1 files changed, 534 insertions, 0 deletions
diff --git a/tools/wks-receive.c b/tools/wks-receive.c
new file mode 100644
index 0000000..e5d2ed4
--- /dev/null
+++ b/tools/wks-receive.c
@@ -0,0 +1,534 @@
+/* wks-receive.c - Receive a WKS mail
+ * Copyright (C) 2016 g10 Code GmbH
+ * Copyright (C) 2016 Bundesamt für Sicherheit in der Informationstechnik
+ *
+ * This file is part of GnuPG.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This file is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "../common/util.h"
+#include "../common/ccparray.h"
+#include "../common/exectool.h"
+#include "gpg-wks.h"
+#include "rfc822parse.h"
+#include "mime-parser.h"
+
+
+/* Limit of acceptable signed data.  */
+#define MAX_SIGNEDDATA 10000
+
+/* Limit of acceptable signature.  */
+#define MAX_SIGNATURE 10000
+
+/* Limit of acceptable encrypted data.  */
+#define MAX_ENCRYPTED 100000
+
+/* Data for a received object.  */
+struct receive_ctx_s
+{
+  mime_parser_t parser;
+  estream_t encrypted;
+  estream_t plaintext;
+  estream_t signeddata;
+  estream_t signature;
+  estream_t key_data;
+  estream_t wkd_data;
+  unsigned int collect_key_data:1;
+  unsigned int collect_wkd_data:1;
+  unsigned int draft_version_2:1;  /* This is a draft version 2 request.  */
+  unsigned int multipart_mixed_seen:1;
+};
+typedef struct receive_ctx_s *receive_ctx_t;
+
+
+
+static void
+decrypt_data_status_cb (void *opaque, const char *keyword, char *args)
+{
+  receive_ctx_t ctx = opaque;
+  (void)ctx;
+  if (DBG_CRYPTO)
+    log_debug ("gpg status: %s %s\n", keyword, args);
+}
+
+
+/* Decrypt the collected data.  */
+static void
+decrypt_data (receive_ctx_t ctx)
+{
+  gpg_error_t err;
+  ccparray_t ccp;
+  const char **argv;
+  int c;
+
+  es_rewind (ctx->encrypted);
+
+  if (!ctx->plaintext)
+    ctx->plaintext = es_fopenmem (0, "w+b");
+  if (!ctx->plaintext)
+    {
+      err = gpg_error_from_syserror ();
+      log_error ("error allocating space for plaintext: %s\n",
+                 gpg_strerror (err));
+      return;
+    }
+
+  ccparray_init (&ccp, 0);
+
+  ccparray_put (&ccp, "--no-options");
+  /* We limit the output to 64 KiB to avoid DoS using compression
+   * tricks.  A regular client will anyway only send a minimal key;
+   * that is one w/o key signatures and attribute packets.  */
+  ccparray_put (&ccp, "--max-output=0x10000");
+  ccparray_put (&ccp, "--batch");
+  if (opt.verbose)
+    ccparray_put (&ccp, "--verbose");
+  ccparray_put (&ccp, "--always-trust");
+  ccparray_put (&ccp, "--decrypt");
+  ccparray_put (&ccp, "--");
+
+  ccparray_put (&ccp, NULL);
+  argv = ccparray_get (&ccp, NULL);
+  if (!argv)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+  err = gnupg_exec_tool_stream (opt.gpg_program, argv, ctx->encrypted,
+                                NULL, ctx->plaintext,
+                                decrypt_data_status_cb, ctx);
+  if (err)
+    {
+      log_error ("decryption failed: %s\n", gpg_strerror (err));
+      goto leave;
+    }
+
+  if (DBG_CRYPTO)
+    {
+      es_rewind (ctx->plaintext);
+      log_debug ("plaintext: '");
+      while ((c = es_getc (ctx->plaintext)) != EOF)
+        log_printf ("%c", c);
+      log_printf ("'\n");
+    }
+  es_rewind (ctx->plaintext);
+
+ leave:
+  xfree (argv);
+}
+
+
+static void
+verify_signature_status_cb (void *opaque, const char *keyword, char *args)
+{
+  receive_ctx_t ctx = opaque;
+  (void)ctx;
+  if (DBG_CRYPTO)
+    log_debug ("gpg status: %s %s\n", keyword, args);
