// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/cert/x509_certificate.h"

#include <openssl/asn1.h>
#include <openssl/bytestring.h>
#include <openssl/crypto.h>
#include <openssl/obj_mac.h>
#include <openssl/pem.h>
#include <openssl/sha.h>
#include <openssl/ssl.h>
#include <openssl/x509v3.h>

#include "base/memory/singleton.h"
#include "base/pickle.h"
#include "base/sha1.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "crypto/openssl_util.h"
#include "crypto/scoped_openssl_types.h"
#include "net/base/net_errors.h"
#include "net/base/net_util.h"
#include "net/cert/x509_util_openssl.h"

#if defined(OS_ANDROID)
#include "base/logging.h"
#include "net/android/network_library.h"
#endif

namespace net {

namespace {

typedef crypto::ScopedOpenSSL<GENERAL_NAMES, GENERAL_NAMES_free>::Type
    ScopedGENERAL_NAMES;

void CreateOSCertHandlesFromPKCS7Bytes(
    const char* data, int length,
    X509Certificate::OSCertHandles* handles) {
  crypto::EnsureOpenSSLInit();
  crypto::OpenSSLErrStackTracer err_cleaner(FROM_HERE);

  CBS der_data;
  CBS_init(&der_data, reinterpret_cast<const uint8_t*>(data), length);
  STACK_OF(X509)* certs = sk_X509_new_null();

  if (PKCS7_get_certificates(certs, &der_data)) {
    for (size_t i = 0; i < sk_X509_num(certs); ++i) {
      X509* x509_cert =
          X509Certificate::DupOSCertHandle(sk_X509_value(certs, i));
      handles->push_back(x509_cert);
    }
  }
  sk_X509_pop_free(certs, X509_free);
}

void ParsePrincipalValues(X509_NAME* name,
                          int nid,
                          std::vector<std::string>* fields) {
  for (int index = -1;
       (index = X509_NAME_get_index_by_NID(name, nid, index)) != -1;) {
    std::string field;
    if (!x509_util::ParsePrincipalValueByIndex(name, index, &field))
      break;
    fields->push_back(field);
  }
}

void ParsePrincipal(X509Certificate::OSCertHandle cert,
                    X509_NAME* x509_name,
                    CertPrincipal* principal) {
  if (!x509_name)
    return;

  ParsePrincipalValues(x509_name, NID_streetAddress,
                       &principal->street_addresses);
  ParsePrincipalValues(x509_name, NID_organizationName,
                       &principal->organization_names);
  ParsePrincipalValues(x509_name, NID_organizationalUnitName,
                       &principal->organization_unit_names);
  ParsePrincipalValues(x509_name, NID_domainComponent,
                       &principal->domain_components);

  x509_util::ParsePrincipalValueByNID(x509_name, NID_commonName,
                                      &principal->common_name);
  x509_util::ParsePrincipalValueByNID(x509_name, NID_localityName,
                                      &principal->locality_name);
  x509_util::ParsePrincipalValueByNID(x509_name, NID_stateOrProvinceName,
                                      &principal->state_or_province_name);
  x509_util::ParsePrincipalValueByNID(x509_name, NID_countryName,
                                      &principal->country_name);
}

void ParseSubjectAltName(X509Certificate::OSCertHandle cert,
                         std::vector<std::string>* dns_names,
                         std::vector<std::string>* ip_addresses) {
  DCHECK(dns_names || ip_addresses);
  int index = X509_get_ext_by_NID(cert, NID_subject_alt_name, -1);
  X509_EXTENSION* alt_name_ext = X509_get_ext(cert, index);
  if (!alt_name_ext)
    return;

  ScopedGENERAL_NAMES alt_names(
      reinterpret_cast<GENERAL_NAMES*>(X509V3_EXT_d2i(alt_name_ext)));
  if (!alt_names.get())
    return;

  for (size_t i = 0; i < sk_GENERAL_NAME_num(alt_names.get()); ++i) {
    const GENERAL_NAME* name = sk_GENERAL_NAME_value(alt_names.get(), i);
    if (name->type == GEN_DNS && dns_names) {
      const unsigned char* dns_name = ASN1_STRING_data(name->d.dNSName);
      if (!dns_name)
        continue;
      int dns_name_len = ASN1_STRING_length(name->d.dNSName);
      dns_names->push_back(
          std::string(reinterpret_cast<const char*>(dns_name), dns_name_len));
    } else if (name->type == GEN_IPADD && ip_addresses) {
      const unsigned char* ip_addr = name->d.iPAddress->data;
      if (!ip_addr)
        continue;
      int ip_addr_len = name->d.iPAddress->length;
      if (ip_addr_len != static_cast<int>(kIPv4AddressSize) &&
          ip_addr_len != static_cast<int>(kIPv6AddressSize)) {
        // http://www.ietf.org/rfc/rfc3280.txt requires subjectAltName iPAddress
        // to have 4 or 16 bytes, whereas in a name constraint it includes a
        // net mask hence 8 or 32 bytes. Logging to help diagnose any mixup.
        LOG(WARNING) << "Bad sized IP Address in cert: " << ip_addr_len;
        continue;
      }
      ip_addresses->push_back(
          std::string(reinterpret_cast<const char*>(ip_addr), ip_addr_len));
    }
  }
}

