matroskadec: Add support for parsing Matroska ContentEncKeyID

This patch adds the enums for the ContentEncryption elements.
This patch also adds support for parsing the ContentEncKeyID. The
ContentEncKeyID is then base64 encoded and stored in the stream's
metadata.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 48 insertions, 5 deletions

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 115c9265eb..eea29daba0 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -39,6 +39,7 @@
 #include "matroska.h"
 #include "libavcodec/bytestream.h"
 #include "libavcodec/mpeg4audio.h"
+#include "libavutil/base64.h"
 #include "libavutil/intfloat.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/avstring.h"
@@ -102,9 +103,15 @@ typedef struct {
 } MatroskaTrackCompression;
 
 typedef struct {
+    uint64_t algo;
+    EbmlBin  key_id;
+} MatroskaTrackEncryption;
+
+typedef struct {
     uint64_t scope;
     uint64_t type;
     MatroskaTrackCompression compression;
+    MatroskaTrackEncryption encryption;
 } MatroskaTrackEncoding;
 
 typedef struct {
@@ -345,10 +352,21 @@ static EbmlSyntax matroska_track_encoding_compression[] = {
     { 0 }
 };
 
+static EbmlSyntax matroska_track_encoding_encryption[] = {
+    { MATROSKA_ID_ENCODINGENCALGO,        EBML_UINT, 0, offsetof(MatroskaTrackEncryption,algo), {.u=0} },
+    { MATROSKA_ID_ENCODINGENCKEYID,       EBML_BIN, 0, offsetof(MatroskaTrackEncryption,key_id) },
+    { MATROSKA_ID_ENCODINGENCAESSETTINGS, EBML_NONE },
+    { MATROSKA_ID_ENCODINGSIGALGO,        EBML_NONE },
+    { MATROSKA_ID_ENCODINGSIGHASHALGO,    EBML_NONE },
+    { MATROSKA_ID_ENCODINGSIGKEYID,       EBML_NONE },
+    { MATROSKA_ID_ENCODINGSIGNATURE,      EBML_NONE },
+    { 0 }
+};
 static EbmlSyntax matroska_track_encoding[] = {
     { MATROSKA_ID_ENCODINGSCOPE,      EBML_UINT, 0, offsetof(MatroskaTrackEncoding,scope), {.u=1} },
     { MATROSKA_ID_ENCODINGTYPE,       EBML_UINT, 0, offsetof(MatroskaTrackEncoding,type), {.u=0} },
     { MATROSKA_ID_ENCODINGCOMPRESSION,EBML_NEST, 0, offsetof(MatroskaTrackEncoding,compression), {.n=matroska_track_encoding_compression} },
+    { MATROSKA_ID_ENCODINGENCRYPTION, EBML_NEST, 0, offsetof(MatroskaTrackEncoding,encryption), {.n=matroska_track_encoding_encryption} },
     { MATROSKA_ID_ENCODINGORDER,      EBML_NONE },
     { 0 }
 };
@@ -1541,6 +1559,7 @@ static int matroska_read_header(AVFormatContext *s)
         int extradata_offset = 0;
         uint32_t fourcc = 0;
         AVIOContext b;
+        char* key_id_base64 = NULL;
 
         /* Apply some sanity checks. */
         if (track->type != MATROSKA_TRACK_TYPE_VIDEO &&
@@ -1571,8 +1590,24 @@ static int matroska_read_header(AVFormatContext *s)
             av_log(matroska->ctx, AV_LOG_ERROR,
                    "Multiple combined encodings not supported");
         } else if (encodings_list->nb_elem == 1) {
-            if (encodings[0].type ||
-                (
+            if (encodings[0].type) {
+                if (encodings[0].encryption.key_id.size > 0) {
+                    /* Save the encryption key id to be stored later as a
+                       metadata tag. */
+                    const int b64_size = AV_BASE64_SIZE(encodings[0].encryption.key_id.size);
+                    key_id_base64 = av_malloc(b64_size);
+                    if (key_id_base64 == NULL)
+                        return AVERROR(ENOMEM);
+
+                    av_base64_encode(key_id_base64, b64_size,
+                                     encodings[0].encryption.key_id.data,
+                                     encodings[0].encryption.key_id.size);
+                } else {
+                    encodings[0].scope = 0;
+                    av_log(matroska->ctx, AV_LOG_ERROR,
+                           "Unsupported encoding type");
+                }
+            } else if (
 #if CONFIG_ZLIB
                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_ZLIB &&
 #endif
@@ -1582,7 +1617,7 @@ static int matroska_read_header(AVFormatContext *s)
 #if CONFIG_LZO
                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_LZO &&
 #endif
-                 encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_HEADERSTRIP)) {
+                 encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_HEADERSTRIP) {
                 encodings[0].scope = 0;
                 av_log(matroska->ctx, AV_LOG_ERROR,
                        "Unsupported encoding type");
@@ -1612,8 +1647,16 @@ static int matroska_read_header(AVFormatContext *s)
         }
 
         st = track->stream = avformat_new_stream(s, NULL);
-        if (st == NULL)
+        if (st == NULL) {
+            av_free(key_id_base64);
             return AVERROR(ENOMEM);
+        }
+
+        if (key_id_base64) {
+            /* export encryption key id as base64 metadata tag */
+            av_dict_set(&st->metadata, "enc_key_id", key_id_base64, 0);
+            av_freep(&key_id_base64);
+        }
 
         if (!strcmp(track->codec_id, "V_MS/VFW/FOURCC")
             && track->codec_priv.size >= 40
@@ -2105,7 +2148,7 @@ static int matroska_parse_frame(MatroskaDemuxContext *matroska,
     int offset = 0, res;
     AVPacket *pkt;
 
-    if (encodings && encodings->scope & 1) {
+    if (encodings && !encodings->type && encodings->scope & 1) {
         res = matroska_decode_buffer(&pkt_data, &pkt_size, track);
         if (res < 0)
             return res;