path: root/mailnews/mime/src/mimemsig.cpp

/* -*- Mode: C; tab-width: 4; 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 "modmimee.h"
#include "mimemsig.h"
#include "nspr.h"

#include "prmem.h"
#include "plstr.h"
#include "prerror.h"
#include "nsMimeTypes.h"
#include "msgCore.h"
#include "nsMimeStringResources.h"
#include "mimemoz2.h"
#include "mimeeobj.h"
#include "nsIMimeConverter.h" // for MimeConverterOutputCallback
#include "mozilla/Attributes.h"

#define MIME_SUPERCLASS mimeMultipartClass
MimeDefClass(MimeMultipartSigned, MimeMultipartSignedClass,
       mimeMultipartSignedClass, &MIME_SUPERCLASS);

static int MimeMultipartSigned_initialize (MimeObject *);
static int MimeMultipartSigned_create_child (MimeObject *);
static int MimeMultipartSigned_close_child(MimeObject *);
static int MimeMultipartSigned_parse_line (const char *, int32_t, MimeObject *);
static int MimeMultipartSigned_parse_child_line (MimeObject *, const char *, int32_t,
                         bool);
static int MimeMultipartSigned_parse_eof (MimeObject *, bool);
static void MimeMultipartSigned_finalize (MimeObject *);

static int MimeMultipartSigned_emit_child (MimeObject *obj);

extern "C" MimeSuppressedCryptoClass mimeSuppressedCryptoClass;

static int
MimeMultipartSignedClassInitialize(MimeMultipartSignedClass *clazz)
{
  MimeObjectClass    *oclass = (MimeObjectClass *)    clazz;
  MimeMultipartClass *mclass = (MimeMultipartClass *) clazz;

  oclass->initialize       = MimeMultipartSigned_initialize;
  oclass->parse_line       = MimeMultipartSigned_parse_line;
  oclass->parse_eof        = MimeMultipartSigned_parse_eof;
  oclass->finalize         = MimeMultipartSigned_finalize;
  mclass->create_child     = MimeMultipartSigned_create_child;
  mclass->parse_child_line = MimeMultipartSigned_parse_child_line;
  mclass->close_child      = MimeMultipartSigned_close_child;

  PR_ASSERT(!oclass->class_initialized);
  return 0;
}

static int
MimeMultipartSigned_initialize (MimeObject *object)
{
  MimeMultipartSigned *sig = (MimeMultipartSigned *) object;

  /* This is an abstract class; it shouldn't be directly instantiated. */
  PR_ASSERT(object->clazz != (MimeObjectClass *) &mimeMultipartSignedClass);

  sig->state = MimeMultipartSignedPreamble;

  return ((MimeObjectClass*)&MIME_SUPERCLASS)->initialize(object);
}

static void
MimeMultipartSigned_cleanup (MimeObject *obj, bool finalizing_p)
{
  MimeMultipart *mult = (MimeMultipart *) obj; /* #58075.  Fix suggested by jwz */
  MimeMultipartSigned *sig = (MimeMultipartSigned *) obj;
  if (sig->part_buffer)
  {
    MimePartBufferDestroy(sig->part_buffer);
    sig->part_buffer = 0;
  }
  if (sig->body_hdrs)
  {
    MimeHeaders_free (sig->body_hdrs);
    sig->body_hdrs = 0;
  }
  if (sig->sig_hdrs)
  {
    MimeHeaders_free (sig->sig_hdrs);
    sig->sig_hdrs = 0;
  }

  mult->state = MimeMultipartEpilogue;  /* #58075.  Fix suggested by jwz */
  sig->state = MimeMultipartSignedEpilogue;

  if (finalizing_p && sig->crypto_closure) {
    /* Don't free these until this object is really going away -- keep them
       around for the lifetime of the MIME object, so that we can get at the
       security info of sub-parts of the currently-displayed message. */
    ((MimeMultipartSignedClass *) obj->clazz)->crypto_free (sig->crypto_closure);
     sig->crypto_closure = 0;
  }

  if (sig->sig_decoder_data)
  {
    MimeDecoderDestroy(sig->sig_decoder_data, true);
    sig->sig_decoder_data = 0;
  }
}

static int
MimeMultipartSigned_parse_eof (MimeObject *obj, bool abort_p)
{
  MimeMultipartSigned *sig = (MimeMultipartSigned *) obj;
  int status = 0;

  if (obj->closed_p) return 0;

