha256_valid = 1;
    } else {
      ret->peer_sha256_valid = 0;
    }
  
    if (!SSL_SESSION_parse_bounded_octet_string(
            &session, ret->original_handshake_hash,
            &ret->original_handshake_hash_len,
            sizeof(ret->original_handshake_hash), kOriginalHandshakeHashTag) ||
        !SSL_SESSION_parse_octet_string(
            &session, &ret->tlsext_signed_cert_timestamp_list,
            &ret->tlsext_signed_cert_timestamp_list_length,
            kSignedCertTimestampListTag) ||
        !SSL_SESSION_parse_octet_string(
            &session, &ret->ocsp_response, &ret->ocsp_response_length,
            kOCSPResponseTag)) {
      goto err;
    }
  
    int extended_master_secret;
    if (!CBS_get_optional_asn1_bool(&session, &extended_master_secret,
                                    kExtendedMasterSecretTag,
                                    0 /* default to false */)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    ret->extended_master_secret = !!extended_master_secret;
  
    uint32_t value;
    if (!SSL_SESSION_parse_u32(&session, &value, kGroupIDTag, 0)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
  
    /* Historically, the group_id field was used for key-exchange-specific
     * information. Discard all but the group ID. */
    if (ret->cipher->algorithm_mkey & (SSL_kRSA | SSL_kDHE)) {
      value = 0;
    }
  
    if (value > 0xffff) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    ret->group_id = (uint16_t)value;
  
    CBS cert_chain;
    CBS_init(&cert_chain, NULL, 0);
    int has_cert_chain;
    if (!CBS_get_optional_asn1(&session, &cert_chain, &has_cert_chain,
                               kCertChainTag) ||
        (has_cert_chain && CBS_len(&cert_chain) == 0)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    if (has_cert_chain && !has_peer) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    if (has_peer || has_cert_chain) {
      ret->certs = sk_CRYPTO_BUFFER_new_null();
      if (ret->certs == NULL) {
        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
        goto err;
      }
  
      if (has_peer) {
        /* TODO(agl): this should use the |SSL_CTX|'s pool. */
        CRYPTO_BUFFER *buffer = CRYPTO_BUFFER_new_from_CBS(&peer, pool);
        if (buffer == NULL ||
            !sk_CRYPTO_BUFFER_push(ret->certs, buffer)) {
          CRYPTO_BUFFER_free(buffer);
          OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
          goto err;
        }
      }
  
      while (CBS_len(&cert_chain) > 0) {
        CBS cert;
        if (!CBS_get_any_asn1_element(&cert_chain, &cert, NULL, NULL) ||
            CBS_len(&cert) == 0) {
          OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
          goto err;
        }
  
        /* TODO(agl): this should use the |SSL_CTX|'s pool. */
        CRYPTO_BUFFER *buffer = CRYPTO_BUFFER_new_from_CBS(&cert, pool);
        if (buffer == NULL ||
            !sk_CRYPTO_BUFFER_push(ret->certs, buffer)) {
          CRYPTO_BUFFER_free(buffer);
          OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
          goto err;
        }
      }
    }
  
    if (!x509_method->session_cache_objects(ret)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
  
    CBS age_add;
    int age_add_present;
    if (!CBS_get_optional_asn1_octet_string(&session, &age_add, &age_add_present,
                                            kTicketAgeAddTag) ||
        (age_add_present &&
         !CBS_get_u32(&age_add, &ret->ticket_age_add)) ||
        CBS_len(&age_add) != 0) {
      goto err;
    }
    ret->ticket_age_add_valid = age_add_present;
  
    int is_server;
    if (!CBS_get_optional_asn1_bool(&session, &is_server, kIsServerTag,
                                    1 /* default to true */)) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
    /* TODO: in time we can include |is_server| for servers too, then we can
       enforce that client and server sessions are never mixed up. */
  
    ret->is_server = is_server;
  
    if (!SSL_SESSION_parse_u16(&session, &ret->peer_signature_algorithm,
                               kPeerSignatureAlgorithmTag, 0) ||
        !SSL_SESSION_parse_u32(&session, &ret->ticket_max_early_data,
                               kTicketMaxEarlyDataTag, 0) ||
        !SSL_SESSION_parse_long(&session, &ret->auth_timeout, kAuthTimeoutTag,
                                ret->timeout) ||
        !SSL_SESSION_parse_octet_string(&session, &ret->early_alpn,
                                        &ret->early_alpn_len, kEarlyALPNTag) ||
        CBS_len(&session) != 0) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      goto err;
    }
  
    return ret;
  
  err:
    SSL_SESSION_free(ret);
    return NULL;
  }
  
  SSL_SESSION *SSL_SESSION_from_bytes(const uint8_t *in, size_t in_len,
                                      const SSL_CTX *ctx) {
    CBS cbs;
    CBS_init(&cbs, in, in_len);
    SSL_SESSION *ret = SSL_SESSION_parse(&cbs, ctx->x509_method, ctx->pool);
    if (ret == NULL) {
      return NULL;
    }
    if (CBS_len(&cbs) != 0) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SSL_SESSION);
      SSL_SESSION_free(ret);
      return NULL;
    }
    return ret;
  }
  