// Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) All rights reserved.
// SPDX-License-Identifier: Apache-2.0

#include <assert.h>
#include <limits.h>
#include <stdio.h>

#include <openssl/asn1t.h>
#include <openssl/evp.h>
#include <openssl/mem.h>
#include <openssl/obj.h>
#include <openssl/pool.h>
#include <openssl/thread.h>
#include <openssl/x509.h>

#include "../asn1/internal.h"
#include "../internal.h"
#include "internal.h"

static CRYPTO_EX_DATA_CLASS g_ex_data_class = CRYPTO_EX_DATA_CLASS_INIT;

ASN1_SEQUENCE_enc(X509_CINF, enc, 0) = {
    ASN1_EXP_OPT(X509_CINF, version, ASN1_INTEGER, 0),
    ASN1_SIMPLE(X509_CINF, serialNumber, ASN1_INTEGER),
    ASN1_SIMPLE(X509_CINF, signature, X509_ALGOR),
    ASN1_SIMPLE(X509_CINF, issuer, X509_NAME),
    ASN1_SIMPLE(X509_CINF, validity, X509_VAL),
    ASN1_SIMPLE(X509_CINF, subject, X509_NAME),
    ASN1_SIMPLE(X509_CINF, key, X509_PUBKEY),
    ASN1_IMP_OPT(X509_CINF, issuerUID, ASN1_BIT_STRING, 1),
    ASN1_IMP_OPT(X509_CINF, subjectUID, ASN1_BIT_STRING, 2),
    ASN1_EXP_SEQUENCE_OF_OPT(X509_CINF, extensions, X509_EXTENSION, 3),
} ASN1_SEQUENCE_END_enc(X509_CINF, X509_CINF)

IMPLEMENT_ASN1_FUNCTIONS(X509_CINF)
// X509 top level structure needs a bit of customisation

static int x509_cb(int operation, ASN1_VALUE **pval, const ASN1_ITEM *it,
                   void *exarg) {
  X509 *ret = (X509 *)*pval;

  switch (operation) {
    case ASN1_OP_NEW_POST:
      ret->ex_flags = 0;
      ret->ex_pathlen = -1;
      ret->skid = NULL;
      ret->akid = NULL;
      ret->aux = NULL;
      ret->crldp = NULL;
      ret->buf = NULL;
      CRYPTO_new_ex_data(&ret->ex_data);
      CRYPTO_MUTEX_init(&ret->lock);
      break;

    case ASN1_OP_D2I_PRE:
      CRYPTO_BUFFER_free(ret->buf);
      ret->buf = NULL;
      break;

    case ASN1_OP_D2I_POST: {
      // The version must be one of v1(0), v2(1), or v3(2).
      long version = X509_VERSION_1;
      if (ret->cert_info->version != NULL) {
        version = ASN1_INTEGER_get(ret->cert_info->version);
        // TODO(https://crbug.com/boringssl/364): |X509_VERSION_1| should
        // also be rejected here. This means an explicitly-encoded X.509v1
        // version. v1 is DEFAULT, so DER requires it be omitted.
        if (version < X509_VERSION_1 || version > X509_VERSION_3) {
          OPENSSL_PUT_ERROR(X509, X509_R_INVALID_VERSION);
          return 0;
        }
      }

      // Per RFC 5280, section 4.1.2.8, these fields require v2 or v3.
      if (version == X509_VERSION_1 && (ret->cert_info->issuerUID != NULL ||
                                        ret->cert_info->subjectUID != NULL)) {
        OPENSSL_PUT_ERROR(X509, X509_R_INVALID_FIELD_FOR_VERSION);
        return 0;
      }