  /* Close off the signature, if we've gotten that far.
   */
  if (sig->state == MimeMultipartSignedSignatureHeaders ||
    sig->state == MimeMultipartSignedSignatureFirstLine ||
    sig->state == MimeMultipartSignedSignatureLine ||
    sig->state == MimeMultipartSignedEpilogue)
  {
    status = (((MimeMultipartSignedClass *) obj->clazz)->crypto_signature_eof) (sig->crypto_closure, abort_p);
    if (status < 0) return status;
  }

  if (!abort_p)
  {
    /* Now that we've read both the signed object and the signature (and
     have presumably verified the signature) write out a blurb, and then
     the signed object.
     */
    status = MimeMultipartSigned_emit_child(obj);
    if (status < 0) return status;
  }

  MimeMultipartSigned_cleanup(obj, false);
  return ((MimeObjectClass*)&MIME_SUPERCLASS)->parse_eof(obj, abort_p);
}


static void
MimeMultipartSigned_finalize (MimeObject *obj)
{
  MimeMultipartSigned_cleanup(obj, true);
  ((MimeObjectClass*)&MIME_SUPERCLASS)->finalize(obj);
}


static int
MimeMultipartSigned_parse_line (const char *line, int32_t length, MimeObject *obj)
{
  MimeMultipart *mult = (MimeMultipart *) obj;
  MimeMultipartSigned *sig = (MimeMultipartSigned *) obj;
  MimeMultipartParseState old_state = mult->state;
  bool hash_line_p = true;
  bool no_headers_p = false;
  int status = 0;

  /* First do the parsing for normal multipart/ objects by handing it off to
   the superclass method.  This includes calling the create_child and
   close_child methods.
   */
  status = (((MimeObjectClass *)(&MIME_SUPERCLASS))
      ->parse_line (line, length, obj));
  if (status < 0) return status;

  /* The instance variable MimeMultipartClass->state tracks motion through
   the various stages of multipart/ parsing.  The instance variable
   MimeMultipartSigned->state tracks the difference between the first
   part (the body) and the second part (the signature.)  This second,
   more specific state variable is updated by noticing the transitions
   of the first, more general state variable.
   */
  if (old_state != mult->state)  /* there has been a state change */
  {
    switch (mult->state)
    {
    case MimeMultipartPreamble:
      PR_ASSERT(0);  /* can't move *in* to preamble state. */
      sig->state = MimeMultipartSignedPreamble;
      break;

    case MimeMultipartHeaders:
      /* If we're moving in to the Headers state, then that means
       that this line is the preceeding boundary string (and we
       should ignore it.)
       */
      hash_line_p = false;

      if (sig->state == MimeMultipartSignedPreamble)
      sig->state = MimeMultipartSignedBodyFirstHeader;
      else if (sig->state == MimeMultipartSignedBodyFirstLine ||
           sig->state == MimeMultipartSignedBodyLine)
      sig->state = MimeMultipartSignedSignatureHeaders;
      else if (sig->state == MimeMultipartSignedSignatureFirstLine ||
           sig->state == MimeMultipartSignedSignatureLine)
      sig->state = MimeMultipartSignedEpilogue;
      break;

    case MimeMultipartPartFirstLine:
      if (sig->state == MimeMultipartSignedBodyFirstHeader)
      {      
        sig->state = MimeMultipartSignedBodyFirstLine;
        no_headers_p = true;
      }
      else if (sig->state == MimeMultipartSignedBodyHeaders)
      sig->state = MimeMultipartSignedBodyFirstLine;
      else if (sig->state == MimeMultipartSignedSignatureHeaders)
      sig->state = MimeMultipartSignedSignatureFirstLine;
      else
      sig->state = MimeMultipartSignedEpilogue;
      break;

    case MimeMultipartPartLine:

