From 4eadb8a704a3fe895224d94d4de3fed7cd9cc191 Mon Sep 17 00:00:00 2001
From: erankor <eran.kornblau@kaltura.com>
Date: Mon, 11 Jun 2018 13:12:27 +0300
Subject: [PATCH] mkv - truncate the element size instead of failing

some elements (e.g. cluster) may not be read in full when processing a
segment.
---
 vod/mkv/ebml.c       | 30 +++++++++++++++++++-----------
 vod/mkv/ebml.h       |  5 ++++-
 vod/mkv/mkv_format.c |  8 ++++----
 3 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/vod/mkv/ebml.c b/vod/mkv/ebml.c
index e1970249..c653f222 100644
--- a/vod/mkv/ebml.c
+++ b/vod/mkv/ebml.c
@@ -97,9 +97,10 @@ ebml_read_num(ebml_context_t* context, uint64_t* result, size_t max_size, int re
 }
 
 static vod_status_t
-ebml_read_size(ebml_context_t* context, uint64_t* result)
+ebml_read_size(ebml_context_t* context, bool_t truncate, uint64_t* result)
 {
 	vod_status_t rc;
+	uint64_t size_left;
 
 	rc = ebml_read_num(context, result, 8, 1);
 	if (rc < 0)
@@ -109,16 +110,22 @@ ebml_read_size(ebml_context_t* context, uint64_t* result)
 		return rc;
 	}
 
+	size_left = context->end_pos - context->cur_pos;
 	if (is_unknown_size(*result, rc))
 	{
-		*result = context->end_pos - context->cur_pos;
+		*result = size_left;
 	}
-	else if (*result > (uint64_t)(context->end_pos - context->cur_pos))
+	else if (*result > size_left)
 	{
-		vod_log_error(VOD_LOG_ERR, context->request_context->log, 0,
-			"ebml_read_size: size %uL greater than the remaining stream bytes %uL", 
-			*result, (uint64_t)(context->end_pos - context->cur_pos));
-		return VOD_BAD_DATA;
+		if (!truncate)
+		{
+			vod_log_error(VOD_LOG_ERR, context->request_context->log, 0,
+				"ebml_read_size: size %uL greater than the remaining stream bytes %uL",
+				*result, size_left);
+			return VOD_BAD_DATA;
+		}
+
+		*result = size_left;
 	}
 
 	return VOD_OK;
@@ -192,11 +199,12 @@ ebml_parse_element(ebml_context_t* context, ebml_spec_t* spec, void* dest)
 	ebml_context_t next_context;
 	uint64_t max_size;
 	uint64_t size;
+	uint32_t type = spec->type & EBML_TYPE_MASK;
 	void* cur_dest;
 	vod_status_t rc;
 
 	// size
-	rc = ebml_read_size(context, &size);
+	rc = ebml_read_size(context, spec->type & EBML_TRUNCATE, &size);
 	if (rc != VOD_OK)
 	{
 		vod_log_debug1(VOD_LOG_DEBUG_LEVEL, context->request_context->log, 0,
@@ -204,13 +212,13 @@ ebml_parse_element(ebml_context_t* context, ebml_spec_t* spec, void* dest)
 		return rc;
 	}
 
-	if (spec->type == EBML_NONE)
+	if (type == EBML_NONE)
 	{
 		context->cur_pos += size;
 		return VOD_OK;
 	}
 
-	max_size = ebml_max_sizes[spec->type];
+	max_size = ebml_max_sizes[type];
 	if (max_size && size > max_size)
 	{
 		vod_log_error(VOD_LOG_ERR, context->request_context->log, 0,
@@ -220,7 +228,7 @@ ebml_parse_element(ebml_context_t* context, ebml_spec_t* spec, void* dest)
 
 	cur_dest = (u_char*)dest + spec->offset;
 
-	switch (spec->type)
+	switch (type)
 	{
 	case EBML_UINT:
 		rc = ebml_read_uint(context, size, cur_dest);
diff --git a/vod/mkv/ebml.h b/vod/mkv/ebml.h
index 907d9ad4..8f0f2020 100644
--- a/vod/mkv/ebml.h
+++ b/vod/mkv/ebml.h
@@ -16,6 +16,9 @@ typedef enum {
 	EBML_BINARY,
 	EBML_MASTER,
 	EBML_CUSTOM,
+
+	EBML_TYPE_MASK = 0x00ffffff,
+	EBML_TRUNCATE = 0x01000000,
 } ebml_type_t;
 
 typedef struct {
@@ -26,7 +29,7 @@ typedef struct {
 
 typedef struct {
 	uint32_t id;
-	ebml_type_t type;
+	uint32_t type;
 	off_t offset;
 	void* child;
 } ebml_spec_t;
diff --git a/vod/mkv/mkv_format.c b/vod/mkv/mkv_format.c
index 032769b4..702eebb9 100644
--- a/vod/mkv/mkv_format.c
+++ b/vod/mkv/mkv_format.c
@@ -144,23 +144,23 @@ static ebml_spec_t mkv_spec_index[] = {
 // cluster
 static ebml_spec_t mkv_spec_cluster_fields[] = {
 	{ MKV_ID_CLUSTERTIMECODE,		EBML_UINT,		offsetof(mkv_cluster_t, timecode),			NULL },
-	{ MKV_ID_SIMPLEBLOCK,			EBML_CUSTOM,	0,											mkv_parse_frame },
+	{ MKV_ID_SIMPLEBLOCK,			EBML_CUSTOM | EBML_TRUNCATE,	0,							mkv_parse_frame },
 	{ 0, EBML_NONE, 0, NULL }
 };
 
 static ebml_spec_t mkv_spec_cluster[] = {
-	{ MKV_ID_CLUSTER,				EBML_MASTER,	0,											mkv_spec_cluster_fields },
+	{ MKV_ID_CLUSTER,				EBML_MASTER | EBML_TRUNCATE,	0,							mkv_spec_cluster_fields },
 	{ 0, EBML_NONE, 0, NULL }
 };
 
 static ebml_spec_t mkv_spec_bitrate_estimate_cluster_fields[] = {
 	{ MKV_ID_CLUSTERTIMECODE,		EBML_UINT,		offsetof(mkv_cluster_t, timecode),			NULL },
-	{ MKV_ID_SIMPLEBLOCK,			EBML_CUSTOM,	0,											mkv_parse_frame_estimate_bitrate },
+	{ MKV_ID_SIMPLEBLOCK,			EBML_CUSTOM | EBML_TRUNCATE,	0,							mkv_parse_frame_estimate_bitrate },
 	{ 0, EBML_NONE, 0, NULL }
 };
 
 static ebml_spec_t mkv_spec_bitrate_estimate_cluster[] = {
-	{ MKV_ID_CLUSTER,				EBML_MASTER,	0,											mkv_spec_bitrate_estimate_cluster_fields },
+	{ MKV_ID_CLUSTER,				EBML_MASTER | EBML_TRUNCATE,	0,							mkv_spec_bitrate_estimate_cluster_fields },
 	{ 0, EBML_NONE, 0, NULL }
 };