struct DERCache {
  unsigned char* data;
  int data_length;
};

void DERCache_free(void* parent, void* ptr, CRYPTO_EX_DATA* ad, int idx,
                   long argl, void* argp) {
  DERCache* der_cache = static_cast<DERCache*>(ptr);
  if (!der_cache)
      return;
  if (der_cache->data)
      OPENSSL_free(der_cache->data);
  OPENSSL_free(der_cache);
}

class X509InitSingleton {
 public:
  static X509InitSingleton* GetInstance() {
    // We allow the X509 store to leak, because it is used from a non-joinable
    // worker that is not stopped on shutdown, hence may still be using
    // OpenSSL library after the AtExit runner has completed.
    return Singleton<X509InitSingleton,
                     LeakySingletonTraits<X509InitSingleton> >::get();
  }
  int der_cache_ex_index() const { return der_cache_ex_index_; }
  X509_STORE* store() const { return store_.get(); }

  void ResetCertStore() {
    store_.reset(X509_STORE_new());
    DCHECK(store_.get());
    X509_STORE_set_default_paths(store_.get());
    // TODO(joth): Enable CRL (see X509_STORE_set_flags(X509_V_FLAG_CRL_CHECK)).
  }

 private:
  friend struct DefaultSingletonTraits<X509InitSingleton>;
  X509InitSingleton() {
    crypto::EnsureOpenSSLInit();
    der_cache_ex_index_ = X509_get_ex_new_index(0, 0, 0, 0, DERCache_free);
    DCHECK_NE(der_cache_ex_index_, -1);
    ResetCertStore();
  }

  int der_cache_ex_index_;
  crypto::ScopedOpenSSL<X509_STORE, X509_STORE_free>::Type store_;

  DISALLOW_COPY_AND_ASSIGN(X509InitSingleton);
};

// Takes ownership of |data| (which must have been allocated by OpenSSL).
DERCache* SetDERCache(X509Certificate::OSCertHandle cert,
                      int x509_der_cache_index,
                      unsigned char* data,
                      int data_length) {
  DERCache* internal_cache = static_cast<DERCache*>(
      OPENSSL_malloc(sizeof(*internal_cache)));
  if (!internal_cache) {
    // We took ownership of |data|, so we must free if we can't add it to
    // |cert|.
    OPENSSL_free(data);
    return NULL;
  }

  internal_cache->data = data;
  internal_cache->data_length = data_length;
  X509_set_ex_data(cert, x509_der_cache_index, internal_cache);
  return internal_cache;
}

// Returns true if |der_cache| points to valid data, false otherwise.
// (note: the DER-encoded data in |der_cache| is owned by |cert|, callers should
// not free it).
bool GetDERAndCacheIfNeeded(X509Certificate::OSCertHandle cert,
                            DERCache* der_cache) {
  int x509_der_cache_index =
      X509InitSingleton::GetInstance()->der_cache_ex_index();

  // Re-encoding the DER data via i2d_X509 is an expensive operation, but it's
  // necessary for comparing two certificates. We re-encode at most once per
  // certificate and cache the data within the X509 cert using X509_set_ex_data.
  DERCache* internal_cache = static_cast<DERCache*>(
      X509_get_ex_data(cert, x509_der_cache_index));
  if (!internal_cache) {
    unsigned char* data = NULL;
    int data_length = i2d_X509(cert, &data);
    if (data_length <= 0 || !data)
      return false;
    internal_cache = SetDERCache(cert, x509_der_cache_index, data, data_length);
    if (!internal_cache)
      return false;
  }
  *der_cache = *internal_cache;
  return true;
}

// Used to free a list of X509_NAMEs and the objects it points to.
void sk_X509_NAME_free_all(STACK_OF(X509_NAME)* sk) {
  sk_X509_NAME_pop_free(sk, X509_NAME_free);
}

}  // namespace

// static
X509Certificate::OSCertHandle X509Certificate::DupOSCertHandle(
    OSCertHandle cert_handle) {
  DCHECK(cert_handle);
  return X509_up_ref(cert_handle);
}

