path: root/comm/mailnews/extensions/smime/nsMsgComposeSecure.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsMsgComposeSecure.h"

#include "ScopedNSSTypes.h"
#include "cert.h"
#include "keyhi.h"
#include "mozilla/RefPtr.h"
#include "mozilla/Components.h"
#include "mozilla/mailnews/MimeEncoder.h"
#include "mozilla/mailnews/MimeHeaderParser.h"
#include "msgCore.h"
#include "nsComponentManagerUtils.h"
#include "nsICryptoHash.h"
#include "nsIMimeConverter.h"
#include "nsIMsgCompFields.h"
#include "nsIMsgIdentity.h"
#include "nsIX509CertDB.h"
#include "nsMemory.h"
#include "nsMimeTypes.h"
#include "nsNSSComponent.h"
#include "nsServiceManagerUtils.h"
#include "nspr.h"
#include "mozpkix/Result.h"
#include "nsNSSCertificate.h"
#include "nsNSSHelper.h"
#include "CryptoTask.h"

using namespace mozilla::mailnews;
using namespace mozilla;
using namespace mozilla::psm;

#define MK_MIME_ERROR_WRITING_FILE -1

#define SMIME_STRBUNDLE_URL "chrome://messenger/locale/am-smime.properties"

// It doesn't make sense to encode the message because the message will be
// displayed only if the MUA doesn't support MIME.
// We need to consider what to do in case the server doesn't support 8BITMIME.
// In short, we can't use non-ASCII characters here.
static const char crypto_multipart_blurb[] =
    "This is a cryptographically signed message in MIME format.";

static void mime_crypto_write_base64(void* closure, const char* buf,
                                     unsigned long size);
static nsresult mime_encoder_output_fn(const char* buf, int32_t size,
                                       void* closure);
static nsresult mime_nested_encoder_output_fn(const char* buf, int32_t size,
                                              void* closure);
static nsresult make_multipart_signed_header_string(bool outer_p,
                                                    char** header_return,
                                                    char** boundary_return,
                                                    int16_t hash_type);
static char* mime_make_separator(const char* prefix);

static void GenerateGlobalRandomBytes(unsigned char* buf, int32_t len) {
  static bool firstTime = true;

  if (firstTime) {
    // Seed the random-number generator with current time so that
    // the numbers will be different every time we run.
    srand((unsigned)PR_Now());
    firstTime = false;
  }

  for (int32_t i = 0; i < len; i++) buf[i] = rand() % 10;
}

char* mime_make_separator(const char* prefix) {
  unsigned char rand_buf[13];
  GenerateGlobalRandomBytes(rand_buf, 12);

  return PR_smprintf(
      "------------%s"
      "%02X%02X%02X%02X"
      "%02X%02X%02X%02X"
      "%02X%02X%02X%02X",
      prefix, rand_buf[0], rand_buf[1], rand_buf[2], rand_buf[3], rand_buf[4],
      rand_buf[5], rand_buf[6], rand_buf[7], rand_buf[8], rand_buf[9],
      rand_buf[10], rand_buf[11]);
}

// end of copied code which needs fixed....

/////////////////////////////////////////////////////////////////////////////////////////
// Implementation of nsMsgComposeSecure
/////////////////////////////////////////////////////////////////////////////////////////

NS_IMPL_ISUPPORTS(nsMsgComposeSecure, nsIMsgComposeSecure)

nsMsgComposeSecure::nsMsgComposeSecure()
    : mSignMessage(false),
      mAlwaysEncryptMessage(false),
      mCryptoState(mime_crypto_none),
      mHashType(0),
      mMultipartSignedBoundary(nullptr),
      mIsDraft(false),
      mBuffer(nullptr),
      mBufferedBytes(0),
      mErrorAlreadyReported(false) {}

nsMsgComposeSecure::~nsMsgComposeSecure() {
  /* destructor code */
  if (mEncryptionContext) {
    if (mBufferedBytes) {
      mEncryptionContext->Update(mBuffer, mBufferedBytes);
      mBufferedBytes = 0;
    }
    mEncryptionContext->Finish();
    mEncryptionContext = nullptr;
  }

  delete[] mBuffer;
  mBuffer = nullptr;

  PR_FREEIF(mMultipartSignedBoundary);
}

NS_IMETHODIMP nsMsgComposeSecure::SetSignMessage(bool value) {
  mSignMessage = value;
  return NS_OK;
}

NS_IMETHODIMP nsMsgComposeSecure::GetSignMessage(bool* _retval) {
  *_retval = mSignMessage;
  return NS_OK;
}

NS_IMETHODIMP nsMsgComposeSecure::SetRequireEncryptMessage(bool value) {
  mAlwaysEncryptMessage = value;
  return NS_OK;
}

NS_IMETHODIMP nsMsgComposeSecure::GetRequireEncryptMessage(bool* _retval) {
  *_retval = mAlwaysEncryptMessage;
  return NS_OK;
}

NS_IMETHODIMP nsMsgComposeSecure::RequiresCryptoEncapsulation(
    nsIMsgIdentity* aIdentity, nsIMsgCompFields* aCompFields,
    bool* aRequiresEncryptionWork) {
  NS_ENSURE_ARG_POINTER(aRequiresEncryptionWork);

  *aRequiresEncryptionWork = false;

  bool alwaysEncryptMessages = false;
  bool signMessage = false;
  nsresult rv = ExtractEncryptionState(aIdentity, aCompFields, &signMessage,
                                       &alwaysEncryptMessages);
  NS_ENSURE_SUCCESS(rv, rv);

  if (alwaysEncryptMessages || signMessage) *aRequiresEncryptionWork = true;

  return NS_OK;
}

nsresult nsMsgComposeSecure::GetSMIMEBundleString(const char16_t* name,
                                                  nsString& outString) {
  outString.Truncate();

  NS_ENSURE_ARG_POINTER(name);

