qtdemux: PIFF box detection and parsing support

The PIFF data is stored in a custom UUID box which is parsed and the
crypto_info of the element is updated accordingly. This allows
downstream decryptors to process and decrypt the protected content.

https://bugzilla.gnome.org/show_bug.cgi?id=753614

diff --git a/gst/isomp4/qtdemux.c b/gst/isomp4/qtdemux.c
index d3653fa..b568c50 100644 (file)
--- a/gst/isomp4/qtdemux.c
+++ b/gst/isomp4/qtdemux.c
@@ -530,8 +530,13 @@ static void qtdemux_do_allocation (GstQTDemux * qtdemux,
 static gboolean qtdemux_pull_mfro_mfra (GstQTDemux * qtdemux);
 static void check_update_duration (GstQTDemux * qtdemux, GstClockTime duration);
 
+static gchar *qtdemux_uuid_bytes_to_string (gconstpointer uuid_bytes);
+
+static GstStructure *qtdemux_get_cenc_sample_properties (GstQTDemux * qtdemux,
+    QtDemuxStream * stream, guint sample_index);
 static void gst_qtdemux_append_protection_system_id (GstQTDemux * qtdemux,
     const gchar * id);
+static void qtdemux_gst_structure_free (GstStructure * gststructure);
 
 static void
 gst_qtdemux_class_init (GstQTDemuxClass * klass)
@@ -2448,6 +2453,174 @@ qtdemux_handle_xmp_taglist (GstQTDemux * qtdemux, GstTagList * taglist,
 }
 