      PR_ASSERT(sig->state == MimeMultipartSignedBodyFirstLine ||
          sig->state == MimeMultipartSignedBodyLine ||
          sig->state == MimeMultipartSignedSignatureFirstLine ||
          sig->state == MimeMultipartSignedSignatureLine);

      if (sig->state == MimeMultipartSignedBodyFirstLine)
      sig->state = MimeMultipartSignedBodyLine;
      else if (sig->state == MimeMultipartSignedSignatureFirstLine)
      sig->state = MimeMultipartSignedSignatureLine;
      break;

    case MimeMultipartEpilogue:
      sig->state = MimeMultipartSignedEpilogue;
      break;

    default:  /* bad state */
      NS_ERROR("bad state in MultipartSigned parse line");
      return -1;
      break;
    }
  }


  /* Perform multipart/signed-related actions on this line based on the state
   of the parser.
   */
  switch (sig->state)
  {
  case MimeMultipartSignedPreamble:
    /* Do nothing. */
    break;

  case MimeMultipartSignedBodyFirstLine:
    /* We have just moved out of the MimeMultipartSignedBodyHeaders
     state, so cache away the headers that apply only to the body part.
     */
    NS_ASSERTION(mult->hdrs, "null multipart hdrs");
    NS_ASSERTION(!sig->body_hdrs, "signed part shouldn't have already have body_hdrs");
    sig->body_hdrs = mult->hdrs;
    mult->hdrs = 0;

    /* fall through. */
   [[fallthrough]];
  case MimeMultipartSignedBodyFirstHeader:
  case MimeMultipartSignedBodyHeaders:
  case MimeMultipartSignedBodyLine:

    if (!sig->crypto_closure)
    {
      /* Set error change */
      PR_SetError(0, 0);
      /* Initialize the signature verification library. */
      sig->crypto_closure = (((MimeMultipartSignedClass *) obj->clazz)
                 ->crypto_init) (obj);
      if (!sig->crypto_closure)
      {
        status = PR_GetError();
        NS_ASSERTION(status < 0, "got non-negative status");
        if (status >= 0)
          status = -1;
        return status;
      }
    }

    if (hash_line_p)
    {
      /* this is the first hashed line if this is the first header
       (that is, if it's the first line in the header state after
       a state change.)
       */
      bool first_line_p
      = (no_headers_p ||
         sig->state == MimeMultipartSignedBodyFirstHeader);

      if (sig->state == MimeMultipartSignedBodyFirstHeader)
      sig->state = MimeMultipartSignedBodyHeaders;

      /* The newline issues here are tricky, since both the newlines
       before and after the boundary string are to be considered part
       of the boundary: this is so that a part can be specified such
       that it does not end in a trailing newline.

       To implement this, we send a newline *before* each line instead
       of after, except for the first line, which is not preceeded by a
       newline.

       For purposes of cryptographic hashing, we always hash line
       breaks as CRLF -- the canonical, on-the-wire linebreaks, since
       we have no idea of knowing what line breaks were used on the
       originating system (SMTP rightly destroys that information.)
       */

      /* Remove the trailing newline... */
      if (length > 0 && line[length-1] == '\n') length--;
      if (length > 0 && line[length-1] == '\r') length--;

      PR_ASSERT(sig->crypto_closure);

      if (!first_line_p)
      {
        /* Push out a preceeding newline... */
        char nl[] = CRLF;
        status = (((MimeMultipartSignedClass *) obj->clazz)
            ->crypto_data_hash (nl, 2, sig->crypto_closure));
        if (status < 0) return status;
      }

