text: /*
   * Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #ifdef OPENSSL_NO_CT
  # error "CT is disabled"
  #endif
  
  #include <stddef.h>
  #include <string.h>
  
  #include <openssl/err.h>
  #include <openssl/obj_mac.h>
  #include <openssl/x509.h>
  
  #include "ct_local.h"
  
  SCT_CTX *SCT_CTX_new(OSSL_LIB_CTX *libctx, const char *propq)
  {
      SCT_CTX *sctx = OPENSSL_zalloc(sizeof(*sctx));
  
      if (sctx == NULL) {
          ERR_raise(ERR_LIB_CT, ERR_R_MALLOC_FAILURE);
          return NULL;
      }
  
      sctx->libctx = libctx;
      if (propq != NULL) {
          sctx->propq = OPENSSL_strdup(propq);
          if (sctx->propq == NULL) {
              ERR_raise(ERR_LIB_CT, ERR_R_MALLOC_FAILURE);
              OPENSSL_free(sctx);
              return NULL;
          }
      }
  
      return sctx;
  }
  
  void SCT_CTX_free(SCT_CTX *sctx)
  {
      if (sctx == NULL)
          return;
      EVP_PKEY_free(sctx->pkey);
      OPENSSL_free(sctx->pkeyhash);
      OPENSSL_free(sctx->ihash);
      OPENSSL_free(sctx->certder);
      OPENSSL_free(sctx->preder);
      OPENSSL_free(sctx->propq);
      OPENSSL_free(sctx);
  }
  
  /*
   * Finds the index of the first extension with the given NID in cert.
   * If there is more than one extension with that NID, *is_duplicated is set to
   * 1, otherwise 0 (unless it is NULL).
   */
  static int ct_x509_get_ext(X509 *cert, int nid, int *is_duplicated)
  {
      int ret = X509_get_ext_by_NID(cert, nid, -1);
  
      if (is_duplicated != NULL)
          *is_duplicated = ret >= 0 && X509_get_ext_by_NID(cert, nid, ret) >= 0;
  
      return ret;
  }
  
  /*
   * Modifies a certificate by deleting extensions and copying the issuer and
   * AKID from the presigner certificate, if necessary.
   * Returns 1 on success, 0 otherwise.
   */
  __owur static int ct_x509_cert_fixup(X509 *cert, X509 *presigner)
  {
      int preidx, certidx;
      int pre_akid_ext_is_dup, cert_akid_ext_is_dup;
  
      if (presigner == NULL)
          return 1;
  
      preidx = ct_x509_get_ext(presigner, NID_authority_key_identifier,
                               &pre_akid_ext_is_dup);
      certidx = ct_x509_get_ext(cert, NID_authority_key_identifier,
                                &cert_akid_ext_is_dup);
  
      /* An error occurred whilst searching for the extension */
      if (preidx < -1 || certidx < -1)
          return 0;
      /* Invalid certificate if they contain duplicate extensions */
      if (pre_akid_ext_is_dup || cert_akid_ext_is_dup)
          return 0;
      /* AKID must be present in both certificate or absent in both */
      if (preidx >= 0 && certidx == -1)
          return 0;
      if (preidx == -1 && certidx >= 0)
          return 0;
      /* Copy issuer name */
      if (!X509_set_issuer_name(cert, X509_get_issuer_name(presigner)))
          return 0;
      if (preidx != -1) {
          /* Retrieve and copy AKID encoding */
          X509_EXTENSION *preext = X509_get_ext(presigner, preidx);
          X509_EXTENSION *certext = X509_get_ext(cert, certidx);
          ASN1_OCTET_STRING *preextdata;
  
          /* Should never happen */
          if (preext == NULL || certext == NULL)
              return 0;
          preextdata = X509_EXTENSION_get_data(preext);
          if (preextdata == NULL ||
              !X509_EXTENSION_set_data(certext, preextdata))
              return 0;
      }
      return 1;
  }
  
  int SCT_CTX_set1_cert(SCT_CTX *sctx, X509 *cert, X509 *presigner)
  {
      unsigned char *certder = NULL, *preder = NULL;
      X509 *pretmp = NULL;
      int certderlen = 0, prederlen = 0;
      int idx = -1;
      int poison_ext_is_dup, sct_ext_is_dup;
      int poison_idx = ct_x509_get_ext(cert, NID_ct_precert_poison, &poison_ext_is_dup);
  
      /* Duplicate poison extensions are present - error */
      if (poison_ext_is_dup)
          goto err;
  