  NS_ENSURE_TRUE(InitializeSMIMEBundle(), NS_ERROR_FAILURE);

  return mSMIMEBundle->GetStringFromName(NS_ConvertUTF16toUTF8(name).get(),
                                         outString);
}

nsresult nsMsgComposeSecure::SMIMEBundleFormatStringFromName(
    const char* name, nsTArray<nsString>& params, nsAString& outString) {
  NS_ENSURE_ARG_POINTER(name);

  if (!InitializeSMIMEBundle()) return NS_ERROR_FAILURE;

  return mSMIMEBundle->FormatStringFromName(name, params, outString);
}

bool nsMsgComposeSecure::InitializeSMIMEBundle() {
  if (mSMIMEBundle) return true;

  nsCOMPtr<nsIStringBundleService> bundleService =
      mozilla::components::StringBundle::Service();
  nsresult rv = bundleService->CreateBundle(SMIME_STRBUNDLE_URL,
                                            getter_AddRefs(mSMIMEBundle));
  NS_ENSURE_SUCCESS(rv, false);

  return true;
}

void nsMsgComposeSecure::SetError(nsIMsgSendReport* sendReport,
                                  const char16_t* bundle_string) {
  if (!sendReport || !bundle_string) return;

  if (mErrorAlreadyReported) return;

  mErrorAlreadyReported = true;

  nsString errorString;
  nsresult res = GetSMIMEBundleString(bundle_string, errorString);
  if (NS_SUCCEEDED(res) && !errorString.IsEmpty()) {
    sendReport->SetMessage(nsIMsgSendReport::process_Current, errorString.get(),
                           true);
  }
}

void nsMsgComposeSecure::SetErrorWithParam(nsIMsgSendReport* sendReport,
                                           const char* bundle_string,
                                           const char* param) {
  if (!sendReport || !bundle_string || !param) return;

  if (mErrorAlreadyReported) return;

  mErrorAlreadyReported = true;

  nsString errorString;
  nsresult res;
  AutoTArray<nsString, 1> params;
  CopyASCIItoUTF16(MakeStringSpan(param), *params.AppendElement());
  res = SMIMEBundleFormatStringFromName(bundle_string, params, errorString);

  if (NS_SUCCEEDED(res) && !errorString.IsEmpty()) {
    sendReport->SetMessage(nsIMsgSendReport::process_Current, errorString.get(),
                           true);
  }
}

nsresult nsMsgComposeSecure::ExtractEncryptionState(
    nsIMsgIdentity* aIdentity, nsIMsgCompFields* aComposeFields,
    bool* aSignMessage, bool* aEncrypt) {
  if (!aComposeFields && !aIdentity)
    return NS_ERROR_FAILURE;  // kick out...invalid args....

  NS_ENSURE_ARG_POINTER(aSignMessage);
  NS_ENSURE_ARG_POINTER(aEncrypt);

  this->GetSignMessage(aSignMessage);
  this->GetRequireEncryptMessage(aEncrypt);

  return NS_OK;
}

// Select a hash algorithm to sign message
// based on subject public key type and size.
static nsresult GetSigningHashFunction(nsIX509Cert* aSigningCert,
                                       int16_t* hashType) {
  // Get the signing certificate
  CERTCertificate* scert = nullptr;
  if (aSigningCert) {
    scert = aSigningCert->GetCert();
  }
  if (!scert) {
    return NS_ERROR_FAILURE;
  }

  UniqueSECKEYPublicKey scertPublicKey(CERT_ExtractPublicKey(scert));
  if (!scertPublicKey) {
    return mozilla::MapSECStatus(SECFailure);
  }
  KeyType subjectPublicKeyType = SECKEY_GetPublicKeyType(scertPublicKey.get());

  // Get the length of the signature in bits.
  unsigned siglen = SECKEY_SignatureLen(scertPublicKey.get()) * 8;
  if (!siglen) {
    return mozilla::MapSECStatus(SECFailure);
  }

  // Select a hash function for signature generation whose security strength
  // meets or exceeds the security strength of the public key, using NIST
  // Special Publication 800-57, Recommendation for Key Management - Part 1:
  // General (Revision 3), where Table 2 specifies the security strength of
  // the public key and Table 3 lists acceptable hash functions. (The security
  // strength of the hash (for digital signatures) is half the length of the
  // output.)
  // [SP 800-57 is available at http://csrc.nist.gov/publications/PubsSPs.html.]
  if (subjectPublicKeyType == rsaKey) {
    // For RSA, siglen is the same as the length of the modulus.

    // SHA-1 provides equivalent security strength for up to 1024 bits
    // SHA-256 provides equivalent security strength for up to 3072 bits

    if (siglen > 3072) {
      *hashType = nsICryptoHash::SHA512;
    } else if (siglen > 1024) {
      *hashType = nsICryptoHash::SHA256;
    } else {
      *hashType = nsICryptoHash::SHA1;
    }
  } else if (subjectPublicKeyType == dsaKey) {
    // For DSA, siglen is twice the length of the q parameter of the key.
    // The security strength of the key is half the length (in bits) of
    // the q parameter of the key.

    // NSS only supports SHA-1, SHA-224, and SHA-256 for DSA signatures.
    // The S/MIME code does not support SHA-224.

    if (siglen >= 512) {  // 512-bit signature = 256-bit q parameter
      *hashType = nsICryptoHash::SHA256;
    } else {
      *hashType = nsICryptoHash::SHA1;
    }
  } else if (subjectPublicKeyType == ecKey) {
    // For ECDSA, siglen is twice the length of the field size. The security
    // strength of the key is half the length (in bits) of the field size.

    if (siglen >= 1024) {  // 1024-bit signature = 512-bit field size
      *hashType = nsICryptoHash::SHA512;
    } else if (siglen >= 768) {  // 768-bit signature = 384-bit field size
      *hashType = nsICryptoHash::SHA384;
    } else if (siglen >= 512) {  // 512-bit signature = 256-bit field size
      *hashType = nsICryptoHash::SHA256;
    } else {
      *hashType = nsICryptoHash::SHA1;
    }
  } else {
    // Unknown key type
    *hashType = nsICryptoHash::SHA256;
    NS_WARNING("GetSigningHashFunction: Subject public key type unknown.");
  }
  return NS_OK;
}