      /* Now push out the line sans trailing newline. */
      if (length > 0)
      status = (((MimeMultipartSignedClass *) obj->clazz)
            ->crypto_data_hash (line,length, sig->crypto_closure));
      if (status < 0) return status;
    }
    break;

  case MimeMultipartSignedSignatureHeaders:

    if (sig->crypto_closure &&
      old_state != mult->state)
    {
      /* We have just moved out of the MimeMultipartSignedBodyLine
       state, so tell the signature verification library that we've
       reached the end of the signed data.
       */
      status = (((MimeMultipartSignedClass *) obj->clazz)
          ->crypto_data_eof) (sig->crypto_closure, false);
      if (status < 0) return status;
    }
    break;

  case MimeMultipartSignedSignatureFirstLine:
    /* We have just moved out of the MimeMultipartSignedSignatureHeaders
     state, so cache away the headers that apply only to the sig part.
     */
    PR_ASSERT(mult->hdrs);
    PR_ASSERT(!sig->sig_hdrs);
    sig->sig_hdrs = mult->hdrs;
    mult->hdrs = 0;


    /* If the signature block has an encoding, set up a decoder for it.
     (Similar logic is in MimeLeafClass->parse_begin.)
     */
    {
    MimeDecoderData *(*fn) (MimeConverterOutputCallback, void*) = 0;
    nsCString encoding;
    encoding.Adopt(MimeHeaders_get (sig->sig_hdrs,
                   HEADER_CONTENT_TRANSFER_ENCODING,
                   true, false));
    if (encoding.IsEmpty())
      ;
    else if (!PL_strcasecmp(encoding.get(), ENCODING_BASE64))
      fn = &MimeB64DecoderInit;
    else if (!PL_strcasecmp(encoding.get(), ENCODING_QUOTED_PRINTABLE))
    {
      sig->sig_decoder_data =
  MimeQPDecoderInit (((MimeConverterOutputCallback)
     (((MimeMultipartSignedClass *) obj->clazz)
          ->crypto_signature_hash)),
    sig->crypto_closure);
      if (!sig->sig_decoder_data)
  return MIME_OUT_OF_MEMORY;
    }
    else if (!PL_strcasecmp(encoding.get(), ENCODING_UUENCODE) ||
             !PL_strcasecmp(encoding.get(), ENCODING_UUENCODE2) ||
             !PL_strcasecmp(encoding.get(), ENCODING_UUENCODE3) ||
             !PL_strcasecmp(encoding.get(), ENCODING_UUENCODE4))
      fn = &MimeUUDecoderInit;
    else if (!PL_strcasecmp(encoding.get(), ENCODING_YENCODE))
      fn = &MimeYDecoderInit;
    if (fn)
      {
      sig->sig_decoder_data =
        fn (((MimeConverterOutputCallback)
           (((MimeMultipartSignedClass *) obj->clazz)
          ->crypto_signature_hash)),
          sig->crypto_closure);
      if (!sig->sig_decoder_data)
        return MIME_OUT_OF_MEMORY;
      }
    }

    /* Show these headers to the crypto module. */
    if (hash_line_p)
    {
      status = (((MimeMultipartSignedClass *) obj->clazz)
          ->crypto_signature_init) (sig->crypto_closure,
                        obj, sig->sig_hdrs);
      if (status < 0) return status;
    }

    /* fall through. */
   [[fallthrough]];
  case MimeMultipartSignedSignatureLine:
    if (hash_line_p)
    {
      /* Feed this line into the signature verification routines. */

      if (sig->sig_decoder_data)
      status = MimeDecoderWrite (sig->sig_decoder_data, line, length, nullptr);
      else
      status = (((MimeMultipartSignedClass *) obj->clazz)
            ->crypto_signature_hash (line, length,
                         sig->crypto_closure));
      if (status < 0) return status;
    }
    break;

  case MimeMultipartSignedEpilogue:
    /* Nothing special to do here. */
    break;

  default:  /* bad state */
    PR_ASSERT(0);
    return -1;
  }

  return status;
}


static int
MimeMultipartSigned_create_child (MimeObject *parent)
{
  /* Don't actually create a child -- we call the superclass create_child
   method later, after we've fully parsed everything.  (And we only call
   it once, for part #1, and never for part #2 (the signature.))
   */
  MimeMultipart *mult = (MimeMultipart *) parent;
  mult->state = MimeMultipartPartFirstLine;
  return 0;
}