      // Per RFC 5280, section 4.1.2.9, extensions require v3.
      if (version != X509_VERSION_3 && ret->cert_info->extensions != NULL) {
        OPENSSL_PUT_ERROR(X509, X509_R_INVALID_FIELD_FOR_VERSION);
        return 0;
      }

      break;
    }

    case ASN1_OP_FREE_POST:
      CRYPTO_MUTEX_cleanup(&ret->lock);
      CRYPTO_free_ex_data(&g_ex_data_class, ret, &ret->ex_data);
      X509_CERT_AUX_free(ret->aux);
      ASN1_OCTET_STRING_free(ret->skid);
      AUTHORITY_KEYID_free(ret->akid);
      CRL_DIST_POINTS_free(ret->crldp);
      GENERAL_NAMES_free(ret->altname);
      NAME_CONSTRAINTS_free(ret->nc);
      CRYPTO_BUFFER_free(ret->buf);
      break;
  }

  return 1;
}

ASN1_SEQUENCE_ref(X509, x509_cb) = {
    ASN1_SIMPLE(X509, cert_info, X509_CINF),
    ASN1_SIMPLE(X509, sig_alg, X509_ALGOR),
    ASN1_SIMPLE(X509, signature, ASN1_BIT_STRING),
} ASN1_SEQUENCE_END_ref(X509, X509)

IMPLEMENT_ASN1_FUNCTIONS(X509)

IMPLEMENT_ASN1_DUP_FUNCTION(X509)

X509 *X509_parse_from_buffer(CRYPTO_BUFFER *buf) {
  if (CRYPTO_BUFFER_len(buf) > LONG_MAX) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
    return 0;
  }

  X509 *x509 = X509_new();
  if (x509 == NULL) {
    return NULL;
  }

  x509->cert_info->enc.alias_only_on_next_parse = 1;

  const uint8_t *inp = CRYPTO_BUFFER_data(buf);
  X509 *x509p = x509;
  X509 *ret = d2i_X509(&x509p, &inp, CRYPTO_BUFFER_len(buf));
  if (ret == NULL ||
      inp - CRYPTO_BUFFER_data(buf) != (ptrdiff_t)CRYPTO_BUFFER_len(buf)) {
    X509_free(x509p);
    return NULL;
  }
  assert(x509p == x509);
  assert(ret == x509);

  CRYPTO_BUFFER_up_ref(buf);
  ret->buf = buf;

  return ret;
}

int X509_up_ref(X509 *x) {
  if (x == NULL) {
    return 0;
  }
  CRYPTO_refcount_inc(&x->references);
  return 1;
}

int X509_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
                          CRYPTO_EX_dup *dup_unused,
                          CRYPTO_EX_free *free_func) {
  int index;
  if (!CRYPTO_get_ex_new_index(&g_ex_data_class, &index, argl, argp,
                               free_func)) {
    return -1;
  }
  return index;
}

int X509_set_ex_data(X509 *r, int idx, void *arg) {
  return (CRYPTO_set_ex_data(&r->ex_data, idx, arg));
}

void *X509_get_ex_data(X509 *r, int idx) {
  return (CRYPTO_get_ex_data(&r->ex_data, idx));
}

// X509_AUX ASN1 routines. X509_AUX is the name given to a certificate with
// extra info tagged on the end. Since these functions set how a certificate
// is trusted they should only be used when the certificate comes from a
// reliable source such as local storage.

X509 *d2i_X509_AUX(X509 **a, const unsigned char **pp, long length) {
  const unsigned char *q = *pp;
  X509 *ret;
  int freeret = 0;

  if (!a || *a == NULL) {
    freeret = 1;
  }
  ret = d2i_X509(a, &q, length);
  // If certificate unreadable then forget it
  if (!ret) {
    return NULL;
  }
  // update length
  length -= q - *pp;
  // Parse auxiliary information if there is any.
  if (length > 0 && !d2i_X509_CERT_AUX(&ret->aux, &q, length)) {
    goto err;
  }
  *pp = q;
  return ret;
err:
  if (freeret) {
    X509_free(ret);
    if (a) {
      *a = NULL;
    }
  }
  return NULL;
}