/* void beginCryptoEncapsulation (in nsOutputFileStream aStream, in boolean
 * aEncrypt, in boolean aSign, in string aRecipeints, in boolean aIsDraft); */
NS_IMETHODIMP nsMsgComposeSecure::BeginCryptoEncapsulation(
    nsIOutputStream* aStream, const char* aRecipients,
    nsIMsgCompFields* aCompFields, nsIMsgIdentity* aIdentity,
    nsIMsgSendReport* sendReport, bool aIsDraft) {
  mErrorAlreadyReported = false;
  nsresult rv = NS_OK;

  // CryptoEncapsulation should be synchronous, therefore it must
  // avoid cert verification or looking up certs, which often involves
  // async OCSP. The message composer should already have looked up
  // and verified certificates whenever the user modified the recipient
  // list, and should have used CacheValidCertForEmail to make those
  // certificates known to us.
  // (That code may use the AsyncFindCertByEmailAddr API which allows
  // lookup and validation to be performed on a background thread,
  // which is required when using OCSP.)

  bool encryptMessages = false;
  bool signMessage = false;
  ExtractEncryptionState(aIdentity, aCompFields, &signMessage,
                         &encryptMessages);

  if (!signMessage && !encryptMessages) return NS_ERROR_FAILURE;

  mStream = aStream;
  mIsDraft = aIsDraft;

  if (encryptMessages && signMessage)
    mCryptoState = mime_crypto_signed_encrypted;
  else if (encryptMessages)
    mCryptoState = mime_crypto_encrypted;
  else if (signMessage)
    mCryptoState = mime_crypto_clear_signed;
  else
    PR_ASSERT(0);

  aIdentity->GetUnicharAttribute("signing_cert_name", mSigningCertName);
  aIdentity->GetCharAttribute("signing_cert_dbkey", mSigningCertDBKey);
  aIdentity->GetUnicharAttribute("encryption_cert_name", mEncryptionCertName);
  aIdentity->GetCharAttribute("encryption_cert_dbkey", mEncryptionCertDBKey);

  rv = MimeCryptoHackCerts(aRecipients, sendReport, encryptMessages,
                           signMessage, aIdentity);
  if (NS_FAILED(rv)) {
    goto FAIL;
  }

  if (signMessage && mSelfSigningCert) {
    rv = GetSigningHashFunction(mSelfSigningCert, &mHashType);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  switch (mCryptoState) {
    case mime_crypto_clear_signed:
      rv = MimeInitMultipartSigned(true, sendReport);
      break;
    case mime_crypto_opaque_signed:
      PR_ASSERT(0); /* #### no api for this yet */
      rv = NS_ERROR_NOT_IMPLEMENTED;
      break;
    case mime_crypto_signed_encrypted:
      rv = MimeInitEncryption(true, sendReport);
      break;
    case mime_crypto_encrypted:
      rv = MimeInitEncryption(false, sendReport);
      break;
    case mime_crypto_none:
      /* This can happen if mime_crypto_hack_certs() decided to turn off
       encryption (by asking the user.) */
      // XXX 1 is not a valid nsresult
      rv = static_cast<nsresult>(1);
      break;
    default:
      PR_ASSERT(0);
      break;
  }

FAIL:
  return rv;
}

/* void finishCryptoEncapsulation (in boolean aAbort); */
NS_IMETHODIMP nsMsgComposeSecure::FinishCryptoEncapsulation(
    bool aAbort, nsIMsgSendReport* sendReport) {
  nsresult rv = NS_OK;

  if (!aAbort) {
    switch (mCryptoState) {
      case mime_crypto_clear_signed:
        rv = MimeFinishMultipartSigned(true, sendReport);
        break;
      case mime_crypto_opaque_signed:
        PR_ASSERT(0); /* #### no api for this yet */
        rv = NS_ERROR_FAILURE;
        break;
      case mime_crypto_signed_encrypted:
        rv = MimeFinishEncryption(true, sendReport);
        break;
      case mime_crypto_encrypted:
        rv = MimeFinishEncryption(false, sendReport);
        break;
      default:
        PR_ASSERT(0);
        rv = NS_ERROR_FAILURE;
        break;
    }
  }
  return rv;
}

nsresult nsMsgComposeSecure::MimeInitMultipartSigned(
    bool aOuter, nsIMsgSendReport* sendReport) {
  /* First, construct and write out the multipart/signed MIME header data.
   */
  nsresult rv = NS_OK;
  char* header = 0;
  uint32_t L;

  rv = make_multipart_signed_header_string(
      aOuter, &header, &mMultipartSignedBoundary, mHashType);

  NS_ENSURE_SUCCESS(rv, rv);

  L = strlen(header);

  if (aOuter) {
    /* If this is the outer block, write it to the file. */
    uint32_t n;
    rv = mStream->Write(header, L, &n);
    if (NS_FAILED(rv) || n < L) {
      // XXX This is -1, not an nsresult
      rv = static_cast<nsresult>(MK_MIME_ERROR_WRITING_FILE);
    }
  } else {
    /* If this is an inner block, feed it through the crypto stream. */
    rv = MimeCryptoWriteBlock(header, L);
  }

  PR_Free(header);
  NS_ENSURE_SUCCESS(rv, rv);

  /* Now initialize the crypto library, so that we can compute a hash
   on the object which we are signing.
   */

  PR_SetError(0, 0);
  mDataHash = do_CreateInstance("@mozilla.org/security/hash;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = mDataHash->Init(mHashType);
  NS_ENSURE_SUCCESS(rv, rv);