static int
MimeMultipartSigned_close_child (MimeObject *obj)
{
  /* The close_child method on MimeMultipartSigned doesn't actually do
   anything to the children list, since the create_child method also
   doesn't do anything.
   */
  MimeMultipart *mult = (MimeMultipart *) obj;
  MimeContainer *cont = (MimeContainer *) obj;
  MimeMultipartSigned *msig = (MimeMultipartSigned *) obj;

  if (msig->part_buffer)
  /* Closes the tmp file, if there is one: doesn't free the part_buffer. */
  MimePartBufferClose(msig->part_buffer);

  if (mult->hdrs)  /* duplicated from MimeMultipart_close_child, ugh. */
  {
    MimeHeaders_free(mult->hdrs);
    mult->hdrs = 0;
  }

  /* Should be no kids yet. */
  PR_ASSERT(cont->nchildren == 0);
  if (cont->nchildren != 0) return -1;

  return 0;
}


static int
MimeMultipartSigned_parse_child_line (MimeObject *obj,
                    const char *line, int32_t length,
                    bool first_line_p)
{
  MimeMultipartSigned *sig = (MimeMultipartSigned *) obj;
  MimeContainer *cont = (MimeContainer *) obj;
  int status = 0;

  /* Shouldn't have made any sub-parts yet. */
  PR_ASSERT(cont->nchildren == 0);
  if (cont->nchildren != 0) return -1;

  switch (sig->state)
  {
  case MimeMultipartSignedPreamble:
  case MimeMultipartSignedBodyFirstHeader:
  case MimeMultipartSignedBodyHeaders:
    // How'd we get here?  Oh well, fall through.
    NS_ERROR("wrong state in parse child line");
    [[fallthrough]];
  case MimeMultipartSignedBodyFirstLine:
    PR_ASSERT(first_line_p);
    if (!sig->part_buffer)
    {
      sig->part_buffer = MimePartBufferCreate();
      if (!sig->part_buffer)
      return MIME_OUT_OF_MEMORY;
    }
    /* fall through */
   [[fallthrough]];
  case MimeMultipartSignedBodyLine:
    {
    /* This is the first part; we are buffering it, and will emit it all
       at the end (so that we know whether the signature matches before
       showing anything to the user.)
     */

    /* The newline issues here are tricky, since both the newlines
       before and after the boundary string are to be considered part
       of the boundary: this is so that a part can be specified such
       that it does not end in a trailing newline.

       To implement this, we send a newline *before* each line instead
       of after, except for the first line, which is not preceeded by a
       newline.
     */

    /* Remove the trailing newline... */
    if (length > 0 && line[length-1] == '\n') length--;
    if (length > 0 && line[length-1] == '\r') length--;

    PR_ASSERT(sig->part_buffer);
    PR_ASSERT(first_line_p ==
          (sig->state == MimeMultipartSignedBodyFirstLine));

    if (!first_line_p)
      {
      /* Push out a preceeding newline... */
      char nl[] = MSG_LINEBREAK;
      status = MimePartBufferWrite (sig->part_buffer, nl, MSG_LINEBREAK_LEN);
      if (status < 0) return status;
      }

    /* Now push out the line sans trailing newline. */
    if (length > 0)
      status = MimePartBufferWrite (sig->part_buffer, line, length);
    if (status < 0) return status;
    }
  break;

  case MimeMultipartSignedSignatureHeaders:
    // How'd we get here?  Oh well, fall through.
    NS_ERROR("should have already parse sig hdrs");
    [[fallthrough]];
  case MimeMultipartSignedSignatureFirstLine:
  case MimeMultipartSignedSignatureLine:
    /* Nothing to do here -- hashing of the signature part is handled up
     in MimeMultipartSigned_parse_line().
     */
    break;

  case MimeMultipartSignedEpilogue:
    /* Too many kids?  MimeMultipartSigned_create_child() should have
     prevented us from getting here. */
    NS_ERROR("too many kids?");
    return -1;
    break;

  default: /* bad state */
    NS_ERROR("bad state in multipart signed parse line");
    return -1;
    break;
  }

  return status;
}


static int
MimeMultipartSigned_emit_child (MimeObject *obj)
{
  MimeMultipartSigned *sig = (MimeMultipartSigned *) obj;
  MimeMultipart *mult = (MimeMultipart *) obj;
  MimeContainer *cont = (MimeContainer *) obj;
  int status = 0;
  MimeObject *body;

  if (!sig->crypto_closure) {
    // We might have decided to skip processing this part.
    return 0;
  }