+}
+
+/* Verify the signed data.  */
+static void
+verify_signature (receive_ctx_t ctx)
+{
+  gpg_error_t err;
+  ccparray_t ccp;
+  const char **argv;
+
+  log_assert (ctx->signeddata);
+  log_assert (ctx->signature);
+  es_rewind (ctx->signeddata);
+  es_rewind (ctx->signature);
+
+  ccparray_init (&ccp, 0);
+
+  ccparray_put (&ccp, "--no-options");
+  ccparray_put (&ccp, "--batch");
+  if (opt.verbose)
+    ccparray_put (&ccp, "--verbose");
+  ccparray_put (&ccp, "--enable-special-filenames");
+  ccparray_put (&ccp, "--status-fd=2");
+  ccparray_put (&ccp, "--always-trust"); /* To avoid trustdb checks.  */
+  ccparray_put (&ccp, "--verify");
+  ccparray_put (&ccp, "--");
+  ccparray_put (&ccp, "-&@INEXTRA@");
+  ccparray_put (&ccp, "-");
+
+  ccparray_put (&ccp, NULL);
+  argv = ccparray_get (&ccp, NULL);
+  if (!argv)
+    {
+      err = gpg_error_from_syserror ();
+      goto leave;
+    }
+  err = gnupg_exec_tool_stream (opt.gpg_program, argv, ctx->signeddata,
+                                ctx->signature, NULL,
+                                verify_signature_status_cb, ctx);
+  if (err)
+    {
+      log_error ("verification failed: %s\n", gpg_strerror (err));
+      goto leave;
+    }
+
+  log_debug ("Fixme: Verification result is not used\n");
+
+ leave:
+  xfree (argv);
+}
+
+
+static gpg_error_t
+collect_encrypted (void *cookie, const char *data)
+{
+  receive_ctx_t ctx = cookie;
+
+  if (!ctx->encrypted)
+    if (!(ctx->encrypted = es_fopenmem (MAX_ENCRYPTED, "w+b,samethread")))
+      return gpg_error_from_syserror ();
+  if (data)
+    es_fputs (data, ctx->encrypted);
+
+  if (es_ferror (ctx->encrypted))
+    return gpg_error_from_syserror ();
+
+  if (!data)
+    {
+      decrypt_data (ctx);
+    }
+
+  return 0;
+}
+
+
+static gpg_error_t
+collect_signeddata (void *cookie, const char *data)
+{
+  receive_ctx_t ctx = cookie;
+
+  if (!ctx->signeddata)
+    if (!(ctx->signeddata = es_fopenmem (MAX_SIGNEDDATA, "w+b,samethread")))
+      return gpg_error_from_syserror ();
+  if (data)
+    es_fputs (data, ctx->signeddata);
+
+  if (es_ferror (ctx->signeddata))
+    return gpg_error_from_syserror ();
+  return 0;
+}
+
+static gpg_error_t
+collect_signature (void *cookie, const char *data)
+{
+  receive_ctx_t ctx = cookie;
+
+  if (!ctx->signature)
+    if (!(ctx->signature = es_fopenmem (MAX_SIGNATURE, "w+b,samethread")))
+      return gpg_error_from_syserror ();
+  if (data)
+    es_fputs (data, ctx->signature);
+
+  if (es_ferror (ctx->signature))
+    return gpg_error_from_syserror ();
+
+  if (!data)
+    {
+      verify_signature (ctx);
+    }
+
+  return 0;
+}
+
+
+/* The callback for the transition from header to body.  We use it to
+ * look at some header values.  */
+static gpg_error_t
+t2body (void *cookie, int level)
+{
+  receive_ctx_t ctx = cookie;
+  rfc822parse_t msg;
+  char *value;
+  size_t valueoff;
+
+  log_info ("t2body for level %d\n", level);
+  if (!level)
+    {
+      /* This is the outermost header.  */
+      msg = mime_parser_rfc822parser (ctx->parser);
+      if (msg)
+        {
+          value = rfc822parse_get_field (msg, "Wks-Draft-Version",
+                                         -1, &valueoff);
+          if (value)
+            {
+              if (atoi(value+valueoff) >= 2 )
+                ctx->draft_version_2 = 1;
+              free (value);
+            }
+        }
+    }
+
+  return 0;
+}
+
+
+static gpg_error_t