  PR_SetError(0, 0);
  return rv;
}

nsresult nsMsgComposeSecure::MimeInitEncryption(bool aSign,
                                                nsIMsgSendReport* sendReport) {
  nsresult rv;
  nsCOMPtr<nsIStringBundleService> bundleSvc =
      mozilla::components::StringBundle::Service();
  NS_ENSURE_TRUE(bundleSvc, NS_ERROR_UNEXPECTED);

  nsCOMPtr<nsIStringBundle> sMIMEBundle;
  nsString mime_smime_enc_content_desc;

  bundleSvc->CreateBundle(SMIME_STRBUNDLE_URL, getter_AddRefs(sMIMEBundle));

  if (!sMIMEBundle) return NS_ERROR_FAILURE;

  sMIMEBundle->GetStringFromName("mime_smimeEncryptedContentDesc",
                                 mime_smime_enc_content_desc);
  NS_ConvertUTF16toUTF8 enc_content_desc_utf8(mime_smime_enc_content_desc);

  nsCOMPtr<nsIMimeConverter> mimeConverter =
      do_GetService("@mozilla.org/messenger/mimeconverter;1", &rv);
  NS_ENSURE_SUCCESS(rv, rv);
  nsCString encodedContentDescription;
  mimeConverter->EncodeMimePartIIStr_UTF8(
      enc_content_desc_utf8, false, sizeof("Content-Description: "),
      nsIMimeConverter::MIME_ENCODED_WORD_SIZE, encodedContentDescription);

  /* First, construct and write out the opaque-crypto-blob MIME header data.
   */

  char* s = PR_smprintf("Content-Type: " APPLICATION_PKCS7_MIME
                        "; name=\"smime.p7m\"; smime-type=enveloped-data" CRLF
                        "Content-Transfer-Encoding: " ENCODING_BASE64 CRLF
                        "Content-Disposition: attachment"
                        "; filename=\"smime.p7m\"" CRLF
                        "Content-Description: %s" CRLF CRLF,
                        encodedContentDescription.get());

  uint32_t L;
  if (!s) return NS_ERROR_OUT_OF_MEMORY;
  L = strlen(s);
  uint32_t n;
  rv = mStream->Write(s, L, &n);
  if (NS_FAILED(rv) || n < L) {
    return NS_ERROR_FAILURE;
  }
  PR_Free(s);
  s = 0;

  /* Now initialize the crypto library, so that we can filter the object
   to be encrypted through it.
   */

  if (!mIsDraft) {
    PR_ASSERT(!mCerts.IsEmpty());
    if (mCerts.IsEmpty()) return NS_ERROR_FAILURE;
  }

  // If a previous call to MimeInitEncryption (this function) failed,
  // the mEncryptionContext already exists and references our
  // mCryptoEncoder. Destroy mEncryptionContext to release the
  // reference prior to resetting mCryptoEncoder.
  if (mEncryptionContext) {
    mEncryptionContext->Finish();
    mEncryptionContext = nullptr;
  }

  // Initialize the base64 encoder
  mCryptoEncoder.reset(
      MimeEncoder::GetBase64Encoder(mime_encoder_output_fn, this));

  /* Initialize the encrypter (and add the sender's cert.) */
  PR_ASSERT(mSelfEncryptionCert);
  PR_SetError(0, 0);
  mEncryptionCinfo = do_CreateInstance(NS_CMSMESSAGE_CONTRACTID, &rv);
  if (NS_FAILED(rv)) return rv;
  rv = mEncryptionCinfo->CreateEncrypted(mCerts);
  if (NS_FAILED(rv)) {
    SetError(sendReport, u"ErrorEncryptMail");
    goto FAIL;
  }

  mEncryptionContext = do_CreateInstance(NS_CMSENCODER_CONTRACTID, &rv);
  if (NS_FAILED(rv)) return rv;

  if (!mBuffer) {
    mBuffer = new char[eBufferSize];
    if (!mBuffer) return NS_ERROR_OUT_OF_MEMORY;
  }

  mBufferedBytes = 0;

  rv = mEncryptionContext->Start(mEncryptionCinfo, mime_crypto_write_base64,
                                 mCryptoEncoder.get());
  if (NS_FAILED(rv)) {
    SetError(sendReport, u"ErrorEncryptMail");
    goto FAIL;
  }

  /* If we're signing, tack a multipart/signed header onto the front of
   the data to be encrypted, and initialize the sign-hashing code too.
   */
  if (aSign) {
    rv = MimeInitMultipartSigned(false, sendReport);
    if (NS_FAILED(rv)) goto FAIL;
  }

FAIL:
  return rv;
}

nsresult nsMsgComposeSecure::MimeFinishMultipartSigned(
    bool aOuter, nsIMsgSendReport* sendReport) {
  nsresult rv;
  nsCOMPtr<nsICMSMessage> cinfo =
      do_CreateInstance(NS_CMSMESSAGE_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsICMSEncoder> encoder =
      do_CreateInstance(NS_CMSENCODER_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  char* header = nullptr;
  nsCOMPtr<nsIStringBundleService> bundleSvc =
      mozilla::components::StringBundle::Service();
  NS_ENSURE_TRUE(bundleSvc, NS_ERROR_UNEXPECTED);

  nsCOMPtr<nsIStringBundle> sMIMEBundle;
  nsString mime_smime_sig_content_desc;

  bundleSvc->CreateBundle(SMIME_STRBUNDLE_URL, getter_AddRefs(sMIMEBundle));

  if (!sMIMEBundle) return NS_ERROR_FAILURE;

  sMIMEBundle->GetStringFromName("mime_smimeSignatureContentDesc",
                                 mime_smime_sig_content_desc);

  NS_ConvertUTF16toUTF8 sig_content_desc_utf8(mime_smime_sig_content_desc);

  /* Compute the hash...
   */

  NS_ENSURE_STATE(mDataHash);
  nsAutoCString hashString;
  rv = mDataHash->Finish(false, hashString);
  mDataHash = nullptr;
  NS_ENSURE_SUCCESS(rv, rv);
  if (PR_GetError() < 0) return NS_ERROR_FAILURE;