  NS_ASSERTION(sig->crypto_closure, "no crypto closure");

  /* Emit some HTML saying whether the signature was cool.
   But don't emit anything if in FO_QUOTE_MESSAGE mode.
   */
  if (obj->options &&
    obj->options->headers != MimeHeadersCitation &&
    obj->options->write_html_p &&
    obj->options->output_fn &&
    sig->crypto_closure)
  {
    // Calling crypto_generate_html may trigger wanted side effects,
    // but we're no longer using its results.
    char *html = (((MimeMultipartSignedClass *) obj->clazz)
          ->crypto_generate_html (sig->crypto_closure));
    PR_FREEIF(html);

    /* Now that we have written out the crypto stamp, the outermost header
     block is well and truly closed.  If this is in fact the outermost
     message, then run the post_header_html_fn now.
     */
    if (obj->options &&
      obj->options->state &&
      obj->options->generate_post_header_html_fn &&
      !obj->options->state->post_header_html_run_p)
    {
      MimeHeaders *outer_headers=nullptr;
      MimeObject *p;
      for (p = obj; p->parent; p = p->parent)
      outer_headers = p->headers;
      NS_ASSERTION(obj->options->state->first_data_written_p,
                   "should have already written some data");
      html = obj->options->generate_post_header_html_fn(NULL,
                          obj->options->html_closure,
                              outer_headers);
      obj->options->state->post_header_html_run_p = true;
      if (html)
      {
        status = MimeObject_write(obj, html, strlen(html), false);
        PR_Free(html);
        if (status < 0) return status;
      }
    }
  }


  /* Oh, this is fairly nasty.  We're skipping over our "create child" method
   and using the one our superclass defines.  Perhaps instead we should add
   a new method on this class, and initialize that method to be the
   create_child method of the superclass.  Whatever.
   */


  /* The superclass method expects to find the headers for the part that it's
   to create in mult->hdrs, so ensure that they're there. */
  NS_ASSERTION(!mult->hdrs, "shouldn't already have hdrs for multipart");
  if (mult->hdrs) MimeHeaders_free(mult->hdrs);
  mult->hdrs = sig->body_hdrs;
  sig->body_hdrs = 0;

  /* Run the superclass create_child method.
   */
  status = (((MimeMultipartClass *)(&MIME_SUPERCLASS))->create_child(obj));
  if (status < 0) return status;

  // Notify the charset of the first part.
  if (obj->options && !(obj->options->override_charset)) {
    MimeObject *firstChild = ((MimeContainer*) obj)->children[0];
    char *disposition = MimeHeaders_get (firstChild->headers,
                                         HEADER_CONTENT_DISPOSITION, 
                                         true,
                                         false);
    // check if need to show as inline
    if (!disposition)
    {
      const char *content_type = firstChild->content_type;
      if (!PL_strcasecmp (content_type, TEXT_PLAIN) ||
          !PL_strcasecmp (content_type, TEXT_HTML) ||
          !PL_strcasecmp (content_type, TEXT_MDL) ||
          !PL_strcasecmp (content_type, MULTIPART_ALTERNATIVE) ||
          !PL_strcasecmp (content_type, MULTIPART_RELATED) ||
          !PL_strcasecmp (content_type, MESSAGE_NEWS) ||
          !PL_strcasecmp (content_type, MESSAGE_RFC822)) {
        char *ct = MimeHeaders_get(mult->hdrs, HEADER_CONTENT_TYPE, false, false);
        if (ct) {
          char *cset = MimeHeaders_get_parameter (ct, "charset", NULL, NULL);
          if (cset) {
            mimeEmitterUpdateCharacterSet(obj->options, cset);
            SetMailCharacterSetToMsgWindow(obj, cset);
            PR_Free(cset);
          }
          PR_Free(ct);
        }
      }
    }
  }
  