 static void
+qtdemux_parse_piff (GstQTDemux * qtdemux, const guint8 * buffer, gint length,
+    guint offset)
+{
+  GstByteReader br;
+  guint8 version;
+  guint32 flags = 0;
+  guint i;
+  guint8 iv_size = 8;
+  QtDemuxStream *stream;
+  GstStructure *structure;
+  QtDemuxCencSampleSetInfo *ss_info = NULL;
+  const gchar *system_id;
+  gboolean uses_sub_sample_encryption = FALSE;
+
+  if (!qtdemux->streams)
+    return;
+
+  stream = qtdemux->streams[0];
+
+  structure = gst_caps_get_structure (stream->caps, 0);
+  if (!gst_structure_has_name (structure, "application/x-cenc")) {
+    GST_WARNING_OBJECT (qtdemux,
+        "Attempting PIFF box parsing on an unencrypted stream.");
+    return;
+  }
+
+  gst_structure_get (structure, GST_PROTECTION_SYSTEM_ID_CAPS_FIELD,
+      G_TYPE_STRING, &system_id, NULL);
+  gst_qtdemux_append_protection_system_id (qtdemux, system_id);
+
+  stream->protected = TRUE;
+  stream->protection_scheme_type = FOURCC_cenc;
+
+  if (!stream->protection_scheme_info)
+    stream->protection_scheme_info = g_new0 (QtDemuxCencSampleSetInfo, 1);
+
+  ss_info = (QtDemuxCencSampleSetInfo *) stream->protection_scheme_info;
+
+  if (ss_info->default_properties)
+    gst_structure_free (ss_info->default_properties);
+
+  ss_info->default_properties =
+      gst_structure_new ("application/x-cenc",
+      "iv_size", G_TYPE_UINT, iv_size, "encrypted", G_TYPE_BOOLEAN, TRUE, NULL);
+
+  if (ss_info->crypto_info) {
+    GST_LOG_OBJECT (qtdemux, "unreffing existing crypto_info");
+    g_ptr_array_free (ss_info->crypto_info, TRUE);
+    ss_info->crypto_info = NULL;
+  }
+
+  /* skip UUID */
+  gst_byte_reader_init (&br, buffer + offset + 16, length - offset - 16);
+
+  if (!gst_byte_reader_get_uint8 (&br, &version)) {
+    GST_ERROR_OBJECT (qtdemux, "Error getting box's version field");
+    return;
+  }
+
+  if (!gst_byte_reader_get_uint24_be (&br, &flags)) {
+    GST_ERROR_OBJECT (qtdemux, "Error getting box's flags field");
+    return;
+  }
+
+  if ((flags & 0x000001)) {
+    guint32 algorithm_id = 0;
+    const guint8 *kid;
+    GstBuffer *kid_buf;
+    gboolean is_encrypted = TRUE;
+
+    if (!gst_byte_reader_get_uint24_le (&br, &algorithm_id)) {
+      GST_ERROR_OBJECT (qtdemux, "Error getting box's algorithm ID field");
+      return;
+    }
+
+    algorithm_id >>= 8;
+    if (algorithm_id == 0) {
+      is_encrypted = FALSE;
+    } else if (algorithm_id == 1) {
+      /* FIXME: maybe store this in properties? */
+      GST_DEBUG_OBJECT (qtdemux, "AES 128-bits CTR encrypted stream");
+    } else if (algorithm_id == 2) {
+      /* FIXME: maybe store this in properties? */
+      GST_DEBUG_OBJECT (qtdemux, "AES 128-bits CBC encrypted stream");
+    }
+
+    if (!gst_byte_reader_get_uint8 (&br, &iv_size))
+      return;
+
+    if (!gst_byte_reader_get_data (&br, 16, &kid))
+      return;
+
+    kid_buf = gst_buffer_new_allocate (NULL, 16, NULL);
+    gst_buffer_fill (kid_buf, 0, kid, 16);
+    if (ss_info->default_properties)
+      gst_structure_free (ss_info->default_properties);
+    ss_info->default_properties =
+        gst_structure_new ("application/x-cenc",
+        "iv_size", G_TYPE_UINT, iv_size,
+        "encrypted", G_TYPE_BOOLEAN, is_encrypted,
+        "kid", GST_TYPE_BUFFER, kid_buf, NULL);
+    GST_DEBUG_OBJECT (qtdemux, "default sample properties: "
+        "is_encrypted=%u, iv_size=%u", is_encrypted, iv_size);
+    gst_buffer_unref (kid_buf);
+  } else if ((flags & 0x000002)) {
+    uses_sub_sample_encryption = TRUE;
+  }
+
+  if (!gst_byte_reader_get_uint32_be (&br, &qtdemux->cenc_aux_sample_count)) {
+    GST_ERROR_OBJECT (qtdemux, "Error getting box's sample count field");
+    return;
+  }
+
+  ss_info->crypto_info =
+      g_ptr_array_new_full (qtdemux->cenc_aux_sample_count,
+      (GDestroyNotify) qtdemux_gst_structure_free);
+
+  for (i = 0; i < qtdemux->cenc_aux_sample_count; ++i) {
+    GstStructure *properties;
+    guint8 *data;
+    GstBuffer *buf;
+
+    properties = qtdemux_get_cenc_sample_properties (qtdemux, stream, i);
+    if (properties == NULL) {
+      GST_ERROR_OBJECT (qtdemux, "failed to get properties for sample %u", i);
+      return;
+    }
+
+    if (!gst_byte_reader_dup_data (&br, iv_size, &data)) {
+      GST_ERROR_OBJECT (qtdemux, "IV data not present for sample %u", i);
+      gst_structure_free (properties);
+      return;
+    }
+    buf = gst_buffer_new_wrapped (data, iv_size);
+    gst_structure_set (properties, "iv", GST_TYPE_BUFFER, buf, NULL);
+    gst_buffer_unref (buf);
+
+    if (uses_sub_sample_encryption) {
+      guint16 n_subsamples;
+
+      if (!gst_byte_reader_get_uint16_be (&br, &n_subsamples)
+          || n_subsamples == 0) {
+        GST_ERROR_OBJECT (qtdemux,
+            "failed to get subsample count for sample %u", i);
+        gst_structure_free (properties);
+        return;
+      }
+      GST_LOG_OBJECT (qtdemux, "subsample count: %u", n_subsamples);
+      if (!gst_byte_reader_dup_data (&br, n_subsamples * 6, &data)) {
+        GST_ERROR_OBJECT (qtdemux, "failed to get subsample data for sample %u",
+            i);
+        gst_structure_free (properties);
+        return;
+      }
+      buf = gst_buffer_new_wrapped (data, n_subsamples * 6);
+      gst_structure_set (properties,
+          "subsample_count", G_TYPE_UINT, n_subsamples,
+          "subsamples", GST_TYPE_BUFFER, buf, NULL);
+      gst_buffer_unref (buf);
+    } else {
+      gst_structure_set (properties, "subsample_count", G_TYPE_UINT, 0, NULL);
+    }
+
+    g_ptr_array_add (ss_info->crypto_info, properties);
+  }
+}
+
+static void
 qtdemux_parse_uuid (GstQTDemux * qtdemux, const guint8 * buffer, gint length)
 {
   static const guint8 xmp_uuid[] = { 0xBE, 0x7A, 0xCF, 0xCB,
@@ -2459,6 +2632,12 @@ qtdemux_parse_uuid (GstQTDemux * qtdemux, const guint8 * buffer, gint length)
     0xd0, 0x8a, 0x4f, 0x18, 0x10, 0xf3, 0x4a, 0x82,
     0xb6, 0xc8, 0x32, 0xd8, 0xab, 0xa1, 0x83, 0xd3
   };
+
+  static const guint8 piff_sample_encryption_uuid[] = {
+    0xa2, 0x39, 0x4f, 0x52, 0x5a, 0x9b, 0x4f, 0x14,
+    0xa2, 0x44, 0x6c, 0x42, 0x7c, 0x64, 0x8d, 0xf4
+  };
+
   guint offset;
 