  /* Write out the headers for the signature.
   */
  uint32_t L;
  header = PR_smprintf(
      CRLF "--%s" CRLF "Content-Type: " APPLICATION_PKCS7_SIGNATURE
           "; name=\"smime.p7s\"" CRLF
           "Content-Transfer-Encoding: " ENCODING_BASE64 CRLF
           "Content-Disposition: attachment; "
           "filename=\"smime.p7s\"" CRLF "Content-Description: %s" CRLF CRLF,
      mMultipartSignedBoundary, sig_content_desc_utf8.get());

  if (!header) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  L = strlen(header);
  if (aOuter) {
    /* If this is the outer block, write it to the file. */
    uint32_t n;
    rv = mStream->Write(header, L, &n);
    if (NS_FAILED(rv) || n < L) {
      // XXX This is -1, not an nsresult
      rv = static_cast<nsresult>(MK_MIME_ERROR_WRITING_FILE);
    }
  } else {
    /* If this is an inner block, feed it through the crypto stream. */
    rv = MimeCryptoWriteBlock(header, L);
  }

  PR_Free(header);
  NS_ENSURE_SUCCESS(rv, rv);

  /* Create the signature...
   */

  NS_ASSERTION(mHashType, "Hash function for signature has not been set.");

  PR_ASSERT(mSelfSigningCert);
  PR_SetError(0, 0);

  nsTArray<uint8_t> digest;
  digest.AppendElements(hashString.get(), hashString.Length());

  rv = cinfo->CreateSigned(mSelfSigningCert, mSelfEncryptionCert, digest,
                           mHashType);
  if (NS_FAILED(rv)) {
    SetError(sendReport, u"ErrorCanNotSignMail");
    return rv;
  }

  // Initialize the base64 encoder for the signature data.
  MOZ_ASSERT(!mSigEncoder, "Shouldn't already have a mSigEncoder");
  mSigEncoder.reset(MimeEncoder::GetBase64Encoder(
      (aOuter ? mime_encoder_output_fn : mime_nested_encoder_output_fn), this));

  /* Write out the signature.
   */
  PR_SetError(0, 0);
  rv = encoder->Start(cinfo, mime_crypto_write_base64, mSigEncoder.get());
  if (NS_FAILED(rv)) {
    SetError(sendReport, u"ErrorCanNotSignMail");
    return rv;
  }

  // We're not passing in any data, so no update needed.
  rv = encoder->Finish();
  if (NS_FAILED(rv)) {
    SetError(sendReport, u"ErrorCanNotSignMail");
    return rv;
  }

  // Shut down the sig's base64 encoder.
  rv = mSigEncoder->Flush();
  mSigEncoder.reset();
  NS_ENSURE_SUCCESS(rv, rv);

  /* Now write out the terminating boundary.
   */
  {
    uint32_t L;
    char* header = PR_smprintf(CRLF "--%s--" CRLF, mMultipartSignedBoundary);
    PR_Free(mMultipartSignedBoundary);
    mMultipartSignedBoundary = 0;

    if (!header) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
    L = strlen(header);
    if (aOuter) {
      /* If this is the outer block, write it to the file. */
      uint32_t n;
      rv = mStream->Write(header, L, &n);
      if (NS_FAILED(rv) || n < L)
        // XXX This is -1, not an nsresult
        rv = static_cast<nsresult>(MK_MIME_ERROR_WRITING_FILE);
    } else {
      /* If this is an inner block, feed it through the crypto stream. */
      rv = MimeCryptoWriteBlock(header, L);
    }
  }

  return rv;
}

/* Helper function for mime_finish_crypto_encapsulation() to close off
   an opaque crypto object (for encrypted or signed-and-encrypted messages.)
 */
nsresult nsMsgComposeSecure::MimeFinishEncryption(
    bool aSign, nsIMsgSendReport* sendReport) {
  nsresult rv;

  /* If this object is both encrypted and signed, close off the
   signature first (since it's inside.) */
  if (aSign) {
    rv = MimeFinishMultipartSigned(false, sendReport);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  /* Close off the opaque encrypted blob.
   */
  PR_ASSERT(mEncryptionContext);

  if (mBufferedBytes) {
    rv = mEncryptionContext->Update(mBuffer, mBufferedBytes);
    mBufferedBytes = 0;
    if (NS_FAILED(rv)) {
      PR_ASSERT(PR_GetError() < 0);
      return rv;
    }
  }

  rv = mEncryptionContext->Finish();
  mEncryptionContext = nullptr;

  if (NS_FAILED(rv)) {
    SetError(sendReport, u"ErrorEncryptMail");
    return rv;
  }

  NS_ENSURE_TRUE(mEncryptionCinfo, NS_ERROR_UNEXPECTED);

  mEncryptionCinfo = nullptr;

  // Shut down the base64 encoder.
  mCryptoEncoder->Flush();
  mCryptoEncoder.reset();

  uint32_t n;
  rv = mStream->Write(CRLF, 2, &n);
  if (NS_FAILED(rv) || n < 2) rv = NS_ERROR_FAILURE;

  return rv;
}

/* Used to figure out what certs should be used when encrypting this message.
 */
nsresult nsMsgComposeSecure::MimeCryptoHackCerts(const char* aRecipients,
                                                 nsIMsgSendReport* sendReport,
                                                 bool aEncrypt, bool aSign,
                                                 nsIMsgIdentity* aIdentity) {
  nsCOMPtr<nsIX509CertDB> certdb = do_GetService(NS_X509CERTDB_CONTRACTID);
  nsresult res = NS_OK;

  PR_ASSERT(aEncrypt || aSign);

  /*
   Signing and encryption certs use the following (per-identity) preferences:
   - "signing_cert_name"/"encryption_cert_name": a string specifying the
     nickname of the certificate
   - "signing_cert_dbkey"/"encryption_cert_dbkey": a Base64 encoded blob
     specifying an nsIX509Cert dbKey (represents serial number
     and issuer DN, which is considered to be unique for X.509 certificates)
  */

  RefPtr<SharedCertVerifier> certVerifier(GetDefaultCertVerifier());
  NS_ENSURE_TRUE(certVerifier, NS_ERROR_UNEXPECTED);