  // The js emitter wants to know about the newly created child.  Because
  //  MimeMultipartSigned dummies out its create_child operation, the logic
  //  in MimeMultipart_parse_line that would normally provide this notification
  //  does not get to fire.
  if (obj->options && obj->options->notify_nested_bodies) {
    MimeObject *kid = ((MimeContainer*) obj)->children[0];
    // The emitter is expecting the content type with parameters; not the fully
    //  parsed thing, so get it from raw.  (We do not do it in the charset
    //  notification block that just happened because it already has complex
    //  if-checks that do not jive with us.
    char *ct = MimeHeaders_get(mult->hdrs, HEADER_CONTENT_TYPE, false,
                               false);
    mimeEmitterAddHeaderField(obj->options, HEADER_CONTENT_TYPE,
                              ct ? ct : "text/plain");
    PR_Free(ct);
    
    char *part_path = mime_part_address(kid);
    if (part_path) {
      mimeEmitterAddHeaderField(obj->options,
                                "x-jsemitter-part-path",
                                part_path);
      PR_Free(part_path);
    }
  }

  /* Retrieve the child that it created.
   */
  NS_ASSERTION(cont->nchildren == 1, "should only have one child");
  if (cont->nchildren != 1)
    return -1;
  body = cont->children[0];
  NS_ASSERTION(body, "missing body");
  if (!body)
    return -1;

  if (mime_typep(body, (MimeObjectClass *)&mimeSuppressedCryptoClass)) {
    ((MimeMultipartSignedClass *)obj->clazz)
      ->crypto_notify_suppressed_child(sig->crypto_closure);
  }

#ifdef MIME_DRAFTS
  if (body->options->decompose_file_p) {
    body->options->signed_p = true;
    if (!mime_typep(body, (MimeObjectClass*)&mimeMultipartClass) &&
    body->options->decompose_file_init_fn)
    body->options->decompose_file_init_fn ( body->options->stream_closure, body->headers );
  }
#endif /* MIME_DRAFTS */

  /* If there's no part_buffer, this is a zero-length signed message? */
  if (sig->part_buffer)
  {
#ifdef MIME_DRAFTS
    if (body->options->decompose_file_p &&
      !mime_typep(body, (MimeObjectClass*)&mimeMultipartClass)  &&
      body->options->decompose_file_output_fn)
      status = MimePartBufferRead (sig->part_buffer,
                 /* The (MimeConverterOutputCallback) cast is to turn the
                  `void' argument into `MimeObject'. */
                 ((MimeConverterOutputCallback)
                 body->options->decompose_file_output_fn),
                 body->options->stream_closure);
    else
#endif /* MIME_DRAFTS */

    status = MimePartBufferRead (sig->part_buffer,
                 /* The (MimeConverterOutputCallback) cast is to turn the
                  `void' argument into `MimeObject'. */
                 ((MimeConverterOutputCallback) body->clazz->parse_buffer),
                body);
    if (status < 0) return status;
  }

  MimeMultipartSigned_cleanup(obj, false);

  /* Done parsing. */
  status = body->clazz->parse_eof(body, false);
  if (status < 0) return status;
  status = body->clazz->parse_end(body, false);
  if (status < 0) return status;

#ifdef MIME_DRAFTS
  if (body->options->decompose_file_p &&
    !mime_typep(body, (MimeObjectClass*)&mimeMultipartClass)  &&
    body->options->decompose_file_close_fn)
    body->options->decompose_file_close_fn(body->options->stream_closure);
#endif /* MIME_DRAFTS */

  /* Put out a separator after every multipart/signed object. */
  status = MimeObject_write_separator(obj);
  if (status < 0) return status;

  return 0;
}