+new_part (void *cookie, const char *mediatype, const char *mediasubtype)
+{
+  receive_ctx_t ctx = cookie;
+  gpg_error_t err = 0;
+
+  ctx->collect_key_data = 0;
+  ctx->collect_wkd_data = 0;
+
+  if (!strcmp (mediatype, "application")
+      && !strcmp (mediasubtype, "pgp-keys"))
+    {
+      log_info ("new '%s/%s' message part\n", mediatype, mediasubtype);
+      if (ctx->key_data)
+        {
+          log_error ("we already got a key - ignoring this part\n");
+          err = gpg_error (GPG_ERR_FALSE);
+        }
+      else
+        {
+          ctx->key_data = es_fopenmem (0, "w+b");
+          if (!ctx->key_data)
+            {
+              err = gpg_error_from_syserror ();
+              log_error ("error allocating space for key: %s\n",
+                         gpg_strerror (err));
+            }
+          else
+            {
+              ctx->collect_key_data = 1;
+              err = gpg_error (GPG_ERR_TRUE); /* We want the part decoded.  */
+            }
+        }
+    }
+  else if (!strcmp (mediatype, "application")
+           && !strcmp (mediasubtype, "vnd.gnupg.wks"))
+    {
+      log_info ("new '%s/%s' message part\n", mediatype, mediasubtype);
+      if (ctx->wkd_data)
+        {
+          log_error ("we already got a wkd part - ignoring this part\n");
+          err = gpg_error (GPG_ERR_FALSE);
+        }
+      else
+        {
+          ctx->wkd_data = es_fopenmem (0, "w+b");
+          if (!ctx->wkd_data)
+            {
+              err = gpg_error_from_syserror ();
+              log_error ("error allocating space for key: %s\n",
+                         gpg_strerror (err));
+            }
+          else
+            {
+              ctx->collect_wkd_data = 1;
+              err = gpg_error (GPG_ERR_TRUE); /* We want the part decoded.  */
+            }
+        }
+    }
+  else if (!strcmp (mediatype, "multipart")
+           && !strcmp (mediasubtype, "mixed"))
+    {
+      ctx->multipart_mixed_seen = 1;
+    }
+  else if (!strcmp (mediatype, "text"))
+    {
+      /* Check that we receive a text part only after a
+       * application/mixed.  This is actually a too simple test and we
+       * should eventually employ a strict MIME structure check.  */
+      if (!ctx->multipart_mixed_seen)
+        err = gpg_error (GPG_ERR_UNEXPECTED_MSG);
+    }
+  else
+    {
+      log_error ("unexpected '%s/%s' message part\n", mediatype, mediasubtype);
+      err = gpg_error (GPG_ERR_FALSE); /* We do not want the part.  */
+    }
+
+  return err;
+}
+
+
+static gpg_error_t
+part_data (void *cookie, const void *data, size_t datalen)
+{
+  receive_ctx_t ctx = cookie;
+
+  if (data)
+    {
+      if (DBG_MIME)
+        log_debug ("part_data: '%.*s'\n", (int)datalen, (const char*)data);
+      if (ctx->collect_key_data)
+        {
+          if (es_write (ctx->key_data, data, datalen, NULL)
+              || es_fputs ("\n", ctx->key_data))
+            return gpg_error_from_syserror ();
+        }
+      if (ctx->collect_wkd_data)
+        {
+          if (es_write (ctx->wkd_data, data, datalen, NULL)
+              || es_fputs ("\n", ctx->wkd_data))
+            return gpg_error_from_syserror ();
+        }
+    }
+  else
+    {
+      if (DBG_MIME)
+        log_debug ("part_data: finished\n");
+      ctx->collect_key_data = 0;
+      ctx->collect_wkd_data = 0;
+    }
+  return 0;
+}
+
+
+/* Receive a WKS mail from FP and process it accordingly.  On success