  // Calling CERT_GetCertNicknames has the desired side effect of
  // traversing all tokens, and bringing up prompts to unlock them.
  nsCOMPtr<nsIInterfaceRequestor> ctx = new PipUIContext();
  CERTCertNicknames* result_unused = CERT_GetCertNicknames(
      CERT_GetDefaultCertDB(), SEC_CERT_NICKNAMES_USER, ctx);
  CERT_FreeNicknames(result_unused);

  nsTArray<nsTArray<uint8_t>> builtChain;
  if (!mEncryptionCertDBKey.IsEmpty()) {
    res = certdb->FindCertByDBKey(mEncryptionCertDBKey,
                                  getter_AddRefs(mSelfEncryptionCert));

    if (NS_SUCCEEDED(res) && mSelfEncryptionCert) {
      nsTArray<uint8_t> certBytes;
      res = mSelfEncryptionCert->GetRawDER(certBytes);
      NS_ENSURE_SUCCESS(res, res);

      if (certVerifier->VerifyCert(
              certBytes, certificateUsageEmailRecipient, mozilla::pkix::Now(),
              nullptr, nullptr, builtChain,
              // Only local checks can run on the main thread.
              // Skipping OCSP for the user's own cert seems accaptable.
              CertVerifier::FLAG_LOCAL_ONLY) != mozilla::pkix::Success) {
        // not suitable for encryption, so unset cert and clear pref
        mSelfEncryptionCert = nullptr;
        mEncryptionCertDBKey.Truncate();
        aIdentity->SetCharAttribute("encryption_cert_dbkey",
                                    mEncryptionCertDBKey);
      }
    }
  }

  // same procedure for the signing cert
  if (!mSigningCertDBKey.IsEmpty()) {
    res = certdb->FindCertByDBKey(mSigningCertDBKey,
                                  getter_AddRefs(mSelfSigningCert));
    if (NS_SUCCEEDED(res) && mSelfSigningCert) {
      nsTArray<uint8_t> certBytes;
      res = mSelfSigningCert->GetRawDER(certBytes);
      NS_ENSURE_SUCCESS(res, res);

      if (certVerifier->VerifyCert(
              certBytes, certificateUsageEmailSigner, mozilla::pkix::Now(),
              nullptr, nullptr, builtChain,
              // Only local checks can run on the main thread.
              // Skipping OCSP for the user's own cert seems accaptable.
              CertVerifier::FLAG_LOCAL_ONLY) != mozilla::pkix::Success) {
        // not suitable for signing, so unset cert and clear pref
        mSelfSigningCert = nullptr;
        mSigningCertDBKey.Truncate();
        aIdentity->SetCharAttribute("signing_cert_dbkey", mSigningCertDBKey);
      }
    }
  }

  // must have both the signing and encryption certs to sign
  if (!mSelfSigningCert && aSign) {
    SetError(sendReport, u"NoSenderSigningCert");
    return NS_ERROR_FAILURE;
  }

  if (!mSelfEncryptionCert && aEncrypt) {
    SetError(sendReport, u"NoSenderEncryptionCert");
    return NS_ERROR_FAILURE;
  }

  if (aEncrypt && mSelfEncryptionCert) {
    // Make sure self's configured cert is prepared for being used
    // as an email recipient cert.
    UniqueCERTCertificate nsscert(mSelfEncryptionCert->GetCert());
    if (!nsscert) {
      return NS_ERROR_FAILURE;
    }
    // XXX: This does not respect the nsNSSShutDownObject protocol.
    if (CERT_SaveSMimeProfile(nsscert.get(), nullptr, nullptr) != SECSuccess) {
      return NS_ERROR_FAILURE;
    }
  }

  /* If the message is to be encrypted, then get the recipient certs */
  if (aEncrypt) {
    nsTArray<nsCString> mailboxes;
    ExtractEmails(EncodedHeader(nsDependentCString(aRecipients)),
                  UTF16ArrayAdapter<>(mailboxes));
    uint32_t count = mailboxes.Length();

    bool already_added_self_cert = false;

    for (uint32_t i = 0; i < count; i++) {
      nsCString mailbox_lowercase;
      ToLowerCase(mailboxes[i], mailbox_lowercase);
      nsCOMPtr<nsIX509Cert> cert;

      nsCString dbKey;
      res = GetCertDBKeyForEmail(mailbox_lowercase, dbKey);
      if (NS_SUCCEEDED(res)) {
        res = certdb->FindCertByDBKey(dbKey, getter_AddRefs(cert));
      }

      if (NS_FAILED(res) || !cert) {
        // Failure to find a valid encryption cert is fatal.
        // Here I assume that mailbox is ascii rather than utf8.
        SetErrorWithParam(sendReport, "MissingRecipientEncryptionCert",
                          mailboxes[i].get());
        return res;
      }

      /* #### see if recipient requests `signedData'.
       if (...) no_clearsigning_p = true;
       (This is the only reason we even bother looking up the certs
       of the recipients if we're sending a signed-but-not-encrypted
       message.)
       */

      if (cert.get() == mSelfEncryptionCert.get()) {
        already_added_self_cert = true;
      }

      mCerts.AppendElement(cert);
    }

    if (!already_added_self_cert) {
      mCerts.AppendElement(mSelfEncryptionCert);
    }
  }
  return res;
}

NS_IMETHODIMP nsMsgComposeSecure::MimeCryptoWriteBlock(const char* buf,
                                                       int32_t size) {
  int status = 0;
  nsresult rv;

  /* If this is a From line, mangle it before signing it.  You just know
   that something somewhere is going to mangle it later, and that's
   going to cause the signature check to fail.