   /* counts as header data */
@@ -2497,6 +2676,8 @@ qtdemux_parse_uuid (GstQTDemux * qtdemux, const guint8 * buffer, gint length)
     GST_ELEMENT_ERROR (qtdemux, STREAM, DECRYPT,
         (_("Cannot play stream because it is encrypted with PlayReady DRM.")),
         (NULL));
+  } else if (memcmp (buffer + offset, piff_sample_encryption_uuid, 16) == 0) {
+    qtdemux_parse_piff (qtdemux, buffer, length, offset);
   } else {
     GST_DEBUG_OBJECT (qtdemux, "Ignoring unknown uuid: %08x-%08x-%08x-%08x",
         GST_READ_UINT32_LE (buffer + offset),
@@ -3390,6 +3571,7 @@ qtdemux_parse_moof (GstQTDemux * qtdemux, const guint8 * buffer, guint length,
     guint64 moof_offset, QtDemuxStream * stream)
 {
   GNode *moof_node, *traf_node, *tfhd_node, *trun_node, *tfdt_node, *mfhd_node;
+  GNode *uuid_node;
   GstByteReader mfhd_data, trun_data, tfhd_data, tfdt_data;
   GNode *saiz_node, *saio_node, *pssh_node;
   GstByteReader saiz_data, saio_data;
@@ -3538,6 +3720,15 @@ qtdemux_parse_moof (GstQTDemux * qtdemux, const guint8 * buffer, guint length,
       trun_node = qtdemux_tree_get_sibling_by_type_full (trun_node, FOURCC_trun,
           &trun_data);
     }
+
+    uuid_node = qtdemux_tree_get_child_by_type (traf_node, FOURCC_uuid);
+    if (uuid_node) {
+      guint8 *uuid_buffer = (guint8 *) uuid_node->data;
+      guint32 box_length = QT_UINT32 (uuid_buffer);
+
+      qtdemux_parse_uuid (qtdemux, uuid_buffer, box_length);
+    }
+
     /* if no new base_offset provided for next traf,
      * base is end of current traf */
     base_offset = running_offset;