// static
void X509Certificate::FreeOSCertHandle(OSCertHandle cert_handle) {
  // Decrement the ref-count for the cert and, if all references are gone,
  // free the memory and any application-specific data associated with the
  // certificate.
  X509_free(cert_handle);
}

void X509Certificate::Initialize() {
  crypto::EnsureOpenSSLInit();
  fingerprint_ = CalculateFingerprint(cert_handle_);
  ca_fingerprint_ = CalculateCAFingerprint(intermediate_ca_certs_);

  ASN1_INTEGER* serial_num = X509_get_serialNumber(cert_handle_);
  if (serial_num) {
    // ASN1_INTEGERS represent the decoded number, in a format internal to
    // OpenSSL. Most notably, this may have leading zeroes stripped off for
    // numbers whose first byte is >= 0x80. Thus, it is necessary to
    // re-encoded the integer back into DER, which is what the interface
    // of X509Certificate exposes, to ensure callers get the proper (DER)
    // value.
    int bytes_required = i2c_ASN1_INTEGER(serial_num, NULL);
    unsigned char* buffer = reinterpret_cast<unsigned char*>(
        WriteInto(&serial_number_, bytes_required + 1));
    int bytes_written = i2c_ASN1_INTEGER(serial_num, &buffer);
    DCHECK_EQ(static_cast<size_t>(bytes_written), serial_number_.size());
  }

  ParsePrincipal(cert_handle_, X509_get_subject_name(cert_handle_), &subject_);
  ParsePrincipal(cert_handle_, X509_get_issuer_name(cert_handle_), &issuer_);
  x509_util::ParseDate(X509_get_notBefore(cert_handle_), &valid_start_);
  x509_util::ParseDate(X509_get_notAfter(cert_handle_), &valid_expiry_);
}

// static
void X509Certificate::ResetCertStore() {
  X509InitSingleton::GetInstance()->ResetCertStore();
}

// static
SHA1HashValue X509Certificate::CalculateFingerprint(OSCertHandle cert) {
  SHA1HashValue sha1;
  unsigned int sha1_size = static_cast<unsigned int>(sizeof(sha1.data));
  int ret = X509_digest(cert, EVP_sha1(), sha1.data, &sha1_size);
  CHECK(ret);
  CHECK_EQ(sha1_size, sizeof(sha1.data));
  return sha1;
}

// static
SHA1HashValue X509Certificate::CalculateCAFingerprint(
    const OSCertHandles& intermediates) {
  SHA1HashValue sha1;
  memset(sha1.data, 0, sizeof(sha1.data));

  SHA_CTX sha1_ctx;
  SHA1_Init(&sha1_ctx);
  DERCache der_cache;
  for (size_t i = 0; i < intermediates.size(); ++i) {
    if (!GetDERAndCacheIfNeeded(intermediates[i], &der_cache))
      return sha1;
    SHA1_Update(&sha1_ctx, der_cache.data, der_cache.data_length);
  }
  SHA1_Final(sha1.data, &sha1_ctx);

  return sha1;
}

// static
X509Certificate::OSCertHandle X509Certificate::CreateOSCertHandleFromBytes(
    const char* data, int length) {
  if (length < 0)
    return NULL;
  crypto::EnsureOpenSSLInit();
  const unsigned char* d2i_data =
      reinterpret_cast<const unsigned char*>(data);
  // Don't cache this data via SetDERCache as this wire format may be not be
  // identical from the i2d_X509 roundtrip.
  X509* cert = d2i_X509(NULL, &d2i_data, length);
  return cert;
}

// static
X509Certificate::OSCertHandles X509Certificate::CreateOSCertHandlesFromBytes(
    const char* data, int length, Format format) {
  OSCertHandles results;
  if (length < 0)
    return results;

  switch (format) {
    case FORMAT_SINGLE_CERTIFICATE: {
      OSCertHandle handle = CreateOSCertHandleFromBytes(data, length);
      if (handle)
        results.push_back(handle);
      break;
    }
    case FORMAT_PKCS7: {
      CreateOSCertHandlesFromPKCS7Bytes(data, length, &results);
      break;
    }
    default: {
      NOTREACHED() << "Certificate format " << format << " unimplemented";
      break;
    }
  }

  return results;
}

void X509Certificate::GetSubjectAltName(
    std::vector<std::string>* dns_names,
    std::vector<std::string>* ip_addrs) const {
  if (dns_names)
    dns_names->clear();
  if (ip_addrs)
    ip_addrs->clear();

  ParseSubjectAltName(cert_handle_, dns_names, ip_addrs);
}

// static
X509_STORE* X509Certificate::cert_store() {
  return X509InitSingleton::GetInstance()->store();
}

// static
bool X509Certificate::GetDEREncoded(X509Certificate::OSCertHandle cert_handle,
                                    std::string* encoded) {
  DERCache der_cache;
  if (!GetDERAndCacheIfNeeded(cert_handle, &der_cache))
    return false;
  encoded->assign(reinterpret_cast<const char*>(der_cache.data),
                  der_cache.data_length);
  return true;
}