   (This assumes that, in the cases where From-mangling must happen,
   this function is called a line at a time.  That happens to be the
   case.)
  */
  if (size >= 5 && buf[0] == 'F' && !strncmp(buf, "From ", 5)) {
    char mangle[] = ">";
    nsresult res = MimeCryptoWriteBlock(mangle, 1);
    if (NS_FAILED(res)) return res;
    // This value will actually be cast back to an nsresult before use, so this
    // cast is reasonable under the circumstances.
    status = static_cast<int>(res);
  }

  /* If we're signing, or signing-and-encrypting, feed this data into
   the computation of the hash. */
  if (mDataHash) {
    PR_SetError(0, 0);
    mDataHash->Update((const uint8_t*)buf, size);
    status = PR_GetError();
    if (status < 0) goto FAIL;
  }

  PR_SetError(0, 0);
  if (mEncryptionContext) {
    /* If we're encrypting, or signing-and-encrypting, write this data
       by filtering it through the crypto library. */

    /* We want to create equally sized encryption strings */
    const char* inputBytesIterator = buf;
    uint32_t inputBytesLeft = size;

    while (inputBytesLeft) {
      const uint32_t spaceLeftInBuffer = eBufferSize - mBufferedBytes;
      const uint32_t bytesToAppend =
          std::min(inputBytesLeft, spaceLeftInBuffer);

      memcpy(mBuffer + mBufferedBytes, inputBytesIterator, bytesToAppend);
      mBufferedBytes += bytesToAppend;

      inputBytesIterator += bytesToAppend;
      inputBytesLeft -= bytesToAppend;

      if (eBufferSize == mBufferedBytes) {
        rv = mEncryptionContext->Update(mBuffer, mBufferedBytes);
        mBufferedBytes = 0;
        if (NS_FAILED(rv)) {
          status = PR_GetError();
          PR_ASSERT(status < 0);
          if (status >= 0) status = -1;
          goto FAIL;
        }
      }
    }
  } else {
    /* If we're not encrypting (presumably just signing) then write this
       data directly to the file. */

    uint32_t n;
    rv = mStream->Write(buf, size, &n);
    if (NS_FAILED(rv) || n < (uint32_t)size) {
      // XXX MK_MIME_ERROR_WRITING_FILE is -1, which is not a valid nsresult
      return static_cast<nsresult>(MK_MIME_ERROR_WRITING_FILE);
    }
  }
FAIL:
  // XXX status sometimes has invalid nsresults like -1 or PR_GetError()
  // assigned to it
  return static_cast<nsresult>(status);
}

/* Returns a string consisting of a Content-Type header, and a boundary
   string, suitable for moving from the header block, down into the body
   of a multipart object.  The boundary itself is also returned (so that
   the caller knows what to write to close it off.)
 */
static nsresult make_multipart_signed_header_string(bool outer_p,
                                                    char** header_return,
                                                    char** boundary_return,
                                                    int16_t hash_type) {
  const char* hashStr;
  *header_return = 0;
  *boundary_return = mime_make_separator("ms");

  if (!*boundary_return) return NS_ERROR_OUT_OF_MEMORY;

  switch (hash_type) {
    case nsICryptoHash::SHA1:
      hashStr = PARAM_MICALG_SHA1;
      break;
    case nsICryptoHash::SHA256:
      hashStr = PARAM_MICALG_SHA256;
      break;
    case nsICryptoHash::SHA384:
      hashStr = PARAM_MICALG_SHA384;
      break;
    case nsICryptoHash::SHA512:
      hashStr = PARAM_MICALG_SHA512;
      break;
    default:
      return NS_ERROR_INVALID_ARG;
  }

  *header_return = PR_smprintf("Content-Type: " MULTIPART_SIGNED
                               "; "
                               "protocol=\"" APPLICATION_PKCS7_SIGNATURE
                               "\"; "
                               "micalg=%s; "
                               "boundary=\"%s\"" CRLF CRLF
                               "%s%s"
                               "--%s" CRLF,
                               hashStr, *boundary_return,
                               (outer_p ? crypto_multipart_blurb : ""),
                               (outer_p ? CRLF CRLF : ""), *boundary_return);

  if (!*header_return) {
    PR_Free(*boundary_return);
    *boundary_return = 0;
    return NS_ERROR_OUT_OF_MEMORY;
  }

  return NS_OK;
}

/* Used as the output function of a SEC_PKCS7EncoderContext -- we feed
   plaintext into the crypto engine, and it calls this function with encrypted
   data; then this function writes a base64-encoded representation of that
   data to the file (by filtering it through the given MimeEncoder object.)

   Also used as the output function of SEC_PKCS7Encode() -- but in that case,
   it's used to write the encoded representation of the signature.  The only
   difference is which MimeEncoder object is used.
 */
static void mime_crypto_write_base64(void* closure, const char* buf,
                                     unsigned long size) {
  MimeEncoder* encoder = (MimeEncoder*)closure;
  nsresult rv = encoder->Write(buf, size);
  PR_SetError(NS_FAILED(rv) ? static_cast<uint32_t>(rv) : 0, 0);
}

/* Used as the output function of MimeEncoder -- when we have generated
   the signature for a multipart/signed object, this is used to write the
   base64-encoded representation of the signature to the file.
 */
// TODO: size should probably be converted to uint32_t
nsresult mime_encoder_output_fn(const char* buf, int32_t size, void* closure) {
  nsMsgComposeSecure* state = (nsMsgComposeSecure*)closure;
  nsCOMPtr<nsIOutputStream> stream;
  state->GetOutputStream(getter_AddRefs(stream));
  uint32_t n;
  nsresult rv = stream->Write((char*)buf, size, &n);
  if (NS_FAILED(rv) || n < (uint32_t)size)
    return NS_ERROR_FAILURE;
  else
    return NS_OK;
}

/* Like mime_encoder_output_fn, except this is used for the case where we
   are both signing and encrypting -- the base64-encoded output of the
   signature should be fed into the crypto engine, rather than being written
   directly to the file.
 */
static nsresult mime_nested_encoder_output_fn(const char* buf, int32_t size,
                                              void* closure) {
  nsMsgComposeSecure* state = (nsMsgComposeSecure*)closure;