+ * the RESULT_CB is called with the mediatype and a stream with the
+ * decrypted data. */
+gpg_error_t
+wks_receive (estream_t fp,
+             gpg_error_t (*result_cb)(void *opaque,
+                                      const char *mediatype,
+                                      estream_t data,
+                                      unsigned int flags),
+             void *cb_data)
+{
+  gpg_error_t err;
+  receive_ctx_t ctx;
+  mime_parser_t parser;
+  estream_t plaintext = NULL;
+  int c;
+  unsigned int flags = 0;
+
+  ctx = xtrycalloc (1, sizeof *ctx);
+  if (!ctx)
+    return gpg_error_from_syserror ();
+
+  err = mime_parser_new (&parser, ctx);
+  if (err)
+    goto leave;
+  if (DBG_PARSER)
+    mime_parser_set_verbose (parser, 1);
+  mime_parser_set_t2body (parser, t2body);
+  mime_parser_set_new_part (parser, new_part);
+  mime_parser_set_part_data (parser, part_data);
+  mime_parser_set_collect_encrypted (parser, collect_encrypted);
+  mime_parser_set_collect_signeddata (parser, collect_signeddata);
+  mime_parser_set_collect_signature (parser, collect_signature);
+
+  ctx->parser = parser;
+
+  err = mime_parser_parse (parser, fp);
+  if (err)
+    goto leave;
+
+  if (ctx->key_data)
+    log_info ("key data found\n");
+  if (ctx->wkd_data)
+    log_info ("wkd data found\n");
+  if (ctx->draft_version_2)
+    {
+      log_info ("draft version 2 requested\n");
+      flags |= WKS_RECEIVE_DRAFT2;
+    }
+
+  if (ctx->plaintext)
+    {
+      if (opt.verbose)
+        log_info ("parsing decrypted message\n");
+      plaintext = ctx->plaintext;
+      ctx->plaintext = NULL;
+      if (ctx->encrypted)
+        es_rewind (ctx->encrypted);
+      if (ctx->signeddata)
+        es_rewind (ctx->signeddata);
+      if (ctx->signature)
+        es_rewind (ctx->signature);
+      err = mime_parser_parse (parser, plaintext);
+      if (err)
+        return err;
+    }
+
+  if (!ctx->key_data && !ctx->wkd_data)
+    {
+      log_error ("no suitable data found in the message\n");
+      err = gpg_error (GPG_ERR_NO_DATA);
+      goto leave;
+    }
+
+  if (ctx->key_data)
+    {
+      if (DBG_MIME)
+        {
+          es_rewind (ctx->key_data);
+          log_debug ("Key: '");
+          log_printf ("\n");
+          while ((c = es_getc (ctx->key_data)) != EOF)
+            log_printf ("%c", c);
+          log_printf ("'\n");
+        }
+      if (result_cb)
+        {
+          es_rewind (ctx->key_data);
+          err = result_cb (cb_data, "application/pgp-keys",
+                           ctx->key_data, flags);
+          if (err)
+            goto leave;
+        }
+    }
+  if (ctx->wkd_data)
+    {
+      if (DBG_MIME)
+        {
+          es_rewind (ctx->wkd_data);
+          log_debug ("WKD: '");
+          log_printf ("\n");
+          while ((c = es_getc (ctx->wkd_data)) != EOF)
+            log_printf ("%c", c);
+          log_printf ("'\n");
+        }
+      if (result_cb)
+        {
+          es_rewind (ctx->wkd_data);
+          err = result_cb (cb_data, "application/vnd.gnupg.wks",
+                           ctx->wkd_data, flags);
+          if (err)
+            goto leave;
+        }
+    }
+
+
+ leave:
+  es_fclose (plaintext);
+  mime_parser_release (parser);
+  ctx->parser = NULL;
+  es_fclose (ctx->encrypted);
+  es_fclose (ctx->plaintext);
+  es_fclose (ctx->signeddata);
+  es_fclose (ctx->signature);
+  es_fclose (ctx->key_data);
+  es_fclose (ctx->wkd_data);
+  xfree (ctx);
+  return err;
+}