      /* If *cert doesn't have a poison extension, it isn't a precert */
      if (poison_idx == -1) {
          /* cert isn't a precert, so we shouldn't have a presigner */
          if (presigner != NULL)
              goto err;
  
          certderlen = i2d_X509(cert, &certder);
          if (certderlen < 0)
              goto err;
      }
  
      /* See if cert has a precert SCTs extension */
      idx = ct_x509_get_ext(cert, NID_ct_precert_scts, &sct_ext_is_dup);
      /* Duplicate SCT extensions are present - error */
      if (sct_ext_is_dup)
          goto err;
  
      if (idx >= 0 && poison_idx >= 0) {
          /*
           * cert can't both contain SCTs (i.e. have an SCT extension) and be a
           * precert (i.e. have a poison extension).
           */
          goto err;
      }
  
      if (idx == -1) {
          idx = poison_idx;
      }
  
      /*
       * If either a poison or SCT extension is present, remove it before encoding
       * cert. This, along with ct_x509_cert_fixup(), gets a TBSCertificate (see
       * RFC5280) from cert, which is what the CT log signed when it produced the
       * SCT.
       */
      if (idx >= 0) {
          /* Take a copy of certificate so we don't modify passed version */
          pretmp = X509_dup(cert);
          if (pretmp == NULL)
              goto err;
  
          X509_EXTENSION_free(X509_delete_ext(pretmp, idx));
  
          if (!ct_x509_cert_fixup(pretmp, presigner))
              goto err;
  
          prederlen = i2d_re_X509_tbs(pretmp, &preder);
          if (prederlen <= 0)
              goto err;
      }
  
      X509_free(pretmp);
  
      OPENSSL_free(sctx->certder);
      sctx->certder = certder;
      sctx->certderlen = certderlen;
  
      OPENSSL_free(sctx->preder);
      sctx->preder = preder;
      sctx->prederlen = prederlen;
  
      return 1;
  err:
      OPENSSL_free(certder);
      OPENSSL_free(preder);
      X509_free(pretmp);
      return 0;
  }
  
  __owur static int ct_public_key_hash(SCT_CTX *sctx, X509_PUBKEY *pkey,
                                       unsigned char **hash, size_t *hash_len)
  {
      int ret = 0;
      unsigned char *md = NULL, *der = NULL;
      int der_len;
      unsigned int md_len;
      EVP_MD *sha256 = EVP_MD_fetch(sctx->libctx, "SHA2-256", sctx->propq);
  
      if (sha256 == NULL)
          goto err;
  
      /* Reuse buffer if possible */
      if (*hash != NULL && *hash_len >= SHA256_DIGEST_LENGTH) {
          md = *hash;
      } else {
          md = OPENSSL_malloc(SHA256_DIGEST_LENGTH);
          if (md == NULL)
              goto err;
      }
  
      /* Calculate key hash */
      der_len = i2d_X509_PUBKEY(pkey, &der);
      if (der_len <= 0)
          goto err;
  
      if (!EVP_Digest(der, der_len, md, &md_len, sha256, NULL))
          goto err;
  
      if (md != *hash) {
          OPENSSL_free(*hash);
          *hash = md;
          *hash_len = SHA256_DIGEST_LENGTH;
      }
  
      md = NULL;
      ret = 1;
   err:
      EVP_MD_free(sha256);
      OPENSSL_free(md);
      OPENSSL_free(der);
      return ret;
  }
  
  int SCT_CTX_set1_issuer(SCT_CTX *sctx, const X509 *issuer)
  {
      return SCT_CTX_set1_issuer_pubkey(sctx, X509_get_X509_PUBKEY(issuer));
  }
  
  int SCT_CTX_set1_issuer_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
  {
      return ct_public_key_hash(sctx, pubkey, &sctx->ihash, &sctx->ihashlen);
  }
  
  int SCT_CTX_set1_pubkey(SCT_CTX *sctx, X509_PUBKEY *pubkey)
  {
      EVP_PKEY *pkey = X509_PUBKEY_get(pubkey);
  
      if (pkey == NULL)
          return 0;
  
      if (!ct_public_key_hash(sctx, pubkey, &sctx->pkeyhash, &sctx->pkeyhashlen)) {
          EVP_PKEY_free(pkey);
          return 0;
      }
  
      EVP_PKEY_free(sctx->pkey);
      sctx->pkey = pkey;
      return 1;
  }
  
  void SCT_CTX_set_time(SCT_CTX *sctx, uint64_t time_in_ms)
  {
      sctx->epoch_time_in_ms = time_in_ms;
  }
  