  // Copy to new null-terminated string so JS glue doesn't crash when
  // MimeCryptoWriteBlock() is implemented in JS.
  nsCString bufWithNull;
  bufWithNull.Assign(buf, size);
  return state->MimeCryptoWriteBlock(bufWithNull.get(), size);
}

class FindSMimeCertTask final : public CryptoTask {
 public:
  FindSMimeCertTask(const nsACString& email,
                    nsIDoneFindCertForEmailCallback* listener)
      : mEmail(email), mListener(listener) {
    MOZ_ASSERT(NS_IsMainThread());
  }
  ~FindSMimeCertTask();

 private:
  virtual nsresult CalculateResult() override;
  virtual void CallCallback(nsresult rv) override;

  const nsCString mEmail;
  nsCOMPtr<nsIX509Cert> mCert;
  nsCOMPtr<nsIDoneFindCertForEmailCallback> mListener;

  static mozilla::StaticMutex sMutex;
};

mozilla::StaticMutex FindSMimeCertTask::sMutex;

void FindSMimeCertTask::CallCallback(nsresult rv) {
  MOZ_ASSERT(NS_IsMainThread());
  nsCOMPtr<nsIX509Cert> cert;
  nsCOMPtr<nsIDoneFindCertForEmailCallback> listener;
  {
    mozilla::StaticMutexAutoLock lock(sMutex);
    if (!mListener) {
      return;
    }
    // We won't need these objects after leaving this function, so let's
    // destroy them early. Also has the benefit that we're already
    // on the main thread. By destroying the listener here, we avoid
    // dispatching in the destructor.
    mCert.swap(cert);
    mListener.swap(listener);
  }
  listener->FindCertDone(mEmail, cert);
}

/*
called by:
  GetValidCertInfo
  GetRecipientCertsInfo
  GetNoCertAddresses
*/
nsresult FindSMimeCertTask::CalculateResult() {
  MOZ_ASSERT(!NS_IsMainThread());

  nsresult rv = BlockUntilLoadableCertsLoaded();
  if (NS_FAILED(rv)) {
    return rv;
  }

  RefPtr<SharedCertVerifier> certVerifier(GetDefaultCertVerifier());
  NS_ENSURE_TRUE(certVerifier, NS_ERROR_UNEXPECTED);

  const nsCString& flatEmailAddress = PromiseFlatCString(mEmail);
  UniqueCERTCertList certlist(
      PK11_FindCertsFromEmailAddress(flatEmailAddress.get(), nullptr));
  if (!certlist) return NS_ERROR_FAILURE;

  // certlist now contains certificates with the right email address,
  // but they might not have the correct usage or might even be invalid

  if (CERT_LIST_END(CERT_LIST_HEAD(certlist), certlist))
    return NS_ERROR_FAILURE;  // no certs found

  CERTCertListNode* node;
  // search for a valid certificate
  for (node = CERT_LIST_HEAD(certlist); !CERT_LIST_END(node, certlist);
       node = CERT_LIST_NEXT(node)) {
    nsTArray<uint8_t> certBytes(node->cert->derCert.data,
                                node->cert->derCert.len);
    nsTArray<nsTArray<uint8_t>> unusedCertChain;

    mozilla::pkix::Result result = certVerifier->VerifyCert(
        certBytes, certificateUsageEmailRecipient, mozilla::pkix::Now(),
        nullptr /*XXX pinarg*/, nullptr /*hostname*/, unusedCertChain);
    if (result == mozilla::pkix::Success) {
      mozilla::StaticMutexAutoLock lock(sMutex);
      mCert = new nsNSSCertificate(node->cert);
      break;
    }
  }

  return NS_OK;
}

/*
 * We need to ensure that the callback is destroyed on the main thread.
 */
class ProxyListenerDestructor final : public mozilla::Runnable {
 public:
  explicit ProxyListenerDestructor(
      nsCOMPtr<nsIDoneFindCertForEmailCallback>&& aListener)
      : mozilla::Runnable("ProxyListenerDestructor"),
        mListener(std::move(aListener)) {}

  NS_IMETHODIMP
  Run() override {
    MOZ_ASSERT(NS_IsMainThread());
    // Release the object referenced by mListener.
    mListener = nullptr;
    return NS_OK;
  }

 private:
  nsCOMPtr<nsIDoneFindCertForEmailCallback> mListener;
};

FindSMimeCertTask::~FindSMimeCertTask() {
  // Unless we already cleaned up inside CallCallback, we must release
  // the listener on the main thread.
  if (mListener && !NS_IsMainThread()) {
    RefPtr<ProxyListenerDestructor> runnable =
        new ProxyListenerDestructor(std::move(mListener));
    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(runnable));
  }
}

NS_IMETHODIMP
nsMsgComposeSecure::CacheValidCertForEmail(const nsACString& email,
                                           const nsACString& certDBKey) {
  mozilla::StaticMutexAutoLock lock(sMutex);
  mValidCertForEmailAddr.InsertOrUpdate(email, certDBKey);
  return NS_OK;
}

NS_IMETHODIMP
nsMsgComposeSecure::HaveValidCertForEmail(const nsACString& email,
                                          bool* _retval) {
  mozilla::StaticMutexAutoLock lock(sMutex);
  *_retval = mValidCertForEmailAddr.Get(email, nullptr);
  return NS_OK;
}

NS_IMETHODIMP
nsMsgComposeSecure::GetCertDBKeyForEmail(const nsACString& email,
                                         nsACString& _retval) {
  mozilla::StaticMutexAutoLock lock(sMutex);
  nsCString dbKey;
  bool found = mValidCertForEmailAddr.Get(email, &dbKey);
  if (found) {
    _retval = dbKey;
  } else {
    _retval.Truncate();
  }
  return NS_OK;
}

NS_IMETHODIMP
nsMsgComposeSecure::AsyncFindCertByEmailAddr(
    const nsACString& email, nsIDoneFindCertForEmailCallback* callback) {
  RefPtr<CryptoTask> task = new FindSMimeCertTask(email, callback);
  return task->Dispatch();
}

mozilla::StaticMutex nsMsgComposeSecure::sMutex;