// Serialize trusted certificate to *pp or just return the required buffer
// length if pp == NULL.  We ultimately want to avoid modifying *pp in the
// error path, but that depends on similar hygiene in lower-level functions.
// Here we avoid compounding the problem.
static int i2d_x509_aux_internal(X509 *a, unsigned char **pp) {
  int length, tmplen;
  unsigned char *start = pp != NULL ? *pp : NULL;

  assert(pp == NULL || *pp != NULL);

  // This might perturb *pp on error, but fixing that belongs in i2d_X509()
  // not here.  It should be that if a == NULL length is zero, but we check
  // both just in case.
  length = i2d_X509(a, pp);
  if (length <= 0 || a == NULL) {
    return length;
  }

  if (a->aux != NULL) {
    tmplen = i2d_X509_CERT_AUX(a->aux, pp);
    if (tmplen < 0) {
      if (start != NULL) {
        *pp = start;
      }
      return tmplen;
    }
    length += tmplen;
  }

  return length;
}

// Serialize trusted certificate to *pp, or just return the required buffer
// length if pp == NULL.
//
// When pp is not NULL, but *pp == NULL, we allocate the buffer, but since
// we're writing two ASN.1 objects back to back, we can't have i2d_X509() do
// the allocation, nor can we allow i2d_X509_CERT_AUX() to increment the
// allocated buffer.
int i2d_X509_AUX(X509 *a, unsigned char **pp) {
  int length;
  unsigned char *tmp;

  // Buffer provided by caller
  if (pp == NULL || *pp != NULL) {
    return i2d_x509_aux_internal(a, pp);
  }

  // Obtain the combined length
  if ((length = i2d_x509_aux_internal(a, NULL)) <= 0) {
    return length;
  }

  // Allocate requisite combined storage
  *pp = tmp = OPENSSL_malloc(length);
  if (tmp == NULL) {
    return -1;  // Push error onto error stack?
  }

  // Encode, but keep *pp at the originally malloced pointer
  length = i2d_x509_aux_internal(a, &tmp);
  if (length <= 0) {
    OPENSSL_free(*pp);
    *pp = NULL;
  }
  return length;
}

int i2d_re_X509_tbs(X509 *x509, unsigned char **outp) {
  asn1_encoding_clear(&x509->cert_info->enc);
  return i2d_X509_CINF(x509->cert_info, outp);
}

int i2d_X509_tbs(X509 *x509, unsigned char **outp) {
  return i2d_X509_CINF(x509->cert_info, outp);
}

int X509_set1_signature_algo(X509 *x509, const X509_ALGOR *algo) {
  X509_ALGOR *copy1 = X509_ALGOR_dup(algo);
  X509_ALGOR *copy2 = X509_ALGOR_dup(algo);
  if (copy1 == NULL || copy2 == NULL) {
    X509_ALGOR_free(copy1);
    X509_ALGOR_free(copy2);
    return 0;
  }

  X509_ALGOR_free(x509->sig_alg);
  x509->sig_alg = copy1;
  X509_ALGOR_free(x509->cert_info->signature);
  x509->cert_info->signature = copy2;
  return 1;
}

int X509_set1_signature_value(X509 *x509, const uint8_t *sig, size_t sig_len) {
  if (!ASN1_STRING_set(x509->signature, sig, sig_len)) {
    return 0;
  }
  x509->signature->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);
  x509->signature->flags |= ASN1_STRING_FLAG_BITS_LEFT;
  return 1;
}

void X509_get0_signature(const ASN1_BIT_STRING **psig, const X509_ALGOR **palg,
                         const X509 *x) {
  if (psig) {
    *psig = x->signature;
  }
  if (palg) {
    *palg = x->sig_alg;
  }
}

int X509_get_signature_nid(const X509 *x) {
  return OBJ_obj2nid(x->sig_alg->algorithm);
}