// static
bool X509Certificate::IsSameOSCert(X509Certificate::OSCertHandle a,
                                   X509Certificate::OSCertHandle b) {
  DCHECK(a && b);
  if (a == b)
    return true;

  // X509_cmp only checks the fingerprint, but we want to compare the whole
  // DER data. Encoding it from OSCertHandle is an expensive operation, so we
  // cache the DER (if not already cached via X509_set_ex_data).
  DERCache der_cache_a, der_cache_b;

  return GetDERAndCacheIfNeeded(a, &der_cache_a) &&
      GetDERAndCacheIfNeeded(b, &der_cache_b) &&
      der_cache_a.data_length == der_cache_b.data_length &&
      memcmp(der_cache_a.data, der_cache_b.data, der_cache_a.data_length) == 0;
}

// static
X509Certificate::OSCertHandle
X509Certificate::ReadOSCertHandleFromPickle(PickleIterator* pickle_iter) {
  const char* data;
  int length;
  if (!pickle_iter->ReadData(&data, &length))
    return NULL;

  return CreateOSCertHandleFromBytes(data, length);
}

// static
bool X509Certificate::WriteOSCertHandleToPickle(OSCertHandle cert_handle,
                                                Pickle* pickle) {
  DERCache der_cache;
  if (!GetDERAndCacheIfNeeded(cert_handle, &der_cache))
    return false;

  return pickle->WriteData(
      reinterpret_cast<const char*>(der_cache.data),
      der_cache.data_length);
}

// static
void X509Certificate::GetPublicKeyInfo(OSCertHandle cert_handle,
                                       size_t* size_bits,
                                       PublicKeyType* type) {
  *type = kPublicKeyTypeUnknown;
  *size_bits = 0;

  crypto::ScopedEVP_PKEY scoped_key(X509_get_pubkey(cert_handle));
  if (!scoped_key.get())
    return;

  CHECK(scoped_key.get());
  EVP_PKEY* key = scoped_key.get();

  switch (key->type) {
    case EVP_PKEY_RSA:
      *type = kPublicKeyTypeRSA;
      *size_bits = EVP_PKEY_size(key) * 8;
      break;
    case EVP_PKEY_DSA:
      *type = kPublicKeyTypeDSA;
      *size_bits = EVP_PKEY_size(key) * 8;
      break;
    case EVP_PKEY_EC:
      *type = kPublicKeyTypeECDSA;
      *size_bits = EVP_PKEY_bits(key);
      break;
    case EVP_PKEY_DH:
      *type = kPublicKeyTypeDH;
      *size_bits = EVP_PKEY_size(key) * 8;
      break;
  }
}

bool X509Certificate::IsIssuedByEncoded(
    const std::vector<std::string>& valid_issuers) {
  if (valid_issuers.empty())
    return false;

  // Convert to a temporary list of X509_NAME objects.
  // It will own the objects it points to.
  crypto::ScopedOpenSSL<STACK_OF(X509_NAME), sk_X509_NAME_free_all>::Type
      issuer_names(sk_X509_NAME_new_null());
  if (!issuer_names.get())
    return false;

  for (std::vector<std::string>::const_iterator it = valid_issuers.begin();
      it != valid_issuers.end(); ++it) {
    const unsigned char* p =
        reinterpret_cast<const unsigned char*>(it->data());
    long len = static_cast<long>(it->length());
    X509_NAME* ca_name = d2i_X509_NAME(NULL, &p, len);
    if (ca_name == NULL)
      return false;
    sk_X509_NAME_push(issuer_names.get(), ca_name);
  }

  // Create a temporary list of X509_NAME objects corresponding
  // to the certificate chain. It doesn't own the object it points to.
  std::vector<X509_NAME*> cert_names;
  X509_NAME* issuer = X509_get_issuer_name(cert_handle_);
  if (issuer == NULL)
    return false;

  cert_names.push_back(issuer);
  for (OSCertHandles::iterator it = intermediate_ca_certs_.begin();
      it != intermediate_ca_certs_.end(); ++it) {
    issuer = X509_get_issuer_name(*it);
    if (issuer == NULL)
      return false;
    cert_names.push_back(issuer);
  }

  // and 'cert_names'.
  for (size_t n = 0; n < cert_names.size(); ++n) {
    for (size_t m = 0; m < sk_X509_NAME_num(issuer_names.get()); ++m) {
      X509_NAME* issuer = sk_X509_NAME_value(issuer_names.get(), m);
      if (X509_NAME_cmp(issuer, cert_names[n]) == 0) {
        return true;
      }
    }
  }

  return false;
}

}  // namespace net